working commit

2026-03-13 19:02:42 +02:00
parent bebbf79c7a
commit 5c1da77f4c
1329 changed files with 314708 additions and 39 deletions
@@ -0,0 +1,5 @@
+language: go
+
+go:
+  - "1.14"
+  - tip
@@ -0,0 +1,27 @@
+Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@@ -0,0 +1,191 @@
+- *赞助 BTC: 1Cbd6oGAUUyBi7X7MaR4np4nTmQZXVgkCW*
+- *赞助 ETH: 0x623A3C3a72186A6336C79b18Ac1eD36e1c71A8a6*
+- *Go语言付费QQ群: 1055927514*
+
+----
+
+# gettext-go: GNU gettext for Go ([Imported By Kubernetes](https://pkg.go.dev/github.com/chai2010/gettext-go@v0.1.0/gettext?tab=importedby))
+
+- PkgDoc: [http://godoc.org/github.com/chai2010/gettext-go](http://godoc.org/github.com/chai2010/gettext-go)
+- PkgDoc: [http://pkg.go.dev/github.com/chai2010/gettext-go](http://pkg.go.dev/github.com/chai2010/gettext-go)
+
+## Install
+
+1. `go get github.com/chai2010/gettext-go`
+2. `go run hello.go`
+
+The godoc.org or go.dev has more information.
+
+## Examples
+
+```Go
+package main
+
+import (
+	"fmt"
+
+	"github.com/chai2010/gettext-go"
+)
+
+func main() {
+	gettext := gettext.New("hello", "./examples/locale").SetLanguage("zh_CN")
+	fmt.Println(gettext.Gettext("Hello, world!"))
+
+	// Output: 你好, 世界!
+}
+```
+
+```Go
+package main
+
+import (
+	"fmt"
+
+	"github.com/chai2010/gettext-go"
+)
+
+func main() {
+	gettext.SetLanguage("zh_CN")
+	gettext.BindLocale(gettext.New("hello", "locale"))
+
+	// gettext.BindLocale("hello", "locale")              // from locale dir
+	// gettext.BindLocale("hello", "locale.zip")          // from locale zip file
+	// gettext.BindLocale("hello", "locale.zip", zipData) // from embedded zip data
+
+	// translate source text
+	fmt.Println(gettext.Gettext("Hello, world!"))
+	// Output: 你好, 世界!
+
+	// if no msgctxt in PO file (only msgid and msgstr),
+	// specify context as "" by
+	fmt.Println(gettext.PGettext("", "Hello, world!"))
+	// Output: 你好, 世界!
+
+	// translate resource
+	fmt.Println(string(gettext.Getdata("poems.txt"))))
+	// Output: ...
+}
+```
+
+Go file: [hello.go](https://github.com/chai2010/gettext-go/blob/master/examples/hello.go); PO file: [hello.po](https://github.com/chai2010/gettext-go/blob/master/examples/locale/default/LC_MESSAGES/hello.po);
+
+----
+
+## API Changes (v0.1.0 vs v1.0.0)
+
+### Renamed package path
+
+| v0.1.0 (old)                                    | v1.0.0 (new)                            |
+| ----------------------------------------------- | --------------------------------------- |
+| `github.com/chai2010/gettext-go/gettext`        | `github.com/chai2010/gettext-go`        |
+| `github.com/chai2010/gettext-go/gettext/po`     | `github.com/chai2010/gettext-go/po`     |
+| `github.com/chai2010/gettext-go/gettext/mo`     | `github.com/chai2010/gettext-go/mo`     |
+| `github.com/chai2010/gettext-go/gettext/plural` | `github.com/chai2010/gettext-go/plural` |
+
+### Renamed functions
+
+| v0.1.0 (old)                       | v1.0.0 (new)                |
+| ---------------------------------- | --------------------------- |
+| `gettext-go/gettext.*`             | `gettext-go.*`              |
+| `gettext-go/gettext.DefaultLocal`  | `gettext-go.DefaultLanguage`|
+| `gettext-go/gettext.BindTextdomain`| `gettext-go.BindLocale`     |
+| `gettext-go/gettext.Textdomain`    | `gettext-go.SetDomain`      |
+| `gettext-go/gettext.SetLocale`     | `gettext-go.SetLanguage`    |
+| `gettext-go/gettext/po.Load`       | `gettext-go/po.LoadFile`    |
+| `gettext-go/gettext/po.LoadData`   | `gettext-go/po.Load`        |
+| `gettext-go/gettext/mo.Load`       | `gettext-go/mo.LoadFile`    |
+| `gettext-go/gettext/mo.LoadData`   | `gettext-go/mo.Load`        |
+
+### Use empty string as the default context for `gettext.Gettext`
+
+```go
+package main
+
+// v0.1.0
+// if the **context** missing, use `callerName(2)` as the context:
+
+// v1.0.0
+// if the **context** missing, use empty string as the context:
+
+func main() {
+	gettext.Gettext("hello")          
+	// v0.1.0 => gettext.PGettext("main.main", "hello")
+	// v1.0.0 => gettext.PGettext("", "hello")
+
+	gettext.DGettext("domain", "hello")
+	// v0.1.0 => gettext.DPGettext("domain", "main.main", "hello")
+	// v1.0.0 => gettext.DPGettext("domain", "", "hello")
+
+	gettext.NGettext("domain", "hello", "hello2", n)
+	// v0.1.0 => gettext.PNGettext("domain", "main.main", "hello", "hello2", n)
+	// v1.0.0 => gettext.PNGettext("domain", "", "hello", "hello2", n)
+
+	gettext.DNGettext("domain", "hello", "hello2", n)
+	// v0.1.0 => gettext.DPNGettext("domain", "main.main", "hello", "hello2", n)
+	// v1.0.0 => gettext.DPNGettext("domain", "", "hello", "hello2", n)
+}
+```
+
+### `BindLocale` support `FileSystem` interface
+
+```go
+// Use FileSystem:
+//	BindLocale(New("poedit", "name", OS("path/to/dir"))) // bind "poedit" domain
+//	BindLocale(New("poedit", "name", OS("path/to.zip"))) // bind "poedit" domain
+```
+
+## New API in v1.0.0
+
+`Gettexter` interface:
+
+```go
+type Gettexter interface {
+	FileSystem() FileSystem
+
+	GetDomain() string
+	SetDomain(domain string) Gettexter
+
+	GetLanguage() string
+	SetLanguage(lang string) Gettexter
+
+	Gettext(msgid string) string
+	PGettext(msgctxt, msgid string) string
+
+	NGettext(msgid, msgidPlural string, n int) string
+	PNGettext(msgctxt, msgid, msgidPlural string, n int) string
+
+	DGettext(domain, msgid string) string
+	DPGettext(domain, msgctxt, msgid string) string
+	DNGettext(domain, msgid, msgidPlural string, n int) string
+	DPNGettext(domain, msgctxt, msgid, msgidPlural string, n int) string
+
+	Getdata(name string) []byte
+	DGetdata(domain, name string) []byte
+}
+
+func New(domain, path string, data ...interface{}) Gettexter
+```
+
+`FileSystem` interface:
+
+```go
+type FileSystem interface {
+	LocaleList() []string
+	LoadMessagesFile(domain, lang, ext string) ([]byte, error)
+	LoadResourceFile(domain, lang, name string) ([]byte, error)
+	String() string
+}
+
+func NewFS(name string, x interface{}) FileSystem
+func OS(root string) FileSystem
+func ZipFS(r *zip.Reader, name string) FileSystem
+func NilFS(name string) FileSystem
+```
+
+----
+
+## BUGS
+
+Please report bugs to <chaishushan@gmail.com>.
+
+Thanks!
@@ -0,0 +1,67 @@
+// Copyright 2013 <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package gettext implements a basic GNU's gettext library.
+
+Example:
+	import (
+		"github.com/chai2010/gettext-go"
+	)
+
+	func main() {
+		gettext.SetLanguage("zh_CN")
+
+		// gettext.BindLocale(gettext.New("hello", "locale"))              // from locale dir
+		// gettext.BindLocale(gettext.New("hello", "locale.zip"))          // from locale zip file
+		// gettext.BindLocale(gettext.New("hello", "locale.zip", zipData)) // from embedded zip data
+
+		gettext.BindLocale(gettext.New("hello", "locale"))
+
+		// translate source text
+		fmt.Println(gettext.Gettext("Hello, world!"))
+		// Output: 你好, 世界!
+
+		// translate resource
+		fmt.Println(string(gettext.Getdata("poems.txt")))
+		// Output: ...
