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-rw-r--r--src/pkg/unicode/letter.go326
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diff --git a/src/pkg/unicode/letter.go b/src/pkg/unicode/letter.go
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--- a/src/pkg/unicode/letter.go
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-// Copyright 2009 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 unicode provides data and functions to test some properties of
-// Unicode code points.
-package unicode
-
-const (
- MaxRune = 0x10FFFF // Maximum valid Unicode code point.
- ReplacementChar = 0xFFFD // Represents invalid code points.
- MaxASCII = 0x7F // maximum ASCII value.
- MaxLatin1 = 0xFF // maximum Latin-1 value.
-)
-
-// RangeTable defines a set of Unicode code points by listing the ranges of
-// code points within the set. The ranges are listed in two slices
-// to save space: a slice of 16-bit ranges and a slice of 32-bit ranges.
-// The two slices must be in sorted order and non-overlapping.
-// Also, R32 should contain only values >= 0x10000 (1<<16).
-type RangeTable struct {
- R16 []Range16
- R32 []Range32
-}
-
-// Range16 represents of a range of 16-bit Unicode code points. The range runs from Lo to Hi
-// inclusive and has the specified stride.
-type Range16 struct {
- Lo uint16
- Hi uint16
- Stride uint16
-}
-
-// Range32 represents of a range of Unicode code points and is used when one or
-// more of the values will not fit in 16 bits. The range runs from Lo to Hi
-// inclusive and has the specified stride. Lo and Hi must always be >= 1<<16.
-type Range32 struct {
- Lo uint32
- Hi uint32
- Stride uint32
-}
-
-// CaseRange represents a range of Unicode code points for simple (one
-// code point to one code point) case conversion.
-// The range runs from Lo to Hi inclusive, with a fixed stride of 1. Deltas
-// are the number to add to the code point to reach the code point for a
-// different case for that character. They may be negative. If zero, it
-// means the character is in the corresponding case. There is a special
-// case representing sequences of alternating corresponding Upper and Lower
-// pairs. It appears with a fixed Delta of
-// {UpperLower, UpperLower, UpperLower}
-// The constant UpperLower has an otherwise impossible delta value.
-type CaseRange struct {
- Lo uint32
- Hi uint32
- Delta d
-}
-
-// SpecialCase represents language-specific case mappings such as Turkish.
-// Methods of SpecialCase customize (by overriding) the standard mappings.
-type SpecialCase []CaseRange
-
-//BUG(r): Provide a mechanism for full case folding (those that involve
-// multiple runes in the input or output).
-
-// Indices into the Delta arrays inside CaseRanges for case mapping.
-const (
- UpperCase = iota
- LowerCase
- TitleCase
- MaxCase
-)
-
-type d [MaxCase]int32 // to make the CaseRanges text shorter
-
-// If the Delta field of a CaseRange is UpperLower or LowerUpper, it means
-// this CaseRange represents a sequence of the form (say)
-// Upper Lower Upper Lower.
-const (
- UpperLower = MaxRune + 1 // (Cannot be a valid delta.)
-)
-
-// is16 uses binary search to test whether rune is in the specified slice of 16-bit ranges.
-func is16(ranges []Range16, rune uint16) bool {
- // binary search over ranges
- lo := 0
- hi := len(ranges)
- for lo < hi {
- m := lo + (hi-lo)/2
- r := ranges[m]
- if r.Lo <= rune && rune <= r.Hi {
- return (rune-r.Lo)%r.Stride == 0
- }
- if rune < r.Lo {
- hi = m
- } else {
- lo = m + 1
- }
- }
- return false
-}
-
-// is32 uses binary search to test whether rune is in the specified slice of 32-bit ranges.
-func is32(ranges []Range32, rune uint32) bool {
- // binary search over ranges
- lo := 0
- hi := len(ranges)
- for lo < hi {
- m := lo + (hi-lo)/2
- r := ranges[m]
- if r.Lo <= rune && rune <= r.Hi {
- return (rune-r.Lo)%r.Stride == 0
- }
- if rune < r.Lo {
- hi = m
- } else {
- lo = m + 1
- }
- }
- return false
-}
-
-// Is tests whether rune is in the specified table of ranges.
-func Is(rangeTab *RangeTable, rune int) bool {
- // common case: rune is ASCII or Latin-1.
- if uint32(rune) <= MaxLatin1 {
- // Only need to check R16, since R32 is always >= 1<<16.
- r16 := uint16(rune)
- for _, r := range rangeTab.R16 {
- if r16 > r.Hi {
- continue
- }
- if r16 < r.Lo {
- return false
- }
- return (r16-r.Lo)%r.Stride == 0
- }
- return false
- }
- r16 := rangeTab.R16
- if len(r16) > 0 && rune <= int(r16[len(r16)-1].Hi) {
- return is16(r16, uint16(rune))
- }
- r32 := rangeTab.R32
- if len(r32) > 0 && rune >= int(r32[0].Lo) {
- return is32(r32, uint32(rune))
- }
- return false
-}
-
-// IsUpper reports whether the rune is an upper case letter.
-func IsUpper(rune int) bool {
- // See comment in IsGraphic.
- if uint32(rune) <= MaxLatin1 {
- return properties[uint8(rune)]&pLu != 0
- }
- return Is(Upper, rune)
-}
-
-// IsLower reports whether the rune is a lower case letter.
