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+// Copyright 2016 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.
+
+//go:generate go run gen.go gen_common.go
+
+// Package plural provides utilities for handling linguistic plurals in text.
+//
+// The definitions in this package are based on the plural rule handling defined
+// in CLDR. See
+// http://unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules for
+// details.
+package plural
+
+import (
+ "golang.org/x/text/internal/number"
+ "golang.org/x/text/language"
+)
+
+// Rules defines the plural rules for all languages for a certain plural type.
+//
+//
+// This package is UNDER CONSTRUCTION and its API may change.
+type Rules struct {
+ rules []pluralCheck
+ index []byte
+ langToIndex []byte
+ inclusionMasks []uint64
+}
+
+var (
+ // Cardinal defines the plural rules for numbers indicating quantities.
+ Cardinal *Rules = cardinal
+
+ // Ordinal defines the plural rules for numbers indicating position
+ // (first, second, etc.).
+ Ordinal *Rules = ordinal
+
+ ordinal = &Rules{
+ ordinalRules,
+ ordinalIndex,
+ ordinalLangToIndex,
+ ordinalInclusionMasks[:],
+ }
+
+ cardinal = &Rules{
+ cardinalRules,
+ cardinalIndex,
+ cardinalLangToIndex,
+ cardinalInclusionMasks[:],
+ }
+)
+
+// getIntApprox converts the digits in slice digits[start:end] to an integer
+// according to the following rules:
+// - Let i be asInt(digits[start:end]), where out-of-range digits are assumed
+// to be zero.
+// - Result n is big if i / 10^nMod > 1.
+// - Otherwise the result is i % 10^nMod.
+//
+// For example, if digits is {1, 2, 3} and start:end is 0:5, then the result
+// for various values of nMod is:
+// - when nMod == 2, n == big
+// - when nMod == 3, n == big
+// - when nMod == 4, n == big
+// - when nMod == 5, n == 12300
+// - when nMod == 6, n == 12300
+// - when nMod == 7, n == 12300
+func getIntApprox(digits []byte, start, end, nMod, big int) (n int) {
+ // Leading 0 digits just result in 0.
+ p := start
+ if p < 0 {
+ p = 0
+ }
+ // Range only over the part for which we have digits.
+ mid := end
+ if mid >= len(digits) {
+ mid = len(digits)
+ }
+ // Check digits more significant that nMod.
+ if q := end - nMod; q > 0 {
+ if q > mid {
+ q = mid
+ }
+ for ; p < q; p++ {
+ if digits[p] != 0 {
+ return big
+ }
+ }
+ }
+ for ; p < mid; p++ {
+ n = 10*n + int(digits[p])
+ }
+ // Multiply for trailing zeros.
+ for ; p < end; p++ {
+ n *= 10
+ }
+ return n
+}
+
+// MatchDigits computes the plural form for the given language and the given
+// decimal floating point digits. The digits are stored in big-endian order and
+// are of value byte(0) - byte(9). The floating point position is indicated by
+// exp and the number of visible decimals is scale. All leading and trailing
+// zeros may be omitted from digits.
+//
+// The following table contains examples of possible arguments to represent
+// the given numbers.
+// decimal digits exp scale
+// 123 []byte{1, 2, 3} 3 0
+// 123.4 []byte{1, 2, 3, 4} 3 1
+// 123.40 []byte{1, 2, 3, 4} 3 2
+// 100000 []byte{1} 6 0
+// 100000.00 []byte{1} 6 3
+func (p *Rules) MatchDigits(t language.Tag, digits []byte, exp, scale int) Form {
+ index, _ := language.CompactIndex(t)
+
+ // Differentiate up to including mod 1000000 for the integer part.
+ n := getIntApprox(digits, 0, exp, 6, 1000000)
+
+ // Differentiate up to including mod 100 for the fractional part.