+	}
+
+Translate directory struct("./examples/locale.zip"):
+
+	Root: "path" or "file.zip/zipBaseName"
+	 +-default                 # locale: $(LC_MESSAGES) or $(LANG) or "default"
+	 |  +-LC_MESSAGES            # just for `gettext.Gettext`
+	 |  |   +-hello.mo             # $(Root)/$(lang)/LC_MESSAGES/$(domain).mo
+	 |  |   +-hello.po             # $(Root)/$(lang)/LC_MESSAGES/$(domain).po
+	 |  |   \-hello.json           # $(Root)/$(lang)/LC_MESSAGES/$(domain).json
+	 |  |
+	 |  \-LC_RESOURCE            # just for `gettext.Getdata`
+	 |      +-hello                # domain map a dir in resource translate
+	 |         +-favicon.ico       # $(Root)/$(lang)/LC_RESOURCE/$(domain)/$(filename)
+	 |         \-poems.txt
+	 |
+	 \-zh_CN                   # simple chinese translate
+	    +-LC_MESSAGES
+	    |   +-hello.po             # try "$(domain).po" first
+	    |   +-hello.mo             # try "$(domain).mo" second
+	    |   \-hello.json           # try "$(domain).json" third
+	    |
+	    \-LC_RESOURCE
+	        +-hello
+	           +-favicon.ico       # $(lang)/$(domain)/favicon.ico
+	           \-poems.txt         # $(lang)/$(domain)/poems.txt
+
+See:
+	http://en.wikipedia.org/wiki/Gettext
+	http://www.gnu.org/software/gettext/manual/html_node
+	http://www.gnu.org/software/gettext/manual/html_node/Header-Entry.html
+	http://www.gnu.org/software/gettext/manual/html_node/PO-Files.html
+	http://www.gnu.org/software/gettext/manual/html_node/MO-Files.html
+	http://www.poedit.net/
+
+Please report bugs to <chaishushan{AT}gmail.com>.
+Thanks!
+*/
+package gettext
@@ -0,0 +1,84 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"archive/zip"
+	"bytes"
+	"fmt"
+)
+
+type FileSystem interface {
+	LocaleList() []string
+	LoadMessagesFile(domain, lang, ext string) ([]byte, error)
+	LoadResourceFile(domain, lang, name string) ([]byte, error)
+	String() string
+}
+
+func NewFS(name string, x interface{}) FileSystem {
+	if x == nil {
+		if name != "" {
+			return OS(name)
+		}
+		return NilFS(name)
+	}
+
+	switch x := x.(type) {
+	case []byte:
+		if len(x) == 0 {
+			return OS(name)
+		}
+		if r, err := zip.NewReader(bytes.NewReader(x), int64(len(x))); err == nil {
+			return ZipFS(r, name)
+		}
+		if fs, err := newJson(x, name); err == nil {
+			return fs
+		}
+	case string:
+		if len(x) == 0 {
+			return OS(name)
+		}
+		if r, err := zip.NewReader(bytes.NewReader([]byte(x)), int64(len(x))); err == nil {
+			return ZipFS(r, name)
+		}
+		if fs, err := newJson([]byte(x), name); err == nil {
+			return fs
+		}
+	case FileSystem:
+		return x
+	}
+
+	return NilFS(name)
+}
+
+func OS(root string) FileSystem {
+	return newOsFS(root)
+}
+
+func ZipFS(r *zip.Reader, name string) FileSystem {
+	return newZipFS(r, name)
+}
+
+func NilFS(name string) FileSystem {
+	return &nilFS{name}
+}
+
+type nilFS struct {
+	name string
+}
+
+func (p *nilFS) LocaleList() []string {
+	return nil
+}
+
+func (p *nilFS) LoadMessagesFile(domain, lang, ext string) ([]byte, error) {
+	return nil, fmt.Errorf("not found")
+}
+func (p *nilFS) LoadResourceFile(domain, lang, name string) ([]byte, error) {
+	return nil, fmt.Errorf("not found")
+}
+func (p *nilFS) String() string {
+	return "gettext.nilfs(" + p.name + ")"
+}
@@ -0,0 +1,66 @@
+// Copyright 2020 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+)
+
+type jsonFS struct {
+	name string
+	x    map[string]struct {
+		LC_MESSAGES map[string][]struct {
+			MsgContext  string   `json:"msgctxt"`      // msgctxt context
+			MsgId       string   `json:"msgid"`        // msgid untranslated-string
+			MsgIdPlural string   `json:"msgid_plural"` // msgid_plural untranslated-string-plural
+			MsgStr      []string `json:"msgstr"`       // msgstr translated-string
+		}
+		LC_RESOURCE map[string]map[string]string
+	}
+}
+
+func isJsonData() bool {
+	return false
+}
+
+func newJson(jsonData []byte, name string) (*jsonFS, error) {
+	p := &jsonFS{name: name}
+	if err := json.Unmarshal(jsonData, &p.x); err != nil {
+		return nil, err
+	}
+
+	return p, nil
+}
+
+func (p *jsonFS) LocaleList() []string {
+	var ss []string
+	for lang := range p.x {
+		ss = append(ss, lang)
+	}
+	sort.Strings(ss)
+	return ss
+}
+
+func (p *jsonFS) LoadMessagesFile(domain, lang, ext string) ([]byte, error) {
+	if v, ok := p.x[lang]; ok {
+		if v, ok := v.LC_MESSAGES[domain+ext]; ok {
+			return json.Marshal(v)
+		}
+	}
+	return nil, fmt.Errorf("not found")
+}
+func (p *jsonFS) LoadResourceFile(domain, lang, name string) ([]byte, error) {
+	if v, ok := p.x[lang]; ok {
+		if v, ok := v.LC_RESOURCE[domain]; ok {
+			return []byte(v[name]), nil
+		}
+	}
+	return nil, fmt.Errorf("not found")
+}
+func (p *jsonFS) String() string {
+	return "gettext.nilfs(" + p.name + ")"
+}
@@ -0,0 +1,91 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"archive/zip"
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"sort"
+	"strings"
+)
+
+type osFS struct {
+	root string
+}
+
+func newOsFS(root string) FileSystem {
+	// locale zip file
+	if fi, err := os.Stat(root); err == nil && !fi.IsDir() {
+		if strings.HasSuffix(strings.ToLower(root), ".zip") {
+			if x, err := ioutil.ReadFile(root); err == nil {
+				if r, err := zip.NewReader(bytes.NewReader(x), int64(len(x))); err == nil {
+					return ZipFS(r, root)
+				}
+			}
+		}
+		if strings.HasSuffix(strings.ToLower(root), ".json") {
+			if x, err := ioutil.ReadFile(root); err == nil {
+				if fs, err := newJson(x, root); err == nil {
+					return fs
+				}
+			}
+		}
+	}
+
+	// locale dir
+	return &osFS{root: root}
+}
+
+func (p *osFS) LocaleList() []string {
+	list, err := ioutil.ReadDir(p.root)
+	if err != nil {
+		return nil
+	}
+	ssMap := make(map[string]bool)
+	for _, dir := range list {
+		if dir.IsDir() {
+			ssMap[dir.Name()] = true
+		}
+	}
+	var locales = make([]string, 0, len(ssMap))
+	for s := range ssMap {
+		locales = append(locales, s)
+	}
+	sort.Strings(locales)
+	return locales
+}
+
+func (p *osFS) LoadMessagesFile(domain, locale, ext string) ([]byte, error) {
+	trName := p.makeMessagesFileName(domain, locale, ext)
+	rcData, err := ioutil.ReadFile(trName)
+	if err != nil {
+		return nil, err
+	}
+	return rcData, nil
+}
+
+func (p *osFS) LoadResourceFile(domain, locale, name string) ([]byte, error) {
+	rcName := p.makeResourceFileName(domain, locale, name)
+	rcData, err := ioutil.ReadFile(rcName)
+	if err != nil {
+		return nil, err
+	}
+	return rcData, nil
+}
+
+func (p *osFS) String() string {
+	return "gettext.localfs(" + p.root + ")"
+}
+
+func (p *osFS) makeMessagesFileName(domain, lang, ext string) string {
+	return fmt.Sprintf("%s/%s/LC_MESSAGES/%s%s", p.root, lang, domain, ext)
+}
+
+func (p *osFS) makeResourceFileName(domain, lang, name string) string {
+	return fmt.Sprintf("%s/%s/LC_RESOURCE/%s/%s", p.root, lang, domain, name)
+}
@@ -0,0 +1,142 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"archive/zip"
+	"fmt"
+	"io/ioutil"
+	"sort"
+	"strings"
+)
+
+type zipFS struct {
+	root string
+	name string
+	r    *zip.Reader
+}
+
+func newZipFS(r *zip.Reader, name string) *zipFS {
+	fs := &zipFS{r: r, name: name}
+	fs.root = fs.zipRoot()
+	return fs
+}
+
+func (p *zipFS) zipName() string {
+	name := p.name
+	if x := strings.LastIndexAny(name, `\/`); x != -1 {
+		name = name[x+1:]
+	}
+	name = strings.TrimSuffix(name, ".zip")
+	return name
+}
+
+func (p *zipFS) zipRoot() string {
+	var somepath string
+	for _, f := range p.r.File {
+		if x := strings.Index(f.Name, "LC_MESSAGES"); x != -1 {
+			somepath = f.Name
+		}
+		if x := strings.Index(f.Name, "LC_RESOURCE"); x != -1 {
+			somepath = f.Name
+		}
+	}
+	if somepath == "" {
+		return p.zipName()
+	}
+
+	ss := strings.Split(somepath, "/")
+	for i, s := range ss {
+		// $(root)/$(lang)/LC_MESSAGES
+		// $(root)/$(lang)/LC_RESOURCE
+		if (s == "LC_MESSAGES" || s == "LC_RESOURCE") && i >= 2 {
+			return strings.Join(ss[:i-1], "/")
+		}
+	}
+
+	return p.zipName()
+}
+
+func (p *zipFS) LocaleList() []string {
+	var locals []string
+	for s := range p.lsZip(p.r) {
+		locals = append(locals, s)
+	}
+	sort.Strings(locals)
+	return locals
+}
+
+func (p *zipFS) LoadMessagesFile(domain, lang, ext string) ([]byte, error) {
