restic/vendor/golang.org/x/text/collate/build/builder.go

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// 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 "golang.org/x/text/collate/build"
import (
"fmt"
"io"
"log"
"sort"
"strings"
"unicode/utf8"
"golang.org/x/text/internal/colltab"
"golang.org/x/text/language"
"golang.org/x/text/unicode/norm"
)
// TODO: optimizations:
// - expandElem is currently 20K. By putting unique colElems in a separate
// table and having a byte array of indexes into this table, we can reduce
// the total size to about 7K. By also factoring out the length bytes, we
// can reduce this to about 6K.
// - trie valueBlocks are currently 100K. There are a lot of sparse blocks
// and many consecutive values with the same stride. This can be further
// compacted.
// - Compress secondary weights into 8 bits.
// - Some LDML specs specify a context element. Currently we simply concatenate
// those. Context can be implemented using the contraction trie. If Builder
// could analyze and detect when using a context makes sense, there is no
// need to expose this construct in the API.
// A Builder builds a root collation table. The user must specify the
// collation elements for each entry. A common use will be to base the weights
// on those specified in the allkeys* file as provided by the UCA or CLDR.
type Builder struct {
index *trieBuilder
root ordering
locale []*Tailoring
t *table
err error
built bool
minNonVar int // lowest primary recorded for a variable
varTop int // highest primary recorded for a non-variable
// indexes used for reusing expansions and contractions
expIndex map[string]int // positions of expansions keyed by their string representation
ctHandle map[string]ctHandle // contraction handles keyed by a concatenation of the suffixes
ctElem map[string]int // contraction elements keyed by their string representation
}
// A Tailoring builds a collation table based on another collation table.
// The table is defined by specifying tailorings to the underlying table.
// See http://unicode.org/reports/tr35/ for an overview of tailoring
// collation tables. The CLDR contains pre-defined tailorings for a variety
// of languages (See http://www.unicode.org/Public/cldr/<version>/core.zip.)
type Tailoring struct {
id string
builder *Builder
index *ordering
anchor *entry
before bool
}
// NewBuilder returns a new Builder.
func NewBuilder() *Builder {
return &Builder{
index: newTrieBuilder(),
root: makeRootOrdering(),
expIndex: make(map[string]int),
ctHandle: make(map[string]ctHandle),
ctElem: make(map[string]int),
}
}
// Tailoring returns a Tailoring for the given locale. One should
// have completed all calls to Add before calling Tailoring.
func (b *Builder) Tailoring(loc language.Tag) *Tailoring {
t := &Tailoring{
id: loc.String(),
builder: b,
index: b.root.clone(),
}
t.index.id = t.id
b.locale = append(b.locale, t)
return t
}
// Add adds an entry to the collation element table, mapping
// a slice of runes to a sequence of collation elements.
// A collation element is specified as list of weights: []int{primary, secondary, ...}.
// The entries are typically obtained from a collation element table
// as defined in http://www.unicode.org/reports/tr10/#Data_Table_Format.
// Note that the collation elements specified by colelems are only used
// as a guide. The actual weights generated by Builder may differ.
// The argument variables is a list of indices into colelems that should contain
// a value for each colelem that is a variable. (See the reference above.)
func (b *Builder) Add(runes []rune, colelems [][]int, variables []int) error {
str := string(runes)
elems := make([]rawCE, len(colelems))
for i, ce := range colelems {
if len(ce) == 0 {
break
}
elems[i] = makeRawCE(ce, 0)
if len(ce) == 1 {
elems[i].w[1] = defaultSecondary
}
if len(ce) <= 2 {
elems[i].w[2] = defaultTertiary
}
if len(ce) <= 3 {
elems[i].w[3] = ce[0]
}
}
for i, ce := range elems {
p := ce.w[0]
isvar := false
for _, j := range variables {
if i == j {
isvar = true
}
}
if isvar {
if p >= b.minNonVar && b.minNonVar > 0 {
return fmt.Errorf("primary value %X of variable is larger than the smallest non-variable %X", p, b.minNonVar)
}
if p > b.varTop {
b.varTop = p
}
} else if p > 1 { // 1 is a special primary value reserved for FFFE
if p <= b.varTop {
return fmt.Errorf("primary value %X of non-variable is smaller than the highest variable %X", p, b.varTop)
}
if b.minNonVar == 0 || p < b.minNonVar {
b.minNonVar = p
}
}
}
elems, err := convertLargeWeights(elems)
if err != nil {
return err
}
cccs := []uint8{}
nfd := norm.NFD.String(str)
for i := range nfd {
cccs = append(cccs, norm.NFD.PropertiesString(nfd[i:]).CCC())
}
if len(cccs) < len(elems) {
if len(cccs) > 2 {
return fmt.Errorf("number of decomposed characters should be greater or equal to the number of collation elements for len(colelems) > 3 (%d < %d)", len(cccs), len(elems))
}
p := len(elems) - 1
for ; p > 0 && elems[p].w[0] == 0; p-- {
elems[p].ccc = cccs[len(cccs)-1]
}
for ; p >= 0; p-- {
elems[p].ccc = cccs[0]
}
} else {
for i := range elems {
elems[i].ccc = cccs[i]
}
}
// doNorm in collate.go assumes that the following conditions hold.