-func IsLower(rune int) bool {
- // See comment in IsGraphic.
- if uint32(rune) <= MaxLatin1 {
- return properties[uint8(rune)]&pLl != 0
- }
- return Is(Lower, rune)
-}
-
-// IsTitle reports whether the rune is a title case letter.
-func IsTitle(rune int) bool {
- if rune <= MaxLatin1 {
- return false
- }
- return Is(Title, rune)
-}
-
-// to maps the rune using the specified case mapping.
-func to(_case int, rune int, caseRange []CaseRange) int {
- if _case < 0 || MaxCase <= _case {
- return ReplacementChar // as reasonable an error as any
- }
- // binary search over ranges
- lo := 0
- hi := len(caseRange)
- for lo < hi {
- m := lo + (hi-lo)/2
- r := caseRange[m]
- if int(r.Lo) <= rune && rune <= int(r.Hi) {
- delta := int(r.Delta[_case])
- if delta > MaxRune {
- // In an Upper-Lower sequence, which always starts with
- // an UpperCase letter, the real deltas always look like:
- // {0, 1, 0} UpperCase (Lower is next)
- // {-1, 0, -1} LowerCase (Upper, Title are previous)
- // The characters at even offsets from the beginning of the
- // sequence are upper case; the ones at odd offsets are lower.
- // The correct mapping can be done by clearing or setting the low
- // bit in the sequence offset.
- // The constants UpperCase and TitleCase are even while LowerCase
- // is odd so we take the low bit from _case.
- return int(r.Lo) + ((rune-int(r.Lo))&^1 | _case&1)
- }
- return rune + delta
- }
- if rune < int(r.Lo) {
- hi = m
- } else {
- lo = m + 1
- }
- }
- return rune
-}
-
-// To maps the rune to the specified case: UpperCase, LowerCase, or TitleCase.
-func To(_case int, rune int) int {
- return to(_case, rune, CaseRanges)
-}
-
-// ToUpper maps the rune to upper case.
-func ToUpper(rune int) int {
- if rune <= MaxASCII {
- if 'a' <= rune && rune <= 'z' {
- rune -= 'a' - 'A'
- }
- return rune
- }
- return To(UpperCase, rune)
-}
-
-// ToLower maps the rune to lower case.
-func ToLower(rune int) int {
- if rune <= MaxASCII {
- if 'A' <= rune && rune <= 'Z' {
- rune += 'a' - 'A'
- }
- return rune
- }
- return To(LowerCase, rune)
-}
-
-// ToTitle maps the rune to title case.
-func ToTitle(rune int) int {
- if rune <= MaxASCII {
- if 'a' <= rune && rune <= 'z' { // title case is upper case for ASCII
- rune -= 'a' - 'A'
- }
- return rune
- }
- return To(TitleCase, rune)
-}
-
-// ToUpper maps the rune to upper case giving priority to the special mapping.
-func (special SpecialCase) ToUpper(rune int) int {
- r := to(UpperCase, rune, []CaseRange(special))
- if r == rune {
- r = ToUpper(rune)
- }
- return r
-}
-
-// ToTitle maps the rune to title case giving priority to the special mapping.
-func (special SpecialCase) ToTitle(rune int) int {
- r := to(TitleCase, rune, []CaseRange(special))
- if r == rune {
- r = ToTitle(rune)
- }
- return r
-}
-
-// ToLower maps the rune to lower case giving priority to the special mapping.
-func (special SpecialCase) ToLower(rune int) int {
- r := to(LowerCase, rune, []CaseRange(special))
- if r == rune {
- r = ToLower(rune)
- }
- return r
-}
-
-// caseOrbit is defined in tables.go as []foldPair. Right now all the
-// entries fit in uint16, so use uint16. If that changes, compilation
-// will fail (the constants in the composite literal will not fit in uint16)
-// and the types here can change to uint32.
-type foldPair struct {
- From uint16
- To uint16
-}
-
-// SimpleFold iterates over Unicode code points equivalent under
-// the Unicode-defined simple case folding. Among the code points
-// equivalent to rune (including rune itself), SimpleFold returns the
-// smallest r >= rune if one exists, or else the smallest r >= 0.
-//
-// For example:
-// SimpleFold('A') = 'a'
-// SimpleFold('a') = 'A'
-//
-// SimpleFold('K') = 'k'
-// SimpleFold('k') = '\u212A' (Kelvin symbol, K)
-// SimpleFold('\u212A') = 'K'
-//
-// SimpleFold('1') = '1'
-//
-func SimpleFold(rune int) int {
- // Consult caseOrbit table for special cases.
- lo := 0
- hi := len(caseOrbit)
- for lo < hi {
- m := lo + (hi-lo)/2
- if int(caseOrbit[m].From) < rune {
- lo = m + 1
- } else {
- hi = m
- }
- }
- if lo < len(caseOrbit) && int(caseOrbit[lo].From) == rune {
- return int(caseOrbit[lo].To)
- }
-
- // No folding specified. This is a one- or two-element
- // equivalence class containing rune and ToLower(rune)
- // and ToUpper(rune) if they are different from rune.
- if l := ToLower(rune); l != rune {
- return l
- }
- return ToUpper(rune)
-}