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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
// https://unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules for
// details.
package plural
import (
"golang.org/x/text/internal/language/compact"
"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 := tagToID(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) {
offset := p.langToIndex[tagToID(t)]
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 {
return matchPlural(p, tagToID(t), n, f, scale)
}
// MatchPlural returns the plural form for the given language and plural
// operands (as defined in
// https://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 {
return matchPlural(p, tagToID(lang), i, f, v)
}
func matchPlural(p *Rules, index compact.ID, 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
}
func tagToID(t language.Tag) compact.ID {
id, _ := compact.RegionalID(compact.Tag(t))
return id
}
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