add tool/measure

.gitignore

@@ -1,4 +1,5 @@
 build
-tool/generate
+tool/build-html-inner
 tool/number
+tool/measure-inner
 

tool/build-html

@@ -1,3 +1,3 @@
 #!/bin/bash
 
-ls src/0*/*.{go,sh} | xargs tool/generate > build/go-by-example.html
+ls src/0*/*.{go,sh} | xargs tool/build-html-inner > build/go-by-example.html

tool/compile

@@ -2,5 +2,6 @@
 
 set -e
 
-go build -o tool/generate tool/src/generate.go 
+go build -o tool/build-html-inner tool/src/build-html-inner.go 
 go build -o tool/number tool/src/number.go
+go build -o tool/measure-inner tool/src/measure-inner.go

tool/measure

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -e
+set -o pipefail
+
+ls src/0*/*.{go,sh} | xargs tool/measure-inner

tool/src/build-html-inner.go

@@ -1,5 +1,3 @@
-// Generate an HTML file from the book source. Derived from golit.
-
 package main
 
 import (

tool/src/measure-inner.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+    "fmt"
+    "io/ioutil"
+    "os"
+    "strings"
+)
+
+func check(err error) {
+    if err != nil {
+        panic(err)
+    }
+}
+
+func readLines(path string) []string {
+    srcBytes, err := ioutil.ReadFile(path)
+    check(err)
+    return strings.Split(string(srcBytes), "\n")
+}
+
+func main() {
+    if len(os.Args) <= 1 {
+        fmt.Fprintln(os.Stderr, "usage: tool/measure *.{go,sh}")
+        os.Exit(1)
+    }
+    foundLongFile := false
+    for _, sourcePath := range os.Args[1:] {
+        foundLongLine := false
+        lines := readLines(sourcePath)
+        for _, line := range lines {
+            if len(line) > 60 && !foundLongLine {
+                fmt.Println(sourcePath)
+                foundLongLine = true
+                foundLongFile = true
+            }
+        }
+    }
+    if foundLongFile {
+        os.Exit(1)
+    }
+}