+++ /dev/null
-// Copyright 2012 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.
-
-package build
-
-import (
- "fmt"
- "io"
- "reflect"
- "sort"
- "strings"
-
- "golang.org/x/text/internal/colltab"
-)
-
-// This file contains code for detecting contractions and generating
-// the necessary tables.
-// Any Unicode Collation Algorithm (UCA) table entry that has more than
-// one rune one the left-hand side is called a contraction.
-// See http://www.unicode.org/reports/tr10/#Contractions for more details.
-//
-// We define the following terms:
-// initial: a rune that appears as the first rune in a contraction.
-// suffix: a sequence of runes succeeding the initial rune
-// in a given contraction.
-// non-initial: a rune that appears in a suffix.
-//
-// A rune may be both a initial and a non-initial and may be so in
-// many contractions. An initial may typically also appear by itself.
-// In case of ambiguities, the UCA requires we match the longest
-// contraction.
-//
-// Many contraction rules share the same set of possible suffixes.
-// We store sets of suffixes in a trie that associates an index with
-// each suffix in the set. This index can be used to look up a
-// collation element associated with the (starter rune, suffix) pair.
-//
-// The trie is defined on a UTF-8 byte sequence.
-// The overall trie is represented as an array of ctEntries. Each node of the trie
-// is represented as a subsequence of ctEntries, where each entry corresponds to
-// a possible match of a next character in the search string. An entry
-// also includes the length and offset to the next sequence of entries
-// to check in case of a match.
-
-const (
- final = 0
- noIndex = 0xFF
-)
-
-// ctEntry associates to a matching byte an offset and/or next sequence of
-// bytes to check. A ctEntry c is called final if a match means that the
-// longest suffix has been found. An entry c is final if c.N == 0.
-// A single final entry can match a range of characters to an offset.
-// A non-final entry always matches a single byte. Note that a non-final
-// entry might still resemble a completed suffix.
-// Examples:
-// The suffix strings "ab" and "ac" can be represented as:
-// []ctEntry{
-// {'a', 1, 1, noIndex}, // 'a' by itself does not match, so i is 0xFF.
-// {'b', 'c', 0, 1}, // "ab" -> 1, "ac" -> 2
-// }
-//
-// The suffix strings "ab", "abc", "abd", and "abcd" can be represented as:
-// []ctEntry{
-// {'a', 1, 1, noIndex}, // 'a' must be followed by 'b'.
-// {'b', 1, 2, 1}, // "ab" -> 1, may be followed by 'c' or 'd'.
-// {'d', 'd', final, 3}, // "abd" -> 3
-// {'c', 4, 1, 2}, // "abc" -> 2, may be followed by 'd'.
-// {'d', 'd', final, 4}, // "abcd" -> 4
-// }
-// See genStateTests in contract_test.go for more examples.
-type ctEntry struct {
- L uint8 // non-final: byte value to match; final: lowest match in range.
- H uint8 // non-final: relative index to next block; final: highest match in range.
- N uint8 // non-final: length of next block; final: final
- I uint8 // result offset. Will be noIndex if more bytes are needed to complete.
-}
-
-// contractTrieSet holds a set of contraction tries. The tries are stored
-// consecutively in the entry field.
-type contractTrieSet []struct{ l, h, n, i uint8 }
-
-// ctHandle is used to identify a trie in the trie set, consisting in an offset
-// in the array and the size of the first node.
-type ctHandle struct {
- index, n int
-}
-
-// appendTrie adds a new trie for the given suffixes to the trie set and returns
-// a handle to it. The handle will be invalid on error.
-func appendTrie(ct *colltab.ContractTrieSet, suffixes []string) (ctHandle, error) {
- es := make([]stridx, len(suffixes))
- for i, s := range suffixes {
- es[i].str = s
- }
- sort.Sort(offsetSort(es))
- for i := range es {
- es[i].index = i + 1
- }
- sort.Sort(genidxSort(es))
- i := len(*ct)
- n, err := genStates(ct, es)
- if err != nil {
- *ct = (*ct)[:i]
- return ctHandle{}, err
- }
- return ctHandle{i, n}, nil
-}
-
-// genStates generates ctEntries for a given suffix set and returns
-// the number of entries for the first node.
-func genStates(ct *colltab.ContractTrieSet, sis []stridx) (int, error) {
- if len(sis) == 0 {
- return 0, fmt.Errorf("genStates: list of suffices must be non-empty")
- }
- start := len(*ct)
- // create entries for differing first bytes.
- for _, si := range sis {
- s := si.str
- if len(s) == 0 {
- continue
- }
- added := false
- c := s[0]
- if len(s) > 1 {
- for j := len(*ct) - 1; j >= start; j-- {
- if (*ct)[j].L == c {
- added = true
- break
- }
- }
- if !added {
- *ct = append(*ct, ctEntry{L: c, I: noIndex})
- }
- } else {
- for j := len(*ct) - 1; j >= start; j-- {
- // Update the offset for longer suffixes with the same byte.
- if (*ct)[j].L == c {
- (*ct)[j].I = uint8(si.index)
- added = true
- }
- // Extend range of final ctEntry, if possible.
- if (*ct)[j].H+1 == c {
- (*ct)[j].H = c
- added = true
- }
- }
- if !added {
- *ct = append(*ct, ctEntry{L: c, H: c, N: final, I: uint8(si.index)})
- }
- }
- }
- n := len(*ct) - start
- // Append nodes for the remainder of the suffixes for each ctEntry.
