// Copyright 2013 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // +build ignore package main // This program generates tables.go: // go run maketables.go | gofmt > tables.go import ( "bufio" "fmt" "log" "net/http" "sort" "strings" ) func main() { fmt.Printf("// generated by go run maketables.go; DO NOT EDIT\n\n") fmt.Printf("// Package traditionalchinese provides Traditional Chinese encodings such as Big5.\n") fmt.Printf(`package traditionalchinese // import "golang.org/x/text/encoding/traditionalchinese"` + "\n\n") res, err := http.Get("http://encoding.spec.whatwg.org/index-big5.txt") if err != nil { log.Fatalf("Get: %v", err) } defer res.Body.Close() mapping := [65536]uint32{} reverse := [65536 * 4]uint16{} scanner := bufio.NewScanner(res.Body) for scanner.Scan() { s := strings.TrimSpace(scanner.Text()) if s == "" || s[0] == '#' { continue } x, y := uint16(0), uint32(0) if _, err := fmt.Sscanf(s, "%d 0x%x", &x, &y); err != nil { log.Fatalf("could not parse %q", s) } if x < 0 || 126*157 <= x { log.Fatalf("Big5 code %d is out of range", x) } mapping[x] = y // The WHATWG spec http://encoding.spec.whatwg.org/#indexes says that // "The index pointer for code point in index is the first pointer // corresponding to code point in index", which would normally mean // that the code below should be guarded by "if reverse[y] == 0", but // last instead of first seems to match the behavior of // "iconv -f UTF-8 -t BIG5". For example, U+8005 者 occurs twice in // http://encoding.spec.whatwg.org/index-big5.txt, as index 2148 // (encoded as "\x8e\xcd") and index 6543 (encoded as "\xaa\xcc") // and "echo 者 | iconv -f UTF-8 -t BIG5 | xxd" gives "\xaa\xcc". c0, c1 := x/157, x%157 if c1 < 0x3f { c1 += 0x40 } else { c1 += 0x62 } reverse[y] = (0x81+c0)<<8 | c1 } if err := scanner.Err(); err != nil { log.Fatalf("scanner error: %v", err) } fmt.Printf("// decode is the decoding table from Big5 code to Unicode.\n") fmt.Printf("// It is defined at http://encoding.spec.whatwg.org/index-big5.txt\n") fmt.Printf("var decode = [...]uint32{\n") for i, v := range mapping { if v != 0 { fmt.Printf("\t%d: 0x%08X,\n", i, v) } } fmt.Printf("}\n\n") // Any run of at least separation continuous zero entries in the reverse map will // be a separate encode table. const separation = 1024 intervals := []interval(nil) low, high := -1, -1 for i, v := range reverse { if v == 0 { continue } if low < 0 { low = i } else if i-high >= separation { if high >= 0 { intervals = append(intervals, interval{low, high}) } low = i } high = i + 1 } if high >= 0 { intervals = append(intervals, interval{low, high}) } sort.Sort(byDecreasingLength(intervals)) fmt.Printf("const numEncodeTables = %d\n\n", len(intervals)) fmt.Printf("// encodeX are the encoding tables from Unicode to Big5 code,\n") fmt.Printf("// sorted by decreasing length.\n") for i, v := range intervals { fmt.Printf("// encode%d: %5d entries for runes in [%6d, %6d).\n", i, v.len(), v.low, v.high) } fmt.Printf("\n") for i, v := range intervals { fmt.Printf("const encode%dLow, encode%dHigh = %d, %d\n\n", i, i, v.low, v.high) fmt.Printf("var encode%d = [...]uint16{\n", i) for j := v.low; j < v.high; j++ { x := reverse[j] if x == 0 { continue } fmt.Printf("\t%d-%d: 0x%04X,\n", j, v.low, x) } fmt.Printf("}\n\n") } } // interval is a half-open interval [low, high). type interval struct { low, high int } func (i interval) len() int { return i.high - i.low } // byDecreasingLength sorts intervals by decreasing length. type byDecreasingLength []interval func (b byDecreasingLength) Len() int { return len(b) } func (b byDecreasingLength) Less(i, j int) bool { return b[i].len() > b[j].len() } func (b byDecreasingLength) Swap(i, j int) { b[i], b[j] = b[j], b[i] }