fonts: use only free fonts

Change-Id: If62e2a30814a0325faff414be99af9772a464489

CNAME

@@ -1 +1 @@
-gopl.io
+www.gopl.io

README.md

@@ -1,21 +1,4 @@
-# The Go Programming Language
 
-This repository provides the downloadable example programs
+This branch holds the source for the http://www.gopl.io website.
-for the book, "The Go Programming Language"; see http://www.gopl.io.
-
-These example programs are licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.<br/>
-<a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png"/></a>
-
-You can download, build, and run the programs with the following commands:
-
-	$ export GOPATH=$HOME/gobook            # choose workspace directory
-	$ go get gopl.io/ch1/helloworld         # fetch, build, install
-	$ $GOPATH/bin/helloworld                # run
-	Hello, 世界
-
-Many of the programs contain comments of the form `//!+` and `//!-`.
-These comments bracket the parts of the programs that are excerpted in the
-book; you can safely ignore them.  In a few cases, programs
-have been reformatted in an unnatural way so that they can be presented
-in stages in the book.
 
+This entire repo is public, so don't check in anything sensitive.

ch1/dup1/main.go

@@ -1,31 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 8.
-//!+
-
-// Dup1 prints the text of each line that appears more than
-// once in the standard input, preceded by its count.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
-func main() {
-	counts := make(map[string]int)
-	input := bufio.NewScanner(os.Stdin)
-	for input.Scan() {
-		counts[input.Text()]++
-	}
-	// NOTE: ignoring potential errors from input.Err()
-	for line, n := range counts {
-		if n > 1 {
-			fmt.Printf("%d\t%s\n", n, line)
-		}
-	}
-}
-
-//!-

ch1/dup2/main.go

@@ -1,48 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 10.
-//!+
-
-// Dup2 prints the count and text of lines that appear more than once
-// in the input.  It reads from stdin or from a list of named files.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
-func main() {
-	counts := make(map[string]int)
-	files := os.Args[1:]
-	if len(files) == 0 {
-		countLines(os.Stdin, counts)
-	} else {
-		for _, arg := range files {
-			f, err := os.Open(arg)
-			if err != nil {
-				fmt.Fprintf(os.Stderr, "dup2: %v\n", err)
-				continue
-			}
-			countLines(f, counts)
-			f.Close()
-		}
-	}
-	for line, n := range counts {
-		if n > 1 {
-			fmt.Printf("%d\t%s\n", n, line)
-		}
-	}
-}
-
-func countLines(f *os.File, counts map[string]int) {
-	input := bufio.NewScanner(f)
-	for input.Scan() {
-		counts[input.Text()]++
-	}
-	// NOTE: ignoring potential errors from input.Err()
-}
-
-//!-

ch1/dup3/main.go

@@ -1,38 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 12.
-
-//!+
-
-// Dup3 prints the count and text of lines that
-// appear more than once in the named input files.
-package main
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"strings"
-)
-
-func main() {
-	counts := make(map[string]int)
-	for _, filename := range os.Args[1:] {
-		data, err := ioutil.ReadFile(filename)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "dup3: %v\n", err)
-			continue
-		}
-		for _, line := range strings.Split(string(data), "\n") {
-			counts[line]++
-		}
-	}
-	for line, n := range counts {
-		if n > 1 {
-			fmt.Printf("%d\t%s\n", n, line)
-		}
-	}
-}
-
-//!-

ch1/echo1/main.go

@@ -1,24 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 4.
-//!+
-
-// Echo1 prints its command-line arguments.
-package main
-
-import (
-	"fmt"
-	"os"
-)
-
-func main() {
-	var s, sep string
-	for i := 1; i < len(os.Args); i++ {
-		s += sep + os.Args[i]
-		sep = " "
-	}
-	fmt.Println(s)
-}
-
-//!-

ch1/echo2/main.go

@@ -1,24 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 6.
-//!+
-
-// Echo2 prints its command-line arguments.
-package main
-
-import (
-	"fmt"
-	"os"
-)
-
-func main() {
-	s, sep := "", ""
-	for _, arg := range os.Args[1:] {
-		s += sep + arg
-		sep = " "
-	}
-	fmt.Println(s)
-}
-
-//!-

ch1/echo3/main.go

@@ -1,20 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 8.
-
-// Echo3 prints its command-line arguments.
-package main
-
-import (
-	"fmt"
-	"os"
-	"strings"
-)
-
-//!+
-func main() {
-	fmt.Println(strings.Join(os.Args[1:], " "))
-}
-
-//!-

ch1/fetch/main.go

@@ -1,34 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 16.
-//!+
-
-// Fetch prints the content found at each specified URL.
-package main
-
-import (
-	"fmt"
-	"io/ioutil"
-	"net/http"
-	"os"
-)
-
-func main() {
-	for _, url := range os.Args[1:] {
-		resp, err := http.Get(url)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "fetch: %v\n", err)
-			os.Exit(1)
-		}
-		b, err := ioutil.ReadAll(resp.Body)
-		resp.Body.Close()
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "fetch: reading %s: %v\n", url, err)
-			os.Exit(1)
-		}
-		fmt.Printf("%s", b)
-	}
-}
-
-//!-

ch1/fetchall/main.go

@@ -1,49 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 17.
-//!+
-
-// Fetchall fetches URLs in parallel and reports their times and sizes.
-package main
-
-import (
-	"fmt"
-	"io"
-	"io/ioutil"
-	"net/http"
-	"os"
-	"time"
-)
-
-func main() {
-	start := time.Now()
-	ch := make(chan string)
-	for _, url := range os.Args[1:] {
-		go fetch(url, ch) // start a goroutine
-	}
-	for range os.Args[1:] {
-		fmt.Println(<-ch) // receive from channel ch
-	}
-	fmt.Printf("%.2fs elapsed\n", time.Since(start).Seconds())
-}
-
-func fetch(url string, ch chan<- string) {
-	start := time.Now()
-	resp, err := http.Get(url)
-	if err != nil {
-		ch <- fmt.Sprint(err) // send to channel ch
-		return
-	}
-
-	nbytes, err := io.Copy(ioutil.Discard, resp.Body)
-	resp.Body.Close() // don't leak resources
-	if err != nil {
-		ch <- fmt.Sprintf("while reading %s: %v", url, err)
-		return
-	}
-	secs := time.Since(start).Seconds()
-	ch <- fmt.Sprintf("%.2fs  %7d  %s", secs, nbytes, url)
-}
-
-//!-

ch1/helloworld/main.go

@@ -1,16 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 1.
-
-// Helloworld is our first Go program.
-//!+
-package main
-
-import "fmt"
-
-func main() {
-	fmt.Println("Hello, 世界")
-}
-
-//!-

ch1/lissajous/main.go

@@ -1,86 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// Run with "web" command-line argument for web server.
-// See page 13.
-//!+main
-
-// Lissajous generates GIF animations of random Lissajous figures.
-package main
-
-import (
-	"image"
-	"image/color"
-	"image/gif"
-	"io"
-	"math"
-	"math/rand"
-	"os"
-)
-
-//!-main
-// Packages not needed by version in book.
-import (
-	"log"
-	"net/http"
-	"time"
-)
-
-//!+main
-
-var palette = []color.Color{color.White, color.Black}
-
-const (
-	whiteIndex = 0 // first color in palette
-	blackIndex = 1 // next color in palette
-)
-
-func main() {
-	//!-main
-	// The sequence of images is deterministic unless we seed
-	// the pseudo-random number generator using the current time.
-	// Thanks to Randall McPherson for pointing out the omission.
-	rand.Seed(time.Now().UTC().UnixNano())
-
-	if len(os.Args) > 1 && os.Args[1] == "web" {
-		//!+http
-		handler := func(w http.ResponseWriter, r *http.Request) {
-			lissajous(w)
-		}
-		http.HandleFunc("/", handler)
-		//!-http
-		log.Fatal(http.ListenAndServe("localhost:8000", nil))
-		return
-	}
-	//!+main
-	lissajous(os.Stdout)
-}
-
-func lissajous(out io.Writer) {
-	const (
-		cycles  = 5     // number of complete x oscillator revolutions
-		res     = 0.001 // angular resolution
-		size    = 100   // image canvas covers [-size..+size]
-		nframes = 64    // number of animation frames
-		delay   = 8     // delay between frames in 10ms units
-	)
-	freq := rand.Float64() * 3.0 // relative frequency of y oscillator
-	anim := gif.GIF{LoopCount: nframes}
-	phase := 0.0 // phase difference
-	for i := 0; i < nframes; i++ {
-		rect := image.Rect(0, 0, 2*size+1, 2*size+1)
-		img := image.NewPaletted(rect, palette)
-		for t := 0.0; t < cycles*2*math.Pi; t += res {
-			x := math.Sin(t)
-			y := math.Sin(t*freq + phase)
-			img.SetColorIndex(size+int(x*size+0.5), size+int(y*size+0.5),
-				blackIndex)
-		}
-		phase += 0.1
-		anim.Delay = append(anim.Delay, delay)
-		anim.Image = append(anim.Image, img)
-	}
-	gif.EncodeAll(out, &anim) // NOTE: ignoring encoding errors
-}
-
-//!-main

ch1/server1/main.go

@@ -1,26 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 19.
-//!+
-
-// Server1 is a minimal "echo" server.
-package main
-
-import (
-	"fmt"
-	"log"
-	"net/http"
-)
-
-func main() {
-	http.HandleFunc("/", handler) // each request calls handler
-	log.Fatal(http.ListenAndServe("localhost:8000", nil))
-}
-
-// handler echoes the Path component of the requested URL.
-func handler(w http.ResponseWriter, r *http.Request) {
-	fmt.Fprintf(w, "URL.Path = %q\n", r.URL.Path)
-}
-
-//!-

ch1/server2/main.go

@@ -1,41 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 20.
-//!+
-
-// Server2 is a minimal "echo" and counter server.
-package main
-
-import (
-	"fmt"
-	"log"
-	"net/http"
-	"sync"
-)
-
-var mu sync.Mutex
-var count int
-
-func main() {
-	http.HandleFunc("/", handler)
-	http.HandleFunc("/count", counter)
-	log.Fatal(http.ListenAndServe("localhost:8000", nil))
-}
-
-// handler echoes the Path component of the requested URL.
-func handler(w http.ResponseWriter, r *http.Request) {
-	mu.Lock()
-	count++
-	mu.Unlock()
-	fmt.Fprintf(w, "URL.Path = %q\n", r.URL.Path)
-}
-
-// counter echoes the number of calls so far.
-func counter(w http.ResponseWriter, r *http.Request) {
-	mu.Lock()
-	fmt.Fprintf(w, "Count %d\n", count)
-	mu.Unlock()
-}
-
-//!-

ch1/server3/main.go

@@ -1,37 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 21.
-
-// Server3 is an "echo" server that displays request parameters.
-package main
-
-import (
-	"fmt"
-	"log"
-	"net/http"
-)
-
-func main() {
-	http.HandleFunc("/", handler)
-	log.Fatal(http.ListenAndServe("localhost:8000", nil))
-}
-
-//!+handler
-// handler echoes the HTTP request.
-func handler(w http.ResponseWriter, r *http.Request) {
-	fmt.Fprintf(w, "%s %s %s\n", r.Method, r.URL, r.Proto)
-	for k, v := range r.Header {
-		fmt.Fprintf(w, "Header[%q] = %q\n", k, v)
-	}
-	fmt.Fprintf(w, "Host = %q\n", r.Host)
-	fmt.Fprintf(w, "RemoteAddr = %q\n", r.RemoteAddr)
-	if err := r.ParseForm(); err != nil {
-		log.Print(err)
-	}
-	for k, v := range r.Form {
-		fmt.Fprintf(w, "Form[%q] = %q\n", k, v)
-	}
-}
-
-//!-handler

ch10/cross/main.go

@@ -1,19 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 295.
-
-// The cross command prints the values of GOOS and GOARCH for this target.
-package main
-
-import (
-	"fmt"
-	"runtime"
-)
-
-//!+
-func main() {
-	fmt.Println(runtime.GOOS, runtime.GOARCH)
-}
-
-//!-

ch10/jpeg/main.go

@@ -1,52 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 287.
-
-//!+main
-
-// The jpeg command reads a PNG image from the standard input
-// and writes it as a JPEG image to the standard output.
-package main
-
-import (
-	"fmt"
-	"image"
-	"image/jpeg"
-	_ "image/png" // register PNG decoder
-	"io"
-	"os"
-)
-
-func main() {
-	if err := toJPEG(os.Stdin, os.Stdout); err != nil {
-		fmt.Fprintf(os.Stderr, "jpeg: %v\n", err)
-		os.Exit(1)
-	}
-}
-
-func toJPEG(in io.Reader, out io.Writer) error {
-	img, kind, err := image.Decode(in)
-	if err != nil {
-		return err
-	}
-	fmt.Fprintln(os.Stderr, "Input format =", kind)
-	return jpeg.Encode(out, img, &jpeg.Options{Quality: 95})
-}
-
-//!-main
-
-/*
-//!+with
-$ go build gopl.io/ch3/mandelbrot
-$ go build gopl.io/ch10/jpeg
-$ ./mandelbrot | ./jpeg >mandelbrot.jpg
-Input format = png
-//!-with
-
-//!+without
-$ go build gopl.io/ch10/jpeg
-$ ./mandelbrot | ./jpeg >mandelbrot.jpg
-jpeg: image: unknown format
-//!-without
-*/

ch11/echo/echo.go

@@ -1,41 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 308.
-//!+
-
-// Echo prints its command-line arguments.
-package main
-
-import (
-	"flag"
-	"fmt"
-	"io"
-	"os"
-	"strings"
-)
-
-var (
-	n = flag.Bool("n", false, "omit trailing newline")
-	s = flag.String("s", " ", "separator")
-)
-
-var out io.Writer = os.Stdout // modified during testing
-
-func main() {
-	flag.Parse()
-	if err := echo(!*n, *s, flag.Args()); err != nil {
-		fmt.Fprintf(os.Stderr, "echo: %v\n", err)
-		os.Exit(1)
-	}
-}
-
-func echo(newline bool, sep string, args []string) error {
-	fmt.Fprint(out, strings.Join(args, sep))
-	if newline {
-		fmt.Fprintln(out)
-	}
-	return nil
-}
-
-//!-

ch11/echo/echo_test.go

@@ -1,45 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// Test of echo command.  Run with: go test gopl.io/ch11/echo
-
-//!+
-package main
-
-import (
-	"bytes"
-	"fmt"
-	"testing"
-)
-
-func TestEcho(t *testing.T) {
-	var tests = []struct {
-		newline bool
-		sep     string
-		args    []string
-		want    string
-	}{
-		{true, "", []string{}, "\n"},
-		{false, "", []string{}, ""},
-		{true, "\t", []string{"one", "two", "three"}, "one\ttwo\tthree\n"},
-		{true, ",", []string{"a", "b", "c"}, "a,b,c\n"},
-		{false, ":", []string{"1", "2", "3"}, "1:2:3"},
-	}
-
-	for _, test := range tests {
-		descr := fmt.Sprintf("echo(%v, %q, %q)",
-			test.newline, test.sep, test.args)
-
-		out = new(bytes.Buffer) // captured output
-		if err := echo(test.newline, test.sep, test.args); err != nil {
-			t.Errorf("%s failed: %v", descr, err)
-			continue
-		}
-		got := out.(*bytes.Buffer).String()
-		if got != test.want {
-			t.Errorf("%s = %q, want %q", descr, got, test.want)
-		}
-	}
-}
-
-//!-

ch11/storage1/storage.go

@@ -1,45 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 311.
-
-// Package storage is part of a hypothetical cloud storage server.
-//!+main
-package storage
-
-import (
-	"fmt"
-	"log"
-	"net/smtp"
-)
-
-var usage = make(map[string]int64)
-
-func bytesInUse(username string) int64 { return usage[username] }
-
-// Email sender configuration.
-// NOTE: never put passwords in source code!
-const sender = "notifications@example.com"
-const password = "correcthorsebatterystaple"
-const hostname = "smtp.example.com"
-
-const template = `Warning: you are using %d bytes of storage,
-%d%% of your quota.`
-
-func CheckQuota(username string) {
-	used := bytesInUse(username)
-	const quota = 1000000000 // 1GB
-	percent := 100 * used / quota
-	if percent < 90 {
-		return // OK
-	}
-	msg := fmt.Sprintf(template, used, percent)
-	auth := smtp.PlainAuth("", sender, password, hostname)
-	err := smtp.SendMail(hostname+":587", auth, sender,
-		[]string{username}, []byte(msg))
-	if err != nil {
-		log.Printf("smtp.SendMail(%s) failed: %s", username, err)
-	}
-}
-
-//!-main