+	trName := p.makeMessagesFileName(domain, lang, ext)
+	for _, f := range p.r.File {
+		if f.Name != trName {
+			continue
+		}
+		rc, err := f.Open()
+		if err != nil {
+			return nil, err
+		}
+		rcData, err := ioutil.ReadAll(rc)
+		rc.Close()
+		return rcData, err
+	}
+	return nil, fmt.Errorf("not found")
+}
+
+func (p *zipFS) LoadResourceFile(domain, lang, name string) ([]byte, error) {
+	rcName := p.makeResourceFileName(domain, lang, name)
+	for _, f := range p.r.File {
+		if f.Name != rcName {
+			continue
+		}
+		rc, err := f.Open()
+		if err != nil {
+			return nil, err
+		}
+		rcData, err := ioutil.ReadAll(rc)
+		rc.Close()
+		return rcData, err
+	}
+	return nil, fmt.Errorf("not found")
+}
+
+func (p *zipFS) String() string {
+	return "gettext.zipfs(" + p.name + ")"
+}
+
+func (p *zipFS) makeMessagesFileName(domain, lang, ext string) string {
+	return fmt.Sprintf("%s/%s/LC_MESSAGES/%s%s", p.root, lang, domain, ext)
+}
+
+func (p *zipFS) makeResourceFileName(domain, lang, name string) string {
+	return fmt.Sprintf("%s/%s/LC_RESOURCE/%s/%s", p.root, lang, domain, name)
+}
+
+func (p *zipFS) lsZip(r *zip.Reader) map[string]bool {
+	ssMap := make(map[string]bool)
+	for _, f := range r.File {
+		if x := strings.Index(f.Name, "LC_MESSAGES"); x != -1 {
+			s := strings.TrimRight(f.Name[:x], `\/`)
+			if x = strings.LastIndexAny(s, `\/`); x != -1 {
+				s = s[x+1:]
+			}
+			if s != "" {
+				ssMap[s] = true
+			}
+			continue
+		}
+		if x := strings.Index(f.Name, "LC_RESOURCE"); x != -1 {
+			s := strings.TrimRight(f.Name[:x], `\/`)
+			if x = strings.LastIndexAny(s, `\/`); x != -1 {
+				s = s[x+1:]
+			}
+			if s != "" {
+				ssMap[s] = true
+			}
+			continue
+		}
+	}
+	return ssMap
+}
@@ -0,0 +1,219 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+var (
+	DefaultLanguage string = getDefaultLanguage() // use $(LC_MESSAGES) or $(LANG) or "default"
+)
+
+type Gettexter interface {
+	FileSystem() FileSystem
+
+	GetDomain() string
+	SetDomain(domain string) Gettexter
+
+	GetLanguage() string
+	SetLanguage(lang string) Gettexter
+
+	Gettext(msgid string) string
+	PGettext(msgctxt, msgid string) string
+
+	NGettext(msgid, msgidPlural string, n int) string
+	PNGettext(msgctxt, msgid, msgidPlural string, n int) string
+
+	DGettext(domain, msgid string) string
+	DPGettext(domain, msgctxt, msgid string) string
+	DNGettext(domain, msgid, msgidPlural string, n int) string
+	DPNGettext(domain, msgctxt, msgid, msgidPlural string, n int) string
+
+	Getdata(name string) []byte
+	DGetdata(domain, name string) []byte
+}
+
+// New create Interface use default language.
+func New(domain, path string, data ...interface{}) Gettexter {
+	return newLocale(domain, path, data...)
+}
+
+var defaultGettexter struct {
+	lang   string
+	domain string
+	Gettexter
+}
+
+func init() {
+	defaultGettexter.lang = getDefaultLanguage()
+	defaultGettexter.domain = "default"
+	defaultGettexter.Gettexter = newLocale("", "")
+}
+
+// BindLocale sets and queries program's domains.
+//
+// Examples:
+//	BindLocale(New("poedit", "locale")) // bind "poedit" domain
+//
+// Use zip file:
+//	BindLocale(New("poedit", "locale.zip"))          // bind "poedit" domain
+//	BindLocale(New("poedit", "locale.zip", zipData)) // bind "poedit" domain
+//
+// Use FileSystem:
+//	BindLocale(New("poedit", "name", OS("path/to/dir"))) // bind "poedit" domain
+//	BindLocale(New("poedit", "name", OS("path/to.zip"))) // bind "poedit" domain
+//
+func BindLocale(g Gettexter) {
+	if g != nil {
+		defaultGettexter.Gettexter = g
+		defaultGettexter.SetLanguage(defaultGettexter.lang)
+	} else {
+		defaultGettexter.Gettexter = newLocale("", "")
+		defaultGettexter.SetLanguage(defaultGettexter.lang)
+	}
+}
+
+// SetLanguage sets and queries the program's current lang.
+//
+// If the lang is not empty string, set the new locale.
+//
+// If the lang is empty string, don't change anything.
+//
+// Returns is the current locale.
+//
+// Examples:
+//	SetLanguage("")      // get locale: return DefaultLocale
+//	SetLanguage("zh_CN") // set locale: return zh_CN
+//	SetLanguage("")      // get locale: return zh_CN
+func SetLanguage(lang string) string {
+	defaultGettexter.SetLanguage(lang)
+	return defaultGettexter.GetLanguage()
+}
+
+// SetDomain sets and retrieves the current message domain.
+//
+// If the domain is not empty string, set the new domains.
+//
+// If the domain is empty string, don't change anything.
+//
+// Returns is the all used domains.
+//
+// Examples:
+//	SetDomain("poedit") // set domain: poedit
+//	SetDomain("")       // get domain: return poedit
+func SetDomain(domain string) string {
+	defaultGettexter.SetDomain(domain)
+	return defaultGettexter.GetDomain()
+}
+
+// Gettext attempt to translate a text string into the user's native language,
+// by looking up the translation in a message catalog.
+//
+// It use the caller's function name as the msgctxt.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.Gettext("Hello") // msgctxt is ""
+//	}
+func Gettext(msgid string) string {
+	return defaultGettexter.Gettext(msgid)
+}
+
+// Getdata attempt to translate a resource file into the user's native language,
+// by looking up the translation in a message catalog.
+//
+// Examples:
+//	func Foo() {
+//		Textdomain("hello")
+//		BindLocale("hello", "locale.zip", nilOrZipData)
+//		poems := gettext.Getdata("poems.txt")
+//	}
+func Getdata(name string) []byte {
+	return defaultGettexter.Getdata(name)
+}
+
+// NGettext attempt to translate a text string into the user's native language,
+// by looking up the appropriate plural form of the translation in a message
+// catalog.
+//
+// It use the caller's function name as the msgctxt.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.NGettext("%d people", "%d peoples", 2)
+//	}
+func NGettext(msgid, msgidPlural string, n int) string {
+	return defaultGettexter.NGettext(msgid, msgidPlural, n)
+}
+
+// PGettext attempt to translate a text string into the user's native language,
+// by looking up the translation in a message catalog.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.PGettext("gettext-go.example", "Hello") // msgctxt is "gettext-go.example"
+//	}
+func PGettext(msgctxt, msgid string) string {
+	return defaultGettexter.PGettext(msgctxt, msgid)
+}
+
+// PNGettext attempt to translate a text string into the user's native language,
+// by looking up the appropriate plural form of the translation in a message
+// catalog.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.PNGettext("gettext-go.example", "%d people", "%d peoples", 2)
+//	}
+func PNGettext(msgctxt, msgid, msgidPlural string, n int) string {
+	return defaultGettexter.PNGettext(msgctxt, msgid, msgidPlural, n)
+}
+
+// DGettext like Gettext(), but looking up the message in the specified domain.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.DGettext("poedit", "Hello")
+//	}
+func DGettext(domain, msgid string) string {
+	return defaultGettexter.DGettext(domain, msgid)
+}
+
+// DNGettext like NGettext(), but looking up the message in the specified domain.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.PNGettext("poedit", "gettext-go.example", "%d people", "%d peoples", 2)
+//	}
+func DNGettext(domain, msgid, msgidPlural string, n int) string {
+	return defaultGettexter.DNGettext(domain, msgid, msgidPlural, n)
+}
+
+// DPGettext like PGettext(), but looking up the message in the specified domain.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.DPGettext("poedit", "gettext-go.example", "Hello")
+//	}
+func DPGettext(domain, msgctxt, msgid string) string {
+	return defaultGettexter.DPGettext(domain, msgctxt, msgid)
+}
+
+// DPNGettext like PNGettext(), but looking up the message in the specified domain.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.DPNGettext("poedit", "gettext-go.example", "%d people", "%d peoples", 2)
+//	}
+func DPNGettext(domain, msgctxt, msgid, msgidPlural string, n int) string {
+	return defaultGettexter.DPNGettext(domain, msgctxt, msgid, msgidPlural, n)
+}
+
+// DGetdata like Getdata(), but looking up the resource in the specified domain.
