1// Copyright 2013 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
7package main
8
9// This program generates tables.go:
10//	go run maketables.go | gofmt > tables.go
11
12// TODO: Emoji extensions?
13// http://www.unicode.org/faq/emoji_dingbats.html
14// http://www.unicode.org/Public/UNIDATA/EmojiSources.txt
15
16import (
17	"bufio"
18	"fmt"
19	"log"
20	"net/http"
21	"sort"
22	"strings"
23)
24
25type entry struct {
26	jisCode, table int
27}
28
29func main() {
30	fmt.Printf("// generated by go run maketables.go; DO NOT EDIT\n\n")
31	fmt.Printf("// Package japanese provides Japanese encodings such as EUC-JP and Shift JIS.\n")
32	fmt.Printf(`package japanese // import "golang.org/x/text/encoding/japanese"` + "\n\n")
33
34	reverse := [65536]entry{}
35	for i := range reverse {
36		reverse[i].table = -1
37	}
38
39	tables := []struct {
40		url  string
41		name string
42	}{
43		{"http://encoding.spec.whatwg.org/index-jis0208.txt", "0208"},
44		{"http://encoding.spec.whatwg.org/index-jis0212.txt", "0212"},
45	}
46	for i, table := range tables {
47		res, err := http.Get(table.url)
48		if err != nil {
49			log.Fatalf("%q: Get: %v", table.url, err)
50		}
51		defer res.Body.Close()
52
53		mapping := [65536]uint16{}
54
55		scanner := bufio.NewScanner(res.Body)
56		for scanner.Scan() {
57			s := strings.TrimSpace(scanner.Text())
58			if s == "" || s[0] == '#' {
59				continue
60			}
61			x, y := 0, uint16(0)
62			if _, err := fmt.Sscanf(s, "%d 0x%x", &x, &y); err != nil {
63				log.Fatalf("%q: could not parse %q", table.url, s)
64			}
65			if x < 0 || 120*94 <= x {
66				log.Fatalf("%q: JIS code %d is out of range", table.url, x)
67			}
68			mapping[x] = y
69			if reverse[y].table == -1 {
70				reverse[y] = entry{jisCode: x, table: i}
71			}
72		}
73		if err := scanner.Err(); err != nil {
74			log.Fatalf("%q: scanner error: %v", table.url, err)
75		}
76
77		fmt.Printf("// jis%sDecode is the decoding table from JIS %s code to Unicode.\n// It is defined at %s\n",
78			table.name, table.name, table.url)
79		fmt.Printf("var jis%sDecode = [...]uint16{\n", table.name)
80		for i, m := range mapping {
81			if m != 0 {
82				fmt.Printf("\t%d: 0x%04X,\n", i, m)
83			}
84		}
85		fmt.Printf("}\n\n")
86	}
87
88	// Any run of at least separation continuous zero entries in the reverse map will
89	// be a separate encode table.
90	const separation = 1024
91
92	intervals := []interval(nil)
93	low, high := -1, -1
94	for i, v := range reverse {
95		if v.table == -1 {
96			continue
97		}
98		if low < 0 {
99			low = i
100		} else if i-high >= separation {
101			if high >= 0 {
102				intervals = append(intervals, interval{low, high})
103			}
104			low = i
105		}
106		high = i + 1
107	}
108	if high >= 0 {
109		intervals = append(intervals, interval{low, high})
110	}
111	sort.Sort(byDecreasingLength(intervals))
112
113	fmt.Printf("const (\n")
114	fmt.Printf("\tjis0208    = 1\n")
115	fmt.Printf("\tjis0212    = 2\n")
116	fmt.Printf("\tcodeMask   = 0x7f\n")
117	fmt.Printf("\tcodeShift  = 7\n")
118	fmt.Printf("\ttableShift = 14\n")
119	fmt.Printf(")\n\n")
120
121	fmt.Printf("const numEncodeTables = %d\n\n", len(intervals))
122	fmt.Printf("// encodeX are the encoding tables from Unicode to JIS code,\n")
123	fmt.Printf("// sorted by decreasing length.\n")
124	for i, v := range intervals {
125		fmt.Printf("// encode%d: %5d entries for runes in [%5d, %5d).\n", i, v.len(), v.low, v.high)
126	}
127	fmt.Printf("//\n")
128	fmt.Printf("// The high two bits of the value record whether the JIS code comes from the\n")
129	fmt.Printf("// JIS0208 table (high bits == 1) or the JIS0212 table (high bits == 2).\n")
130	fmt.Printf("// The low 14 bits are two 7-bit unsigned integers j1 and j2 that form the\n")
131	fmt.Printf("// JIS code (94*j1 + j2) within that table.\n")
132	fmt.Printf("\n")
133
134	for i, v := range intervals {
135		fmt.Printf("const encode%dLow, encode%dHigh = %d, %d\n\n", i, i, v.low, v.high)
136		fmt.Printf("var encode%d = [...]uint16{\n", i)
137		for j := v.low; j < v.high; j++ {
138			x := reverse[j]
139			if x.table == -1 {
140				continue
141			}
142			fmt.Printf("\t%d - %d: jis%s<<14 | 0x%02X<<7 | 0x%02X,\n",
143				j, v.low, tables[x.table].name, x.jisCode/94, x.jisCode%94)
144		}
145		fmt.Printf("}\n\n")
146	}
147}
148
149// interval is a half-open interval [low, high).
150type interval struct {
151	low, high int
152}
153
154func (i interval) len() int { return i.high - i.low }
155
156// byDecreasingLength sorts intervals by decreasing length.
157type byDecreasingLength []interval
158
159func (b byDecreasingLength) Len() int           { return len(b) }
160func (b byDecreasingLength) Less(i, j int) bool { return b[i].len() > b[j].len() }
161func (b byDecreasingLength) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
162