ch11/storage2/quota_test.go

@@ -1,53 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-//!+test
-package storage
-
-import (
-	"strings"
-	"testing"
-)
-
-func TestCheckQuotaNotifiesUser(t *testing.T) {
-	var notifiedUser, notifiedMsg string
-	notifyUser = func(user, msg string) {
-		notifiedUser, notifiedMsg = user, msg
-	}
-
-	const user = "joe@example.org"
-	usage[user] = 980000000 // simulate a 980MB-used condition
-
-	CheckQuota(user)
-	if notifiedUser == "" && notifiedMsg == "" {
-		t.Fatalf("notifyUser not called")
-	}
-	if notifiedUser != user {
-		t.Errorf("wrong user (%s) notified, want %s",
-			notifiedUser, user)
-	}
-	const wantSubstring = "98% of your quota"
-	if !strings.Contains(notifiedMsg, wantSubstring) {
-		t.Errorf("unexpected notification message <<%s>>, "+
-			"want substring %q", notifiedMsg, wantSubstring)
-	}
-}
-
-//!-test
-
-/*
-//!+defer
-func TestCheckQuotaNotifiesUser(t *testing.T) {
-	// Save and restore original notifyUser.
-	saved := notifyUser
-	defer func() { notifyUser = saved }()
-
-	// Install the test's fake notifyUser.
-	var notifiedUser, notifiedMsg string
-	notifyUser = func(user, msg string) {
-		notifiedUser, notifiedMsg = user, msg
-	}
-	// ...rest of test...
-}
-//!-defer
-*/

ch11/storage2/storage.go

@@ -1,49 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 312.
-
-// Package storage is part of a hypothetical cloud storage server.
-package storage
-
-import (
-	"fmt"
-	"log"
-	"net/smtp"
-)
-
-var usage = make(map[string]int64)
-
-func bytesInUse(username string) int64 { return usage[username] }
-
-// E-mail sender configuration.
-// NOTE: never put passwords in source code!
-const sender = "notifications@example.com"
-const password = "correcthorsebatterystaple"
-const hostname = "smtp.example.com"
-
-const template = `Warning: you are using %d bytes of storage,
-%d%% of your quota.`
-
-//!+factored
-var notifyUser = func(username, msg string) {
-	auth := smtp.PlainAuth("", sender, password, hostname)
-	err := smtp.SendMail(hostname+":587", auth, sender,
-		[]string{username}, []byte(msg))
-	if err != nil {
-		log.Printf("smtp.SendMail(%s) failed: %s", username, err)
-	}
-}
-
-func CheckQuota(username string) {
-	used := bytesInUse(username)
-	const quota = 1000000000 // 1GB
-	percent := 100 * used / quota
-	if percent < 90 {
-		return // OK
-	}
-	msg := fmt.Sprintf(template, used, percent)
-	notifyUser(username, msg)
-}
-
-//!-factored

ch11/word1/word.go

@@ -1,21 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 303.
-//!+
-
-// Package word provides utilities for word games.
-package word
-
-// IsPalindrome reports whether s reads the same forward and backward.
-// (Our first attempt.)
-func IsPalindrome(s string) bool {
-	for i := range s {
-		if s[i] != s[len(s)-1-i] {
-			return false
-		}
-	}
-	return true
-}
-
-//!-

ch11/word1/word_test.go

@@ -1,43 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-//!+test
-package word
-
-import "testing"
-
-func TestPalindrome(t *testing.T) {
-	if !IsPalindrome("detartrated") {
-		t.Error(`IsPalindrome("detartrated") = false`)
-	}
-	if !IsPalindrome("kayak") {
-		t.Error(`IsPalindrome("kayak") = false`)
-	}
-}
-
-func TestNonPalindrome(t *testing.T) {
-	if IsPalindrome("palindrome") {
-		t.Error(`IsPalindrome("palindrome") = true`)
-	}
-}
-
-//!-test
-
-// The tests below are expected to fail.
-// See package gopl.io/ch11/word2 for the fix.
-
-//!+more
-func TestFrenchPalindrome(t *testing.T) {
-	if !IsPalindrome("été") {
-		t.Error(`IsPalindrome("été") = false`)
-	}
-}
-
-func TestCanalPalindrome(t *testing.T) {
-	input := "A man, a plan, a canal: Panama"
-	if !IsPalindrome(input) {
-		t.Errorf(`IsPalindrome(%q) = false`, input)
-	}
-}
-
-//!-more

ch11/word2/word.go

@@ -1,29 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 305.
-//!+
-
-// Package word provides utilities for word games.
-package word
-
-import "unicode"
-
-// IsPalindrome reports whether s reads the same forward and backward.
-// Letter case is ignored, as are non-letters.
-func IsPalindrome(s string) bool {
-	var letters []rune
-	for _, r := range s {
-		if unicode.IsLetter(r) {
-			letters = append(letters, unicode.ToLower(r))
-		}
-	}
-	for i := range letters {
-		if letters[i] != letters[len(letters)-1-i] {
-			return false
-		}
-	}
-	return true
-}
-
-//!-

ch11/word2/word_test.go

@@ -1,148 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package word
-
-import (
-	"fmt"
-	"math/rand"
-	"time"
-)
-
-//!+bench
-
-import "testing"
-
-//!-bench
-
-//!+test
-func TestIsPalindrome(t *testing.T) {
-	var tests = []struct {
-		input string
-		want  bool
-	}{
-		{"", true},
-		{"a", true},
-		{"aa", true},
-		{"ab", false},
-		{"kayak", true},
-		{"detartrated", true},
-		{"A man, a plan, a canal: Panama", true},
-		{"Evil I did dwell; lewd did I live.", true},
-		{"Able was I ere I saw Elba", true},
-		{"été", true},
-		{"Et se resservir, ivresse reste.", true},
-		{"palindrome", false}, // non-palindrome
-		{"desserts", false},   // semi-palindrome
-	}
-	for _, test := range tests {
-		if got := IsPalindrome(test.input); got != test.want {
-			t.Errorf("IsPalindrome(%q) = %v", test.input, got)
-		}
-	}
-}
-
-//!-test
-
-//!+bench
-func BenchmarkIsPalindrome(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		IsPalindrome("A man, a plan, a canal: Panama")
-	}
-}
-
-//!-bench
-
-//!+example
-
-func ExampleIsPalindrome() {
-	fmt.Println(IsPalindrome("A man, a plan, a canal: Panama"))
-	fmt.Println(IsPalindrome("palindrome"))
-	// Output:
-	// true
-	// false
-}
-
-//!-example
-
-/*
-//!+random
-import "math/rand"
-
-//!-random
-*/
-
-//!+random
-// randomPalindrome returns a palindrome whose length and contents
-// are derived from the pseudo-random number generator rng.
-func randomPalindrome(rng *rand.Rand) string {
-	n := rng.Intn(25) // random length up to 24
-	runes := make([]rune, n)
-	for i := 0; i < (n+1)/2; i++ {
-		r := rune(rng.Intn(0x1000)) // random rune up to '\u0999'
-		runes[i] = r
-		runes[n-1-i] = r
-	}
-	return string(runes)
-}
-
-func TestRandomPalindromes(t *testing.T) {
-	// Initialize a pseudo-random number generator.
-	seed := time.Now().UTC().UnixNano()
-	t.Logf("Random seed: %d", seed)
-	rng := rand.New(rand.NewSource(seed))
-
-	for i := 0; i < 1000; i++ {
-		p := randomPalindrome(rng)
-		if !IsPalindrome(p) {
-			t.Errorf("IsPalindrome(%q) = false", p)
-		}
-	}
-}
-
-//!-random
-
-/*
-// Answer for Exercicse 11.1: Modify randomPalindrome to exercise
-// IsPalindrome's handling of punctuation and spaces.
-
-// WARNING: the conversion r -> upper -> lower doesn't preserve
-// the value of r in some cases, e.g., µ Μ, ſ S, ı I
-
-// randomPalindrome returns a palindrome whose length and contents
-// are derived from the pseudo-random number generator rng.
-func randomNoisyPalindrome(rng *rand.Rand) string {
-	n := rng.Intn(25) // random length up to 24
-	runes := make([]rune, n)
-	for i := 0; i < (n+1)/2; i++ {
-		r := rune(rng.Intn(0x200)) // random rune up to \u99
-		runes[i] = r
-		r1 := r
-		if unicode.IsLetter(r) && unicode.IsLower(r) {
-			r = unicode.ToUpper(r)
-			if unicode.ToLower(r) != r1 {
-				fmt.Printf("cap? %c %c\n", r1, r)
-			}
-		}
-		runes[n-1-i] = r
-	}
-	return "?" + string(runes) + "!"
-}
-
-func TestRandomNoisyPalindromes(t *testing.T) {
-	// Initialize a pseudo-random number generator.
-	seed := time.Now().UTC().UnixNano()
-	t.Logf("Random seed: %d", seed)
-	rng := rand.New(rand.NewSource(seed))
-
-	n := 0
-	for i := 0; i < 1000; i++ {
-		p := randomNoisyPalindrome(rng)
-		if !IsPalindrome(p) {
-			t.Errorf("IsNoisyPalindrome(%q) = false", p)
-			n++
-		}
-	}
-	fmt.Fprintf(os.Stderr, "fail = %d\n", n)
-}
-*/

ch12/display/display.go

@@ -1,90 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 333.
-
-// Package display provides a means to display structured data.
-package display
-
-import (
-	"fmt"
-	"reflect"
-	"strconv"
-)
-
-//!+Display
-
-func Display(name string, x interface{}) {
-	fmt.Printf("Display %s (%T):\n", name, x)
-	display(name, reflect.ValueOf(x))
-}
-
-//!-Display
-
-// formatAtom formats a value without inspecting its internal structure.
-// It is a copy of the the function in gopl.io/ch11/format.
-func formatAtom(v reflect.Value) string {
-	switch v.Kind() {
-	case reflect.Invalid:
-		return "invalid"
-	case reflect.Int, reflect.Int8, reflect.Int16,
-		reflect.Int32, reflect.Int64:
-		return strconv.FormatInt(v.Int(), 10)
-	case reflect.Uint, reflect.Uint8, reflect.Uint16,
-		reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		return strconv.FormatUint(v.Uint(), 10)
-	// ...floating-point and complex cases omitted for brevity...
-	case reflect.Bool:
-		if v.Bool() {
-			return "true"
-		}
-		return "false"
-	case reflect.String:
-		return strconv.Quote(v.String())
-	case reflect.Chan, reflect.Func, reflect.Ptr,
-		reflect.Slice, reflect.Map:
-		return v.Type().String() + " 0x" +
-			strconv.FormatUint(uint64(v.Pointer()), 16)
-	default: // reflect.Array, reflect.Struct, reflect.Interface
-		return v.Type().String() + " value"
-	}
-}
-
-//!+display
-func display(path string, v reflect.Value) {
-	switch v.Kind() {
-	case reflect.Invalid:
-		fmt.Printf("%s = invalid\n", path)
-	case reflect.Slice, reflect.Array:
-		for i := 0; i < v.Len(); i++ {
-			display(fmt.Sprintf("%s[%d]", path, i), v.Index(i))
-		}
-	case reflect.Struct:
-		for i := 0; i < v.NumField(); i++ {
-			fieldPath := fmt.Sprintf("%s.%s", path, v.Type().Field(i).Name)
-			display(fieldPath, v.Field(i))
-		}
-	case reflect.Map:
-		for _, key := range v.MapKeys() {
-			display(fmt.Sprintf("%s[%s]", path,
-				formatAtom(key)), v.MapIndex(key))
-		}
-	case reflect.Ptr:
-		if v.IsNil() {
-			fmt.Printf("%s = nil\n", path)
-		} else {
-			display(fmt.Sprintf("(*%s)", path), v.Elem())
-		}
-	case reflect.Interface:
-		if v.IsNil() {
-			fmt.Printf("%s = nil\n", path)
-		} else {
-			fmt.Printf("%s.type = %s\n", path, v.Elem().Type())
-			display(path+".value", v.Elem())
-		}
-	default: // basic types, channels, funcs
-		fmt.Printf("%s = %s\n", path, formatAtom(v))
-	}
-}
-
-//!-display

ch12/display/display_test.go

@@ -1,259 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package display
-
-import (
-	"io"
-	"net"
-	"os"
-	"reflect"
-	"sync"
-	"testing"
-
-	"gopl.io/ch7/eval"
-)
-
-// NOTE: we can't use !+..!- comments to excerpt these tests
-// into the book because it defeats the Example mechanism,
-// which requires the // Output comment to be at the end
-// of the function.
-
-func Example_expr() {
-	e, _ := eval.Parse("sqrt(A / pi)")
-	Display("e", e)
-	// Output:
-	// Display e (eval.call):
-	// e.fn = "sqrt"
-	// e.args[0].type = eval.binary
-	// e.args[0].value.op = 47
-	// e.args[0].value.x.type = eval.Var
-	// e.args[0].value.x.value = "A"
-	// e.args[0].value.y.type = eval.Var
-	// e.args[0].value.y.value = "pi"
-}
-
-func Example_slice() {
-	Display("slice", []*int{new(int), nil})
-	// Output:
-	// Display slice ([]*int):
-	// (*slice[0]) = 0
-	// slice[1] = nil
-}
-
-func Example_nilInterface() {
-	var w io.Writer
-	Display("w", w)
-	// Output:
-	// Display w (<nil>):
-	// w = invalid
-}
-
-func Example_ptrToInterface() {
-	var w io.Writer
-	Display("&w", &w)
-	// Output:
-	// Display &w (*io.Writer):
-	// (*&w) = nil
-}
-
-func Example_struct() {
-	Display("x", struct{ x interface{} }{3})
-	// Output:
-	// Display x (struct { x interface {} }):
-	// x.x.type = int
-	// x.x.value = 3
-}
-
-func Example_interface() {
-	var i interface{} = 3
-	Display("i", i)
-	// Output:
-	// Display i (int):
-	// i = 3
-}
-
-func Example_ptrToInterface2() {
-	var i interface{} = 3
-	Display("&i", &i)
-	// Output:
-	// Display &i (*interface {}):
-	// (*&i).type = int
-	// (*&i).value = 3
-}
-
-func Example_array() {
-	Display("x", [1]interface{}{3})
-	// Output:
-	// Display x ([1]interface {}):
-	// x[0].type = int
-	// x[0].value = 3
-}
-
-func Example_movie() {
-	//!+movie
-	type Movie struct {
-		Title, Subtitle string
-		Year            int
-		Color           bool
-		Actor           map[string]string
-		Oscars          []string
-		Sequel          *string
-	}
-	//!-movie
-	//!+strangelove
-	strangelove := Movie{
-		Title:    "Dr. Strangelove",
-		Subtitle: "How I Learned to Stop Worrying and Love the Bomb",
-		Year:     1964,
-		Color:    false,
-		Actor: map[string]string{
-			"Dr. Strangelove":            "Peter Sellers",
-			"Grp. Capt. Lionel Mandrake": "Peter Sellers",
-			"Pres. Merkin Muffley":       "Peter Sellers",
-			"Gen. Buck Turgidson":        "George C. Scott",
-			"Brig. Gen. Jack D. Ripper":  "Sterling Hayden",
-			`Maj. T.J. "King" Kong`:      "Slim Pickens",
-		},
-
-		Oscars: []string{
-			"Best Actor (Nomin.)",
-			"Best Adapted Screenplay (Nomin.)",
-			"Best Director (Nomin.)",
-			"Best Picture (Nomin.)",
-		},
-	}
-	//!-strangelove
-	Display("strangelove", strangelove)
-
-	// We don't use an Output: comment since displaying
-	// a map is nondeterministic.
-	/*
-		//!+output
-		Display strangelove (display.Movie):
-		strangelove.Title = "Dr. Strangelove"
-		strangelove.Subtitle = "How I Learned to Stop Worrying and Love the Bomb"
-		strangelove.Year = 1964
-		strangelove.Color = false
-		strangelove.Actor["Gen. Buck Turgidson"] = "George C. Scott"
-		strangelove.Actor["Brig. Gen. Jack D. Ripper"] = "Sterling Hayden"
-		strangelove.Actor["Maj. T.J. \"King\" Kong"] = "Slim Pickens"
-		strangelove.Actor["Dr. Strangelove"] = "Peter Sellers"
-		strangelove.Actor["Grp. Capt. Lionel Mandrake"] = "Peter Sellers"
-		strangelove.Actor["Pres. Merkin Muffley"] = "Peter Sellers"
-		strangelove.Oscars[0] = "Best Actor (Nomin.)"
-		strangelove.Oscars[1] = "Best Adapted Screenplay (Nomin.)"
-		strangelove.Oscars[2] = "Best Director (Nomin.)"
-		strangelove.Oscars[3] = "Best Picture (Nomin.)"
-		strangelove.Sequel = nil
-		//!-output
-	*/
-}
-
-// This test ensures that the program terminates without crashing.
-func Test(t *testing.T) {
-	// Some other values (YMMV)
-	Display("os.Stderr", os.Stderr)
-	// Output:
-	// Display os.Stderr (*os.File):
-	// (*(*os.Stderr).file).fd = 2
-	// (*(*os.Stderr).file).name = "/dev/stderr"
-	// (*(*os.Stderr).file).nepipe = 0
-
-	var w io.Writer = os.Stderr
-	Display("&w", &w)
-	// Output:
-	// Display &w (*io.Writer):
-	// (*&w).type = *os.File
-	// (*(*(*&w).value).file).fd = 2
-	// (*(*(*&w).value).file).name = "/dev/stderr"
-	// (*(*(*&w).value).file).nepipe = 0
-
-	var locker sync.Locker = new(sync.Mutex)
-	Display("(&locker)", &locker)
-	// Output:
-	// Display (&locker) (*sync.Locker):
-	// (*(&locker)).type = *sync.Mutex
-	// (*(*(&locker)).value).state = 0
-	// (*(*(&locker)).value).sema = 0
-
-	Display("locker", locker)
-	// Output:
-	// Display locker (*sync.Mutex):
-	// (*locker).state = 0
-	// (*locker).sema = 0
-	// (*(&locker)) = nil
-
-	locker = nil
-	Display("(&locker)", &locker)
-	// Output:
-	// Display (&locker) (*sync.Locker):
-	// (*(&locker)) = nil
-
-	ips, _ := net.LookupHost("golang.org")
-	Display("ips", ips)
-	// Output:
-	// Display ips ([]string):
-	// ips[0] = "173.194.68.141"
-	// ips[1] = "2607:f8b0:400d:c06::8d"
-
-	// Even metarecursion!  (YMMV)
-	Display("rV", reflect.ValueOf(os.Stderr))
-	// Output:
-	// Display rV (reflect.Value):
-	// (*rV.typ).size = 8
-	// (*rV.typ).ptrdata = 8
-	// (*rV.typ).hash = 871609668
-	// (*rV.typ)._ = 0
-	// ...
-
-	// a pointer that points to itself
-	type P *P
-	var p P
-	p = &p
-	if false {
-		Display("p", p)
-		// Output:
-		// Display p (display.P):
-		// ...stuck, no output...
-	}
-
-	// a map that contains itself
-	type M map[string]M
-	m := make(M)
-	m[""] = m
-	if false {
-		Display("m", m)
-		// Output:
-		// Display m (display.M):
-		// ...stuck, no output...
-	}
-
-	// a slice that contains itself
-	type S []S
-	s := make(S, 1)
-	s[0] = s
-	if false {
-		Display("s", s)
-		// Output:
-		// Display s (display.S):
-		// ...stuck, no output...
-	}
-
-	// a linked list that eats its own tail
-	type Cycle struct {
-		Value int
-		Tail  *Cycle
-	}
-	var c Cycle
-	c = Cycle{42, &c}
-	if false {
-		Display("c", c)
-		// Output:
-		// Display c (display.Cycle):
-		// c.Value = 42
-		// (*c.Tail).Value = 42
-		// (*(*c.Tail).Tail).Value = 42
-		// ...ad infinitum...
-	}
-}