+//
+// Examples:
+//	func Foo() {
+//		msg := gettext.DGetdata("hello", "poems.txt")
+//	}
+func DGetdata(domain, name string) []byte {
+	return defaultGettexter.DGetdata(domain, name)
+}
@@ -0,0 +1,205 @@
+// Copyright 2020 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"fmt"
+	"sync"
+)
+
+type _Locale struct {
+	mutex     sync.Mutex
+	fs        FileSystem
+	lang      string
+	domain    string
+	trMap     map[string]*translator
+	trCurrent *translator
+}
+
+var _ Gettexter = (*_Locale)(nil)
+
+func newLocale(domain, path string, data ...interface{}) *_Locale {
+	if domain == "" {
+		domain = "default"
+	}
+	p := &_Locale{
+		lang:   DefaultLanguage,
+		domain: domain,
+	}
+	if len(data) > 0 {
+		p.fs = NewFS(path, data[0])
+	} else {
+		p.fs = NewFS(path, nil)
+	}
+
+	p.syncTrMap()
+	return p
+}
+
+func (p *_Locale) makeTrMapKey(domain, _Locale string) string {
+	return domain + "_$$$_" + _Locale
+}
+
+func (p *_Locale) FileSystem() FileSystem {
+	return p.fs
+}
+
+func (p *_Locale) GetLanguage() string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+
+	return p.lang
+}
+func (p *_Locale) SetLanguage(lang string) Gettexter {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+
+	if lang == "" {
+		lang = DefaultLanguage
+	}
+	if lang == p.lang {
+		return p
+	}
+
+	p.lang = lang
+	p.syncTrMap()
+	return p
+}
+
+func (p *_Locale) GetDomain() string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.domain
+}
+
+func (p *_Locale) SetDomain(domain string) Gettexter {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+
+	if domain == "" || domain == p.domain {
+		return p
+	}
+
+	p.domain = domain
+	p.syncTrMap()
+	return p
+}
+
+func (p *_Locale) syncTrMap() {
+	p.trMap = make(map[string]*translator)
+	trMapKey := p.makeTrMapKey(p.domain, p.lang)
+
+	if tr, ok := p.trMap[trMapKey]; ok {
+		p.trCurrent = tr
+		return
+	}
+
+	// try load po file
+	if data, err := p.fs.LoadMessagesFile(p.domain, p.lang, ".po"); err == nil {
+		if tr, err := newPoTranslator(fmt.Sprintf("%s_%s.po", p.domain, p.lang), data); err == nil {
+			p.trMap[trMapKey] = tr
+			p.trCurrent = tr
+			return
+		}
+	}
+
+	// try load mo file
+	if data, err := p.fs.LoadMessagesFile(p.domain, p.lang, ".mo"); err == nil {
+		if tr, err := newMoTranslator(fmt.Sprintf("%s_%s.mo", p.domain, p.lang), data); err == nil {
+			p.trMap[trMapKey] = tr
+			p.trCurrent = tr
+			return
+		}
+	}
+
+	// try load json file
+	if data, err := p.fs.LoadMessagesFile(p.domain, p.lang, ".json"); err == nil {
+		if tr, err := newJsonTranslator(p.lang, fmt.Sprintf("%s_%s.json", p.domain, p.lang), data); err == nil {
+			p.trMap[trMapKey] = tr
+			p.trCurrent = tr
+			return
+		}
+	}
+
+	// no po/mo file
+	p.trMap[trMapKey] = nilTranslator
+	p.trCurrent = nilTranslator
+	return
+}
+
+func (p *_Locale) Gettext(msgid string) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.trCurrent.PGettext("", msgid)
+}
+
+func (p *_Locale) PGettext(msgctxt, msgid string) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.trCurrent.PGettext(msgctxt, msgid)
+}
+
+func (p *_Locale) NGettext(msgid, msgidPlural string, n int) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.trCurrent.PNGettext("", msgid, msgidPlural, n)
+}
+
+func (p *_Locale) PNGettext(msgctxt, msgid, msgidPlural string, n int) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.trCurrent.PNGettext(msgctxt, msgid, msgidPlural, n)
+}
+
+func (p *_Locale) DGettext(domain, msgid string) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.gettext(domain, "", msgid, "", 0)
+}
+
+func (p *_Locale) DNGettext(domain, msgid, msgidPlural string, n int) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.gettext(domain, "", msgid, msgidPlural, n)
+}
+
+func (p *_Locale) DPGettext(domain, msgctxt, msgid string) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.gettext(domain, msgctxt, msgid, "", 0)
+}
+
+func (p *_Locale) DPNGettext(domain, msgctxt, msgid, msgidPlural string, n int) string {
+	p.mutex.Lock()
+	defer p.mutex.Unlock()
+	return p.gettext(domain, msgctxt, msgid, msgidPlural, n)
+}
+
+func (p *_Locale) Getdata(name string) []byte {
+	return p.getdata(p.domain, name)
+}
+
+func (p *_Locale) DGetdata(domain, name string) []byte {
+	return p.getdata(domain, name)
+}
+
+func (p *_Locale) gettext(domain, msgctxt, msgid, msgidPlural string, n int) string {
+	if f, ok := p.trMap[p.makeTrMapKey(domain, p.lang)]; ok {
+		return f.PNGettext(msgctxt, msgid, msgidPlural, n)
+	}
+	return msgid
+}
+
+func (p *_Locale) getdata(domain, name string) []byte {
+	if data, err := p.fs.LoadResourceFile(domain, p.lang, name); err == nil {
+		return data
+	}
+	if p.lang != "default" {
+		if data, err := p.fs.LoadResourceFile(domain, "default", name); err == nil {
+			return data
+		}
+	}
+	return nil
+}
@@ -0,0 +1,74 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package mo provides support for reading and writing GNU MO file.
+
+Examples:
+	import (
+		"github.com/chai2010/gettext-go/mo"
+	)
+
+	func main() {
+		moFile, err := mo.LoadFile("test.mo")
+		if err != nil {
+			log.Fatal(err)
+		}
+		fmt.Printf("%v", moFile)
+	}
+
+GNU MO file struct:
+
+	        byte
+	             +------------------------------------------+
+	          0  | magic number = 0x950412de                |
+	             |                                          |
+	          4  | file format revision = 0                 |
+	             |                                          |
+	          8  | number of strings                        |  == N
+	             |                                          |
+	         12  | offset of table with original strings    |  == O
+	             |                                          |
+	         16  | offset of table with translation strings |  == T
+	             |                                          |
+	         20  | size of hashing table                    |  == S
+	             |                                          |
+	         24  | offset of hashing table                  |  == H
+	             |                                          |
+	             .                                          .
+	             .    (possibly more entries later)         .
+	             .                                          .
+	             |                                          |
+	          O  | length & offset 0th string  ----------------.
+	      O + 8  | length & offset 1st string  ------------------.
+	              ...                                    ...   | |
+	O + ((N-1)*8)| length & offset (N-1)th string           |  | |
+	             |                                          |  | |
+	          T  | length & offset 0th translation  ---------------.
+	      T + 8  | length & offset 1st translation  -----------------.
+	              ...                                    ...   | | | |
+	T + ((N-1)*8)| length & offset (N-1)th translation      |  | | | |
+	             |                                          |  | | | |
+	          H  | start hash table                         |  | | | |
+	              ...                                    ...   | | | |
+	  H + S * 4  | end hash table                           |  | | | |
+	             |                                          |  | | | |
+	             | NUL terminated 0th string  <----------------' | | |
+	             |                                          |    | | |
+	             | NUL terminated 1st string  <------------------' | |
+	             |                                          |      | |
+	              ...                                    ...       | |
+	             |                                          |      | |
+	             | NUL terminated 0th translation  <---------------' |
+	             |                                          |        |
+	             | NUL terminated 1st translation  <-----------------'
+	             |                                          |
+	              ...                                    ...
+	             |                                          |
+	             +------------------------------------------+
+
+The GNU MO file specification is at
+http://www.gnu.org/software/gettext/manual/html_node/MO-Files.html.
+*/
+package mo
@@ -0,0 +1,105 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mo
+
+import (
+	"bytes"
+	"encoding/binary"
+	"sort"
+	"strings"
+)
+
+type moHeader struct {
+	MagicNumber  uint32
+	MajorVersion uint16
+	MinorVersion uint16
+	MsgIdCount   uint32
+	MsgIdOffset  uint32
+	MsgStrOffset uint32
+	HashSize     uint32
+	HashOffset   uint32
+}
+
+type moStrPos struct {
+	Size uint32 // must keep fields order
+	Addr uint32
+}
+
+func encodeFile(f *File) []byte {
+	hdr := &moHeader{
+		MagicNumber: MoMagicLittleEndian,
+	}
+	data := encodeData(hdr, f)
+	data = append(encodeHeader(hdr), data...)
