route/vendor/golang.org/x/text/collate/collate.go

404 lines
9.4 KiB
Go

// 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.
// TODO: remove hard-coded versions when we have implemented fractional weights.
// The current implementation is incompatible with later CLDR versions.
//go:generate go run maketables.go -cldr=23 -unicode=6.2.0
// Package collate contains types for comparing and sorting Unicode strings
// according to a given collation order.
package collate // import "golang.org/x/text/collate"
import (
"bytes"
"strings"
"golang.org/x/text/internal/colltab"
"golang.org/x/text/language"
)
// Collator provides functionality for comparing strings for a given
// collation order.
type Collator struct {
options
sorter sorter
_iter [2]iter
}
func (c *Collator) iter(i int) *iter {
// TODO: evaluate performance for making the second iterator optional.
return &c._iter[i]
}
// Supported returns the list of languages for which collating differs from its parent.
func Supported() []language.Tag {
// TODO: use language.Coverage instead.
t := make([]language.Tag, len(tags))
copy(t, tags)
return t
}
func init() {
ids := strings.Split(availableLocales, ",")
tags = make([]language.Tag, len(ids))
for i, s := range ids {
tags[i] = language.Raw.MustParse(s)
}
}
var tags []language.Tag
// New returns a new Collator initialized for the given locale.
func New(t language.Tag, o ...Option) *Collator {
index := colltab.MatchLang(t, tags)
c := newCollator(getTable(locales[index]))
// Set options from the user-supplied tag.
c.setFromTag(t)
// Set the user-supplied options.
c.setOptions(o)
c.init()
return c
}
// NewFromTable returns a new Collator for the given Weighter.
func NewFromTable(w colltab.Weighter, o ...Option) *Collator {
c := newCollator(w)
c.setOptions(o)
c.init()
return c
}
func (c *Collator) init() {
if c.numeric {
c.t = colltab.NewNumericWeighter(c.t)
}
c._iter[0].init(c)
c._iter[1].init(c)
}
// Buffer holds keys generated by Key and KeyString.
type Buffer struct {
buf [4096]byte
key []byte
}
func (b *Buffer) init() {
if b.key == nil {
b.key = b.buf[:0]
}
}
// Reset clears the buffer from previous results generated by Key and KeyString.
func (b *Buffer) Reset() {
b.key = b.key[:0]
}
// Compare returns an integer comparing the two byte slices.
// The result will be 0 if a==b, -1 if a < b, and +1 if a > b.
func (c *Collator) Compare(a, b []byte) int {
// TODO: skip identical prefixes once we have a fast way to detect if a rune is
// part of a contraction. This would lead to roughly a 10% speedup for the colcmp regtest.
c.iter(0).SetInput(a)
c.iter(1).SetInput(b)
if res := c.compare(); res != 0 {
return res
}
if !c.ignore[colltab.Identity] {
return bytes.Compare(a, b)
}
return 0
}
// CompareString returns an integer comparing the two strings.
// The result will be 0 if a==b, -1 if a < b, and +1 if a > b.
func (c *Collator) CompareString(a, b string) int {
// TODO: skip identical prefixes once we have a fast way to detect if a rune is
// part of a contraction. This would lead to roughly a 10% speedup for the colcmp regtest.
c.iter(0).SetInputString(a)
c.iter(1).SetInputString(b)
if res := c.compare(); res != 0 {
return res
}
if !c.ignore[colltab.Identity] {
if a < b {
return -1
} else if a > b {
return 1
}
}
return 0
}
func compareLevel(f func(i *iter) int, a, b *iter) int {
a.pce = 0
b.pce = 0
for {
va := f(a)
vb := f(b)
if va != vb {
if va < vb {
return -1
}
return 1
} else if va == 0 {
break
}
}
return 0
}
func (c *Collator) compare() int {
ia, ib := c.iter(0), c.iter(1)
// Process primary level
if c.alternate != altShifted {
// TODO: implement script reordering
if res := compareLevel((*iter).nextPrimary, ia, ib); res != 0 {
return res
}
} else {
// TODO: handle shifted
}
if !c.ignore[colltab.Secondary] {
f := (*iter).nextSecondary
if c.backwards {
f = (*iter).prevSecondary
}
if res := compareLevel(f, ia, ib); res != 0 {
return res
}
}
// TODO: special case handling (Danish?)
if !c.ignore[colltab.Tertiary] || c.caseLevel {
if res := compareLevel((*iter).nextTertiary, ia, ib); res != 0 {
return res
}
if !c.ignore[colltab.Quaternary] {
if res := compareLevel((*iter).nextQuaternary, ia, ib); res != 0 {
return res
}
}
}
return 0
}
// Key returns the collation key for str.
// Passing the buffer buf may avoid memory allocations.
// The returned slice will point to an allocation in Buffer and will remain
// valid until the next call to buf.Reset().
func (c *Collator) Key(buf *Buffer, str []byte) []byte {
// See http://www.unicode.org/reports/tr10/#Main_Algorithm for more details.
buf.init()
return c.key(buf, c.getColElems(str))
}
// KeyFromString returns the collation key for str.
// Passing the buffer buf may avoid memory allocations.