ch12/format/format.go

@@ -1,44 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 332.
-
-// Package format provides an Any function that can format any value.
-//!+
-package format
-
-import (
-	"reflect"
-	"strconv"
-)
-
-// Any formats any value as a string.
-func Any(value interface{}) string {
-	return formatAtom(reflect.ValueOf(value))
-}
-
-// formatAtom formats a value without inspecting its internal structure.
-func formatAtom(v reflect.Value) string {
-	switch v.Kind() {
-	case reflect.Invalid:
-		return "invalid"
-	case reflect.Int, reflect.Int8, reflect.Int16,
-		reflect.Int32, reflect.Int64:
-		return strconv.FormatInt(v.Int(), 10)
-	case reflect.Uint, reflect.Uint8, reflect.Uint16,
-		reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		return strconv.FormatUint(v.Uint(), 10)
-	// ...floating-point and complex cases omitted for brevity...
-	case reflect.Bool:
-		return strconv.FormatBool(v.Bool())
-	case reflect.String:
-		return strconv.Quote(v.String())
-	case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Slice, reflect.Map:
-		return v.Type().String() + " 0x" +
-			strconv.FormatUint(uint64(v.Pointer()), 16)
-	default: // reflect.Array, reflect.Struct, reflect.Interface
-		return v.Type().String() + " value"
-	}
-}
-
-//!-

ch12/format/format_test.go

@@ -1,24 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package format_test
-
-import (
-	"fmt"
-	"testing"
-	"time"
-
-	"gopl.io/ch12/format"
-)
-
-func Test(t *testing.T) {
-	// The pointer values are just examples, and may vary from run to run.
-	//!+time
-	var x int64 = 1
-	var d time.Duration = 1 * time.Nanosecond
-	fmt.Println(format.Any(x))                  // "1"
-	fmt.Println(format.Any(d))                  // "1"
-	fmt.Println(format.Any([]int64{x}))         // "[]int64 0x8202b87b0"
-	fmt.Println(format.Any([]time.Duration{d})) // "[]time.Duration 0x8202b87e0"
-	//!-time
-}

ch12/methods/methods.go

@@ -1,29 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 351.
-
-// Package methods provides a function to print the methods of any value.
-package methods
-
-import (
-	"fmt"
-	"reflect"
-	"strings"
-)
-
-//!+print
-// Print prints the method set of the value x.
-func Print(x interface{}) {
-	v := reflect.ValueOf(x)
-	t := v.Type()
-	fmt.Printf("type %s\n", t)
-
-	for i := 0; i < v.NumMethod(); i++ {
-		methType := v.Method(i).Type()
-		fmt.Printf("func (%s) %s%s\n", t, t.Method(i).Name,
-			strings.TrimPrefix(methType.String(), "func"))
-	}
-}
-
-//!-print

ch12/methods/methods_test.go

@@ -1,49 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package methods_test
-
-import (
-	"strings"
-	"time"
-
-	"gopl.io/ch12/methods"
-)
-
-func ExamplePrintDuration() {
-	methods.Print(time.Hour)
-	// Output:
-	// type time.Duration
-	// func (time.Duration) Hours() float64
-	// func (time.Duration) Minutes() float64
-	// func (time.Duration) Nanoseconds() int64
-	// func (time.Duration) Seconds() float64
-	// func (time.Duration) String() string
-}
-
-func ExamplePrintReplacer() {
-	methods.Print(new(strings.Replacer))
-	// Output:
-	// type *strings.Replacer
-	// func (*strings.Replacer) Replace(string) string
-	// func (*strings.Replacer) WriteString(io.Writer, string) (int, error)
-}
-
-/*
-//!+output
-methods.Print(time.Hour)
-// Output:
-// type time.Duration
-// func (time.Duration) Hours() float64
-// func (time.Duration) Minutes() float64
-// func (time.Duration) Nanoseconds() int64
-// func (time.Duration) Seconds() float64
-// func (time.Duration) String() string
-
-methods.Print(new(strings.Replacer))
-// Output:
-// type *strings.Replacer
-// func (*strings.Replacer) Replace(string) string
-// func (*strings.Replacer) WriteString(io.Writer, string) (int, error)
-//!-output
-*/

ch12/params/params.go

@@ -1,90 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 349.
-
-// Package params provides a reflection-based parser for URL parameters.
-package params
-
-import (
-	"fmt"
-	"net/http"
-	"reflect"
-	"strconv"
-	"strings"
-)
-
-//!+Unpack
-
-// Unpack populates the fields of the struct pointed to by ptr
-// from the HTTP request parameters in req.
-func Unpack(req *http.Request, ptr interface{}) error {
-	if err := req.ParseForm(); err != nil {
-		return err
-	}
-
-	// Build map of fields keyed by effective name.
-	fields := make(map[string]reflect.Value)
-	v := reflect.ValueOf(ptr).Elem() // the struct variable
-	for i := 0; i < v.NumField(); i++ {
-		fieldInfo := v.Type().Field(i) // a reflect.StructField
-		tag := fieldInfo.Tag           // a reflect.StructTag
-		name := tag.Get("http")
-		if name == "" {
-			name = strings.ToLower(fieldInfo.Name)
-		}
-		fields[name] = v.Field(i)
-	}
-
-	// Update struct field for each parameter in the request.
-	for name, values := range req.Form {
-		f := fields[name]
-		if !f.IsValid() {
-			continue // ignore unrecognized HTTP parameters
-		}
-		for _, value := range values {
-			if f.Kind() == reflect.Slice {
-				elem := reflect.New(f.Type().Elem()).Elem()
-				if err := populate(elem, value); err != nil {
-					return fmt.Errorf("%s: %v", name, err)
-				}
-				f.Set(reflect.Append(f, elem))
-			} else {
-				if err := populate(f, value); err != nil {
-					return fmt.Errorf("%s: %v", name, err)
-				}
-			}
-		}
-	}
-	return nil
-}
-
-//!-Unpack
-
-//!+populate
-func populate(v reflect.Value, value string) error {
-	switch v.Kind() {
-	case reflect.String:
-		v.SetString(value)
-
-	case reflect.Int:
-		i, err := strconv.ParseInt(value, 10, 64)
-		if err != nil {
-			return err
-		}
-		v.SetInt(i)
-
-	case reflect.Bool:
-		b, err := strconv.ParseBool(value)
-		if err != nil {
-			return err
-		}
-		v.SetBool(b)
-
-	default:
-		return fmt.Errorf("unsupported kind %s", v.Type())
-	}
-	return nil
-}
-
-//!-populate

ch12/search/main.go

@@ -1,60 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 348.
-
-// Search is a demo of the params.Unpack function.
-package main
-
-import (
-	"fmt"
-	"log"
-	"net/http"
-)
-
-//!+
-
-import "gopl.io/ch12/params"
-
-// search implements the /search URL endpoint.
-func search(resp http.ResponseWriter, req *http.Request) {
-	var data struct {
-		Labels     []string `http:"l"`
-		MaxResults int      `http:"max"`
-		Exact      bool     `http:"x"`
-	}
-	data.MaxResults = 10 // set default
-	if err := params.Unpack(req, &data); err != nil {
-		http.Error(resp, err.Error(), http.StatusBadRequest) // 400
-		return
-	}
-
-	// ...rest of handler...
-	fmt.Fprintf(resp, "Search: %+v\n", data)
-}
-
-//!-
-
-func main() {
-	http.HandleFunc("/search", search)
-	log.Fatal(http.ListenAndServe(":12345", nil))
-}
-
-/*
-//!+output
-$ go build gopl.io/ch12/search
-$ ./search &
-$ ./fetch 'http://localhost:12345/search'
-Search: {Labels:[] MaxResults:10 Exact:false}
-$ ./fetch 'http://localhost:12345/search?l=golang&l=programming'
-Search: {Labels:[golang programming] MaxResults:10 Exact:false}
-$ ./fetch 'http://localhost:12345/search?l=golang&l=programming&max=100'
-Search: {Labels:[golang programming] MaxResults:100 Exact:false}
-$ ./fetch 'http://localhost:12345/search?x=true&l=golang&l=programming'
-Search: {Labels:[golang programming] MaxResults:10 Exact:true}
-$ ./fetch 'http://localhost:12345/search?q=hello&x=123'
-x: strconv.ParseBool: parsing "123": invalid syntax
-$ ./fetch 'http://localhost:12345/search?q=hello&max=lots'
-max: strconv.ParseInt: parsing "lots": invalid syntax
-//!-output
-*/

ch12/sexpr/decode.go

@@ -1,162 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 344.
-
-// Package sexpr provides a means for converting Go objects to and
-// from S-expressions.
-package sexpr
-
-import (
-	"bytes"
-	"fmt"
-	"reflect"
-	"strconv"
-	"text/scanner"
-)
-
-//!+Unmarshal
-// Unmarshal parses S-expression data and populates the variable
-// whose address is in the non-nil pointer out.
-func Unmarshal(data []byte, out interface{}) (err error) {
-	lex := &lexer{scan: scanner.Scanner{Mode: scanner.GoTokens}}
-	lex.scan.Init(bytes.NewReader(data))
-	lex.next() // get the first token
-	defer func() {
-		// NOTE: this is not an example of ideal error handling.
-		if x := recover(); x != nil {
-			err = fmt.Errorf("error at %s: %v", lex.scan.Position, x)
-		}
-	}()
-	read(lex, reflect.ValueOf(out).Elem())
-	return nil
-}
-
-//!-Unmarshal
-
-//!+lexer
-type lexer struct {
-	scan  scanner.Scanner
-	token rune // the current token
-}
-
-func (lex *lexer) next()        { lex.token = lex.scan.Scan() }
-func (lex *lexer) text() string { return lex.scan.TokenText() }
-
-func (lex *lexer) consume(want rune) {
-	if lex.token != want { // NOTE: Not an example of good error handling.
-		panic(fmt.Sprintf("got %q, want %q", lex.text(), want))
-	}
-	lex.next()
-}
-
-//!-lexer
-
-// The read function is a decoder for a small subset of well-formed
-// S-expressions.  For brevity of our example, it takes many dubious
-// shortcuts.
-//
-// The parser assumes
-// - that the S-expression input is well-formed; it does no error checking.
-// - that the S-expression input corresponds to the type of the variable.
-// - that all numbers in the input are non-negative decimal integers.
-// - that all keys in ((key value) ...) struct syntax are unquoted symbols.
-// - that the input does not contain dotted lists such as (1 2 . 3).
-// - that the input does not contain Lisp reader macros such 'x and #'x.
-//
-// The reflection logic assumes
-// - that v is always a variable of the appropriate type for the
-//   S-expression value.  For example, v must not be a boolean,
-//   interface, channel, or function, and if v is an array, the input
-//   must have the correct number of elements.
-// - that v in the top-level call to read has the zero value of its
-//   type and doesn't need clearing.
-// - that if v is a numeric variable, it is a signed integer.
-
-//!+read
-func read(lex *lexer, v reflect.Value) {
-	switch lex.token {
-	case scanner.Ident:
-		// The only valid identifiers are
-		// "nil" and struct field names.
-		if lex.text() == "nil" {
-			v.Set(reflect.Zero(v.Type()))
-			lex.next()
-			return
-		}
-	case scanner.String:
-		s, _ := strconv.Unquote(lex.text()) // NOTE: ignoring errors
-		v.SetString(s)
-		lex.next()
-		return
-	case scanner.Int:
-		i, _ := strconv.Atoi(lex.text()) // NOTE: ignoring errors
-		v.SetInt(int64(i))
-		lex.next()
-		return
-	case '(':
-		lex.next()
-		readList(lex, v)
-		lex.next() // consume ')'
-		return
-	}
-	panic(fmt.Sprintf("unexpected token %q", lex.text()))
-}
-
-//!-read
-
-//!+readlist
-func readList(lex *lexer, v reflect.Value) {
-	switch v.Kind() {
-	case reflect.Array: // (item ...)
-		for i := 0; !endList(lex); i++ {
-			read(lex, v.Index(i))
-		}
-
-	case reflect.Slice: // (item ...)
-		for !endList(lex) {
-			item := reflect.New(v.Type().Elem()).Elem()
-			read(lex, item)
-			v.Set(reflect.Append(v, item))
-		}
-
-	case reflect.Struct: // ((name value) ...)
-		for !endList(lex) {
-			lex.consume('(')
-			if lex.token != scanner.Ident {
-				panic(fmt.Sprintf("got token %q, want field name", lex.text()))
-			}
-			name := lex.text()
-			lex.next()
-			read(lex, v.FieldByName(name))
-			lex.consume(')')
-		}
-
-	case reflect.Map: // ((key value) ...)
-		v.Set(reflect.MakeMap(v.Type()))
-		for !endList(lex) {
-			lex.consume('(')
-			key := reflect.New(v.Type().Key()).Elem()
-			read(lex, key)
-			value := reflect.New(v.Type().Elem()).Elem()
-			read(lex, value)
-			v.SetMapIndex(key, value)
-			lex.consume(')')
-		}
-
-	default:
-		panic(fmt.Sprintf("cannot decode list into %v", v.Type()))
-	}
-}
-
-func endList(lex *lexer) bool {
-	switch lex.token {
-	case scanner.EOF:
-		panic("end of file")
-	case ')':
-		return true
-	}
-	return false
-}
-
-//!-readlist

ch12/sexpr/encode.go

@@ -1,97 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 339.
-
-package sexpr
-
-import (
-	"bytes"
-	"fmt"
-	"reflect"
-)
-
-//!+Marshal
-// Marshal encodes a Go value in S-expression form.
-func Marshal(v interface{}) ([]byte, error) {
-	var buf bytes.Buffer
-	if err := encode(&buf, reflect.ValueOf(v)); err != nil {
-		return nil, err
-	}
-	return buf.Bytes(), nil
-}
-
-//!-Marshal
-
-// encode writes to buf an S-expression representation of v.
-//!+encode
-func encode(buf *bytes.Buffer, v reflect.Value) error {
-	switch v.Kind() {
-	case reflect.Invalid:
-		buf.WriteString("nil")
-
-	case reflect.Int, reflect.Int8, reflect.Int16,
-		reflect.Int32, reflect.Int64:
-		fmt.Fprintf(buf, "%d", v.Int())
-
-	case reflect.Uint, reflect.Uint8, reflect.Uint16,
-		reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		fmt.Fprintf(buf, "%d", v.Uint())
-
-	case reflect.String:
-		fmt.Fprintf(buf, "%q", v.String())
-
-	case reflect.Ptr:
-		return encode(buf, v.Elem())
-
-	case reflect.Array, reflect.Slice: // (value ...)
-		buf.WriteByte('(')
-		for i := 0; i < v.Len(); i++ {
-			if i > 0 {
-				buf.WriteByte(' ')
-			}
-			if err := encode(buf, v.Index(i)); err != nil {
-				return err
-			}
-		}
-		buf.WriteByte(')')
-
-	case reflect.Struct: // ((name value) ...)
-		buf.WriteByte('(')
-		for i := 0; i < v.NumField(); i++ {
-			if i > 0 {
-				buf.WriteByte(' ')
-			}
-			fmt.Fprintf(buf, "(%s ", v.Type().Field(i).Name)
-			if err := encode(buf, v.Field(i)); err != nil {
-				return err
-			}
-			buf.WriteByte(')')
-		}
-		buf.WriteByte(')')
-
-	case reflect.Map: // ((key value) ...)
-		buf.WriteByte('(')
-		for i, key := range v.MapKeys() {
-			if i > 0 {
-				buf.WriteByte(' ')
-			}
-			buf.WriteByte('(')
-			if err := encode(buf, key); err != nil {
-				return err
-			}
-			buf.WriteByte(' ')
-			if err := encode(buf, v.MapIndex(key)); err != nil {
-				return err
-			}
-			buf.WriteByte(')')
-		}
-		buf.WriteByte(')')
-
-	default: // float, complex, bool, chan, func, interface
-		return fmt.Errorf("unsupported type: %s", v.Type())
-	}
-	return nil
-}
-
-//!-encode