+	return data
+}
+
+// encode data and init moHeader
+func encodeData(hdr *moHeader, f *File) []byte {
+	msgList := []Message{f.MimeHeader.toMessage()}
+	for _, v := range f.Messages {
+		if len(v.MsgId) == 0 {
+			continue
+		}
+		if len(v.MsgStr) == 0 && len(v.MsgStrPlural) == 0 {
+			continue
+		}
+		msgList = append(msgList, v)
+	}
+	sort.Slice(msgList, func(i, j int) bool {
+		return msgList[i].less(&msgList[j])
+	})
+
+	var buf bytes.Buffer
+	var msgIdPosList = make([]moStrPos, len(msgList))
+	var msgStrPosList = make([]moStrPos, len(msgList))
+	for i, v := range msgList {
+		// write msgid
+		msgId := encodeMsgId(v)
+		msgIdPosList[i].Addr = uint32(buf.Len() + MoHeaderSize)
+		msgIdPosList[i].Size = uint32(len(msgId))
+		buf.WriteString(msgId)
+		// write msgstr
+		msgStr := encodeMsgStr(v)
+		msgStrPosList[i].Addr = uint32(buf.Len() + MoHeaderSize)
+		msgStrPosList[i].Size = uint32(len(msgStr))
+		buf.WriteString(msgStr)
+	}
+
+	hdr.MsgIdOffset = uint32(buf.Len() + MoHeaderSize)
+	binary.Write(&buf, binary.LittleEndian, msgIdPosList)
+	hdr.MsgStrOffset = uint32(buf.Len() + MoHeaderSize)
+	binary.Write(&buf, binary.LittleEndian, msgStrPosList)
+
+	hdr.MsgIdCount = uint32(len(msgList))
+	return buf.Bytes()
+}
+
+// must called after encodeData
+func encodeHeader(hdr *moHeader) []byte {
+	var buf bytes.Buffer
+	binary.Write(&buf, binary.LittleEndian, hdr)
+	return buf.Bytes()
+}
+
+func encodeMsgId(v Message) string {
+	if v.MsgContext != "" && v.MsgIdPlural != "" {
+		return v.MsgContext + EotSeparator + v.MsgId + NulSeparator + v.MsgIdPlural
+	}
+	if v.MsgContext != "" && v.MsgIdPlural == "" {
+		return v.MsgContext + EotSeparator + v.MsgId
+	}
+	if v.MsgContext == "" && v.MsgIdPlural != "" {
+		return v.MsgId + NulSeparator + v.MsgIdPlural
+	}
+	return v.MsgId
+}
+
+func encodeMsgStr(v Message) string {
+	if v.MsgIdPlural != "" {
+		return strings.Join(v.MsgStrPlural, NulSeparator)
+	}
+	return v.MsgStr
+}
@@ -0,0 +1,197 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mo
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io/ioutil"
+	"strings"
+)
+
+const (
+	MoHeaderSize        = 28
+	MoMagicLittleEndian = 0x950412de
+	MoMagicBigEndian    = 0xde120495
+
+	EotSeparator = "\x04" // msgctxt and msgid separator
+	NulSeparator = "\x00" // msgid and msgstr separator
+)
+
+// File represents an MO File.
+//
+// See http://www.gnu.org/software/gettext/manual/html_node/MO-Files.html
+type File struct {
+	MagicNumber  uint32
+	MajorVersion uint16
+	MinorVersion uint16
+	MsgIdCount   uint32
+	MsgIdOffset  uint32
+	MsgStrOffset uint32
+	HashSize     uint32
+	HashOffset   uint32
+	MimeHeader   Header
+	Messages     []Message
+}
+
+// Load loads mo file format data.
+func Load(data []byte) (*File, error) {
+	return loadData(data)
+}
+
+// Load loads a named mo file.
+func LoadFile(path string) (*File, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return loadData(data)
+}
+
+func loadData(data []byte) (*File, error) {
+	r := bytes.NewReader(data)
+
+	var magicNumber uint32
+	if err := binary.Read(r, binary.LittleEndian, &magicNumber); err != nil {
+		return nil, fmt.Errorf("gettext: %v", err)
+	}
+	var bo binary.ByteOrder
+	switch magicNumber {
+	case MoMagicLittleEndian:
+		bo = binary.LittleEndian
+	case MoMagicBigEndian:
+		bo = binary.BigEndian
+	default:
+		return nil, fmt.Errorf("gettext: %v", "invalid magic number")
+	}
+
+	var header struct {
+		MajorVersion uint16
+		MinorVersion uint16
+		MsgIdCount   uint32
+		MsgIdOffset  uint32
+		MsgStrOffset uint32
+		HashSize     uint32
+		HashOffset   uint32
+	}
+	if err := binary.Read(r, bo, &header); err != nil {
+		return nil, fmt.Errorf("gettext: %v", err)
+	}
+	if v := header.MajorVersion; v != 0 && v != 1 {
+		return nil, fmt.Errorf("gettext: %v", "invalid version number")
+	}
+	if v := header.MinorVersion; v != 0 && v != 1 {
+		return nil, fmt.Errorf("gettext: %v", "invalid version number")
+	}
+
+	msgIdStart := make([]uint32, header.MsgIdCount)
+	msgIdLen := make([]uint32, header.MsgIdCount)
+	if _, err := r.Seek(int64(header.MsgIdOffset), 0); err != nil {
+		return nil, fmt.Errorf("gettext: %v", err)
+	}
+	for i := 0; i < int(header.MsgIdCount); i++ {
+		if err := binary.Read(r, bo, &msgIdLen[i]); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+		if err := binary.Read(r, bo, &msgIdStart[i]); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+	}
+
+	msgStrStart := make([]int32, header.MsgIdCount)
+	msgStrLen := make([]int32, header.MsgIdCount)
+	if _, err := r.Seek(int64(header.MsgStrOffset), 0); err != nil {
+		return nil, fmt.Errorf("gettext: %v", err)
+	}
+	for i := 0; i < int(header.MsgIdCount); i++ {
+		if err := binary.Read(r, bo, &msgStrLen[i]); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+		if err := binary.Read(r, bo, &msgStrStart[i]); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+	}
+
+	file := &File{
+		MagicNumber:  magicNumber,
+		MajorVersion: header.MajorVersion,
+		MinorVersion: header.MinorVersion,
+		MsgIdCount:   header.MsgIdCount,
+		MsgIdOffset:  header.MsgIdOffset,
+		MsgStrOffset: header.MsgStrOffset,
+		HashSize:     header.HashSize,
+		HashOffset:   header.HashOffset,
+	}
+	for i := 0; i < int(header.MsgIdCount); i++ {
+		if _, err := r.Seek(int64(msgIdStart[i]), 0); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+		msgIdData := make([]byte, msgIdLen[i])
+		if _, err := r.Read(msgIdData); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+
+		if _, err := r.Seek(int64(msgStrStart[i]), 0); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+		msgStrData := make([]byte, msgStrLen[i])
+		if _, err := r.Read(msgStrData); err != nil {
+			return nil, fmt.Errorf("gettext: %v", err)
+		}
+
+		if len(msgIdData) == 0 {
+			var msg = Message{
+				MsgId:  string(msgIdData),
+				MsgStr: string(msgStrData),
+			}
+			file.MimeHeader.fromMessage(&msg)
+		} else {
+			var msg = Message{
+				MsgId:  string(msgIdData),
+				MsgStr: string(msgStrData),
+			}
+			// Is this a context message?
+			if idx := strings.Index(msg.MsgId, EotSeparator); idx != -1 {
+				msg.MsgContext, msg.MsgId = msg.MsgId[:idx], msg.MsgId[idx+1:]
+			}
+			// Is this a plural message?
+			if idx := strings.Index(msg.MsgId, NulSeparator); idx != -1 {
+				msg.MsgId, msg.MsgIdPlural = msg.MsgId[:idx], msg.MsgId[idx+1:]
+				msg.MsgStrPlural = strings.Split(msg.MsgStr, NulSeparator)
+				msg.MsgStr = ""
+			}
+			file.Messages = append(file.Messages, msg)
+		}
+	}
+
+	return file, nil
+}
+
+// Save saves a mo file.
+func (f *File) Save(name string) error {
+	return ioutil.WriteFile(name, f.Data(), 0666)
+}
+
+// Save returns a mo file format data.
+func (f *File) Data() []byte {
+	return encodeFile(f)
+}
+
+// String returns the po format file string.
+func (f *File) String() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "# version: %d.%d\n", f.MajorVersion, f.MinorVersion)
+	fmt.Fprintf(&buf, "%s\n", f.MimeHeader.String())
+	fmt.Fprintf(&buf, "\n")
+
+	for k, v := range f.Messages {
+		fmt.Fprintf(&buf, `msgid "%v"`+"\n", k)
+		fmt.Fprintf(&buf, `msgstr "%s"`+"\n", v.MsgStr)
+		fmt.Fprintf(&buf, "\n")
+	}
+
+	return buf.String()
+}
@@ -0,0 +1,109 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mo
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+)
+
+// Header is the initial comments "SOME DESCRIPTIVE TITLE", "YEAR"
+// and "FIRST AUTHOR <EMAIL@ADDRESS>, YEAR" ought to be replaced by sensible information.