// The returned slice will point to an allocation in Buffer and will retain
// valid until the next call to buf.ResetKeys().
func (c *Collator) KeyFromString(buf *Buffer, str string) []byte {
// See http://www.unicode.org/reports/tr10/#Main_Algorithm for more details.
buf.init()
return c.key(buf, c.getColElemsString(str))
}
func (c *Collator) key(buf *Buffer, w []colltab.Elem) []byte {
processWeights(c.alternate, c.t.Top(), w)
kn := len(buf.key)
c.keyFromElems(buf, w)
return buf.key[kn:]
}
func (c *Collator) getColElems(str []byte) []colltab.Elem {
i := c.iter(0)
i.SetInput(str)
for i.Next() {
}
return i.Elems
}
func (c *Collator) getColElemsString(str string) []colltab.Elem {
i := c.iter(0)
i.SetInputString(str)
for i.Next() {
}
return i.Elems
}
type iter struct {
wa [512]colltab.Elem
colltab.Iter
pce int
}
func (i *iter) init(c *Collator) {
i.Weighter = c.t
i.Elems = i.wa[:0]
}
func (i *iter) nextPrimary() int {
for {
for ; i.pce < i.N; i.pce++ {
if v := i.Elems[i.pce].Primary(); v != 0 {
i.pce++
return v
}
}
if !i.Next() {
return 0
}
}
panic("should not reach here")
}
func (i *iter) nextSecondary() int {
for ; i.pce < len(i.Elems); i.pce++ {
if v := i.Elems[i.pce].Secondary(); v != 0 {
i.pce++
return v
}
}
return 0
}
func (i *iter) prevSecondary() int {
for ; i.pce < len(i.Elems); i.pce++ {
if v := i.Elems[len(i.Elems)-i.pce-1].Secondary(); v != 0 {
i.pce++
return v
}
}
return 0
}
func (i *iter) nextTertiary() int {
for ; i.pce < len(i.Elems); i.pce++ {
if v := i.Elems[i.pce].Tertiary(); v != 0 {
i.pce++
return int(v)
}
}
return 0
}
func (i *iter) nextQuaternary() int {
for ; i.pce < len(i.Elems); i.pce++ {
if v := i.Elems[i.pce].Quaternary(); v != 0 {
i.pce++
return v
}
}
return 0
}
func appendPrimary(key []byte, p int) []byte {
// Convert to variable length encoding; supports up to 23 bits.
if p <= 0x7FFF {
key = append(key, uint8(p>>8), uint8(p))
} else {
key = append(key, uint8(p>>16)|0x80, uint8(p>>8), uint8(p))
}
return key
}
// keyFromElems converts the weights ws to a compact sequence of bytes.
// The result will be appended to the byte buffer in buf.
func (c *Collator) keyFromElems(buf *Buffer, ws []colltab.Elem) {
for _, v := range ws {
if w := v.Primary(); w > 0 {
buf.key = appendPrimary(buf.key, w)
}
}
if !c.ignore[colltab.Secondary] {
buf.key = append(buf.key, 0, 0)
// TODO: we can use one 0 if we can guarantee that all non-zero weights are > 0xFF.
if !c.backwards {
for _, v := range ws {
if w := v.Secondary(); w > 0 {
buf.key = append(buf.key, uint8(w>>8), uint8(w))
}
}
} else {
for i := len(ws) - 1; i >= 0; i-- {
if w := ws[i].Secondary(); w > 0 {
buf.key = append(buf.key, uint8(w>>8), uint8(w))
}
}
}
} else if c.caseLevel {
buf.key = append(buf.key, 0, 0)
}
if !c.ignore[colltab.Tertiary] || c.caseLevel {
buf.key = append(buf.key, 0, 0)
for _, v := range ws {
if w := v.Tertiary(); w > 0 {
buf.key = append(buf.key, uint8(w))
}
}
// Derive the quaternary weights from the options and other levels.
// Note that we represent MaxQuaternary as 0xFF. The first byte of the
// representation of a primary weight is always smaller than 0xFF,
// so using this single byte value will compare correctly.
if !c.ignore[colltab.Quaternary] && c.alternate >= altShifted {
if c.alternate == altShiftTrimmed {
lastNonFFFF := len(buf.key)
buf.key = append(buf.key, 0)
for _, v := range ws {
if w := v.Quaternary(); w == colltab.MaxQuaternary {
buf.key = append(buf.key, 0xFF)
} else if w > 0 {
buf.key = appendPrimary(buf.key, w)
lastNonFFFF = len(buf.key)
}
}
buf.key = buf.key[:lastNonFFFF]
} else {
buf.key = append(buf.key, 0)
for _, v := range ws {
if w := v.Quaternary(); w == colltab.MaxQuaternary {
buf.key = append(buf.key, 0xFF)
} else if w > 0 {
buf.key = appendPrimary(buf.key, w)
}
}
}
}
}
}
func processWeights(vw alternateHandling, top uint32, wa []colltab.Elem) {
ignore := false
vtop := int(top)
switch vw {
case altShifted, altShiftTrimmed:
for i := range wa {
if p := wa[i].Primary(); p <= vtop && p != 0 {
wa[i] = colltab.MakeQuaternary(p)
ignore = true
} else if p == 0 {
if ignore {
wa[i] = colltab.Ignore
}
} else {
ignore = false
}
}
case altBlanked:
for i := range wa {
if p := wa[i].Primary(); p <= vtop && (ignore || p != 0) {
wa[i] = colltab.Ignore
ignore = true
} else {
ignore = false
}
}
}
}