ch12/sexpr/pretty.go

@@ -1,183 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package sexpr
-
-// This file implements the algorithm described in Derek C. Oppen's
-// 1979 Stanford technical report, "Pretty Printing".
-
-import (
-	"bytes"
-	"fmt"
-	"reflect"
-)
-
-func MarshalIndent(v interface{}) ([]byte, error) {
-	p := printer{width: margin}
-	if err := pretty(&p, reflect.ValueOf(v)); err != nil {
-		return nil, err
-	}
-	return p.Bytes(), nil
-}
-
-const margin = 80
-
-type token struct {
-	kind rune // one of "s ()" (string, blank, start, end)
-	str  string
-	size int
-}
-
-type printer struct {
-	tokens []*token // FIFO buffer
-	stack  []*token // stack of open ' ' and '(' tokens
-	rtotal int      // total number of spaces needed to print stream
-
-	bytes.Buffer
-	indents []int
-	width   int // remaining space
-}
-
-func (p *printer) string(str string) {
-	tok := &token{kind: 's', str: str, size: len(str)}
-	if len(p.stack) == 0 {
-		p.print(tok)
-	} else {
-		p.tokens = append(p.tokens, tok)
-		p.rtotal += len(str)
-	}
-}
-func (p *printer) pop() (top *token) {
-	last := len(p.stack) - 1
-	top, p.stack = p.stack[last], p.stack[:last]
-	return
-}
-func (p *printer) begin() {
-	if len(p.stack) == 0 {
-		p.rtotal = 1
-	}
-	t := &token{kind: '(', size: -p.rtotal}
-	p.tokens = append(p.tokens, t)
-	p.stack = append(p.stack, t) // push
-	p.string("(")
-}
-func (p *printer) end() {
-	p.string(")")
-	p.tokens = append(p.tokens, &token{kind: ')'})
-	x := p.pop()
-	x.size += p.rtotal
-	if x.kind == ' ' {
-		p.pop().size += p.rtotal
-	}
-	if len(p.stack) == 0 {
-		for _, tok := range p.tokens {
-			p.print(tok)
-		}
-		p.tokens = nil
-	}
-}
-func (p *printer) space() {
-	last := len(p.stack) - 1
-	x := p.stack[last]
-	if x.kind == ' ' {
-		x.size += p.rtotal
-		p.stack = p.stack[:last] // pop
-	}
-	t := &token{kind: ' ', size: -p.rtotal}
-	p.tokens = append(p.tokens, t)
-	p.stack = append(p.stack, t)
-	p.rtotal++
-}
-func (p *printer) print(t *token) {
-	switch t.kind {
-	case 's':
-		p.WriteString(t.str)
-		p.width -= len(t.str)
-	case '(':
-		p.indents = append(p.indents, p.width)
-	case ')':
-		p.indents = p.indents[:len(p.indents)-1] // pop
-	case ' ':
-		if t.size > p.width {
-			p.width = p.indents[len(p.indents)-1] - 1
-			fmt.Fprintf(&p.Buffer, "\n%*s", margin-p.width, "")
-		} else {
-			p.WriteByte(' ')
-			p.width--
-		}
-	}
-}
-func (p *printer) stringf(format string, args ...interface{}) {
-	p.string(fmt.Sprintf(format, args...))
-}
-
-func pretty(p *printer, v reflect.Value) error {
-	switch v.Kind() {
-	case reflect.Invalid:
-		p.string("nil")
-
-	case reflect.Int, reflect.Int8, reflect.Int16,
-		reflect.Int32, reflect.Int64:
-		p.stringf("%d", v.Int())
-
-	case reflect.Uint, reflect.Uint8, reflect.Uint16,
-		reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		p.stringf("%d", v.Uint())
-
-	case reflect.String:
-		p.stringf("%q", v.String())
-
-	case reflect.Array, reflect.Slice: // (value ...)
-		p.begin()
-		for i := 0; i < v.Len(); i++ {
-			if i > 0 {
-				p.space()
-			}
-			if err := pretty(p, v.Index(i)); err != nil {
-				return err
-			}
-		}
-		p.end()
-
-	case reflect.Struct: // ((name value ...)
-		p.begin()
-		for i := 0; i < v.NumField(); i++ {
-			if i > 0 {
-				p.space()
-			}
-			p.begin()
-			p.string(v.Type().Field(i).Name)
-			p.space()
-			if err := pretty(p, v.Field(i)); err != nil {
-				return err
-			}
-			p.end()
-		}
-		p.end()
-
-	case reflect.Map: // ((key value ...)
-		p.begin()
-		for i, key := range v.MapKeys() {
-			if i > 0 {
-				p.space()
-			}
-			p.begin()
-			if err := pretty(p, key); err != nil {
-				return err
-			}
-			p.space()
-			if err := pretty(p, v.MapIndex(key)); err != nil {
-				return err
-			}
-			p.end()
-		}
-		p.end()
-
-	case reflect.Ptr:
-		return pretty(p, v.Elem())
-
-	default: // float, complex, bool, chan, func, interface
-		return fmt.Errorf("unsupported type: %s", v.Type())
-	}
-	return nil
-}

ch12/sexpr/sexpr_test.go

@@ -1,74 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package sexpr
-
-import (
-	"reflect"
-	"testing"
-)
-
-// Test verifies that encoding and decoding a complex data value
-// produces an equal result.
-//
-// The test does not make direct assertions about the encoded output
-// because the output depends on map iteration order, which is
-// nondeterministic.  The output of the t.Log statements can be
-// inspected by running the test with the -v flag:
-//
-// 	$ go test -v gopl.io/ch12/sexpr
-//
-func Test(t *testing.T) {
-	type Movie struct {
-		Title, Subtitle string
-		Year            int
-		Actor           map[string]string
-		Oscars          []string
-		Sequel          *string
-	}
-	strangelove := Movie{
-		Title:    "Dr. Strangelove",
-		Subtitle: "How I Learned to Stop Worrying and Love the Bomb",
-		Year:     1964,
-		Actor: map[string]string{
-			"Dr. Strangelove":            "Peter Sellers",
-			"Grp. Capt. Lionel Mandrake": "Peter Sellers",
-			"Pres. Merkin Muffley":       "Peter Sellers",
-			"Gen. Buck Turgidson":        "George C. Scott",
-			"Brig. Gen. Jack D. Ripper":  "Sterling Hayden",
-			`Maj. T.J. "King" Kong`:      "Slim Pickens",
-		},
-		Oscars: []string{
-			"Best Actor (Nomin.)",
-			"Best Adapted Screenplay (Nomin.)",
-			"Best Director (Nomin.)",
-			"Best Picture (Nomin.)",
-		},
-	}
-
-	// Encode it
-	data, err := Marshal(strangelove)
-	if err != nil {
-		t.Fatalf("Marshal failed: %v", err)
-	}
-	t.Logf("Marshal() = %s\n", data)
-
-	// Decode it
-	var movie Movie
-	if err := Unmarshal(data, &movie); err != nil {
-		t.Fatalf("Unmarshal failed: %v", err)
-	}
-	t.Logf("Unmarshal() = %+v\n", movie)
-
-	// Check equality.
-	if !reflect.DeepEqual(movie, strangelove) {
-		t.Fatal("not equal")
-	}
-
-	// Pretty-print it:
-	data, err = MarshalIndent(strangelove)
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Logf("MarshalIdent() = %s\n", data)
-}

ch13/bzip-print/bzip2.c

@@ -1,28 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 362.
-// This is the version that appears in print,
-// but it does not comply with the proposed
-// rules for passing pointers between Go and C.
-// (https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md)
-// See gopl.io/ch13/bzip for an updated version.
-
-//!+
-/* This file is gopl.io/ch13/bzip/bzip2.c,         */
-/* a simple wrapper for libbzip2 suitable for cgo. */
-#include <bzlib.h>
-
-int bz2compress(bz_stream *s, int action,
-                char *in, unsigned *inlen, char *out, unsigned *outlen) {
-  s->next_in = in;
-  s->avail_in = *inlen;
-  s->next_out = out;
-  s->avail_out = *outlen;
-  int r = BZ2_bzCompress(s, action);
-  *inlen -= s->avail_in;
-  *outlen -= s->avail_out;
-  return r;
-}
-
-//!-

ch13/bzip-print/bzip2.go

@@ -1,96 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 362.
-// This is the version that appears in print,
-// but it does not comply with the proposed
-// rules for passing pointers between Go and C.
-// (https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md)
-// See gopl.io/ch13/bzip for an updated version.
-//!+
-
-// Package bzip provides a writer that uses bzip2 compression (bzip.org).
-package bzip
-
-/*
-#cgo CFLAGS: -I/usr/include
-#cgo LDFLAGS: -L/usr/lib -lbz2
-#include <bzlib.h>
-int bz2compress(bz_stream *s, int action,
-                char *in, unsigned *inlen, char *out, unsigned *outlen);
-*/
-import "C"
-
-import (
-	"io"
-	"unsafe"
-)
-
-type writer struct {
-	w      io.Writer // underlying output stream
-	stream *C.bz_stream
-	outbuf [64 * 1024]byte
-}
-
-// NewWriter returns a writer for bzip2-compressed streams.
-func NewWriter(out io.Writer) io.WriteCloser {
-	const (
-		blockSize  = 9
-		verbosity  = 0
-		workFactor = 30
-	)
-	w := &writer{w: out, stream: new(C.bz_stream)}
-	C.BZ2_bzCompressInit(w.stream, blockSize, verbosity, workFactor)
-	return w
-}
-
-//!-
-
-//!+write
-func (w *writer) Write(data []byte) (int, error) {
-	if w.stream == nil {
-		panic("closed")
-	}
-	var total int // uncompressed bytes written
-
-	for len(data) > 0 {
-		inlen, outlen := C.uint(len(data)), C.uint(cap(w.outbuf))
-		C.bz2compress(w.stream, C.BZ_RUN,
-			(*C.char)(unsafe.Pointer(&data[0])), &inlen,
-			(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
-		total += int(inlen)
-		data = data[inlen:]
-		if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
-			return total, err
-		}
-	}
-	return total, nil
-}
-
-//!-write
-
-//!+close
-// Close flushes the compressed data and closes the stream.
-// It does not close the underlying io.Writer.
-func (w *writer) Close() error {
-	if w.stream == nil {
-		panic("closed")
-	}
-	defer func() {
-		C.BZ2_bzCompressEnd(w.stream)
-		w.stream = nil
-	}()
-	for {
-		inlen, outlen := C.uint(0), C.uint(cap(w.outbuf))
-		r := C.bz2compress(w.stream, C.BZ_FINISH, nil, &inlen,
-			(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
-		if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
-			return err
-		}
-		if r == C.BZ_STREAM_END {
-			return nil
-		}
-	}
-}
-
-//!-close

ch13/bzip-print/bzip2_test.go

@@ -1,40 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package bzip_test
-
-import (
-	"bytes"
-	"compress/bzip2" // reader
-	"io"
-	"testing"
-
-	"gopl.io/ch13/bzip" // writer
-)
-
-func TestBzip2(t *testing.T) {
-	var compressed, uncompressed bytes.Buffer
-	w := bzip.NewWriter(&compressed)
-
-	// Write a repetitive message in a million pieces,
-	// compressing one copy but not the other.
-	tee := io.MultiWriter(w, &uncompressed)
-	for i := 0; i < 1000000; i++ {
-		io.WriteString(tee, "hello")
-	}
-	if err := w.Close(); err != nil {
-		t.Fatal(err)
-	}
-
-	// Check the size of the compressed stream.
-	if got, want := compressed.Len(), 255; got != want {
-		t.Errorf("1 million hellos compressed to %d bytes, want %d", got, want)
-	}
-
-	// Decompress and compare with original.
-	var decompressed bytes.Buffer
-	io.Copy(&decompressed, bzip2.NewReader(&compressed))
-	if !bytes.Equal(uncompressed.Bytes(), decompressed.Bytes()) {
-		t.Error("decompression yielded a different message")
-	}
-}

ch13/bzip/bzip2.c

@@ -1,32 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 362.
-//
-// The version of this program that appeared in the first and second
-// printings did not comply with the proposed rules for passing
-// pointers between Go and C, described here:
-// https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md
-//
-// The version below, which appears in the third printing,
-// has been corrected.  See bzip2.go for explanation.
-
-//!+
-/* This file is gopl.io/ch13/bzip/bzip2.c,         */
-/* a simple wrapper for libbzip2 suitable for cgo. */
-#include <bzlib.h>
-
-int bz2compress(bz_stream *s, int action,
-                char *in, unsigned *inlen, char *out, unsigned *outlen) {
-  s->next_in = in;
-  s->avail_in = *inlen;
-  s->next_out = out;
-  s->avail_out = *outlen;
-  int r = BZ2_bzCompress(s, action);
-  *inlen -= s->avail_in;
-  *outlen -= s->avail_out;
-  s->next_in = s->next_out = NULL;
-  return r;
-}
-
-//!-

ch13/bzip/bzip2.go

@@ -1,111 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 362.
-//
-// The version of this program that appeared in the first and second
-// printings did not comply with the proposed rules for passing
-// pointers between Go and C, described here:
-// https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md
-//
-// The rules forbid a C function like bz2compress from storing 'in'
-// and 'out' (pointers to variables allocated by Go) into the Go
-// variable 's', even temporarily.
-//
-// The version below, which appears in the third printing, has been
-// corrected.  To comply with the rules, the bz_stream variable must
-// be allocated by C code.  We have introduced two C functions,
-// bz2alloc and bz2free, to allocate and free instances of the
-// bz_stream type.  Also, we have changed bz2compress so that before
-// it returns, it clears the fields of the bz_stream that contain
-// pointers to Go variables.
-
-//!+
-
-// Package bzip provides a writer that uses bzip2 compression (bzip.org).
-package bzip
-
-/*
-#cgo CFLAGS: -I/usr/include
-#cgo LDFLAGS: -L/usr/lib -lbz2
-#include <bzlib.h>
-#include <stdlib.h>
-bz_stream* bz2alloc() { return calloc(1, sizeof(bz_stream)); }
-int bz2compress(bz_stream *s, int action,
-                char *in, unsigned *inlen, char *out, unsigned *outlen);
-void bz2free(bz_stream* s) { free(s); }
-*/
-import "C"
-
-import (
-	"io"
-	"unsafe"
-)
-
-type writer struct {
-	w      io.Writer // underlying output stream
-	stream *C.bz_stream
-	outbuf [64 * 1024]byte
-}
-
-// NewWriter returns a writer for bzip2-compressed streams.
-func NewWriter(out io.Writer) io.WriteCloser {
-	const blockSize = 9
-	const verbosity = 0
-	const workFactor = 30
-	w := &writer{w: out, stream: C.bz2alloc()}
-	C.BZ2_bzCompressInit(w.stream, blockSize, verbosity, workFactor)
-	return w
-}
-
-//!-
-
-//!+write
-func (w *writer) Write(data []byte) (int, error) {
-	if w.stream == nil {
-		panic("closed")
-	}
-	var total int // uncompressed bytes written
-
-	for len(data) > 0 {
-		inlen, outlen := C.uint(len(data)), C.uint(cap(w.outbuf))
-		C.bz2compress(w.stream, C.BZ_RUN,
-			(*C.char)(unsafe.Pointer(&data[0])), &inlen,
-			(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
-		total += int(inlen)
-		data = data[inlen:]
-		if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
-			return total, err
-		}
-	}
-	return total, nil
-}
-
-//!-write
-
-//!+close
-// Close flushes the compressed data and closes the stream.
-// It does not close the underlying io.Writer.
-func (w *writer) Close() error {
-	if w.stream == nil {
-		panic("closed")
-	}
-	defer func() {
-		C.BZ2_bzCompressEnd(w.stream)
-		C.bz2free(w.stream)
-		w.stream = nil
-	}()
-	for {
-		inlen, outlen := C.uint(0), C.uint(cap(w.outbuf))
-		r := C.bz2compress(w.stream, C.BZ_FINISH, nil, &inlen,
-			(*C.char)(unsafe.Pointer(&w.outbuf)), &outlen)
-		if _, err := w.w.Write(w.outbuf[:outlen]); err != nil {
-			return err
-		}
-		if r == C.BZ_STREAM_END {
-			return nil
-		}
-	}
-}
-
-//!-close