if len(elems) > 1 && len(cccs) > 1 && cccs[0] != 0 && cccs[0] != cccs[len(cccs)-1] {
return fmt.Errorf("incompatible CCC values for expansion %X (%d)", runes, cccs)
}
b.root.newEntry(str, elems)
return nil
}
func (t *Tailoring) setAnchor(anchor string) error {
anchor = norm.NFC.String(anchor)
a := t.index.find(anchor)
if a == nil {
a = t.index.newEntry(anchor, nil)
a.implicit = true
a.modified = true
for _, r := range []rune(anchor) {
e := t.index.find(string(r))
e.lock = true
}
}
t.anchor = a
return nil
}
// SetAnchor sets the point after which elements passed in subsequent calls to
// Insert will be inserted. It is equivalent to the reset directive in an LDML
// specification. See Insert for an example.
// SetAnchor supports the following logical reset positions:
// <first_tertiary_ignorable/>, <last_teriary_ignorable/>, <first_primary_ignorable/>,
// and <last_non_ignorable/>.
func (t *Tailoring) SetAnchor(anchor string) error {
if err := t.setAnchor(anchor); err != nil {
return err
}
t.before = false
return nil
}
// SetAnchorBefore is similar to SetAnchor, except that subsequent calls to
// Insert will insert entries before the anchor.
func (t *Tailoring) SetAnchorBefore(anchor string) error {
if err := t.setAnchor(anchor); err != nil {
return err
}
t.before = true
return nil
}
// Insert sets the ordering of str relative to the entry set by the previous
// call to SetAnchor or Insert. The argument extend corresponds
// to the extend elements as defined in LDML. A non-empty value for extend
// will cause the collation elements corresponding to extend to be appended
// to the collation elements generated for the entry added by Insert.
// This has the same net effect as sorting str after the string anchor+extend.
// See http://www.unicode.org/reports/tr10/#Tailoring_Example for details
// on parametric tailoring and http://unicode.org/reports/tr35/#Collation_Elements
// for full details on LDML.
//
// Examples: create a tailoring for Swedish, where "ä" is ordered after "z"
// at the primary sorting level:
// t := b.Tailoring("se")
// t.SetAnchor("z")
// t.Insert(colltab.Primary, "ä", "")
// Order "ü" after "ue" at the secondary sorting level:
// t.SetAnchor("ue")
// t.Insert(colltab.Secondary, "ü","")
// or
// t.SetAnchor("u")
// t.Insert(colltab.Secondary, "ü", "e")
// Order "q" afer "ab" at the secondary level and "Q" after "q"
// at the tertiary level:
// t.SetAnchor("ab")
// t.Insert(colltab.Secondary, "q", "")
// t.Insert(colltab.Tertiary, "Q", "")
// Order "b" before "a":
// t.SetAnchorBefore("a")
// t.Insert(colltab.Primary, "b", "")
// Order "0" after the last primary ignorable:
// t.SetAnchor("<last_primary_ignorable/>")
// t.Insert(colltab.Primary, "0", "")
func (t *Tailoring) Insert(level colltab.Level, str, extend string) error {
if t.anchor == nil {
return fmt.Errorf("%s:Insert: no anchor point set for tailoring of %s", t.id, str)
}
str = norm.NFC.String(str)
e := t.index.find(str)
if e == nil {
e = t.index.newEntry(str, nil)
} else if e.logical != noAnchor {
return fmt.Errorf("%s:Insert: cannot reinsert logical reset position %q", t.id, e.str)
}
if e.lock {
return fmt.Errorf("%s:Insert: cannot reinsert element %q", t.id, e.str)
}
a := t.anchor
// Find the first element after the anchor which differs at a level smaller or
// equal to the given level. Then insert at this position.
