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// Copyright 2017 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 plural
import (
"fmt"
"io/ioutil"
"reflect"
"strconv"
"golang.org/x/text/internal/catmsg"
"golang.org/x/text/internal/number"
"golang.org/x/text/language"
"golang.org/x/text/message/catalog"
)
// TODO: consider deleting this interface. Maybe VisibleDigits is always
// sufficient and practical.
// Interface is used for types that can determine their own plural form.
type Interface interface {
// PluralForm reports the plural form for the given language of the
// underlying value. It also returns the integer value. If the integer value
// is larger than fits in n, PluralForm may return a value modulo
// 10,000,000.
PluralForm(t language.Tag, scale int) (f Form, n int)
}
// Selectf returns the first case for which its selector is a match for the
// arg-th substitution argument to a formatting call, formatting it as indicated
// by format.
//
// The cases argument are pairs of selectors and messages. Selectors are of type
// string or Form. Messages are of type string or catalog.Message. A selector
// matches an argument if:
// - it is "other" or Other
// - it matches the plural form of the argument: "zero", "one", "two", "few",
// or "many", or the equivalent Form
// - it is of the form "=x" where x is an integer that matches the value of
// the argument.
// - it is of the form "<x" where x is an integer that is larger than the
// argument.
//
// The format argument determines the formatting parameters for which to
// determine the plural form. This is especially relevant for non-integer
// values.
//
// The format string may be "", in which case a best-effort attempt is made to
// find a reasonable representation on which to base the plural form. Examples
// of format strings are:
// - %.2f decimal with scale 2
// - %.2e scientific notation with precision 3 (scale + 1)
// - %d integer
func Selectf(arg int, format string, cases ...interface{}) catalog.Message {
var p parser
// Intercept the formatting parameters of format by doing a dummy print.
fmt.Fprintf(ioutil.Discard, format, &p)
m := &message{arg, kindDefault, 0, cases}
switch p.verb {
case 'g':
m.kind = kindPrecision
m.scale = p.scale
case 'f':
m.kind = kindScale
m.scale = p.scale
case 'e':
m.kind = kindScientific
m.scale = p.scale
case 'd':
m.kind = kindScale
m.scale = 0
default:
// TODO: do we need to handle errors?
}
return m
}
type parser struct {
verb rune
scale int
}
func (p *parser) Format(s fmt.State, verb rune) {
p.verb = verb
p.scale = -1
if prec, ok := s.Precision(); ok {
p.scale = prec
}
}
type message struct {
arg int
kind int
scale int
cases []interface{}
}
const (
// Start with non-ASCII to allow skipping values.
kindDefault = 0x80 + iota
kindScale // verb f, number of fraction digits follows
kindScientific // verb e, number of fraction digits follows
kindPrecision // verb g, number of significant digits follows
)
var handle = catmsg.Register("golang.org/x/text/feature/plural:plural", execute)
func (m *message) Compile(e *catmsg.Encoder) error {
e.EncodeMessageType(handle)
e.EncodeUint(uint64(m.arg))
e.EncodeUint(uint64(m.kind))
if m.kind > kindDefault {
e.EncodeUint(uint64(m.scale))
}
forms := validForms(cardinal, e.Language())
for i := 0; i < len(m.cases); {
if err := compileSelector(e, forms, m.cases[i]); err != nil {
return err
}
if i++; i >= len(m.cases) {
return fmt.Errorf("plural: no message defined for selector %v", m.cases[i-1])
}
var msg catalog.Message
switch x := m.cases[i].(type) {
case string:
msg = catalog.String(x)
case catalog.Message:
msg = x
default:
return fmt.Errorf("plural: message of type %T; must be string or catalog.Message", x)
}
if err := e.EncodeMessage(msg); err != nil {
return err
}
i++
}
return nil
}
func compileSelector(e *catmsg.Encoder, valid []Form, selector interface{}) error {
form := Other
switch x := selector.(type) {
case string:
if x == "" {
return fmt.Errorf("plural: empty selector")
}
if c := x[0]; c == '=' || c == '<' {
val, err := strconv.ParseUint(x[1:], 10, 16)
if err != nil {
return fmt.Errorf("plural: invalid number in selector %q: %v", selector, err)
}
e.EncodeUint(uint64(c))
e.EncodeUint(val)
return nil
}
var ok bool
form, ok = countMap[x]
if !ok {
return fmt.Errorf("plural: invalid plural form %q", selector)
}
case Form:
form = x
default:
return fmt.Errorf("plural: selector of type %T; want string or Form", selector)
}
ok := false
for _, f := range valid {
if f == form {
ok = true
break
}
}
if !ok {
return fmt.Errorf("plural: form %q not supported for language %q", selector, e.Language())
}
e.EncodeUint(uint64(form))
return nil
}
func execute(d *catmsg.Decoder) bool {
lang := d.Language()
argN := int(d.DecodeUint())
kind := int(d.DecodeUint())
scale := -1 // default
if kind > kindDefault {
scale = int(d.DecodeUint())
}
form := Other
n := -1
if arg := d.Arg(argN); arg == nil {
// Default to Other.
} else if x, ok := arg.(number.VisibleDigits); ok {
d := x.Digits(nil, lang, scale)
form, n = cardinal.matchDisplayDigits(lang, &d)
} else if x, ok := arg.(Interface); ok {
// This covers lists and formatters from the number package.
form, n = x.PluralForm(lang, scale)
} else {
var f number.Formatter
switch kind {
case kindScale:
f.InitDecimal(lang)
f.SetScale(scale)
case kindScientific:
f.InitScientific(lang)
f.SetScale(scale)
case kindPrecision:
f.InitDecimal(lang)
f.SetPrecision(scale)
case kindDefault:
// sensible default
f.InitDecimal(lang)
if k := reflect.TypeOf(arg).Kind(); reflect.Int <= k && k <= reflect.Uintptr {
f.SetScale(0)
} else {
f.SetScale(2)
}
}
var dec number.Decimal // TODO: buffer in Printer
dec.Convert(f.RoundingContext, arg)
v := number.FormatDigits(&dec, f.RoundingContext)
if !v.NaN && !v.Inf {
form, n = cardinal.matchDisplayDigits(d.Language(), &v)
}
}
for !d.Done() {
f := d.DecodeUint()
if (f == '=' && n == int(d.DecodeUint())) ||
(f == '<' && 0 <= n && n < int(d.DecodeUint())) ||
form == Form(f) ||
Other == Form(f) {
return d.ExecuteMessage()
}
d.SkipMessage()
}
return false
}
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