ch13/bzip/bzip2_test.go

@@ -1,40 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package bzip_test
-
-import (
-	"bytes"
-	"compress/bzip2" // reader
-	"io"
-	"testing"
-
-	"gopl.io/ch13/bzip" // writer
-)
-
-func TestBzip2(t *testing.T) {
-	var compressed, uncompressed bytes.Buffer
-	w := bzip.NewWriter(&compressed)
-
-	// Write a repetitive message in a million pieces,
-	// compressing one copy but not the other.
-	tee := io.MultiWriter(w, &uncompressed)
-	for i := 0; i < 1000000; i++ {
-		io.WriteString(tee, "hello")
-	}
-	if err := w.Close(); err != nil {
-		t.Fatal(err)
-	}
-
-	// Check the size of the compressed stream.
-	if got, want := compressed.Len(), 255; got != want {
-		t.Errorf("1 million hellos compressed to %d bytes, want %d", got, want)
-	}
-
-	// Decompress and compare with original.
-	var decompressed bytes.Buffer
-	io.Copy(&decompressed, bzip2.NewReader(&compressed))
-	if !bytes.Equal(uncompressed.Bytes(), decompressed.Bytes()) {
-		t.Error("decompression yielded a different message")
-	}
-}

ch13/bzipper/main.go

@@ -1,29 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 365.
-
-//!+
-
-// Bzipper reads input, bzip2-compresses it, and writes it out.
-package main
-
-import (
-	"io"
-	"log"
-	"os"
-
-	"gopl.io/ch13/bzip"
-)
-
-func main() {
-	w := bzip.NewWriter(os.Stdout)
-	if _, err := io.Copy(w, os.Stdin); err != nil {
-		log.Fatalf("bzipper: %v\n", err)
-	}
-	if err := w.Close(); err != nil {
-		log.Fatalf("bzipper: close: %v\n", err)
-	}
-}
-
-//!-

ch13/equal/equal.go

@@ -1,127 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 359.
-
-// Package equal provides a deep equivalence relation for arbitrary values.
-package equal
-
-import (
-	"reflect"
-	"unsafe"
-)
-
-//!+
-func equal(x, y reflect.Value, seen map[comparison]bool) bool {
-	if !x.IsValid() || !y.IsValid() {
-		return x.IsValid() == y.IsValid()
-	}
-	if x.Type() != y.Type() {
-		return false
-	}
-
-	// ...cycle check omitted (shown later)...
-
-	//!-
-	//!+cyclecheck
-	// cycle check
-	if x.CanAddr() && y.CanAddr() {
-		xptr := unsafe.Pointer(x.UnsafeAddr())
-		yptr := unsafe.Pointer(y.UnsafeAddr())
-		if xptr == yptr {
-			return true // identical references
-		}
-		c := comparison{xptr, yptr, x.Type()}
-		if seen[c] {
-			return true // already seen
-		}
-		seen[c] = true
-	}
-	//!-cyclecheck
-	//!+
-	switch x.Kind() {
-	case reflect.Bool:
-		return x.Bool() == y.Bool()
-
-	case reflect.String:
-		return x.String() == y.String()
-
-	// ...numeric cases omitted for brevity...
-
-	//!-
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
-		reflect.Int64:
-		return x.Int() == y.Int()
-
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
-		reflect.Uint64, reflect.Uintptr:
-		return x.Uint() == y.Uint()
-
-	case reflect.Float32, reflect.Float64:
-		return x.Float() == y.Float()
-
-	case reflect.Complex64, reflect.Complex128:
-		return x.Complex() == y.Complex()
-	//!+
-	case reflect.Chan, reflect.UnsafePointer, reflect.Func:
-		return x.Pointer() == y.Pointer()
-
-	case reflect.Ptr, reflect.Interface:
-		return equal(x.Elem(), y.Elem(), seen)
-
-	case reflect.Array, reflect.Slice:
-		if x.Len() != y.Len() {
-			return false
-		}
-		for i := 0; i < x.Len(); i++ {
-			if !equal(x.Index(i), y.Index(i), seen) {
-				return false
-			}
-		}
-		return true
-
-	// ...struct and map cases omitted for brevity...
-	//!-
-	case reflect.Struct:
-		for i, n := 0, x.NumField(); i < n; i++ {
-			if !equal(x.Field(i), y.Field(i), seen) {
-				return false
-			}
-		}
-		return true
-
-	case reflect.Map:
-		if x.Len() != y.Len() {
-			return false
-		}
-		for _, k := range x.MapKeys() {
-			if !equal(x.MapIndex(k), y.MapIndex(k), seen) {
-				return false
-			}
-		}
-		return true
-		//!+
-	}
-	panic("unreachable")
-}
-
-//!-
-
-//!+comparison
-// Equal reports whether x and y are deeply equal.
-//!-comparison
-//
-// Map keys are always compared with ==, not deeply.
-// (This matters for keys containing pointers or interfaces.)
-//!+comparison
-func Equal(x, y interface{}) bool {
-	seen := make(map[comparison]bool)
-	return equal(reflect.ValueOf(x), reflect.ValueOf(y), seen)
-}
-
-type comparison struct {
-	x, y unsafe.Pointer
-	t    reflect.Type
-}
-
-//!-comparison

ch13/equal/equal_test.go

@@ -1,133 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package equal
-
-import (
-	"bytes"
-	"fmt"
-	"testing"
-)
-
-func TestEqual(t *testing.T) {
-	one, oneAgain, two := 1, 1, 2
-
-	type CyclePtr *CyclePtr
-	var cyclePtr1, cyclePtr2 CyclePtr
-	cyclePtr1 = &cyclePtr1
-	cyclePtr2 = &cyclePtr2
-
-	type CycleSlice []CycleSlice
-	var cycleSlice = make(CycleSlice, 1)
-	cycleSlice[0] = cycleSlice
-
-	ch1, ch2 := make(chan int), make(chan int)
-	var ch1ro <-chan int = ch1
-
-	type mystring string
-
-	var iface1, iface1Again, iface2 interface{} = &one, &oneAgain, &two
-
-	for _, test := range []struct {
-		x, y interface{}
-		want bool
-	}{
-		// basic types
-		{1, 1, true},
-		{1, 2, false},   // different values
-		{1, 1.0, false}, // different types
-		{"foo", "foo", true},
-		{"foo", "bar", false},
-		{mystring("foo"), "foo", false}, // different types
-		// slices
-		{[]string{"foo"}, []string{"foo"}, true},
-		{[]string{"foo"}, []string{"bar"}, false},
-		{[]string{}, []string(nil), true},
-		// slice cycles
-		{cycleSlice, cycleSlice, true},
-		// maps
-		{
-			map[string][]int{"foo": {1, 2, 3}},
-			map[string][]int{"foo": {1, 2, 3}},
-			true,
-		},
-		{
-			map[string][]int{"foo": {1, 2, 3}},
-			map[string][]int{"foo": {1, 2, 3, 4}},
-			false,
-		},
-		{
-			map[string][]int{},
-			map[string][]int(nil),
-			true,
-		},
-		// pointers
-		{&one, &one, true},
-		{&one, &two, false},
-		{&one, &oneAgain, true},
-		{new(bytes.Buffer), new(bytes.Buffer), true},
-		// pointer cycles
-		{cyclePtr1, cyclePtr1, true},
-		{cyclePtr2, cyclePtr2, true},
-		{cyclePtr1, cyclePtr2, true}, // they're deeply equal
-		// functions
-		{(func())(nil), (func())(nil), true},
-		{(func())(nil), func() {}, false},
-		{func() {}, func() {}, false},
-		// arrays
-		{[...]int{1, 2, 3}, [...]int{1, 2, 3}, true},
-		{[...]int{1, 2, 3}, [...]int{1, 2, 4}, false},
-		// channels
-		{ch1, ch1, true},
-		{ch1, ch2, false},
-		{ch1ro, ch1, false}, // NOTE: not equal
-		// interfaces
-		{&iface1, &iface1, true},
-		{&iface1, &iface2, false},
-		{&iface1Again, &iface1, true},
-	} {
-		if Equal(test.x, test.y) != test.want {
-			t.Errorf("Equal(%v, %v) = %t",
-				test.x, test.y, !test.want)
-		}
-	}
-}
-
-func Example_equal() {
-	//!+
-	fmt.Println(Equal([]int{1, 2, 3}, []int{1, 2, 3}))        // "true"
-	fmt.Println(Equal([]string{"foo"}, []string{"bar"}))      // "false"
-	fmt.Println(Equal([]string(nil), []string{}))             // "true"
-	fmt.Println(Equal(map[string]int(nil), map[string]int{})) // "true"
-	//!-
-
-	// Output:
-	// true
-	// false
-	// true
-	// true
-}
-
-func Example_equalCycle() {
-	//!+cycle
-	// Circular linked lists a -> b -> a and c -> c.
-	type link struct {
-		value string
-		tail  *link
-	}
-	a, b, c := &link{value: "a"}, &link{value: "b"}, &link{value: "c"}
-	a.tail, b.tail, c.tail = b, a, c
-	fmt.Println(Equal(a, a)) // "true"
-	fmt.Println(Equal(b, b)) // "true"
-	fmt.Println(Equal(c, c)) // "true"
-	fmt.Println(Equal(a, b)) // "false"
-	fmt.Println(Equal(a, c)) // "false"
-	//!-cycle
-
-	// Output:
-	// true
-	// true
-	// true
-	// false
-	// false
-}

ch13/unsafeptr/main.go

@@ -1,38 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 357.
-
-// Package unsafeptr demonstrates basic use of unsafe.Pointer.
-package main
-
-import (
-	"fmt"
-	"unsafe"
-)
-
-func main() {
-	//!+main
-	var x struct {
-		a bool
-		b int16
-		c []int
-	}
-
-	// equivalent to pb := &x.b
-	pb := (*int16)(unsafe.Pointer(
-		uintptr(unsafe.Pointer(&x)) + unsafe.Offsetof(x.b)))
-	*pb = 42
-
-	fmt.Println(x.b) // "42"
-	//!-main
-}
-
-/*
-//!+wrong
-	// NOTE: subtly incorrect!
-	tmp := uintptr(unsafe.Pointer(&x)) + unsafe.Offsetof(x.b)
-	pb := (*int16)(unsafe.Pointer(tmp))
-	*pb = 42
-//!-wrong
-*/

ch2/boiling/main.go

@@ -1,22 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 29.
-//!+
-
-// Boiling prints the boiling point of water.
-package main
-
-import "fmt"
-
-const boilingF = 212.0
-
-func main() {
-	var f = boilingF
-	var c = (f - 32) * 5 / 9
-	fmt.Printf("boiling point = %g°F or %g°C\n", f, c)
-	// Output:
-	// boiling point = 212°F or 100°C
-}
-
-//!-

ch2/cf/main.go

@@ -1,32 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 43.
-//!+
-
-// Cf converts its numeric argument to Celsius and Fahrenheit.
-package main
-
-import (
-	"fmt"
-	"os"
-	"strconv"
-
-	"gopl.io/ch2/tempconv"
-)
-
-func main() {
-	for _, arg := range os.Args[1:] {
-		t, err := strconv.ParseFloat(arg, 64)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "cf: %v\n", err)
-			os.Exit(1)
-		}
-		f := tempconv.Fahrenheit(t)
-		c := tempconv.Celsius(t)
-		fmt.Printf("%s = %s, %s = %s\n",
-			f, tempconv.FToC(f), c, tempconv.CToF(c))
-	}
-}
-
-//!-

ch2/echo4/main.go

@@ -1,27 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 33.
-//!+
-
-// Echo4 prints its command-line arguments.
-package main
-
-import (
-	"flag"
-	"fmt"
-	"strings"
-)
-
-var n = flag.Bool("n", false, "omit trailing newline")
-var sep = flag.String("s", " ", "separator")
-
-func main() {
-	flag.Parse()
-	fmt.Print(strings.Join(flag.Args(), *sep))
-	if !*n {
-		fmt.Println()
-	}
-}
-
-//!-

ch2/ftoc/main.go

@@ -1,22 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 29.
-//!+
-
-// Ftoc prints two Fahrenheit-to-Celsius conversions.
-package main
-
-import "fmt"
-
-func main() {
-	const freezingF, boilingF = 32.0, 212.0
-	fmt.Printf("%g°F = %g°C\n", freezingF, fToC(freezingF)) // "32°F = 0°C"
-	fmt.Printf("%g°F = %g°C\n", boilingF, fToC(boilingF))   // "212°F = 100°C"
-}
-
-func fToC(f float64) float64 {
-	return (f - 32) * 5 / 9
-}
-
-//!-

ch2/popcount/main.go

@@ -1,31 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 45.
-
-// (Package doc comment intentionally malformed to demonstrate golint.)
-//!+
-package popcount
-
-// pc[i] is the population count of i.
-var pc [256]byte
-
-func init() {
-	for i := range pc {
-		pc[i] = pc[i/2] + byte(i&1)
-	}
-}
-
-// PopCount returns the population count (number of set bits) of x.
-func PopCount(x uint64) int {
-	return int(pc[byte(x>>(0*8))] +
-		pc[byte(x>>(1*8))] +
-		pc[byte(x>>(2*8))] +
-		pc[byte(x>>(3*8))] +
-		pc[byte(x>>(4*8))] +
-		pc[byte(x>>(5*8))] +
-		pc[byte(x>>(6*8))] +
-		pc[byte(x>>(7*8))])
-}
-
-//!-

ch2/popcount/popcount_test.go

@@ -1,89 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package popcount_test
-
-import (
-	"testing"
-
-	"gopl.io/ch2/popcount"
-)
-
-// -- Alternative implementations --
-
-func BitCount(x uint64) int {
-	// Hacker's Delight, Figure 5-2.
-	x = x - ((x >> 1) & 0x5555555555555555)
-	x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333)
-	x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f
-	x = x + (x >> 8)
-	x = x + (x >> 16)
-	x = x + (x >> 32)
-	return int(x & 0x7f)
-}
-
-func PopCountByClearing(x uint64) int {
-	n := 0
-	for x != 0 {
-		x = x & (x - 1) // clear rightmost non-zero bit
-		n++
-	}
-	return n
-}
-
-func PopCountByShifting(x uint64) int {
-	n := 0
-	for i := uint(0); i < 64; i++ {
-		if x&(1<<i) != 0 {
-			n++
-		}
-	}
-	return n
-}
-
-// -- Benchmarks --
-
-func BenchmarkPopCount(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		popcount.PopCount(0x1234567890ABCDEF)
-	}
-}
-
-func BenchmarkBitCount(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		BitCount(0x1234567890ABCDEF)
-	}
-}
-
-func BenchmarkPopCountByClearing(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		PopCountByClearing(0x1234567890ABCDEF)
-	}
-}
-
-func BenchmarkPopCountByShifting(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		PopCountByShifting(0x1234567890ABCDEF)
-	}
-}
-
-// Go 1.6, 2.67GHz Xeon
-// $ go test -cpu=4 -bench=. gopl.io/ch2/popcount
-// BenchmarkPopCount-4                  200000000         6.30 ns/op
-// BenchmarkBitCount-4                  300000000         4.15 ns/op
-// BenchmarkPopCountByClearing-4        30000000         45.2 ns/op
-// BenchmarkPopCountByShifting-4        10000000        153 ns/op
-//
-// Go 1.6, 2.5GHz Intel Core i5
-// $ go test -cpu=4 -bench=. gopl.io/ch2/popcount
-// BenchmarkPopCount-4                  200000000         7.52 ns/op
-// BenchmarkBitCount-4                  500000000         3.36 ns/op
-// BenchmarkPopCountByClearing-4        50000000         34.3 ns/op
-// BenchmarkPopCountByShifting-4        20000000        108 ns/op
-//
-// Go 1.7, 3.5GHz Xeon
-// $ go test -cpu=4 -bench=. gopl.io/ch2/popcount
-// BenchmarkPopCount-12                 2000000000        0.28 ns/op
-// BenchmarkBitCount-12                 2000000000        0.27 ns/op
-// BenchmarkPopCountByClearing-12       100000000        18.5 ns/op
-// BenchmarkPopCountByShifting-12       20000000         70.1 ns/op

ch2/tempconv/conv.go

@@ -1,16 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 41.
-
-//!+
-
-package tempconv
-
-// CToF converts a Celsius temperature to Fahrenheit.
-func CToF(c Celsius) Fahrenheit { return Fahrenheit(c*9/5 + 32) }
-
-// FToC converts a Fahrenheit temperature to Celsius.
-func FToC(f Fahrenheit) Celsius { return Celsius((f - 32) * 5 / 9) }
-
-//!-

ch2/tempconv/tempconv.go

@@ -1,23 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-//!+
-
-// Package tempconv performs Celsius and Fahrenheit conversions.
-package tempconv
-
-import "fmt"
-
-type Celsius float64
-type Fahrenheit float64
-
-const (
-	AbsoluteZeroC Celsius = -273.15
-	FreezingC     Celsius = 0
-	BoilingC      Celsius = 100
-)
-
-func (c Celsius) String() string    { return fmt.Sprintf("%g°C", c) }
-func (f Fahrenheit) String() string { return fmt.Sprintf("%g°F", f) }
-
-//!-

