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//go:build ignore
6// +build ignore
7
8package main
9
10// This program generates tables.go:
11//	go run maketables.go | gofmt > tables.go
12
13import (
14	"bufio"
15	"fmt"
16	"log"
17	"net/http"
18	"sort"
19	"strings"
20)
21
22func main() {
23	fmt.Printf("// generated by go run maketables.go; DO NOT EDIT\n\n")
24	fmt.Printf("// Package korean provides Korean encodings such as EUC-KR.\n")
25	fmt.Printf(`package korean // import "golang.org/x/text/encoding/korean"` + "\n\n")
26
27	res, err := http.Get("http://encoding.spec.whatwg.org/index-euc-kr.txt")
28	if err != nil {
29		log.Fatalf("Get: %v", err)
30	}
31	defer res.Body.Close()
32
33	mapping := [65536]uint16{}
34	reverse := [65536]uint16{}
35
36	scanner := bufio.NewScanner(res.Body)
37	for scanner.Scan() {
38		s := strings.TrimSpace(scanner.Text())
39		if s == "" || s[0] == '#' {
40			continue
41		}
42		x, y := uint16(0), uint16(0)
43		if _, err := fmt.Sscanf(s, "%d 0x%x", &x, &y); err != nil {
44			log.Fatalf("could not parse %q", s)
45		}
46		if x < 0 || 178*(0xc7-0x81)+(0xfe-0xc7)*94+(0xff-0xa1) <= x {
47			log.Fatalf("EUC-KR code %d is out of range", x)
48		}
49		mapping[x] = y
50		if reverse[y] == 0 {
51			c0, c1 := uint16(0), uint16(0)
52			if x < 178*(0xc7-0x81) {
53				c0 = uint16(x/178) + 0x81
54				c1 = uint16(x % 178)
55				switch {
56				case c1 < 1*26:
57					c1 += 0x41
58				case c1 < 2*26:
59					c1 += 0x47
60				default:
61					c1 += 0x4d
62				}
63			} else {
64				x -= 178 * (0xc7 - 0x81)
65				c0 = uint16(x/94) + 0xc7
66				c1 = uint16(x%94) + 0xa1
67			}
68			reverse[y] = c0<<8 | c1
69		}
70	}
71	if err := scanner.Err(); err != nil {
72		log.Fatalf("scanner error: %v", err)
73	}
74
75	fmt.Printf("// decode is the decoding table from EUC-KR code to Unicode.\n")
76	fmt.Printf("// It is defined at http://encoding.spec.whatwg.org/index-euc-kr.txt\n")
77	fmt.Printf("var decode = [...]uint16{\n")
78	for i, v := range mapping {
79		if v != 0 {
80			fmt.Printf("\t%d: 0x%04X,\n", i, v)
81		}
82	}
83	fmt.Printf("}\n\n")
84
85	// Any run of at least separation continuous zero entries in the reverse map will
86	// be a separate encode table.
87	const separation = 1024
88
89	intervals := []interval(nil)
90	low, high := -1, -1
91	for i, v := range reverse {
92		if v == 0 {
93			continue
94		}
95		if low < 0 {
96			low = i
97		} else if i-high >= separation {
98			if high >= 0 {
99				intervals = append(intervals, interval{low, high})
100			}
101			low = i
102		}
103		high = i + 1
104	}
105	if high >= 0 {
106		intervals = append(intervals, interval{low, high})
107	}
108	sort.Sort(byDecreasingLength(intervals))
109
110	fmt.Printf("const numEncodeTables = %d\n\n", len(intervals))
111	fmt.Printf("// encodeX are the encoding tables from Unicode to EUC-KR code,\n")
112	fmt.Printf("// sorted by decreasing length.\n")
113	for i, v := range intervals {
114		fmt.Printf("// encode%d: %5d entries for runes in [%5d, %5d).\n", i, v.len(), v.low, v.high)
115	}
116	fmt.Printf("\n")
117
118	for i, v := range intervals {
119		fmt.Printf("const encode%dLow, encode%dHigh = %d, %d\n\n", i, i, v.low, v.high)
120		fmt.Printf("var encode%d = [...]uint16{\n", i)
121		for j := v.low; j < v.high; j++ {
122			x := reverse[j]
123			if x == 0 {
124				continue
125			}
126			fmt.Printf("\t%d-%d: 0x%04X,\n", j, v.low, x)
127		}
128		fmt.Printf("}\n\n")
129	}
130}
131
132// interval is a half-open interval [low, high).
133type interval struct {
134	low, high int
135}
136
137func (i interval) len() int { return i.high - i.low }
138
139// byDecreasingLength sorts intervals by decreasing length.
140type byDecreasingLength []interval
141
142func (b byDecreasingLength) Len() int           { return len(b) }
143func (b byDecreasingLength) Less(i, j int) bool { return b[i].len() > b[j].len() }
144func (b byDecreasingLength) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
145