// See http://unicode.org/reports/tr35/#Collation_Elements, Section 5.14.5 for details.
e.before = t.before
if t.before {
t.before = false
if a.prev == nil {
a.insertBefore(e)
} else {
for a = a.prev; a.level > level; a = a.prev {
}
a.insertAfter(e)
}
e.level = level
} else {
for ; a.level > level; a = a.next {
}
e.level = a.level
if a != e {
a.insertAfter(e)
a.level = level
} else {
// We don't set a to prev itself. This has the effect of the entry
// getting new collation elements that are an increment of itself.
// This is intentional.
a.prev.level = level
}
}
e.extend = norm.NFD.String(extend)
e.exclude = false
e.modified = true
e.elems = nil
t.anchor = e
return nil
}
func (o *ordering) getWeight(e *entry) []rawCE {
if len(e.elems) == 0 && e.logical == noAnchor {
if e.implicit {
for _, r := range e.runes {
e.elems = append(e.elems, o.getWeight(o.find(string(r)))...)
}
} else if e.before {
count := [colltab.Identity + 1]int{}
a := e
for ; a.elems == nil && !a.implicit; a = a.next {
count[a.level]++
}
e.elems = []rawCE{makeRawCE(a.elems[0].w, a.elems[0].ccc)}
for i := colltab.Primary; i < colltab.Quaternary; i++ {
if count[i] != 0 {
e.elems[0].w[i] -= count[i]
break
}
}
if e.prev != nil {
o.verifyWeights(e.prev, e, e.prev.level)
}
} else {
prev := e.prev
e.elems = nextWeight(prev.level, o.getWeight(prev))
o.verifyWeights(e, e.next, e.level)
}
}
return e.elems
}
func (o *ordering) addExtension(e *entry) {
if ex := o.find(e.extend); ex != nil {
e.elems = append(e.elems, ex.elems...)
} else {
for _, r := range []rune(e.extend) {
e.elems = append(e.elems, o.find(string(r)).elems...)
}
}
e.extend = ""
}
func (o *ordering) verifyWeights(a, b *entry, level colltab.Level) error {
if level == colltab.Identity || b == nil || b.elems == nil || a.elems == nil {
return nil
}
for i := colltab.Primary; i < level; i++ {
if a.elems[0].w[i] < b.elems[0].w[i] {
return nil
}
}
if a.elems[0].w[level] >= b.elems[0].w[level] {
err := fmt.Errorf("%s:overflow: collation elements of %q (%X) overflows those of %q (%X) at level %d (%X >= %X)", o.id, a.str, a.runes, b.str, b.runes, level, a.elems, b.elems)
log.Println(err)
// TODO: return the error instead, or better, fix the conflicting entry by making room.
}
return nil
}
func (b *Builder) error(e error) {
if e != nil {
b.err = e
}
}
func (b *Builder) errorID(locale string, e error) {
if e != nil {
b.err = fmt.Errorf("%s:%v", locale, e)
}
}
// patchNorm ensures that NFC and NFD counterparts are consistent.
func (o *ordering) patchNorm() {
// Insert the NFD counterparts, if necessary.
for _, e := range o.ordered {
nfd := norm.NFD.String(e.str)
if nfd != e.str {
if e0 := o.find(nfd); e0 != nil && !e0.modified {
e0.elems = e.elems
} else if e.modified && !equalCEArrays(o.genColElems(nfd), e.elems) {
e := o.newEntry(nfd, e.elems)
e.modified = true
}
}
}
// Update unchanged composed forms if one of their parts changed.
for _, e := range o.ordered {
nfd := norm.NFD.String(e.str)
if e.modified || nfd == e.str {
continue
}
if e0 := o.find(nfd); e0 != nil {
e.elems = e0.elems
} else {
e.elems = o.genColElems(nfd)
if norm.NFD.LastBoundary([]byte(nfd)) == 0 {
r := []rune(nfd)
head := string(r[0])
tail := ""
for i := 1; i < len(r); i++ {
s := norm.NFC.String(head + string(r[i]))
if e0 := o.find(s); e0 != nil && e0.modified {
head = s
} else {
tail += string(r[i])
}
}
e.elems = append(o.genColElems(head), o.genColElems(tail)...)
