1// Copyright 2012 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// +build ignore
6
7//
8// usage:
9//
10// go run makeisprint.go -output isprint.go
11//
12
13package main
14
15import (
16	"bytes"
17	"flag"
18	"fmt"
19	"go/format"
20	"io/ioutil"
21	"log"
22	"unicode"
23)
24
25var filename = flag.String("output", "isprint.go", "output file name")
26
27var (
28	range16  []uint16
29	except16 []uint16
30	range32  []uint32
31	except32 []uint32
32)
33
34// bsearch16 returns the smallest i such that a[i] >= x.
35// If there is no such i, bsearch16 returns len(a).
36func bsearch16(a []uint16, x uint16) int {
37	i, j := 0, len(a)
38	for i < j {
39		h := i + (j-i)/2
40		if a[h] < x {
41			i = h + 1
42		} else {
43			j = h
44		}
45	}
46	return i
47}
48
49// bsearch32 returns the smallest i such that a[i] >= x.
50// If there is no such i, bsearch32 returns len(a).
51func bsearch32(a []uint32, x uint32) int {
52	i, j := 0, len(a)
53	for i < j {
54		h := i + (j-i)/2
55		if a[h] < x {
56			i = h + 1
57		} else {
58			j = h
59		}
60	}
61	return i
62}
63
64func isPrint(r rune) bool {
65	// Same algorithm, either on uint16 or uint32 value.
66	// First, find first i such that rang[i] >= x.
67	// This is the index of either the start or end of a pair that might span x.
68	// The start is even (rang[i&^1]) and the end is odd (rang[i|1]).
69	// If we find x in a range, make sure x is not in exception list.
70
71	if 0 <= r && r < 1<<16 {
72		rr, rang, except := uint16(r), range16, except16
73		i := bsearch16(rang, rr)
74		if i >= len(rang) || rr < rang[i&^1] || rang[i|1] < rr {
75			return false
76		}
77		j := bsearch16(except, rr)
78		return j >= len(except) || except[j] != rr
79	}
80
81	rr, rang, except := uint32(r), range32, except32
82	i := bsearch32(rang, rr)
83	if i >= len(rang) || rr < rang[i&^1] || rang[i|1] < rr {
84		return false
85	}
86	j := bsearch32(except, rr)
87	return j >= len(except) || except[j] != rr
88}
89
90func scan(min, max rune) (rang, except []uint32) {
91	lo := rune(-1)
92	for i := min; ; i++ {
93		if (i > max || !unicode.IsPrint(i)) && lo >= 0 {
94			// End range, but avoid flip flop.
95			if i+1 <= max && unicode.IsPrint(i+1) {
96				except = append(except, uint32(i))
97				continue
98			}
99			rang = append(rang, uint32(lo), uint32(i-1))
100			lo = -1
101		}
102		if i > max {
103			break
104		}
105		if lo < 0 && unicode.IsPrint(i) {
106			lo = i
107		}
108	}
109	return
110}
111
112func to16(x []uint32) []uint16 {
113	var y []uint16
114	for _, v := range x {
115		if uint32(uint16(v)) != v {
116			panic("bad 32->16 conversion")
117		}
118		y = append(y, uint16(v))
119	}
120	return y
121}
122
123func main() {
124	flag.Parse()
125
126	rang, except := scan(0, 0xFFFF)
127	range16 = to16(rang)
128	except16 = to16(except)
129	range32, except32 = scan(0x10000, unicode.MaxRune)
130
131	for i := rune(0); i <= unicode.MaxRune; i++ {
132		if isPrint(i) != unicode.IsPrint(i) {
133			log.Fatalf("%U: isPrint=%v, want %v\n", i, isPrint(i), unicode.IsPrint(i))
134		}
135	}
136
137	var buf bytes.Buffer
138
139	fmt.Fprintf(&buf, `// Copyright 2013 The Go Authors. All rights reserved.
140// Use of this source code is governed by a BSD-style
141// license that can be found in the LICENSE file.`+"\n\n")
142	fmt.Fprintf(&buf, "// DO NOT EDIT.  GENERATED BY\n")
143	fmt.Fprintf(&buf, "//     go run makeisprint.go -output isprint.go\n\n")
144	fmt.Fprintf(&buf, "package strconv\n\n")
145
146	fmt.Fprintf(&buf, "// (%d+%d+%d)*2 + (%d)*4 = %d bytes\n\n",
147		len(range16), len(except16), len(except32),
148		len(range32),
149		(len(range16)+len(except16)+len(except32))*2+
150			(len(range32))*4)
151
152	fmt.Fprintf(&buf, "var isPrint16 = []uint16{\n")
153	for i := 0; i < len(range16); i += 2 {
154		fmt.Fprintf(&buf, "\t%#04x, %#04x,\n", range16[i], range16[i+1])
155	}
156	fmt.Fprintf(&buf, "}\n\n")
157
158	fmt.Fprintf(&buf, "var isNotPrint16 = []uint16{\n")
159	for _, r := range except16 {
160		fmt.Fprintf(&buf, "\t%#04x,\n", r)
161	}
162	fmt.Fprintf(&buf, "}\n\n")
163
164	fmt.Fprintf(&buf, "var isPrint32 = []uint32{\n")
165	for i := 0; i < len(range32); i += 2 {
166		fmt.Fprintf(&buf, "\t%#06x, %#06x,\n", range32[i], range32[i+1])
167	}
168	fmt.Fprintf(&buf, "}\n\n")
169
170	fmt.Fprintf(&buf, "var isNotPrint32 = []uint16{ // add 0x10000 to each entry\n")
171	for _, r := range except32 {
172		if r >= 0x20000 {
173			log.Fatalf("%U too big for isNotPrint32\n", r)
174		}
175		fmt.Fprintf(&buf, "\t%#04x,\n", r-0x10000)
176	}
177	fmt.Fprintf(&buf, "}\n\n")
178
179	// The list of graphic but not "printable" runes is short. Just make one easy table.
180	fmt.Fprintf(&buf, "// isGraphic lists the graphic runes not matched by IsPrint.\n")
181	fmt.Fprintf(&buf, "var isGraphic = []uint16{\n")
182	for r := rune(0); r <= unicode.MaxRune; r++ {
183		if unicode.IsPrint(r) != unicode.IsGraphic(r) {
184			// Sanity check.
185			if !unicode.IsGraphic(r) {
186				log.Fatalf("%U is printable but not graphic\n", r)
187			}
188			if r > 0xFFFF { // We expect only 16-bit values.
189				log.Fatalf("%U too big for isGraphic\n", r)
190			}
191			fmt.Fprintf(&buf, "\t%#04x,\n", r)
192		}
193	}
194	fmt.Fprintf(&buf, "}\n")
195
196	data, err := format.Source(buf.Bytes())
197	if err != nil {
198		log.Fatal(err)
199	}
200	err = ioutil.WriteFile(*filename, data, 0644)
201	if err != nil {
202		log.Fatal(err)
203	}
204}
205