+ f := getIntApprox(digits, exp, exp+scale, 2, 100)
+
+ return matchPlural(p, index, n, f, scale)
+}
+
+func (p *Rules) matchDisplayDigits(t language.Tag, d *number.Digits) (Form, int) {
+ n := getIntApprox(d.Digits, 0, int(d.Exp), 6, 1000000)
+ return p.MatchDigits(t, d.Digits, int(d.Exp), d.NumFracDigits()), n
+}
+
+func validForms(p *Rules, t language.Tag) (forms []Form) {
+ index, _ := language.CompactIndex(t)
+ offset := p.langToIndex[index]
+ rules := p.rules[p.index[offset]:p.index[offset+1]]
+
+ forms = append(forms, Other)
+ last := Other
+ for _, r := range rules {
+ if cat := Form(r.cat & formMask); cat != andNext && last != cat {
+ forms = append(forms, cat)
+ last = cat
+ }
+ }
+ return forms
+}
+
+func (p *Rules) matchComponents(t language.Tag, n, f, scale int) Form {
+ index, _ := language.CompactIndex(t)
+ return matchPlural(p, index, n, f, scale)
+}
+
+// MatchPlural returns the plural form for the given language and plural
+// operands (as defined in
+// http://unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules):
+// where
+// n absolute value of the source number (integer and decimals)
+// input
+// i integer digits of n.
+// v number of visible fraction digits in n, with trailing zeros.
+// w number of visible fraction digits in n, without trailing zeros.
+// f visible fractional digits in n, with trailing zeros (f = t * 10^(v-w))
+// t visible fractional digits in n, without trailing zeros.
+//
+// If any of the operand values is too large to fit in an int, it is okay to
+// pass the value modulo 10,000,000.
+func (p *Rules) MatchPlural(lang language.Tag, i, v, w, f, t int) Form {
+ index, _ := language.CompactIndex(lang)
+ return matchPlural(p, index, i, f, v)
+}
+
+func matchPlural(p *Rules, index int, n, f, v int) Form {
+ nMask := p.inclusionMasks[n%maxMod]
+ // Compute the fMask inline in the rules below, as it is relatively rare.
+ // fMask := p.inclusionMasks[f%maxMod]
+ vMask := p.inclusionMasks[v%maxMod]
+
+ // Do the matching
+ offset := p.langToIndex[index]
+ rules := p.rules[p.index[offset]:p.index[offset+1]]
+ for i := 0; i < len(rules); i++ {
+ rule := rules[i]
+ setBit := uint64(1 << rule.setID)
+ var skip bool
+ switch op := opID(rule.cat >> opShift); op {
+ case opI: // i = x
+ skip = n >= numN || nMask&setBit == 0
+
+ case opI | opNotEqual: // i != x
+ skip = n < numN && nMask&setBit != 0
+
+ case opI | opMod: // i % m = x
+ skip = nMask&setBit == 0
+
+ case opI | opMod | opNotEqual: // i % m != x
+ skip = nMask&setBit != 0
+
+ case opN: // n = x
+ skip = f != 0 || n >= numN || nMask&setBit == 0
+
+ case opN | opNotEqual: // n != x
+ skip = f == 0 && n < numN && nMask&setBit != 0
+
+ case opN | opMod: // n % m = x
+ skip = f != 0 || nMask&setBit == 0
+
+ case opN | opMod | opNotEqual: // n % m != x
+ skip = f == 0 && nMask&setBit != 0
+
+ case opF: // f = x
+ skip = f >= numN || p.inclusionMasks[f%maxMod]&setBit == 0
+
+ case opF | opNotEqual: // f != x
+ skip = f < numN && p.inclusionMasks[f%maxMod]&setBit != 0
+
+ case opF | opMod: // f % m = x
+ skip = p.inclusionMasks[f%maxMod]&setBit == 0
+
+ case opF | opMod | opNotEqual: // f % m != x
+ skip = p.inclusionMasks[f%maxMod]&setBit != 0
+
+ case opV: // v = x
+ skip = v < numN && vMask&setBit == 0
+
+ case opV | opNotEqual: // v != x
+ skip = v < numN && vMask&setBit != 0
+
+ case opW: // w == 0
+ skip = f != 0
+
+ case opW | opNotEqual: // w != 0
+ skip = f == 0
+
+ // Hard-wired rules that cannot be handled by our algorithm.
+
+ case opBretonM:
+ skip = f != 0 || n == 0 || n%1000000 != 0
+
+ case opAzerbaijan00s:
+ // 100,200,300,400,500,600,700,800,900
+ skip = n == 0 || n >= 1000 || n%100 != 0
+
+ case opItalian800:
+ skip = (f != 0 || n >= numN || nMask&setBit == 0) && n != 800
+ }
+ if skip {
+ // advance over AND entries.
+ for ; i < len(rules) && rules[i].cat&formMask == andNext; i++ {
+ }
+ continue
+ }
+ // return if we have a final entry.
+ if cat := rule.cat & formMask; cat != andNext {
+ return Form(cat)
+ }
+ }
+ return Other
+}