}
}
}
// Exclude entries for which the individual runes generate the same collation elements.
for _, e := range o.ordered {
if len(e.runes) > 1 && equalCEArrays(o.genColElems(e.str), e.elems) {
e.exclude = true
}
}
}
func (b *Builder) buildOrdering(o *ordering) {
for _, e := range o.ordered {
o.getWeight(e)
}
for _, e := range o.ordered {
o.addExtension(e)
}
o.patchNorm()
o.sort()
simplify(o)
b.processExpansions(o) // requires simplify
b.processContractions(o) // requires simplify
t := newNode()
for e := o.front(); e != nil; e, _ = e.nextIndexed() {
if !e.skip() {
ce, err := e.encode()
b.errorID(o.id, err)
t.insert(e.runes[0], ce)
}
}
o.handle = b.index.addTrie(t)
}
func (b *Builder) build() (*table, error) {
if b.built {
return b.t, b.err
}
b.built = true
b.t = &table{
Table: colltab.Table{
MaxContractLen: utf8.UTFMax,
VariableTop: uint32(b.varTop),
},
}
b.buildOrdering(&b.root)
b.t.root = b.root.handle
for _, t := range b.locale {
b.buildOrdering(t.index)
if b.err != nil {
break
}
}
i, err := b.index.generate()
b.t.trie = *i
b.t.Index = colltab.Trie{
Index: i.index,
Values: i.values,
Index0: i.index[blockSize*b.t.root.lookupStart:],
Values0: i.values[blockSize*b.t.root.valueStart:],
}
b.error(err)
return b.t, b.err
}
// Build builds the root Collator.
func (b *Builder) Build() (colltab.Weighter, error) {
table, err := b.build()
if err != nil {
return nil, err
}
return table, nil
}
// Build builds a Collator for Tailoring t.
func (t *Tailoring) Build() (colltab.Weighter, error) {
// TODO: implement.
return nil, nil
}
// Print prints the tables for b and all its Tailorings as a Go file
// that can be included in the Collate package.
func (b *Builder) Print(w io.Writer) (n int, err error) {
p := func(nn int, e error) {
n += nn
if err == nil {
err = e
}
}
t, err := b.build()
if err != nil {
return 0, err
}
p(fmt.Fprintf(w, `var availableLocales = "und`))
for _, loc := range b.locale {
if loc.id != "und" {
p(fmt.Fprintf(w, ",%s", loc.id))
}
}
p(fmt.Fprint(w, "\"\n\n"))
p(fmt.Fprintf(w, "const varTop = 0x%x\n\n", b.varTop))
p(fmt.Fprintln(w, "var locales = [...]tableIndex{"))
for _, loc := range b.locale {
if loc.id == "und" {
p(t.fprintIndex(w, loc.index.handle, loc.id))
}
}
for _, loc := range b.locale {
if loc.id != "und" {
p(t.fprintIndex(w, loc.index.handle, loc.id))
}
}
p(fmt.Fprint(w, "}\n\n"))
n, _, err = t.fprint(w, "main")
return
}
// reproducibleFromNFKD checks whether the given expansion could be generated
// from an NFKD expansion.
func reproducibleFromNFKD(e *entry, exp, nfkd []rawCE) bool {
// Length must be equal.
if len(exp) != len(nfkd) {
return false
}
for i, ce := range exp {
// Primary and secondary values should be equal.
if ce.w[0] != nfkd[i].w[0] || ce.w[1] != nfkd[i].w[1] {
return false
}
// Tertiary values should be equal to maxTertiary for third element onwards.
// TODO: there seem to be a lot of cases in CLDR (e.g. ㏭ in zh.xml) that can
// simply be dropped. Try this out by dropping the following code.
if i >= 2 && ce.w[2] != maxTertiary {
return false
}
if _, err := makeCE(ce); err != nil {
// Simply return false. The error will be caught elsewhere.
return false
}
}
return true
}
func simplify(o *ordering) {
// Runes that are a starter of a contraction should not be removed.