+//
+// See http://www.gnu.org/software/gettext/manual/html_node/Header-Entry.html#Header-Entry
+type Header struct {
+	ProjectIdVersion        string // Project-Id-Version: PACKAGE VERSION
+	ReportMsgidBugsTo       string // Report-Msgid-Bugs-To: FIRST AUTHOR <EMAIL@ADDRESS>
+	POTCreationDate         string // POT-Creation-Date: YEAR-MO-DA HO:MI+ZONE
+	PORevisionDate          string // PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE
+	LastTranslator          string // Last-Translator: FIRST AUTHOR <EMAIL@ADDRESS>
+	LanguageTeam            string // Language-Team: golang-china
+	Language                string // Language: zh_CN
+	MimeVersion             string // MIME-Version: 1.0
+	ContentType             string // Content-Type: text/plain; charset=UTF-8
+	ContentTransferEncoding string // Content-Transfer-Encoding: 8bit
+	PluralForms             string // Plural-Forms: nplurals=2; plural=n == 1 ? 0 : 1;
+	XGenerator              string // X-Generator: Poedit 1.5.5
+	UnknowFields            map[string]string
+}
+
+func (p *Header) fromMessage(msg *Message) {
+	if msg.MsgId != "" || msg.MsgStr == "" {
+		return
+	}
+	lines := strings.Split(msg.MsgStr, "\n")
+	for i := 0; i < len(lines); i++ {
+		idx := strings.Index(lines[i], ":")
+		if idx < 0 {
+			continue
+		}
+		key := strings.TrimSpace(lines[i][:idx])
+		val := strings.TrimSpace(lines[i][idx+1:])
+		switch strings.ToUpper(key) {
+		case strings.ToUpper("Project-Id-Version"):
+			p.ProjectIdVersion = val
+		case strings.ToUpper("Report-Msgid-Bugs-To"):
+			p.ReportMsgidBugsTo = val
+		case strings.ToUpper("POT-Creation-Date"):
+			p.POTCreationDate = val
+		case strings.ToUpper("PO-Revision-Date"):
+			p.PORevisionDate = val
+		case strings.ToUpper("Last-Translator"):
+			p.LastTranslator = val
+		case strings.ToUpper("Language-Team"):
+			p.LanguageTeam = val
+		case strings.ToUpper("Language"):
+			p.Language = val
+		case strings.ToUpper("MIME-Version"):
+			p.MimeVersion = val
+		case strings.ToUpper("Content-Type"):
+			p.ContentType = val
+		case strings.ToUpper("Content-Transfer-Encoding"):
+			p.ContentTransferEncoding = val
+		case strings.ToUpper("Plural-Forms"):
+			p.PluralForms = val
+		case strings.ToUpper("X-Generator"):
+			p.XGenerator = val
+		default:
+			if p.UnknowFields == nil {
+				p.UnknowFields = make(map[string]string)
+			}
+			p.UnknowFields[key] = val
+		}
+	}
+}
+
+func (p *Header) toMessage() Message {
+	return Message{
+		MsgStr: p.String(),
+	}
+}
+
+// String returns the po format header string.
+func (p Header) String() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, `msgid ""`+"\n")
+	fmt.Fprintf(&buf, `msgstr ""`+"\n")
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Project-Id-Version", p.ProjectIdVersion)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Report-Msgid-Bugs-To", p.ReportMsgidBugsTo)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "POT-Creation-Date", p.POTCreationDate)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "PO-Revision-Date", p.PORevisionDate)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Last-Translator", p.LastTranslator)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Language-Team", p.LanguageTeam)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Language", p.Language)
+	if p.MimeVersion != "" {
+		fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "MIME-Version", p.MimeVersion)
+	}
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Content-Type", p.ContentType)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Content-Transfer-Encoding", p.ContentTransferEncoding)
+	if p.XGenerator != "" {
+		fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "X-Generator", p.XGenerator)
+	}
+	for k, v := range p.UnknowFields {
+		fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", k, v)
+	}
+	return buf.String()
+}
@@ -0,0 +1,52 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mo
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// A MO file is made up of many entries,
+// each entry holding the relation between an original untranslated string
+// and its corresponding translation.
+//
+// See http://www.gnu.org/software/gettext/manual/html_node/MO-Files.html
+type Message struct {
+	MsgContext   string   // msgctxt context
+	MsgId        string   // msgid untranslated-string
+	MsgIdPlural  string   // msgid_plural untranslated-string-plural
+	MsgStr       string   // msgstr translated-string
+	MsgStrPlural []string // msgstr[0] translated-string-case-0
+}
+
+// String returns the po format entry string.
+func (p Message) String() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "msgid %s", encodePoString(p.MsgId))
+	if p.MsgIdPlural != "" {
+		fmt.Fprintf(&buf, "msgid_plural %s", encodePoString(p.MsgIdPlural))
+	}
+	if p.MsgStr != "" {
+		fmt.Fprintf(&buf, "msgstr %s", encodePoString(p.MsgStr))
+	}
+	for i := 0; i < len(p.MsgStrPlural); i++ {
+		fmt.Fprintf(&buf, "msgstr[%d] %s", i, encodePoString(p.MsgStrPlural[i]))
+	}
+	return buf.String()
+}
+
+func (m_i *Message) less(m_j *Message) bool {
+	if a, b := m_i.MsgContext, m_j.MsgContext; a != b {
+		return a < b
+	}
+	if a, b := m_i.MsgId, m_j.MsgId; a != b {
+		return a < b
+	}
+	if a, b := m_i.MsgIdPlural, m_j.MsgIdPlural; a != b {
+		return a < b
+	}
+	return false
+}
@@ -0,0 +1,110 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mo
+
+import (
+	"bytes"
+	"strings"
+)
+
+func decodePoString(text string) string {
+	lines := strings.Split(text, "\n")
+	for i := 0; i < len(lines); i++ {
+		left := strings.Index(lines[i], `"`)
+		right := strings.LastIndex(lines[i], `"`)
+		if left < 0 || right < 0 || left == right {
+			lines[i] = ""
+			continue
+		}
+		line := lines[i][left+1 : right]
+		data := make([]byte, 0, len(line))
+		for i := 0; i < len(line); i++ {
+			if line[i] != '\\' {
+				data = append(data, line[i])
+				continue
+			}
+			if i+1 >= len(line) {
+				break
+			}
+			switch line[i+1] {
+			case 'n': // \\n -> \n
+				data = append(data, '\n')
+				i++
+			case 't': // \\t -> \n
+				data = append(data, '\t')
+				i++
+			case '\\': // \\\ -> ?
+				data = append(data, '\\')
+				i++
+			}
+		}
+		lines[i] = string(data)
+	}
+	return strings.Join(lines, "")
+}
+
+func encodePoString(text string) string {
+	var buf bytes.Buffer
+	lines := strings.Split(text, "\n")
+	for i := 0; i < len(lines); i++ {
+		if lines[i] == "" {
+			if i != len(lines)-1 {
+				buf.WriteString(`"\n"` + "\n")
+			}
+			continue
+		}
+		buf.WriteRune('"')
+		for _, r := range lines[i] {
+			switch r {
+			case '\\':
+				buf.WriteString(`\\`)
+			case '"':
+				buf.WriteString(`\"`)
+			case '\n':
+				buf.WriteString(`\n`)
+			case '\t':
+				buf.WriteString(`\t`)
+			default:
+				buf.WriteRune(r)
+			}
+		}
+		buf.WriteString(`\n"` + "\n")
+	}
+	return buf.String()
+}
+
+func encodeCommentPoString(text string) string {
+	var buf bytes.Buffer
+	lines := strings.Split(text, "\n")
+	if len(lines) > 1 {
+		buf.WriteString(`""` + "\n")
+	}
+	for i := 0; i < len(lines); i++ {
+		if len(lines) > 0 {
+			buf.WriteString("#| ")
+		}
+		buf.WriteRune('"')
+		for _, r := range lines[i] {
+			switch r {
+			case '\\':
+				buf.WriteString(`\\`)
+			case '"':
+				buf.WriteString(`\"`)
+			case '\n':
+				buf.WriteString(`\n`)
+			case '\t':
+				buf.WriteString(`\t`)
+			default:
+				buf.WriteRune(r)
+			}
+		}
+		if i < len(lines)-1 {
+			buf.WriteString(`\n"` + "\n")
+		} else {
+			buf.WriteString(`"`)
+		}
+	}
+	return buf.String()
+}
@@ -0,0 +1,36 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. 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 provides standard plural formulas.