ch2/tempconv0/celsius.go

@@ -1,27 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 39.
-//!+
-
-// Package tempconv performs Celsius and Fahrenheit temperature computations.
-package tempconv
-
-import "fmt"
-
-type Celsius float64
-type Fahrenheit float64
-
-const (
-	AbsoluteZeroC Celsius = -273.15
-	FreezingC     Celsius = 0
-	BoilingC      Celsius = 100
-)
-
-func CToF(c Celsius) Fahrenheit { return Fahrenheit(c*9/5 + 32) }
-
-func FToC(f Fahrenheit) Celsius { return Celsius((f - 32) * 5 / 9) }
-
-//!-
-
-func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }

ch2/tempconv0/tempconv_test.go

@@ -1,45 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package tempconv
-
-import "fmt"
-
-func Example_one() {
-	{
-		//!+arith
-		fmt.Printf("%g\n", BoilingC-FreezingC) // "100" °C
-		boilingF := CToF(BoilingC)
-		fmt.Printf("%g\n", boilingF-CToF(FreezingC)) // "180" °F
-		//!-arith
-	}
-	/*
-		//!+arith
-		fmt.Printf("%g\n", boilingF-FreezingC)       // compile error: type mismatch
-		//!-arith
-	*/
-
-	// Output:
-	// 100
-	// 180
-}
-
-func Example_two() {
-	//!+printf
-	c := FToC(212.0)
-	fmt.Println(c.String()) // "100°C"
-	fmt.Printf("%v\n", c)   // "100°C"; no need to call String explicitly
-	fmt.Printf("%s\n", c)   // "100°C"
-	fmt.Println(c)          // "100°C"
-	fmt.Printf("%g\n", c)   // "100"; does not call String
-	fmt.Println(float64(c)) // "100"; does not call String
-	//!-printf
-
-	// Output:
-	// 100°C
-	// 100°C
-	// 100°C
-	// 100°C
-	// 100
-	// 100
-}

ch3/basename1/main.go

@@ -1,44 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 72.
-
-// Basename1 reads file names from stdin and prints the base name of each one.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
-func main() {
-	input := bufio.NewScanner(os.Stdin)
-	for input.Scan() {
-		fmt.Println(basename(input.Text()))
-	}
-	// NOTE: ignoring potential errors from input.Err()
-}
-
-//!+
-// basename removes directory components and a .suffix.
-// e.g., a => a, a.go => a, a/b/c.go => c, a/b.c.go => b.c
-func basename(s string) string {
-	// Discard last '/' and everything before.
-	for i := len(s) - 1; i >= 0; i-- {
-		if s[i] == '/' {
-			s = s[i+1:]
-			break
-		}
-	}
-	// Preserve everything before last '.'.
-	for i := len(s) - 1; i >= 0; i-- {
-		if s[i] == '.' {
-			s = s[:i]
-			break
-		}
-	}
-	return s
-}
-
-//!-

ch3/basename2/main.go

@@ -1,36 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 72.
-
-// Basename2 reads file names from stdin and prints the base name of each one.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-	"strings"
-)
-
-func main() {
-	input := bufio.NewScanner(os.Stdin)
-	for input.Scan() {
-		fmt.Println(basename(input.Text()))
-	}
-	// NOTE: ignoring potential errors from input.Err()
-}
-
-// basename removes directory components and a trailing .suffix.
-// e.g., a => a, a.go => a, a/b/c.go => c, a/b.c.go => b.c
-//!+
-func basename(s string) string {
-	slash := strings.LastIndex(s, "/") // -1 if "/" not found
-	s = s[slash+1:]
-	if dot := strings.LastIndex(s, "."); dot >= 0 {
-		s = s[:dot]
-	}
-	return s
-}
-
-//!-

ch3/comma/main.go

@@ -1,40 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 73.
-
-// Comma prints its argument numbers with a comma at each power of 1000.
-//
-// Example:
-// 	$ go build gopl.io/ch3/comma
-//	$ ./comma 1 12 123 1234 1234567890
-// 	1
-// 	12
-// 	123
-// 	1,234
-// 	1,234,567,890
-//
-package main
-
-import (
-	"fmt"
-	"os"
-)
-
-func main() {
-	for i := 1; i < len(os.Args); i++ {
-		fmt.Printf("  %s\n", comma(os.Args[i]))
-	}
-}
-
-//!+
-// comma inserts commas in a non-negative decimal integer string.
-func comma(s string) string {
-	n := len(s)
-	if n <= 3 {
-		return s
-	}
-	return comma(s[:n-3]) + "," + s[n-3:]
-}
-
-//!-

ch3/mandelbrot/main.go

@@ -1,84 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 61.
-//!+
-
-// Mandelbrot emits a PNG image of the Mandelbrot fractal.
-package main
-
-import (
-	"image"
-	"image/color"
-	"image/png"
-	"math/cmplx"
-	"os"
-)
-
-func main() {
-	const (
-		xmin, ymin, xmax, ymax = -2, -2, +2, +2
-		width, height          = 1024, 1024
-	)
-
-	img := image.NewRGBA(image.Rect(0, 0, width, height))
-	for py := 0; py < height; py++ {
-		y := float64(py)/height*(ymax-ymin) + ymin
-		for px := 0; px < width; px++ {
-			x := float64(px)/width*(xmax-xmin) + xmin
-			z := complex(x, y)
-			// Image point (px, py) represents complex value z.
-			img.Set(px, py, mandelbrot(z))
-		}
-	}
-	png.Encode(os.Stdout, img) // NOTE: ignoring errors
-}
-
-func mandelbrot(z complex128) color.Color {
-	const iterations = 200
-	const contrast = 15
-
-	var v complex128
-	for n := uint8(0); n < iterations; n++ {
-		v = v*v + z
-		if cmplx.Abs(v) > 2 {
-			return color.Gray{255 - contrast*n}
-		}
-	}
-	return color.Black
-}
-
-//!-
-
-// Some other interesting functions:
-
-func acos(z complex128) color.Color {
-	v := cmplx.Acos(z)
-	blue := uint8(real(v)*128) + 127
-	red := uint8(imag(v)*128) + 127
-	return color.YCbCr{192, blue, red}
-}
-
-func sqrt(z complex128) color.Color {
-	v := cmplx.Sqrt(z)
-	blue := uint8(real(v)*128) + 127
-	red := uint8(imag(v)*128) + 127
-	return color.YCbCr{128, blue, red}
-}
-
-// f(x) = x^4 - 1
-//
-// z' = z - f(z)/f'(z)
-//    = z - (z^4 - 1) / (4 * z^3)
-//    = z - (z - 1/z^3) / 4
-func newton(z complex128) color.Color {
-	const iterations = 37
-	const contrast = 7
-	for i := uint8(0); i < iterations; i++ {
-		z -= (z - 1/(z*z*z)) / 4
-		if cmplx.Abs(z*z*z*z-1) < 1e-6 {
-			return color.Gray{255 - contrast*i}
-		}
-	}
-	return color.Black
-}

ch3/netflag/netflag.go

@@ -1,30 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 77.
-
-// Netflag demonstrates an integer type used as a bit field.
-package main
-
-import (
-	"fmt"
-	. "net"
-)
-
-//!+
-func IsUp(v Flags) bool     { return v&FlagUp == FlagUp }
-func TurnDown(v *Flags)     { *v &^= FlagUp }
-func SetBroadcast(v *Flags) { *v |= FlagBroadcast }
-func IsCast(v Flags) bool   { return v&(FlagBroadcast|FlagMulticast) != 0 }
-
-func main() {
-	var v Flags = FlagMulticast | FlagUp
-	fmt.Printf("%b %t\n", v, IsUp(v)) // "10001 true"
-	TurnDown(&v)
-	fmt.Printf("%b %t\n", v, IsUp(v)) // "10000 false"
-	SetBroadcast(&v)
-	fmt.Printf("%b %t\n", v, IsUp(v))   // "10010 false"
-	fmt.Printf("%b %t\n", v, IsCast(v)) // "10010 true"
-}
-
-//!-

ch3/printints/main.go

@@ -1,33 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 74.
-
-// Printints demonstrates the use of bytes.Buffer to format a string.
-package main
-
-import (
-	"bytes"
-	"fmt"
-)
-
-//!+
-// intsToString is like fmt.Sprint(values) but adds commas.
-func intsToString(values []int) string {
-	var buf bytes.Buffer
-	buf.WriteByte('[')
-	for i, v := range values {
-		if i > 0 {
-			buf.WriteString(", ")
-		}
-		fmt.Fprintf(&buf, "%d", v)
-	}
-	buf.WriteByte(']')
-	return buf.String()
-}
-
-func main() {
-	fmt.Println(intsToString([]int{1, 2, 3})) // "[1, 2, 3]"
-}
-
-//!-

ch3/surface/main.go

@@ -1,62 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 58.
-//!+
-
-// Surface computes an SVG rendering of a 3-D surface function.
-package main
-
-import (
-	"fmt"
-	"math"
-)
-
-const (
-	width, height = 600, 320            // canvas size in pixels
-	cells         = 100                 // number of grid cells
-	xyrange       = 30.0                // axis ranges (-xyrange..+xyrange)
-	xyscale       = width / 2 / xyrange // pixels per x or y unit
-	zscale        = height * 0.4        // pixels per z unit
-	angle         = math.Pi / 6         // angle of x, y axes (=30°)
-)
-
-var sin30, cos30 = math.Sin(angle), math.Cos(angle) // sin(30°), cos(30°)
-
-func main() {
-	fmt.Printf("<svg xmlns='http://www.w3.org/2000/svg' "+
-		"style='stroke: grey; fill: white; stroke-width: 0.7' "+
-		"width='%d' height='%d'>", width, height)
-	for i := 0; i < cells; i++ {
-		for j := 0; j < cells; j++ {
-			ax, ay := corner(i+1, j)
-			bx, by := corner(i, j)
-			cx, cy := corner(i, j+1)
-			dx, dy := corner(i+1, j+1)
-			fmt.Printf("<polygon points='%g,%g %g,%g %g,%g %g,%g'/>\n",
-				ax, ay, bx, by, cx, cy, dx, dy)
-		}
-	}
-	fmt.Println("</svg>")
-}
-
-func corner(i, j int) (float64, float64) {
-	// Find point (x,y) at corner of cell (i,j).
-	x := xyrange * (float64(i)/cells - 0.5)
-	y := xyrange * (float64(j)/cells - 0.5)
-
-	// Compute surface height z.
-	z := f(x, y)
-
-	// Project (x,y,z) isometrically onto 2-D SVG canvas (sx,sy).
-	sx := width/2 + (x-y)*cos30*xyscale
-	sy := height/2 + (x+y)*sin30*xyscale - z*zscale
-	return sx, sy
-}
-
-func f(x, y float64) float64 {
-	r := math.Hypot(x, y) // distance from (0,0)
-	return math.Sin(r) / r
-}
-
-//!-

ch4/append/main.go

@@ -1,79 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 88.
-
-// Append illustrates the behavior of the built-in append function.
-package main
-
-import "fmt"
-
-func appendslice(x []int, y ...int) []int {
-	var z []int
-	zlen := len(x) + len(y)
-	if zlen <= cap(x) {
-		// There is room to expand the slice.
-		z = x[:zlen]
-	} else {
-		// There is insufficient space.
-		// Grow by doubling, for amortized linear complexity.
-		zcap := zlen
-		if zcap < 2*len(x) {
-			zcap = 2 * len(x)
-		}
-		z = make([]int, zlen, zcap)
-		copy(z, x)
-	}
-	copy(z[len(x):], y)
-	return z
-}
-
-//!+append
-func appendInt(x []int, y int) []int {
-	var z []int
-	zlen := len(x) + 1
-	if zlen <= cap(x) {
-		// There is room to grow.  Extend the slice.
-		z = x[:zlen]
-	} else {
-		// There is insufficient space.  Allocate a new array.
-		// Grow by doubling, for amortized linear complexity.
-		zcap := zlen
-		if zcap < 2*len(x) {
-			zcap = 2 * len(x)
-		}
-		z = make([]int, zlen, zcap)
-		copy(z, x) // a built-in function; see text
-	}
-	z[len(x)] = y
-	return z
-}
-
-//!-append
-
-//!+growth
-func main() {
-	var x, y []int
-	for i := 0; i < 10; i++ {
-		y = appendInt(x, i)
-		fmt.Printf("%d  cap=%d\t%v\n", i, cap(y), y)
-		x = y
-	}
-}
-
-//!-growth
-
-/*
-//!+output
-0  cap=1   [0]
-1  cap=2   [0 1]
-2  cap=4   [0 1 2]
-3  cap=4   [0 1 2 3]
-4  cap=8   [0 1 2 3 4]
-5  cap=8   [0 1 2 3 4 5]
-6  cap=8   [0 1 2 3 4 5 6]
-7  cap=8   [0 1 2 3 4 5 6 7]
-8  cap=16  [0 1 2 3 4 5 6 7 8]
-9  cap=16  [0 1 2 3 4 5 6 7 8 9]
-//!-output
-*/

ch4/autoescape/main.go

@@ -1,30 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 117.
-
-// Autoescape demonstrates automatic HTML escaping in html/template.
-package main
-
-import (
-	"html/template"
-	"log"
-	"os"
-)
-
-//!+
-func main() {
-	const templ = `<p>A: {{.A}}</p><p>B: {{.B}}</p>`
-	t := template.Must(template.New("escape").Parse(templ))
-	var data struct {
-		A string        // untrusted plain text
-		B template.HTML // trusted HTML
-	}
-	data.A = "<b>Hello!</b>"
-	data.B = "<b>Hello!</b>"
-	if err := t.Execute(os.Stdout, data); err != nil {
-		log.Fatal(err)
-	}
-}
-
-//!-

ch4/charcount/main.go

@@ -1,56 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 97.
-//!+
-
-// Charcount computes counts of Unicode characters.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"io"
-	"os"
-	"unicode"
-	"unicode/utf8"
-)
-
-func main() {
-	counts := make(map[rune]int)    // counts of Unicode characters
-	var utflen [utf8.UTFMax + 1]int // count of lengths of UTF-8 encodings
-	invalid := 0                    // count of invalid UTF-8 characters
-
-	in := bufio.NewReader(os.Stdin)
-	for {
-		r, n, err := in.ReadRune() // returns rune, nbytes, error
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "charcount: %v\n", err)
-			os.Exit(1)
-		}
-		if r == unicode.ReplacementChar && n == 1 {
-			invalid++
-			continue
-		}
-		counts[r]++
-		utflen[n]++
-	}
-	fmt.Printf("rune\tcount\n")
-	for c, n := range counts {
-		fmt.Printf("%q\t%d\n", c, n)
-	}
-	fmt.Print("\nlen\tcount\n")
-	for i, n := range utflen {
-		if i > 0 {
-			fmt.Printf("%d\t%d\n", i, n)
-		}
-	}
-	if invalid > 0 {
-		fmt.Printf("\n%d invalid UTF-8 characters\n", invalid)
-	}
-}
-
-//!-

ch4/dedup/main.go

@@ -1,33 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 96.
-
-// Dedup prints only one instance of each line; duplicates are removed.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
-//!+
-func main() {
-	seen := make(map[string]bool) // a set of strings
-	input := bufio.NewScanner(os.Stdin)
-	for input.Scan() {
-		line := input.Text()
-		if !seen[line] {
-			seen[line] = true
-			fmt.Println(line)
-		}
-	}
-
-	if err := input.Err(); err != nil {
-		fmt.Fprintf(os.Stderr, "dedup: %v\n", err)
-		os.Exit(1)
-	}
-}
-
-//!-

ch4/embed/main.go

@@ -1,46 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 106.
-
-// Embed demonstrates basic struct embedding.
-package main
-
-import "fmt"
-
-type Point struct{ X, Y int }
-
-type Circle struct {
-	Point
-	Radius int
-}
-
-type Wheel struct {
-	Circle
-	Spokes int
-}
-
-func main() {
-	var w Wheel
-	//!+
-	w = Wheel{Circle{Point{8, 8}, 5}, 20}
-
-	w = Wheel{
-		Circle: Circle{
-			Point:  Point{X: 8, Y: 8},
-			Radius: 5,
-		},
-		Spokes: 20, // NOTE: trailing comma necessary here (and at Radius)
-	}
-
-	fmt.Printf("%#v\n", w)
-	// Output:
-	// Wheel{Circle:Circle{Point:Point{X:8, Y:8}, Radius:5}, Spokes:20}
-
-	w.X = 42
-
-	fmt.Printf("%#v\n", w)
-	// Output:
-	// Wheel{Circle:Circle{Point:Point{X:42, Y:8}, Radius:5}, Spokes:20}
-	//!-
-}

ch4/github/github.go

@@ -1,35 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 110.
-//!+
-
-// Package github provides a Go API for the GitHub issue tracker.
-// See https://developer.github.com/v3/search/#search-issues.
-package github
-
-import "time"
-
-const IssuesURL = "https://api.github.com/search/issues"
-
-type IssuesSearchResult struct {
-	TotalCount int `json:"total_count"`
-	Items      []*Issue
-}
-
-type Issue struct {
-	Number    int
-	HTMLURL   string `json:"html_url"`
-	Title     string
-	State     string
-	User      *User
-	CreatedAt time.Time `json:"created_at"`
-	Body      string    // in Markdown format
-}
-
-type User struct {
-	Login   string
-	HTMLURL string `json:"html_url"`
-}
-
-//!-

