...

# Source file src/strconv/makeisprint.go

## Documentation: strconv

```  // Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style

// +build ignore

//
// usage:
//
// go run makeisprint.go -output isprint.go
//

package main

import (
"bytes"
"flag"
"fmt"
"go/format"
"io/ioutil"
"log"
"unicode"
)

var filename = flag.String("output", "isprint.go", "output file name")

var (
range16  []uint16
except16 []uint16
range32  []uint32
except32 []uint32
)

// bsearch16 returns the smallest i such that a[i] >= x.
// If there is no such i, bsearch16 returns len(a).
func bsearch16(a []uint16, x uint16) int {
i, j := 0, len(a)
for i < j {
h := i + (j-i)/2
if a[h] < x {
i = h + 1
} else {
j = h
}
}
return i
}

// bsearch32 returns the smallest i such that a[i] >= x.
// If there is no such i, bsearch32 returns len(a).
func bsearch32(a []uint32, x uint32) int {
i, j := 0, len(a)
for i < j {
h := i + (j-i)/2
if a[h] < x {
i = h + 1
} else {
j = h
}
}
return i
}

func isPrint(r rune) bool {
// Same algorithm, either on uint16 or uint32 value.
// First, find first i such that rang[i] >= x.
// This is the index of either the start or end of a pair that might span x.
// The start is even (rang[i&^1]) and the end is odd (rang[i|1]).
// If we find x in a range, make sure x is not in exception list.

if 0 <= r && r < 1<<16 {
rr, rang, except := uint16(r), range16, except16
i := bsearch16(rang, rr)
if i >= len(rang) || rr < rang[i&^1] || rang[i|1] < rr {
return false
}
j := bsearch16(except, rr)
return j >= len(except) || except[j] != rr
}

rr, rang, except := uint32(r), range32, except32
i := bsearch32(rang, rr)
if i >= len(rang) || rr < rang[i&^1] || rang[i|1] < rr {
return false
}
j := bsearch32(except, rr)
return j >= len(except) || except[j] != rr
}

func scan(min, max rune) (rang, except []uint32) {
lo := rune(-1)
for i := min; ; i++ {
if (i > max || !unicode.IsPrint(i)) && lo >= 0 {
// End range, but avoid flip flop.
if i+1 <= max && unicode.IsPrint(i+1) {
except = append(except, uint32(i))
continue
}
rang = append(rang, uint32(lo), uint32(i-1))
lo = -1
}
if i > max {
break
}
if lo < 0 && unicode.IsPrint(i) {
lo = i
}
}
return
}

func to16(x []uint32) []uint16 {
var y []uint16
for _, v := range x {
if uint32(uint16(v)) != v {
}
y = append(y, uint16(v))
}
return y
}

func main() {
flag.Parse()

rang, except := scan(0, 0xFFFF)
range16 = to16(rang)
except16 = to16(except)
range32, except32 = scan(0x10000, unicode.MaxRune)

for i := rune(0); i <= unicode.MaxRune; i++ {
if isPrint(i) != unicode.IsPrint(i) {
log.Fatalf("%U: isPrint=%v, want %v\n", i, isPrint(i), unicode.IsPrint(i))
}
}

var buf bytes.Buffer

// Use of this source code is governed by a BSD-style
fmt.Fprintf(&buf, "// DO NOT EDIT.  GENERATED BY\n")
fmt.Fprintf(&buf, "//     go run makeisprint.go -output isprint.go\n\n")
fmt.Fprintf(&buf, "package strconv\n\n")

fmt.Fprintf(&buf, "// (%d+%d+%d)*2 + (%d)*4 = %d bytes\n\n",
len(range16), len(except16), len(except32),
len(range32),
(len(range16)+len(except16)+len(except32))*2+
(len(range32))*4)

fmt.Fprintf(&buf, "var isPrint16 = []uint16{\n")
for i := 0; i < len(range16); i += 2 {
fmt.Fprintf(&buf, "\t%#04x, %#04x,\n", range16[i], range16[i+1])
}
fmt.Fprintf(&buf, "}\n\n")

fmt.Fprintf(&buf, "var isNotPrint16 = []uint16{\n")
for _, r := range except16 {
fmt.Fprintf(&buf, "\t%#04x,\n", r)
}
fmt.Fprintf(&buf, "}\n\n")

fmt.Fprintf(&buf, "var isPrint32 = []uint32{\n")
for i := 0; i < len(range32); i += 2 {
fmt.Fprintf(&buf, "\t%#06x, %#06x,\n", range32[i], range32[i+1])
}
fmt.Fprintf(&buf, "}\n\n")

fmt.Fprintf(&buf, "var isNotPrint32 = []uint16{ // add 0x10000 to each entry\n")
for _, r := range except32 {
if r >= 0x20000 {
log.Fatalf("%U too big for isNotPrint32\n", r)
}
fmt.Fprintf(&buf, "\t%#04x,\n", r-0x10000)
}
fmt.Fprintf(&buf, "}\n\n")

// The list of graphic but not "printable" runes is short. Just make one easy table.
fmt.Fprintf(&buf, "// isGraphic lists the graphic runes not matched by IsPrint.\n")
fmt.Fprintf(&buf, "var isGraphic = []uint16{\n")
for r := rune(0); r <= unicode.MaxRune; r++ {
if unicode.IsPrint(r) != unicode.IsGraphic(r) {
// Sanity check.
if !unicode.IsGraphic(r) {
log.Fatalf("%U is printable but not graphic\n", r)
}
if r > 0xFFFF { // We expect only 16-bit values.
log.Fatalf("%U too big for isGraphic\n", r)
}
fmt.Fprintf(&buf, "\t%#04x,\n", r)
}
}
fmt.Fprintf(&buf, "}\n")

data, err := format.Source(buf.Bytes())
if err != nil {
log.Fatal(err)
}
err = ioutil.WriteFile(*filename, data, 0644)
if err != nil {
log.Fatal(err)
}
}

```

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