+
+Examples:
+	import (
+		"github.com/chai2010/gettext-go/plural"
+	)
+
+	func main() {
+		enFormula := plural.Formula("en_US")
+		xxFormula := plural.Formula("zh_CN")
+
+		fmt.Printf("%s: %d\n", "en", enFormula(0))
+		fmt.Printf("%s: %d\n", "en", enFormula(1))
+		fmt.Printf("%s: %d\n", "en", enFormula(2))
+		fmt.Printf("%s: %d\n", "??", xxFormula(0))
+		fmt.Printf("%s: %d\n", "??", xxFormula(1))
+		fmt.Printf("%s: %d\n", "??", xxFormula(2))
+		fmt.Printf("%s: %d\n", "??", xxFormula(9))
+		// Output:
+		// en: 0
+		// en: 0
+		// en: 1
+		// ??: 0
+		// ??: 0
+		// ??: 1
+		// ??: 8
+	}
+
+See http://www.gnu.org/software/gettext/manual/html_node/Plural-forms.html
+*/
+package plural
@@ -0,0 +1,181 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. 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 (
+	"strings"
+)
+
+// Formula provides the language's standard plural formula.
+func Formula(lang string) func(n int) int {
+	if idx := index(lang); idx != -1 {
+		return formulaTable[fmtForms(FormsTable[idx].Value)]
+	}
+	if idx := index("??"); idx != -1 {
+		return formulaTable[fmtForms(FormsTable[idx].Value)]
+	}
+	return func(n int) int {
+		return n
+	}
+}
+
+func index(lang string) int {
+	for i := 0; i < len(FormsTable); i++ {
+		if strings.HasPrefix(lang, FormsTable[i].Lang) {
+			return i
+		}
+	}
+	return -1
+}
+
+func fmtForms(forms string) string {
+	forms = strings.TrimSpace(forms)
+	forms = strings.Replace(forms, " ", "", -1)
+	return forms
+}
+
+var formulaTable = map[string]func(n int) int{
+	fmtForms("nplurals=n; plural=n-1;"): func(n int) int {
+		if n > 0 {
+			return n - 1
+		}
+		return 0
+	},
+	fmtForms("nplurals=1; plural=0;"): func(n int) int {
+		return 0
+	},
+	fmtForms("nplurals=2; plural=(n != 1);"): func(n int) int {
+		if n <= 1 {
+			return 0
+		}
+		return 1
+	},
+	fmtForms("nplurals=2; plural=(n > 1);"): func(n int) int {
+		if n <= 1 {
+			return 0
+		}
+		return 1
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n != 0 ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n != 0 {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=n==1 ? 0 : n==2 ? 1 : 2;"): func(n int) int {
+		if n == 1 {
+			return 0
+		}
+		if n == 2 {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=n==1 ? 0 : (n==0 || (n%100 > 0 && n%100 < 20)) ? 1 : 2;"): func(n int) int {
+		if n == 1 {
+			return 0
+		}
+		if n == 0 || (n%100 > 0 && n%100 < 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n%10 >= 2 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n%10 == 1 && n%100 != 11 {
+			return 0
+		}
+		if n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n==1) ? 0 : (n>=2 && n<=4) ? 1 : 2;"): func(n int) int {
+		if n == 1 {
+			return 0
+		}
+		if n >= 2 && n <= 4 {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n==1) ? 0 : (n>=2 && n<=4) ? 1 : 2;"): func(n int) int {
+		if n == 1 {
+			return 0
+		}
+		if n >= 2 && n <= 4 {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=3; plural=(n==1 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"): func(n int) int {
+		if n == 1 {
+			return 0
+		}
+		if n%10 >= 2 && n%10 <= 4 && (n%100 < 10 || n%100 >= 20) {
+			return 1
+		}
+		return 2
+	},
+	fmtForms("nplurals=4; plural=(n%100==1 ? 0 : n%100==2 ? 1 : n%100==3 || n%100==4 ? 2 : 3);"): func(n int) int {
+		if n%100 == 1 {
+			return 0
+		}
+		if n%100 == 2 {
+			return 1
+		}
+		if n%100 == 3 || n%100 == 4 {
+			return 2
+		}
+		return 3
+	},
+}
@@ -0,0 +1,55 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. 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
+
+// FormsTable are standard hard-coded plural rules.
+// The application developers and the translators need to understand them.
+//
+// See GNU's gettext library source code: gettext/gettext-tools/src/plural-table.c
+var FormsTable = []struct {
+	Lang     string
+	Language string
+	Value    string
+}{
+	{"??", "Unknown", "nplurals=1; plural=0;"},
+	{"ja", "Japanese", "nplurals=1; plural=0;"},
+	{"vi", "Vietnamese", "nplurals=1; plural=0;"},
+	{"ko", "Korean", "nplurals=1; plural=0;"},
+	{"en", "English", "nplurals=2; plural=(n != 1);"},
+	{"de", "German", "nplurals=2; plural=(n != 1);"},
+	{"nl", "Dutch", "nplurals=2; plural=(n != 1);"},
+	{"sv", "Swedish", "nplurals=2; plural=(n != 1);"},
+	{"da", "Danish", "nplurals=2; plural=(n != 1);"},
+	{"no", "Norwegian", "nplurals=2; plural=(n != 1);"},
+	{"nb", "Norwegian Bokmal", "nplurals=2; plural=(n != 1);"},
+	{"nn", "Norwegian Nynorsk", "nplurals=2; plural=(n != 1);"},
+	{"fo", "Faroese", "nplurals=2; plural=(n != 1);"},
+	{"es", "Spanish", "nplurals=2; plural=(n != 1);"},
+	{"pt", "Portuguese", "nplurals=2; plural=(n != 1);"},
+	{"it", "Italian", "nplurals=2; plural=(n != 1);"},
+	{"bg", "Bulgarian", "nplurals=2; plural=(n != 1);"},
+	{"el", "Greek", "nplurals=2; plural=(n != 1);"},
+	{"fi", "Finnish", "nplurals=2; plural=(n != 1);"},
+	{"et", "Estonian", "nplurals=2; plural=(n != 1);"},
+	{"he", "Hebrew", "nplurals=2; plural=(n != 1);"},
+	{"eo", "Esperanto", "nplurals=2; plural=(n != 1);"},
+	{"hu", "Hungarian", "nplurals=2; plural=(n != 1);"},
+	{"tr", "Turkish", "nplurals=2; plural=(n != 1);"},
+	{"pt_BR", "Brazilian", "nplurals=2; plural=(n > 1);"},
+	{"fr", "French", "nplurals=2; plural=(n > 1);"},
+	{"lv", "Latvian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n != 0 ? 1 : 2);"},
+	{"ga", "Irish", "nplurals=3; plural=n==1 ? 0 : n==2 ? 1 : 2;"},
+	{"ro", "Romanian", "nplurals=3; plural=n==1 ? 0 : (n==0 || (n%100 > 0 && n%100 < 20)) ? 1 : 2;"},
+	{"lt", "Lithuanian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"ru", "Russian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"uk", "Ukrainian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"be", "Belarusian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"sr", "Serbian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"hr", "Croatian", "nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"cs", "Czech", "nplurals=3; plural=(n==1) ? 0 : (n>=2 && n<=4) ? 1 : 2;"},
+	{"sk", "Slovak", "nplurals=3; plural=(n==1) ? 0 : (n>=2 && n<=4) ? 1 : 2;"},
+	{"pl", "Polish", "nplurals=3; plural=(n==1 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"},
+	{"sl", "Slovenian", "nplurals=4; plural=(n%100==1 ? 0 : n%100==2 ? 1 : n%100==3 || n%100==4 ? 2 : 3);"},
+}
@@ -0,0 +1,270 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// Comment represents every message's comments.
+type Comment struct {
+	StartLine         int      // comment start line
+	TranslatorComment string   // #  translator-comments // TrimSpace
+	ExtractedComment  string   // #. extracted-comments
+	ReferenceFile     []string // #: src/msgcmp.c:338 src/po-lex.c:699
+	ReferenceLine     []int    // #: src/msgcmp.c:338 src/po-lex.c:699
+	Flags             []string // #, fuzzy,c-format,range:0..10
+	PrevMsgContext    string   // #| msgctxt previous-context
+	PrevMsgId         string   // #| msgid previous-untranslated-string
+}
+
+func (p *Comment) less(q *Comment) bool {
+	if p.StartLine != 0 || q.StartLine != 0 {
+		return p.StartLine < q.StartLine
+	}
+	if a, b := len(p.ReferenceFile), len(q.ReferenceFile); a != b {
+		return a < b
+	}
+	for i := 0; i < len(p.ReferenceFile); i++ {
+		if a, b := p.ReferenceFile[i], q.ReferenceFile[i]; a != b {
+			return a < b
+		}
+		if a, b := p.ReferenceLine[i], q.ReferenceLine[i]; a != b {
+			return a < b
+		}
+	}
+	return false
+}
+
+func (p *Comment) readPoComment(r *lineReader) (err error) {
+	*p = Comment{}
+	if err = r.skipBlankLine(); err != nil {
+		return err
+	}
+	defer func(oldPos int) {
+		newPos := r.currentPos()
+		if newPos != oldPos && err == io.EOF {
+			err = nil
+		}
+	}(r.currentPos())
+
+	p.StartLine = r.currentPos() + 1
+	for {
+		var s string
+		if s, _, err = r.currentLine(); err != nil {
+			return
+		}
+		if len(s) == 0 || s[0] != '#' {
+			return
+		}
+
+		if err = p.readTranslatorComment(r); err != nil {
+			return
+		}
+		if err = p.readExtractedComment(r); err != nil {
+			return
+		}
+		if err = p.readReferenceComment(r); err != nil {
+			return
+		}
+		if err = p.readFlagsComment(r); err != nil {
+			return
+		}
+		if err = p.readPrevMsgContext(r); err != nil {
+			return
+		}
+		if err = p.readPrevMsgId(r); err != nil {
+			return
+		}
+	}
+}
+
+func (p *Comment) readTranslatorComment(r *lineReader) (err error) {
+	const prefix = "# " // .,:|
+	for {
+		var s string
+		if s, _, err = r.readLine(); err != nil {
+			return err
+		}
+		if len(s) < 1 || s[0] != '#' {
+			r.unreadLine()
+			return nil
+		}
+		if len(s) >= 2 {
+			switch s[1] {
+			case '.', ',', ':', '|':
+				r.unreadLine()
+				return nil
+			}
+		}
+		if p.TranslatorComment != "" {
+			p.TranslatorComment += "\n"
+		}
+		p.TranslatorComment += strings.TrimSpace(s[1:])
+	}
+}
+
+func (p *Comment) readExtractedComment(r *lineReader) (err error) {
+	const prefix = "#."