// (To date, there is only Kannada character 0CCA.)
keep := make(map[rune]bool)
for e := o.front(); e != nil; e, _ = e.nextIndexed() {
if len(e.runes) > 1 {
keep[e.runes[0]] = true
}
}
// Tag entries for which the runes NFKD decompose to identical values.
for e := o.front(); e != nil; e, _ = e.nextIndexed() {
s := e.str
nfkd := norm.NFKD.String(s)
nfd := norm.NFD.String(s)
if e.decompose || len(e.runes) > 1 || len(e.elems) == 1 || keep[e.runes[0]] || nfkd == nfd {
continue
}
if reproducibleFromNFKD(e, e.elems, o.genColElems(nfkd)) {
e.decompose = true
}
}
}
// appendExpansion converts the given collation sequence to
// collation elements and adds them to the expansion table.
// It returns an index to the expansion table.
func (b *Builder) appendExpansion(e *entry) int {
t := b.t
i := len(t.ExpandElem)
ce := uint32(len(e.elems))
t.ExpandElem = append(t.ExpandElem, ce)
for _, w := range e.elems {
ce, err := makeCE(w)
if err != nil {
b.error(err)
return -1
}
t.ExpandElem = append(t.ExpandElem, ce)
}
return i
}
// processExpansions extracts data necessary to generate
// the extraction tables.
func (b *Builder) processExpansions(o *ordering) {
for e := o.front(); e != nil; e, _ = e.nextIndexed() {
if !e.expansion() {
continue
}
key := fmt.Sprintf("%v", e.elems)
i, ok := b.expIndex[key]
if !ok {
i = b.appendExpansion(e)
b.expIndex[key] = i
}
e.expansionIndex = i
}
}
func (b *Builder) processContractions(o *ordering) {
// Collate contractions per starter rune.
starters := []rune{}
cm := make(map[rune][]*entry)
for e := o.front(); e != nil; e, _ = e.nextIndexed() {
if e.contraction() {
if len(e.str) > b.t.MaxContractLen {
b.t.MaxContractLen = len(e.str)
}
r := e.runes[0]
if _, ok := cm[r]; !ok {
starters = append(starters, r)
}
cm[r] = append(cm[r], e)
}
}
// Add entries of single runes that are at a start of a contraction.
for e := o.front(); e != nil; e, _ = e.nextIndexed() {
if !e.contraction() {
r := e.runes[0]
if _, ok := cm[r]; ok {
cm[r] = append(cm[r], e)
}
}
}
// Build the tries for the contractions.
t := b.t
for _, r := range starters {
l := cm[r]
// Compute suffix strings. There are 31 different contraction suffix
// sets for 715 contractions and 82 contraction starter runes as of
// version 6.0.0.
sufx := []string{}
hasSingle := false
for _, e := range l {
if len(e.runes) > 1 {
sufx = append(sufx, string(e.runes[1:]))
} else {
hasSingle = true
}
}
if !hasSingle {
b.error(fmt.Errorf("no single entry for starter rune %U found", r))
continue
}
// Unique the suffix set.
sort.Strings(sufx)
key := strings.Join(sufx, "\n")
handle, ok := b.ctHandle[key]
if !ok {
var err error
handle, err = appendTrie(&t.ContractTries, sufx)
if err != nil {
b.error(err)
}
b.ctHandle[key] = handle
}
// Bucket sort entries in index order.
es := make([]*entry, len(l))
for _, e := range l {
var p, sn int
if len(e.runes) > 1 {
str := []byte(string(e.runes[1:]))
p, sn = lookup(&t.ContractTries, handle, str)
if sn != len(str) {
log.Fatalf("%s: processContractions: unexpected length for '%X'; len=%d; want %d", o.id, e.runes, sn, len(str))
}
}
if es[p] != nil {
log.Fatalf("%s: multiple contractions for position %d for rune %U", o.id, p, e.runes[0])
}
es[p] = e
}
// Create collation elements for contractions.
elems := []uint32{}
for _, e := range es {
ce, err := e.encodeBase()
b.errorID(o.id, err)
elems = append(elems, ce)
}
key = fmt.Sprintf("%v", elems)
i, ok := b.ctElem[key]
if !ok {
i = len(t.ContractElem)
b.ctElem[key] = i
t.ContractElem = append(t.ContractElem, elems...)
}
// Store info in entry for starter rune.
es[0].contractionIndex = i
es[0].contractionHandle = handle
}
}