mirror of https://github.com/tidwall/tile38.git
116 lines
3.1 KiB
Go
116 lines
3.1 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ignore
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// This program generates the trie for width operations. The generated table
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// includes width category information as well as the normalization mappings.
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package main
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import (
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"bytes"
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"fmt"
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"io"
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"log"
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"math"
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"unicode/utf8"
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"golang.org/x/text/internal/gen"
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"golang.org/x/text/internal/triegen"
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)
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// See gen_common.go for flags.
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func main() {
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gen.Init()
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genTables()
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genTests()
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gen.Repackage("gen_trieval.go", "trieval.go", "width")
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gen.Repackage("gen_common.go", "common_test.go", "width")
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}
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func genTables() {
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t := triegen.NewTrie("width")
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// fold and inverse mappings. See mapComment for a description of the format
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// of each entry. Add dummy value to make an index of 0 mean no mapping.
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inverse := [][4]byte{{}}
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mapping := map[[4]byte]int{[4]byte{}: 0}
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getWidthData(func(r rune, tag elem, alt rune) {
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idx := 0
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if alt != 0 {
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var buf [4]byte
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buf[0] = byte(utf8.EncodeRune(buf[1:], alt))
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s := string(r)
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buf[buf[0]] ^= s[len(s)-1]
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var ok bool
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if idx, ok = mapping[buf]; !ok {
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idx = len(mapping)
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if idx > math.MaxUint8 {
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log.Fatalf("Index %d does not fit in a byte.", idx)
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}
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mapping[buf] = idx
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inverse = append(inverse, buf)
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}
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}
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t.Insert(r, uint64(tag|elem(idx)))
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})
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w := &bytes.Buffer{}
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gen.WriteUnicodeVersion(w)
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sz, err := t.Gen(w)
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if err != nil {
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log.Fatal(err)
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}
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sz += writeMappings(w, inverse)
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fmt.Fprintf(w, "// Total table size %d bytes (%dKiB)\n", sz, sz/1024)
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gen.WriteGoFile(*outputFile, "width", w.Bytes())
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}
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const inverseDataComment = `
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// inverseData contains 4-byte entries of the following format:
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// <length> <modified UTF-8-encoded rune> <0 padding>
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// The last byte of the UTF-8-encoded rune is xor-ed with the last byte of the
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// UTF-8 encoding of the original rune. Mappings often have the following
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// pattern:
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// Ａ -> A (U+FF21 -> U+0041)
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// Ｂ -> B (U+FF22 -> U+0042)
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// ...
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// By xor-ing the last byte the same entry can be shared by many mappings. This
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// reduces the total number of distinct entries by about two thirds.
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// The resulting entry for the aforementioned mappings is
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// { 0x01, 0xE0, 0x00, 0x00 }
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// Using this entry to map U+FF21 (UTF-8 [EF BC A1]), we get
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// E0 ^ A1 = 41.
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// Similarly, for U+FF22 (UTF-8 [EF BC A2]), we get
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// E0 ^ A2 = 42.
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// Note that because of the xor-ing, the byte sequence stored in the entry is
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// not valid UTF-8.`
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func writeMappings(w io.Writer, data [][4]byte) int {
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fmt.Fprintln(w, inverseDataComment)
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fmt.Fprintf(w, "var inverseData = [%d][4]byte{\n", len(data))
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for _, x := range data {
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fmt.Fprintf(w, "{ 0x%02x, 0x%02x, 0x%02x, 0x%02x },\n", x[0], x[1], x[2], x[3])
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}
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fmt.Fprintln(w, "}")
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return len(data) * 4
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}
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func genTests() {
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w := &bytes.Buffer{}
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fmt.Fprintf(w, "\nvar mapRunes = map[rune]struct{r rune; e elem}{\n")
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getWidthData(func(r rune, tag elem, alt rune) {
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if alt != 0 {
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fmt.Fprintf(w, "\t0x%X: {0x%X, 0x%X},\n", r, alt, tag)
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}
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})
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fmt.Fprintln(w, "}")
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gen.WriteGoFile("runes_test.go", "width", w.Bytes())
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}
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