ch4/github/search.go

@@ -1,53 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-//!+
-
-package github
-
-import (
-	"encoding/json"
-	"fmt"
-	"net/http"
-	"net/url"
-	"strings"
-)
-
-// SearchIssues queries the GitHub issue tracker.
-func SearchIssues(terms []string) (*IssuesSearchResult, error) {
-	q := url.QueryEscape(strings.Join(terms, " "))
-	resp, err := http.Get(IssuesURL + "?q=" + q)
-	if err != nil {
-		return nil, err
-	}
-	//!-
-	// For long-term stability, instead of http.Get, use the
-	// variant below which adds an HTTP request header indicating
-	// that only version 3 of the GitHub API is acceptable.
-	//
-	//   req, err := http.NewRequest("GET", IssuesURL+"?q="+q, nil)
-	//   if err != nil {
-	//       return nil, err
-	//   }
-	//   req.Header.Set(
-	//       "Accept", "application/vnd.github.v3.text-match+json")
-	//   resp, err := http.DefaultClient.Do(req)
-	//!+
-
-	// We must close resp.Body on all execution paths.
-	// (Chapter 5 presents 'defer', which makes this simpler.)
-	if resp.StatusCode != http.StatusOK {
-		resp.Body.Close()
-		return nil, fmt.Errorf("search query failed: %s", resp.Status)
-	}
-
-	var result IssuesSearchResult
-	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
-		resp.Body.Close()
-		return nil, err
-	}
-	resp.Body.Close()
-	return &result, nil
-}
-
-//!-

ch4/graph/main.go

@@ -1,43 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 99.
-
-// Graph shows how to use a map of maps to represent a directed graph.
-package main
-
-import "fmt"
-
-//!+
-var graph = make(map[string]map[string]bool)
-
-func addEdge(from, to string) {
-	edges := graph[from]
-	if edges == nil {
-		edges = make(map[string]bool)
-		graph[from] = edges
-	}
-	edges[to] = true
-}
-
-func hasEdge(from, to string) bool {
-	return graph[from][to]
-}
-
-//!-
-
-func main() {
-	addEdge("a", "b")
-	addEdge("c", "d")
-	addEdge("a", "d")
-	addEdge("d", "a")
-	fmt.Println(hasEdge("a", "b"))
-	fmt.Println(hasEdge("c", "d"))
-	fmt.Println(hasEdge("a", "d"))
-	fmt.Println(hasEdge("d", "a"))
-	fmt.Println(hasEdge("x", "b"))
-	fmt.Println(hasEdge("c", "d"))
-	fmt.Println(hasEdge("x", "d"))
-	fmt.Println(hasEdge("d", "x"))
-
-}

ch4/issues/main.go

@@ -1,52 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 112.
-//!+
-
-// Issues prints a table of GitHub issues matching the search terms.
-package main
-
-import (
-	"fmt"
-	"log"
-	"os"
-
-	"gopl.io/ch4/github"
-)
-
-//!+
-func main() {
-	result, err := github.SearchIssues(os.Args[1:])
-	if err != nil {
-		log.Fatal(err)
-	}
-	fmt.Printf("%d issues:\n", result.TotalCount)
-	for _, item := range result.Items {
-		fmt.Printf("#%-5d %9.9s %.55s\n",
-			item.Number, item.User.Login, item.Title)
-	}
-}
-
-//!-
-
-/*
-//!+textoutput
-$ go build gopl.io/ch4/issues
-$ ./issues repo:golang/go is:open json decoder
-13 issues:
-#5680    eaigner encoding/json: set key converter on en/decoder
-#6050  gopherbot encoding/json: provide tokenizer
-#8658  gopherbot encoding/json: use bufio
-#8462  kortschak encoding/json: UnmarshalText confuses json.Unmarshal
-#5901        rsc encoding/json: allow override type marshaling
-#9812  klauspost encoding/json: string tag not symmetric
-#7872  extempora encoding/json: Encoder internally buffers full output
-#9650    cespare encoding/json: Decoding gives errPhase when unmarshalin
-#6716  gopherbot encoding/json: include field name in unmarshal error me
-#6901  lukescott encoding/json, encoding/xml: option to treat unknown fi
-#6384    joeshaw encoding/json: encode precise floating point integers u
-#6647    btracey x/tools/cmd/godoc: display type kind of each named type
-#4237  gjemiller encoding/base64: URLEncoding padding is optional
-//!-textoutput
-*/

ch4/issueshtml/main.go

@@ -1,52 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 115.
-
-// Issueshtml prints an HTML table of issues matching the search terms.
-package main
-
-import (
-	"log"
-	"os"
-
-	"gopl.io/ch4/github"
-)
-
-//!+template
-import "html/template"
-
-var issueList = template.Must(template.New("issuelist").Parse(`
-<h1>{{.TotalCount}} issues</h1>
-<table>
-<tr style='text-align: left'>
-  <th>#</th>
-  <th>State</th>
-  <th>User</th>
-  <th>Title</th>
-</tr>
-{{range .Items}}
-<tr>
-  <td><a href='{{.HTMLURL}}'>{{.Number}}</a></td>
-  <td>{{.State}}</td>
-  <td><a href='{{.User.HTMLURL}}'>{{.User.Login}}</a></td>
-  <td><a href='{{.HTMLURL}}'>{{.Title}}</a></td>
-</tr>
-{{end}}
-</table>
-`))
-
-//!-template
-
-//!+
-func main() {
-	result, err := github.SearchIssues(os.Args[1:])
-	if err != nil {
-		log.Fatal(err)
-	}
-	if err := issueList.Execute(os.Stdout, result); err != nil {
-		log.Fatal(err)
-	}
-}
-
-//!-

ch4/issuesreport/main.go

@@ -1,89 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 113.
-
-// Issuesreport prints a report of issues matching the search terms.
-package main
-
-import (
-	"log"
-	"os"
-	"text/template"
-	"time"
-
-	"gopl.io/ch4/github"
-)
-
-//!+template
-const templ = `{{.TotalCount}} issues:
-{{range .Items}}----------------------------------------
-Number: {{.Number}}
-User:   {{.User.Login}}
-Title:  {{.Title | printf "%.64s"}}
-Age:    {{.CreatedAt | daysAgo}} days
-{{end}}`
-
-//!-template
-
-//!+daysAgo
-func daysAgo(t time.Time) int {
-	return int(time.Since(t).Hours() / 24)
-}
-
-//!-daysAgo
-
-//!+exec
-var report = template.Must(template.New("issuelist").
-	Funcs(template.FuncMap{"daysAgo": daysAgo}).
-	Parse(templ))
-
-func main() {
-	result, err := github.SearchIssues(os.Args[1:])
-	if err != nil {
-		log.Fatal(err)
-	}
-	if err := report.Execute(os.Stdout, result); err != nil {
-		log.Fatal(err)
-	}
-}
-
-//!-exec
-
-func noMust() {
-	//!+parse
-	report, err := template.New("report").
-		Funcs(template.FuncMap{"daysAgo": daysAgo}).
-		Parse(templ)
-	if err != nil {
-		log.Fatal(err)
-	}
-	//!-parse
-	result, err := github.SearchIssues(os.Args[1:])
-	if err != nil {
-		log.Fatal(err)
-	}
-	if err := report.Execute(os.Stdout, result); err != nil {
-		log.Fatal(err)
-	}
-}
-
-/*
-//!+output
-$ go build gopl.io/ch4/issuesreport
-$ ./issuesreport repo:golang/go is:open json decoder
-13 issues:
-----------------------------------------
-Number: 5680
-User:   eaigner
-Title:  encoding/json: set key converter on en/decoder
-Age:    750 days
-----------------------------------------
-Number: 6050
-User:   gopherbot
-Title:  encoding/json: provide tokenizer
-Age:    695 days
-----------------------------------------
-...
-//!-output
-*/

ch4/movie/main.go

@@ -1,104 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 108.
-
-// Movie prints Movies as JSON.
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"log"
-)
-
-//!+
-type Movie struct {
-	Title  string
-	Year   int  `json:"released"`
-	Color  bool `json:"color,omitempty"`
-	Actors []string
-}
-
-var movies = []Movie{
-	{Title: "Casablanca", Year: 1942, Color: false,
-		Actors: []string{"Humphrey Bogart", "Ingrid Bergman"}},
-	{Title: "Cool Hand Luke", Year: 1967, Color: true,
-		Actors: []string{"Paul Newman"}},
-	{Title: "Bullitt", Year: 1968, Color: true,
-		Actors: []string{"Steve McQueen", "Jacqueline Bisset"}},
-	// ...
-}
-
-//!-
-
-func main() {
-	{
-		//!+Marshal
-		data, err := json.Marshal(movies)
-		if err != nil {
-			log.Fatalf("JSON marshaling failed: %s", err)
-		}
-		fmt.Printf("%s\n", data)
-		//!-Marshal
-	}
-
-	{
-		//!+MarshalIndent
-		data, err := json.MarshalIndent(movies, "", "    ")
-		if err != nil {
-			log.Fatalf("JSON marshaling failed: %s", err)
-		}
-		fmt.Printf("%s\n", data)
-		//!-MarshalIndent
-
-		//!+Unmarshal
-		var titles []struct{ Title string }
-		if err := json.Unmarshal(data, &titles); err != nil {
-			log.Fatalf("JSON unmarshaling failed: %s", err)
-		}
-		fmt.Println(titles) // "[{Casablanca} {Cool Hand Luke} {Bullitt}]"
-		//!-Unmarshal
-	}
-}
-
-/*
-//!+output
-[{"Title":"Casablanca","released":1942,"Actors":["Humphrey Bogart","Ingr
-id Bergman"]},{"Title":"Cool Hand Luke","released":1967,"color":true,"Ac
-tors":["Paul Newman"]},{"Title":"Bullitt","released":1968,"color":true,"
-Actors":["Steve McQueen","Jacqueline Bisset"]}]
-//!-output
-*/
-
-/*
-//!+indented
-[
-    {
-        "Title": "Casablanca",
-        "released": 1942,
-        "Actors": [
-            "Humphrey Bogart",
-            "Ingrid Bergman"
-        ]
-    },
-    {
-        "Title": "Cool Hand Luke",
-        "released": 1967,
-        "color": true,
-        "Actors": [
-            "Paul Newman"
-        ]
-    },
-    {
-        "Title": "Bullitt",
-        "released": 1968,
-        "color": true,
-        "Actors": [
-            "Steve McQueen",
-            "Jacqueline Bisset"
-        ]
-    }
-]
-//!-indented
-*/

ch4/nonempty/main.go

@@ -1,47 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 91.
-
-//!+nonempty
-
-// Nonempty is an example of an in-place slice algorithm.
-package main
-
-import "fmt"
-
-// nonempty returns a slice holding only the non-empty strings.
-// The underlying array is modified during the call.
-func nonempty(strings []string) []string {
-	i := 0
-	for _, s := range strings {
-		if s != "" {
-			strings[i] = s
-			i++
-		}
-	}
-	return strings[:i]
-}
-
-//!-nonempty
-
-func main() {
-	//!+main
-	data := []string{"one", "", "three"}
-	fmt.Printf("%q\n", nonempty(data)) // `["one" "three"]`
-	fmt.Printf("%q\n", data)           // `["one" "three" "three"]`
-	//!-main
-}
-
-//!+alt
-func nonempty2(strings []string) []string {
-	out := strings[:0] // zero-length slice of original
-	for _, s := range strings {
-		if s != "" {
-			out = append(out, s)
-		}
-	}
-	return out
-}
-
-//!-alt

ch4/rev/main.go

@@ -1,60 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 86.
-
-// Rev reverses a slice.
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-	"strconv"
-	"strings"
-)
-
-func main() {
-	//!+array
-	a := [...]int{0, 1, 2, 3, 4, 5}
-	reverse(a[:])
-	fmt.Println(a) // "[5 4 3 2 1 0]"
-	//!-array
-
-	//!+slice
-	s := []int{0, 1, 2, 3, 4, 5}
-	// Rotate s left by two positions.
-	reverse(s[:2])
-	reverse(s[2:])
-	reverse(s)
-	fmt.Println(s) // "[2 3 4 5 0 1]"
-	//!-slice
-
-	// Interactive test of reverse.
-	input := bufio.NewScanner(os.Stdin)
-outer:
-	for input.Scan() {
-		var ints []int
-		for _, s := range strings.Fields(input.Text()) {
-			x, err := strconv.ParseInt(s, 10, 64)
-			if err != nil {
-				fmt.Fprintln(os.Stderr, err)
-				continue outer
-			}
-			ints = append(ints, int(x))
-		}
-		reverse(ints)
-		fmt.Printf("%v\n", ints)
-	}
-	// NOTE: ignoring potential errors from input.Err()
-}
-
-//!+rev
-// reverse reverses a slice of ints in place.
-func reverse(s []int) {
-	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
-		s[i], s[j] = s[j], s[i]
-	}
-}
-
-//!-rev

ch4/sha256/main.go

@@ -1,25 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 83.
-
-// The sha256 command computes the SHA256 hash (an array) of a string.
-package main
-
-import "fmt"
-
-//!+
-import "crypto/sha256"
-
-func main() {
-	c1 := sha256.Sum256([]byte("x"))
-	c2 := sha256.Sum256([]byte("X"))
-	fmt.Printf("%x\n%x\n%t\n%T\n", c1, c2, c1 == c2, c1)
-	// Output:
-	// 2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881
-	// 4b68ab3847feda7d6c62c1fbcbeebfa35eab7351ed5e78f4ddadea5df64b8015
-	// false
-	// [32]uint8
-}
-
-//!-

ch4/treesort/sort.go

@@ -1,50 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 101.
-
-// Package treesort provides insertion sort using an unbalanced binary tree.
-package treesort
-
-//!+
-type tree struct {
-	value       int
-	left, right *tree
-}
-
-// Sort sorts values in place.
-func Sort(values []int) {
-	var root *tree
-	for _, v := range values {
-		root = add(root, v)
-	}
-	appendValues(values[:0], root)
-}
-
-// appendValues appends the elements of t to values in order
-// and returns the resulting slice.
-func appendValues(values []int, t *tree) []int {
-	if t != nil {
-		values = appendValues(values, t.left)
-		values = append(values, t.value)
-		values = appendValues(values, t.right)
-	}
-	return values
-}
-
-func add(t *tree, value int) *tree {
-	if t == nil {
-		// Equivalent to return &tree{value: value}.
-		t = new(tree)
-		t.value = value
-		return t
-	}
-	if value < t.value {
-		t.left = add(t.left, value)
-	} else {
-		t.right = add(t.right, value)
-	}
-	return t
-}
-
-//!-

ch4/treesort/sort_test.go

@@ -1,23 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-package treesort_test
-
-import (
-	"math/rand"
-	"sort"
-	"testing"
-
-	"gopl.io/ch4/treesort"
-)
-
-func TestSort(t *testing.T) {
-	data := make([]int, 50)
-	for i := range data {
-		data[i] = rand.Int() % 50
-	}
-	treesort.Sort(data)
-	if !sort.IntsAreSorted(data) {
-		t.Errorf("not sorted: %v", data)
-	}
-}

ch5/defer1/defer.go

@@ -1,48 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 150.
-
-// Defer1 demonstrates a deferred call being invoked during a panic.
-package main
-
-import "fmt"
-
-//!+f
-func main() {
-	f(3)
-}
-
-func f(x int) {
-	fmt.Printf("f(%d)\n", x+0/x) // panics if x == 0
-	defer fmt.Printf("defer %d\n", x)
-	f(x - 1)
-}
-
-//!-f
-
-/*
-//!+stdout
-f(3)
-f(2)
-f(1)
-defer 1
-defer 2
-defer 3
-//!-stdout
-
-//!+stderr
-panic: runtime error: integer divide by zero
-main.f(0)
-        src/gopl.io/ch5/defer1/defer.go:14
-main.f(1)
-        src/gopl.io/ch5/defer1/defer.go:16
-main.f(2)
-        src/gopl.io/ch5/defer1/defer.go:16
-
-main.f(3)
-        src/gopl.io/ch5/defer1/defer.go:16
-main.main()
-        src/gopl.io/ch5/defer1/defer.go:10
-//!-stderr
-*/

ch5/defer2/defer.go

@@ -1,51 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 151.
-
-// Defer2 demonstrates a deferred call to runtime.Stack during a panic.
-package main
-
-import (
-	"fmt"
-	"os"
-	"runtime"
-)
-
-//!+
-func main() {
-	defer printStack()
-	f(3)
-}
-
-func printStack() {
-	var buf [4096]byte
-	n := runtime.Stack(buf[:], false)
-	os.Stdout.Write(buf[:n])
-}
-
-//!-
-
-func f(x int) {
-	fmt.Printf("f(%d)\n", x+0/x) // panics if x == 0
-	defer fmt.Printf("defer %d\n", x)
-	f(x - 1)
-}
-
-/*
-//!+printstack
-goroutine 1 [running]:
-main.printStack()
-	src/gopl.io/ch5/defer2/defer.go:20
-main.f(0)
-	src/gopl.io/ch5/defer2/defer.go:27
-main.f(1)
-	src/gopl.io/ch5/defer2/defer.go:29
-main.f(2)
-	src/gopl.io/ch5/defer2/defer.go:29
-main.f(3)
-	src/gopl.io/ch5/defer2/defer.go:29
-main.main()
-	src/gopl.io/ch5/defer2/defer.go:15
-//!-printstack
-*/

