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// Copyright 2015 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 message implements formatted I/O for localized strings with functions
// analogous to the fmt's print functions.
//
// These are the important differences with fmt:
// - Output varies per locale.
// - The '#' flag is used to bypass localization.
//
// NOTE: Under construction. See https://golang.org/design/12750-localization
// and its corresponding proposal issue https://golang.org/issues/12750.
package message // import "golang.org/x/text/message"
import (
"io"
"os"
"golang.org/x/text/language"
"golang.org/x/text/message/catalog"
)
// TODO: allow more than one goroutine per printer. This will allow porting from
// fmt much less error prone.
// A Printer implements language-specific formatted I/O analogous to the fmt
// package. Only one goroutine may use a Printer at the same time.
type Printer struct {
// Wrap the fields in a hidden type to hide some of the implemented methods.
printer printer
// NOTE: limiting one goroutine per Printer allows for many optimizations
// and simplifications. We can consider removing this restriction down the
// road if it the benefits do not seem to outweigh the disadvantages.
}
type options struct {
cat *catalog.Catalog
// TODO:
// - allow %s to print integers in written form (tables are likely too large
// to enable this by default).
// - list behavior
//
}
// An Option defines an option of a Printer.
type Option func(o *options)
// Catalog defines the catalog to be used.
func Catalog(c *catalog.Catalog) Option {
return func(o *options) { o.cat = c }
}
// NewPrinter returns a Printer that formats messages tailored to language t.
func NewPrinter(t language.Tag, opts ...Option) *Printer {
options := &options{
cat: defaultCatalog,
}
for _, o := range opts {
o(options)
}
p := &Printer{printer{
tag: t,
}}
p.printer.toDecimal.InitDecimal(t)
p.printer.toScientific.InitScientific(t)
p.printer.catContext = options.cat.Context(t, &p.printer)
return p
}
// Sprint is like fmt.Sprint, but using language-specific formatting.
func (p *Printer) Sprint(a ...interface{}) string {
p.printer.reset()
p.printer.doPrint(a)
return p.printer.String()
}
// Fprint is like fmt.Fprint, but using language-specific formatting.
func (p *Printer) Fprint(w io.Writer, a ...interface{}) (n int, err error) {
p.printer.reset()
p.printer.doPrint(a)
n64, err := io.Copy(w, &p.printer.Buffer)
return int(n64), err
}
// Print is like fmt.Print, but using language-specific formatting.
func (p *Printer) Print(a ...interface{}) (n int, err error) {
return p.Fprint(os.Stdout, a...)
}
// Sprintln is like fmt.Sprintln, but using language-specific formatting.
func (p *Printer) Sprintln(a ...interface{}) string {
p.printer.reset()
p.printer.doPrintln(a)
return p.printer.String()
}
// Fprintln is like fmt.Fprintln, but using language-specific formatting.
func (p *Printer) Fprintln(w io.Writer, a ...interface{}) (n int, err error) {
p.printer.reset()
p.printer.doPrintln(a)
n64, err := io.Copy(w, &p.printer.Buffer)
return int(n64), err
}
// Println is like fmt.Println, but using language-specific formatting.
func (p *Printer) Println(a ...interface{}) (n int, err error) {
return p.Fprintln(os.Stdout, a...)
}
// Sprintf is like fmt.Sprintf, but using language-specific formatting.
func (p *Printer) Sprintf(key Reference, a ...interface{}) string {
lookupAndFormat(p, key, a)
return p.printer.String()
}
// Fprintf is like fmt.Fprintf, but using language-specific formatting.
func (p *Printer) Fprintf(w io.Writer, key Reference, a ...interface{}) (n int, err error) {
lookupAndFormat(p, key, a)
return w.Write(p.printer.Bytes())
}
// Printf is like fmt.Printf, but using language-specific formatting.
func (p *Printer) Printf(key Reference, a ...interface{}) (n int, err error) {
lookupAndFormat(p, key, a)
return os.Stdout.Write(p.printer.Bytes())
}
func lookupAndFormat(p *Printer, r Reference, a []interface{}) {
p.printer.reset()
p.printer.args = a
var id, msg string
switch v := r.(type) {
case string:
id, msg = v, v
case key:
id, msg = v.id, v.fallback
default:
panic("key argument is not a Reference")
}
if p.printer.catContext.Execute(id) == catalog.ErrNotFound {
if p.printer.catContext.Execute(msg) == catalog.ErrNotFound {
p.printer.Render(msg)
return
}
}
}
// Arg implements catmsg.Renderer.
func (p *printer) Arg(i int) interface{} { // TODO, also return "ok" bool
if uint(i) < uint(len(p.args)) {
return p.args[i]
}
return nil
}
// Render implements catmsg.Renderer.
func (p *printer) Render(msg string) {
p.doPrintf(msg)
}
// A Reference is a string or a message reference.
type Reference interface {
// TODO: also allow []string
}
// Key creates a message Reference for a message where the given id is used for
// message lookup and the fallback is returned when no matches are found.
func Key(id string, fallback string) Reference {
return key{id, fallback}
}
type key struct {
id, fallback string
}