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
12import (
13	"bufio"
14	"fmt"
15	"log"
16	"net/http"
17	"sort"
18	"strings"
19)
20
21func main() {
22	fmt.Printf("// generated by go run maketables.go; DO NOT EDIT\n\n")
23	fmt.Printf("// Package korean provides Korean encodings such as EUC-KR.\n")
24	fmt.Printf(`package korean // import "golang.org/x/text/encoding/korean"` + "\n\n")
25
26	res, err := http.Get("http://encoding.spec.whatwg.org/index-euc-kr.txt")
27	if err != nil {
28		log.Fatalf("Get: %v", err)
29	}
30	defer res.Body.Close()
31
32	mapping := [65536]uint16{}
33	reverse := [65536]uint16{}
34
35	scanner := bufio.NewScanner(res.Body)
36	for scanner.Scan() {
37		s := strings.TrimSpace(scanner.Text())
38		if s == "" || s[0] == '#' {
39			continue
40		}
41		x, y := uint16(0), uint16(0)
42		if _, err := fmt.Sscanf(s, "%d 0x%x", &x, &y); err != nil {
43			log.Fatalf("could not parse %q", s)
44		}
45		if x < 0 || 178*(0xc7-0x81)+(0xfe-0xc7)*94+(0xff-0xa1) <= x {
46			log.Fatalf("EUC-KR code %d is out of range", x)
47		}
48		mapping[x] = y
49		if reverse[y] == 0 {
50			c0, c1 := uint16(0), uint16(0)
51			if x < 178*(0xc7-0x81) {
52				c0 = uint16(x/178) + 0x81
53				c1 = uint16(x % 178)
54				switch {
55				case c1 < 1*26:
56					c1 += 0x41
57				case c1 < 2*26:
58					c1 += 0x47
59				default:
60					c1 += 0x4d
61				}
62			} else {
63				x -= 178 * (0xc7 - 0x81)
64				c0 = uint16(x/94) + 0xc7
65				c1 = uint16(x%94) + 0xa1
66			}
67			reverse[y] = c0<<8 | c1
68		}
69	}
70	if err := scanner.Err(); err != nil {
71		log.Fatalf("scanner error: %v", err)
72	}
73
74	fmt.Printf("// decode is the decoding table from EUC-KR code to Unicode.\n")
75	fmt.Printf("// It is defined at http://encoding.spec.whatwg.org/index-euc-kr.txt\n")
76	fmt.Printf("var decode = [...]uint16{\n")
77	for i, v := range mapping {
78		if v != 0 {
79			fmt.Printf("\t%d: 0x%04X,\n", i, v)
80		}
81	}
82	fmt.Printf("}\n\n")
83
84	// Any run of at least separation continuous zero entries in the reverse map will
85	// be a separate encode table.
86	const separation = 1024
87
88	intervals := []interval(nil)
89	low, high := -1, -1
90	for i, v := range reverse {
91		if v == 0 {
92			continue
93		}
94		if low < 0 {
95			low = i
96		} else if i-high >= separation {
97			if high >= 0 {
98				intervals = append(intervals, interval{low, high})
99			}
100			low = i
101		}
102		high = i + 1
103	}
104	if high >= 0 {
105		intervals = append(intervals, interval{low, high})
106	}
107	sort.Sort(byDecreasingLength(intervals))
108
109	fmt.Printf("const numEncodeTables = %d\n\n", len(intervals))
110	fmt.Printf("// encodeX are the encoding tables from Unicode to EUC-KR code,\n")
111	fmt.Printf("// sorted by decreasing length.\n")
112	for i, v := range intervals {
113		fmt.Printf("// encode%d: %5d entries for runes in [%5d, %5d).\n", i, v.len(), v.low, v.high)
114	}
115	fmt.Printf("\n")
116
117	for i, v := range intervals {
118		fmt.Printf("const encode%dLow, encode%dHigh = %d, %d\n\n", i, i, v.low, v.high)
119		fmt.Printf("var encode%d = [...]uint16{\n", i)
120		for j := v.low; j < v.high; j++ {
121			x := reverse[j]
122			if x == 0 {
123				continue
124			}
125			fmt.Printf("\t%d-%d: 0x%04X,\n", j, v.low, x)
126		}
127		fmt.Printf("}\n\n")
128	}
129}
130
131// interval is a half-open interval [low, high).
132type interval struct {
133	low, high int
134}
135
136func (i interval) len() int { return i.high - i.low }
137
138// byDecreasingLength sorts intervals by decreasing length.
139type byDecreasingLength []interval
140
141func (b byDecreasingLength) Len() int           { return len(b) }
142func (b byDecreasingLength) Less(i, j int) bool { return b[i].len() > b[j].len() }
143func (b byDecreasingLength) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
144