- sp := 0
- for i, end := start, len(*ct); i < end; i++ {
- fe := (*ct)[i]
- if fe.H == 0 { // uninitialized non-final
- ln := len(*ct) - start - n
- if ln > 0xFF {
- return 0, fmt.Errorf("genStates: relative block offset too large: %d > 255", ln)
- }
- fe.H = uint8(ln)
- // Find first non-final strings with same byte as current entry.
- for ; sis[sp].str[0] != fe.L; sp++ {
- }
- se := sp + 1
- for ; se < len(sis) && len(sis[se].str) > 1 && sis[se].str[0] == fe.L; se++ {
- }
- sl := sis[sp:se]
- sp = se
- for i, si := range sl {
- sl[i].str = si.str[1:]
- }
- nn, err := genStates(ct, sl)
- if err != nil {
- return 0, err
- }
- fe.N = uint8(nn)
- (*ct)[i] = fe
- }
- }
- sort.Sort(entrySort((*ct)[start : start+n]))
- return n, nil
-}
-
-// There may be both a final and non-final entry for a byte if the byte
-// is implied in a range of matches in the final entry.
-// We need to ensure that the non-final entry comes first in that case.
-type entrySort colltab.ContractTrieSet
-
-func (fe entrySort) Len() int { return len(fe) }
-func (fe entrySort) Swap(i, j int) { fe[i], fe[j] = fe[j], fe[i] }
-func (fe entrySort) Less(i, j int) bool {
- return fe[i].L > fe[j].L
-}
-
-// stridx is used for sorting suffixes and their associated offsets.
-type stridx struct {
- str string
- index int
-}
-
-// For computing the offsets, we first sort by size, and then by string.
-// This ensures that strings that only differ in the last byte by 1
-// are sorted consecutively in increasing order such that they can
-// be packed as a range in a final ctEntry.
-type offsetSort []stridx
-
-func (si offsetSort) Len() int { return len(si) }
-func (si offsetSort) Swap(i, j int) { si[i], si[j] = si[j], si[i] }
-func (si offsetSort) Less(i, j int) bool {
- if len(si[i].str) != len(si[j].str) {
- return len(si[i].str) > len(si[j].str)
- }
- return si[i].str < si[j].str
-}
-
-// For indexing, we want to ensure that strings are sorted in string order, where
-// for strings with the same prefix, we put longer strings before shorter ones.
-type genidxSort []stridx
-
-func (si genidxSort) Len() int { return len(si) }
-func (si genidxSort) Swap(i, j int) { si[i], si[j] = si[j], si[i] }
-func (si genidxSort) Less(i, j int) bool {
- if strings.HasPrefix(si[j].str, si[i].str) {
- return false
- }
- if strings.HasPrefix(si[i].str, si[j].str) {
- return true
- }
- return si[i].str < si[j].str
-}
-
-// lookup matches the longest suffix in str and returns the associated offset
-// and the number of bytes consumed.
-func lookup(ct *colltab.ContractTrieSet, h ctHandle, str []byte) (index, ns int) {
- states := (*ct)[h.index:]
- p := 0
- n := h.n
- for i := 0; i < n && p < len(str); {
- e := states[i]
- c := str[p]
- if c >= e.L {
- if e.L == c {
- p++
- if e.I != noIndex {
- index, ns = int(e.I), p
- }
- if e.N != final {
- // set to new state
- i, states, n = 0, states[int(e.H)+n:], int(e.N)
- } else {
- return
- }
- continue
- } else if e.N == final && c <= e.H {
- p++
- return int(c-e.L) + int(e.I), p
- }
- }
- i++
- }
- return
-}
-
-// print writes the contractTrieSet t as compilable Go code to w. It returns
-// the total number of bytes written and the size of the resulting data structure in bytes.
-func print(t *colltab.ContractTrieSet, w io.Writer, name string) (n, size int, err error) {
- update3 := func(nn, sz int, e error) {
- n += nn
- if err == nil {
- err = e
- }
- size += sz
- }
- update2 := func(nn int, e error) { update3(nn, 0, e) }
-
- update3(printArray(*t, w, name))
- update2(fmt.Fprintf(w, "var %sContractTrieSet = ", name))
- update3(printStruct(*t, w, name))
- update2(fmt.Fprintln(w))
- return
-}
-
-func printArray(ct colltab.ContractTrieSet, w io.Writer, name string) (n, size int, err error) {
- p := func(f string, a ...interface{}) {
- nn, e := fmt.Fprintf(w, f, a...)
- n += nn
- if err == nil {
- err = e
- }
- }
- size = len(ct) * 4
- p("// %sCTEntries: %d entries, %d bytes\n", name, len(ct), size)
- p("var %sCTEntries = [%d]struct{L,H,N,I uint8}{\n", name, len(ct))
- for _, fe := range ct {
- p("\t{0x%X, 0x%X, %d, %d},\n", fe.L, fe.H, fe.N, fe.I)
- }
- p("}\n")
- return
-}
-
-func printStruct(ct colltab.ContractTrieSet, w io.Writer, name string) (n, size int, err error) {
- n, err = fmt.Fprintf(w, "colltab.ContractTrieSet( %sCTEntries[:] )", name)
- size = int(reflect.TypeOf(ct).Size())
- return
-}
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