ch5/fetch/main.go

@@ -1,54 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 148.
-
-// Fetch saves the contents of a URL into a local file.
-package main
-
-import (
-	"fmt"
-	"io"
-	"net/http"
-	"os"
-	"path"
-)
-
-//!+
-// Fetch downloads the URL and returns the
-// name and length of the local file.
-func fetch(url string) (filename string, n int64, err error) {
-	resp, err := http.Get(url)
-	if err != nil {
-		return "", 0, err
-	}
-	defer resp.Body.Close()
-
-	local := path.Base(resp.Request.URL.Path)
-	if local == "/" {
-		local = "index.html"
-	}
-	f, err := os.Create(local)
-	if err != nil {
-		return "", 0, err
-	}
-	n, err = io.Copy(f, resp.Body)
-	// Close file, but prefer error from Copy, if any.
-	if closeErr := f.Close(); err == nil {
-		err = closeErr
-	}
-	return local, n, err
-}
-
-//!-
-
-func main() {
-	for _, url := range os.Args[1:] {
-		local, n, err := fetch(url)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "fetch %s: %v\n", url, err)
-			continue
-		}
-		fmt.Fprintf(os.Stderr, "%s => %s (%d bytes).\n", url, local, n)
-	}
-}

ch5/findlinks1/main.go

@@ -1,76 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 122.
-//!+main
-
-// Findlinks1 prints the links in an HTML document read from standard input.
-package main
-
-import (
-	"fmt"
-	"os"
-
-	"golang.org/x/net/html"
-)
-
-func main() {
-	doc, err := html.Parse(os.Stdin)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "findlinks1: %v\n", err)
-		os.Exit(1)
-	}
-	for _, link := range visit(nil, doc) {
-		fmt.Println(link)
-	}
-}
-
-//!-main
-
-//!+visit
-// visit appends to links each link found in n and returns the result.
-func visit(links []string, n *html.Node) []string {
-	if n.Type == html.ElementNode && n.Data == "a" {
-		for _, a := range n.Attr {
-			if a.Key == "href" {
-				links = append(links, a.Val)
-			}
-		}
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		links = visit(links, c)
-	}
-	return links
-}
-
-//!-visit
-
-/*
-//!+html
-package html
-
-type Node struct {
-	Type                    NodeType
-	Data                    string
-	Attr                    []Attribute
-	FirstChild, NextSibling *Node
-}
-
-type NodeType int32
-
-const (
-	ErrorNode NodeType = iota
-	TextNode
-	DocumentNode
-	ElementNode
-	CommentNode
-	DoctypeNode
-)
-
-type Attribute struct {
-	Key, Val string
-}
-
-func Parse(r io.Reader) (*Node, error)
-//!-html
-*/

ch5/findlinks2/main.go

@@ -1,69 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 125.
-
-// Findlinks2 does an HTTP GET on each URL, parses the
-// result as HTML, and prints the links within it.
-//
-// Usage:
-//	findlinks url ...
-package main
-
-import (
-	"fmt"
-	"net/http"
-	"os"
-
-	"golang.org/x/net/html"
-)
-
-// visit appends to links each link found in n, and returns the result.
-func visit(links []string, n *html.Node) []string {
-	if n.Type == html.ElementNode && n.Data == "a" {
-		for _, a := range n.Attr {
-			if a.Key == "href" {
-				links = append(links, a.Val)
-			}
-		}
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		links = visit(links, c)
-	}
-	return links
-}
-
-//!+
-func main() {
-	for _, url := range os.Args[1:] {
-		links, err := findLinks(url)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "findlinks2: %v\n", err)
-			continue
-		}
-		for _, link := range links {
-			fmt.Println(link)
-		}
-	}
-}
-
-// findLinks performs an HTTP GET request for url, parses the
-// response as HTML, and extracts and returns the links.
-func findLinks(url string) ([]string, error) {
-	resp, err := http.Get(url)
-	if err != nil {
-		return nil, err
-	}
-	if resp.StatusCode != http.StatusOK {
-		resp.Body.Close()
-		return nil, fmt.Errorf("getting %s: %s", url, resp.Status)
-	}
-	doc, err := html.Parse(resp.Body)
-	resp.Body.Close()
-	if err != nil {
-		return nil, fmt.Errorf("parsing %s as HTML: %v", url, err)
-	}
-	return visit(nil, doc), nil
-}
-
-//!-

ch5/findlinks3/findlinks.go

@@ -1,56 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 139.
-
-// Findlinks3 crawls the web, starting with the URLs on the command line.
-package main
-
-import (
-	"fmt"
-	"log"
-	"os"
-
-	"gopl.io/ch5/links"
-)
-
-//!+breadthFirst
-// breadthFirst calls f for each item in the worklist.
-// Any items returned by f are added to the worklist.
-// f is called at most once for each item.
-func breadthFirst(f func(item string) []string, worklist []string) {
-	seen := make(map[string]bool)
-	for len(worklist) > 0 {
-		items := worklist
-		worklist = nil
-		for _, item := range items {
-			if !seen[item] {
-				seen[item] = true
-				worklist = append(worklist, f(item)...)
-			}
-		}
-	}
-}
-
-//!-breadthFirst
-
-//!+crawl
-func crawl(url string) []string {
-	fmt.Println(url)
-	list, err := links.Extract(url)
-	if err != nil {
-		log.Print(err)
-	}
-	return list
-}
-
-//!-crawl
-
-//!+main
-func main() {
-	// Crawl the web breadth-first,
-	// starting from the command-line arguments.
-	breadthFirst(crawl, os.Args[1:])
-}
-
-//!-main

ch5/links/links.go

@@ -1,67 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 138.
-//!+Extract
-
-// Package links provides a link-extraction function.
-package links
-
-import (
-	"fmt"
-	"net/http"
-
-	"golang.org/x/net/html"
-)
-
-// Extract makes an HTTP GET request to the specified URL, parses
-// the response as HTML, and returns the links in the HTML document.
-func Extract(url string) ([]string, error) {
-	resp, err := http.Get(url)
-	if err != nil {
-		return nil, err
-	}
-	if resp.StatusCode != http.StatusOK {
-		resp.Body.Close()
-		return nil, fmt.Errorf("getting %s: %s", url, resp.Status)
-	}
-
-	doc, err := html.Parse(resp.Body)
-	resp.Body.Close()
-	if err != nil {
-		return nil, fmt.Errorf("parsing %s as HTML: %v", url, err)
-	}
-
-	var links []string
-	visitNode := func(n *html.Node) {
-		if n.Type == html.ElementNode && n.Data == "a" {
-			for _, a := range n.Attr {
-				if a.Key != "href" {
-					continue
-				}
-				link, err := resp.Request.URL.Parse(a.Val)
-				if err != nil {
-					continue // ignore bad URLs
-				}
-				links = append(links, link.String())
-			}
-		}
-	}
-	forEachNode(doc, visitNode, nil)
-	return links, nil
-}
-
-//!-Extract
-
-// Copied from gopl.io/ch5/outline2.
-func forEachNode(n *html.Node, pre, post func(n *html.Node)) {
-	if pre != nil {
-		pre(n)
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		forEachNode(c, pre, post)
-	}
-	if post != nil {
-		post(n)
-	}
-}

ch5/outline/main.go

@@ -1,36 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 123.
-
-// Outline prints the outline of an HTML document tree.
-package main
-
-import (
-	"fmt"
-	"os"
-
-	"golang.org/x/net/html"
-)
-
-//!+
-func main() {
-	doc, err := html.Parse(os.Stdin)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "outline: %v\n", err)
-		os.Exit(1)
-	}
-	outline(nil, doc)
-}
-
-func outline(stack []string, n *html.Node) {
-	if n.Type == html.ElementNode {
-		stack = append(stack, n.Data) // push tag
-		fmt.Println(stack)
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		outline(stack, c)
-	}
-}
-
-//!-

ch5/outline2/outline.go

@@ -1,80 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 133.
-
-// Outline prints the outline of an HTML document tree.
-package main
-
-import (
-	"fmt"
-	"net/http"
-	"os"
-
-	"golang.org/x/net/html"
-)
-
-func main() {
-	for _, url := range os.Args[1:] {
-		outline(url)
-	}
-}
-
-func outline(url string) error {
-	resp, err := http.Get(url)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-
-	doc, err := html.Parse(resp.Body)
-	if err != nil {
-		return err
-	}
-
-	//!+call
-	forEachNode(doc, startElement, endElement)
-	//!-call
-
-	return nil
-}
-
-//!+forEachNode
-// forEachNode calls the functions pre(x) and post(x) for each node
-// x in the tree rooted at n. Both functions are optional.
-// pre is called before the children are visited (preorder) and
-// post is called after (postorder).
-func forEachNode(n *html.Node, pre, post func(n *html.Node)) {
-	if pre != nil {
-		pre(n)
-	}
-
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		forEachNode(c, pre, post)
-	}
-
-	if post != nil {
-		post(n)
-	}
-}
-
-//!-forEachNode
-
-//!+startend
-var depth int
-
-func startElement(n *html.Node) {
-	if n.Type == html.ElementNode {
-		fmt.Printf("%*s<%s>\n", depth*2, "", n.Data)
-		depth++
-	}
-}
-
-func endElement(n *html.Node) {
-	if n.Type == html.ElementNode {
-		depth--
-		fmt.Printf("%*s</%s>\n", depth*2, "", n.Data)
-	}
-}
-
-//!-startend

ch5/squares/main.go

@@ -1,30 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 135.
-
-// The squares program demonstrates a function value with state.
-package main
-
-import "fmt"
-
-//!+
-// squares returns a function that returns
-// the next square number each time it is called.
-func squares() func() int {
-	var x int
-	return func() int {
-		x++
-		return x * x
-	}
-}
-
-func main() {
-	f := squares()
-	fmt.Println(f()) // "1"
-	fmt.Println(f()) // "4"
-	fmt.Println(f()) // "9"
-	fmt.Println(f()) // "16"
-}
-
-//!-

ch5/sum/main.go

@@ -1,33 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 142.
-
-// The sum program demonstrates a variadic function.
-package main
-
-import "fmt"
-
-//!+
-func sum(vals ...int) int {
-	total := 0
-	for _, val := range vals {
-		total += val
-	}
-	return total
-}
-
-//!-
-
-func main() {
-	//!+main
-	fmt.Println(sum())           //  "0"
-	fmt.Println(sum(3))          //  "3"
-	fmt.Println(sum(1, 2, 3, 4)) //  "10"
-	//!-main
-
-	//!+slice
-	values := []int{1, 2, 3, 4}
-	fmt.Println(sum(values...)) // "10"
-	//!-slice
-}

ch5/title1/title.go

@@ -1,82 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 144.
-
-// Title1 prints the title of an HTML document specified by a URL.
-package main
-
-/*
-//!+output
-$ go build gopl.io/ch5/title1
-$ ./title1 http://gopl.io
-The Go Programming Language
-$ ./title1 https://golang.org/doc/effective_go.html
-Effective Go - The Go Programming Language
-$ ./title1 https://golang.org/doc/gopher/frontpage.png
-title: https://golang.org/doc/gopher/frontpage.png
-    has type image/png, not text/html
-//!-output
-*/
-
-import (
-	"fmt"
-	"net/http"
-	"os"
-	"strings"
-
-	"golang.org/x/net/html"
-)
-
-// Copied from gopl.io/ch5/outline2.
-func forEachNode(n *html.Node, pre, post func(n *html.Node)) {
-	if pre != nil {
-		pre(n)
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		forEachNode(c, pre, post)
-	}
-	if post != nil {
-		post(n)
-	}
-}
-
-//!+
-func title(url string) error {
-	resp, err := http.Get(url)
-	if err != nil {
-		return err
-	}
-
-	// Check Content-Type is HTML (e.g., "text/html; charset=utf-8").
-	ct := resp.Header.Get("Content-Type")
-	if ct != "text/html" && !strings.HasPrefix(ct, "text/html;") {
-		resp.Body.Close()
-		return fmt.Errorf("%s has type %s, not text/html", url, ct)
-	}
-
-	doc, err := html.Parse(resp.Body)
-	resp.Body.Close()
-	if err != nil {
-		return fmt.Errorf("parsing %s as HTML: %v", url, err)
-	}
-
-	visitNode := func(n *html.Node) {
-		if n.Type == html.ElementNode && n.Data == "title" &&
-			n.FirstChild != nil {
-			fmt.Println(n.FirstChild.Data)
-		}
-	}
-	forEachNode(doc, visitNode, nil)
-	return nil
-}
-
-//!-
-
-func main() {
-	for _, arg := range os.Args[1:] {
-		if err := title(arg); err != nil {
-			fmt.Fprintf(os.Stderr, "title: %v\n", err)
-		}
-	}
-}

ch5/title2/title.go

@@ -1,72 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 145.
-
-// Title2 prints the title of an HTML document specified by a URL.
-// It uses defer to simplify closing the response body stream.
-package main
-
-import (
-	"fmt"
-	"net/http"
-	"os"
-	"strings"
-
-	"golang.org/x/net/html"
-)
-
-// Copied from gopl.io/ch5/outline2.
-func forEachNode(n *html.Node, pre, post func(n *html.Node)) {
-	if pre != nil {
-		pre(n)
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		forEachNode(c, pre, post)
-	}
-	if post != nil {
-		post(n)
-	}
-}
-
-//!+
-func title(url string) error {
-	resp, err := http.Get(url)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-
-	ct := resp.Header.Get("Content-Type")
-	if ct != "text/html" && !strings.HasPrefix(ct, "text/html;") {
-		return fmt.Errorf("%s has type %s, not text/html", url, ct)
-	}
-
-	doc, err := html.Parse(resp.Body)
-	if err != nil {
-		return fmt.Errorf("parsing %s as HTML: %v", url, err)
-	}
-
-	// ...print doc's title element...
-	//!-
-	visitNode := func(n *html.Node) {
-		if n.Type == html.ElementNode && n.Data == "title" &&
-			n.FirstChild != nil {
-			fmt.Println(n.FirstChild.Data)
-		}
-	}
-	forEachNode(doc, visitNode, nil)
-	//!+
-
-	return nil
-}
-
-//!-
-
-func main() {
-	for _, arg := range os.Args[1:] {
-		if err := title(arg); err != nil {
-			fmt.Fprintf(os.Stderr, "title: %v\n", err)
-		}
-	}
-}

ch5/title3/title.go

@@ -1,99 +0,0 @@
-// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-
-// See page 153.
-
-// Title3 prints the title of an HTML document specified by a URL.
-package main
-
-import (
-	"fmt"
-	"net/http"
-	"os"
-	"strings"
-
-	"golang.org/x/net/html"
-)
-
-// Copied from gopl.io/ch5/outline2.
-func forEachNode(n *html.Node, pre, post func(n *html.Node)) {
-	if pre != nil {
-		pre(n)
-	}
-	for c := n.FirstChild; c != nil; c = c.NextSibling {
-		forEachNode(c, pre, post)
-	}
-	if post != nil {
-		post(n)
-	}
-}
-
-//!+
-// soleTitle returns the text of the first non-empty title element
-// in doc, and an error if there was not exactly one.
-func soleTitle(doc *html.Node) (title string, err error) {
-	type bailout struct{}
-
-	defer func() {
-		switch p := recover(); p {
-		case nil:
-			// no panic
-		case bailout{}:
-			// "expected" panic
-			err = fmt.Errorf("multiple title elements")
-		default:
-			panic(p) // unexpected panic; carry on panicking
-		}
-	}()
-
-	// Bail out of recursion if we find more than one non-empty title.
-	forEachNode(doc, func(n *html.Node) {
-		if n.Type == html.ElementNode && n.Data == "title" &&
-			n.FirstChild != nil {
-			if title != "" {
-				panic(bailout{}) // multiple title elements
-			}
-			title = n.FirstChild.Data
-		}
-	}, nil)
-	if title == "" {
-		return "", fmt.Errorf("no title element")
-	}
-	return title, nil
-}
-
-//!-
-
-func title(url string) error {
-	resp, err := http.Get(url)
-	if err != nil {
-		return err
-	}
-
-	// Check Content-Type is HTML (e.g., "text/html; charset=utf-8").
-	ct := resp.Header.Get("Content-Type")
-	if ct != "text/html" && !strings.HasPrefix(ct, "text/html;") {
-		resp.Body.Close()
-		return fmt.Errorf("%s has type %s, not text/html", url, ct)
-	}
-
-	doc, err := html.Parse(resp.Body)
-	resp.Body.Close()
-	if err != nil {
-		return fmt.Errorf("parsing %s as HTML: %v", url, err)
-	}
-	title, err := soleTitle(doc)
-	if err != nil {
-		return err
-	}
-	fmt.Println(title)
-	return nil
-}
-
-func main() {
-	for _, arg := range os.Args[1:] {
-		if err := title(arg); err != nil {
-			fmt.Fprintf(os.Stderr, "title: %v\n", err)
-		}
-	}
-}