+	for {
+		var s string
+		if s, _, err = r.readLine(); err != nil {
+			return err
+		}
+		if len(s) < len(prefix) || s[:len(prefix)] != prefix {
+			r.unreadLine()
+			return nil
+		}
+		if p.ExtractedComment != "" {
+			p.ExtractedComment += "\n"
+		}
+		p.ExtractedComment += strings.TrimSpace(s[len(prefix):])
+	}
+}
+
+func (p *Comment) readReferenceComment(r *lineReader) (err error) {
+	const prefix = "#:"
+	for {
+		var s string
+		if s, _, err = r.readLine(); err != nil {
+			return err
+		}
+		if len(s) < len(prefix) || s[:len(prefix)] != prefix {
+			r.unreadLine()
+			return nil
+		}
+		ss := strings.Split(strings.TrimSpace(s[len(prefix):]), " ")
+		for i := 0; i < len(ss); i++ {
+			idx := strings.Index(ss[i], ":")
+			if idx <= 0 {
+				continue
+			}
+			name := strings.TrimSpace(ss[i][:idx])
+			line, _ := strconv.Atoi(strings.TrimSpace(ss[i][idx+1:]))
+			p.ReferenceFile = append(p.ReferenceFile, name)
+			p.ReferenceLine = append(p.ReferenceLine, line)
+		}
+	}
+}
+
+func (p *Comment) readFlagsComment(r *lineReader) (err error) {
+	const prefix = "#,"
+	for {
+		var s string
+		if s, _, err = r.readLine(); err != nil {
+			return err
+		}
+		if len(s) < len(prefix) || s[:len(prefix)] != prefix {
+			r.unreadLine()
+			return nil
+		}
+		ss := strings.Split(strings.TrimSpace(s[len(prefix):]), ",")
+		for i := 0; i < len(ss); i++ {
+			p.Flags = append(p.Flags, strings.TrimSpace(ss[i]))
+		}
+	}
+}
+
+func (p *Comment) readPrevMsgContext(r *lineReader) (err error) {
+	var s string
+	if s, _, err = r.currentLine(); err != nil {
+		return
+	}
+	if !rePrevMsgContextComments.MatchString(s) {
+		return
+	}
+	p.PrevMsgContext, err = p.readString(r)
+	return
+}
+
+func (p *Comment) readPrevMsgId(r *lineReader) (err error) {
+	var s string
+	if s, _, err = r.currentLine(); err != nil {
+		return
+	}
+	if !rePrevMsgIdComments.MatchString(s) {
+		return
+	}
+	p.PrevMsgId, err = p.readString(r)
+	return
+}
+
+func (p *Comment) readString(r *lineReader) (msg string, err error) {
+	var s string
+	if s, _, err = r.readLine(); err != nil {
+		return
+	}
+	msg += decodePoString(s)
+	for {
+		if s, _, err = r.readLine(); err != nil {
+			return
+		}
+		if !reStringLineComments.MatchString(s) {
+			r.unreadLine()
+			break
+		}
+		msg += decodePoString(s)
+	}
+	return
+}
+
+// GetFuzzy gets the fuzzy flag.
+func (p *Comment) GetFuzzy() bool {
+	for _, s := range p.Flags {
+		if s == "fuzzy" {
+			return true
+		}
+	}
+	return false
+}
+
+// SetFuzzy sets the fuzzy flag.
+func (p *Comment) SetFuzzy(fuzzy bool) {
+	//
+}
+
+// String returns the po format comment string.
+func (p Comment) String() string {
+	var buf bytes.Buffer
+	if p.TranslatorComment != "" {
+		ss := strings.Split(p.TranslatorComment, "\n")
+		for i := 0; i < len(ss); i++ {
+			fmt.Fprintf(&buf, "# %s\n", ss[i])
+		}
+	}
+	if p.ExtractedComment != "" {
+		ss := strings.Split(p.ExtractedComment, "\n")
+		for i := 0; i < len(ss); i++ {
+			fmt.Fprintf(&buf, "#. %s\n", ss[i])
+		}
+	}
+	if a, b := len(p.ReferenceFile), len(p.ReferenceLine); a != 0 && a == b {
+		fmt.Fprintf(&buf, "#:")
+		for i := 0; i < len(p.ReferenceFile); i++ {
+			fmt.Fprintf(&buf, " %s:%d", p.ReferenceFile[i], p.ReferenceLine[i])
+		}
+		fmt.Fprintf(&buf, "\n")
+	}
+	if len(p.Flags) != 0 {
+		fmt.Fprintf(&buf, "#, %s", p.Flags[0])
+		for i := 1; i < len(p.Flags); i++ {
+			fmt.Fprintf(&buf, ", %s", p.Flags[i])
+		}
+		fmt.Fprintf(&buf, "\n")
+	}
+	if p.PrevMsgContext != "" {
+		s := encodeCommentPoString(p.PrevMsgContext)
+		fmt.Fprintf(&buf, "#| msgctxt %s\n", s)
+	}
+	if p.PrevMsgId != "" {
+		s := encodeCommentPoString(p.PrevMsgId)
+		fmt.Fprintf(&buf, "#| msgid %s\n", s)
+	}
+	return buf.String()
+}
@@ -0,0 +1,24 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package po provides support for reading and writing GNU PO file.
+
+Examples:
+	import (
+		"github.com/chai2010/gettext-go/po"
+	)
+
+	func main() {
+		poFile, err := po.LoadFile("test.po")
+		if err != nil {
+			log.Fatal(err)
+		}
+		fmt.Printf("%v", poFile)
+	}
+
+The GNU PO file specification is at
+http://www.gnu.org/software/gettext/manual/html_node/PO-Files.html.
+*/
+package po
@@ -0,0 +1,81 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"sort"
+)
+
+// File represents an PO File.
+//
+// See http://www.gnu.org/software/gettext/manual/html_node/PO-Files.html
+type File struct {
+	MimeHeader Header
+	Messages   []Message
+}
+
+// Load loads po file format data.
+func Load(data []byte) (*File, error) {
+	return loadData(data)
+}
+
+// LoadFile loads a named po file.
+func LoadFile(path string) (*File, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return loadData(data)
+}
+
+func loadData(data []byte) (*File, error) {
+	r := newLineReader(string(data))
+	var file File
+	for {
+		var msg Message
+		if err := msg.readPoEntry(r); err != nil {
+			if err == io.EOF {
+				return &file, nil
+			}
+			return nil, err
+		}
+		if msg.MsgId == "" {
+			file.MimeHeader.parseHeader(&msg)
+			continue
+		}
+		file.Messages = append(file.Messages, msg)
+	}
+}
+
+// Save saves a po file.
+func (f *File) Save(name string) error {
+	return ioutil.WriteFile(name, []byte(f.String()), 0666)
+}
+
+// Save returns a po file format data.
+func (f *File) Data() []byte {
+	// sort the massge as ReferenceFile/ReferenceLine field
+	var messages []Message
+	messages = append(messages, f.Messages...)
+	sort.Slice(messages, func(i, j int) bool {
+		return messages[i].less(&messages[j])
+	})
+
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "%s\n", f.MimeHeader.String())
+	for i := 0; i < len(messages); i++ {
+		fmt.Fprintf(&buf, "%s\n", messages[i].String())
+	}
+	return buf.Bytes()
+}
+
+// String returns the po format file string.
+func (f *File) String() string {
+	return string(f.Data())
+}
@@ -0,0 +1,106 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+)
+
+// Header is the initial comments "SOME DESCRIPTIVE TITLE", "YEAR"
+// and "FIRST AUTHOR <EMAIL@ADDRESS>, YEAR" ought to be replaced by sensible information.
+//
+// See http://www.gnu.org/software/gettext/manual/html_node/Header-Entry.html#Header-Entry
+type Header struct {
+	Comment                        // Header Comments
+	ProjectIdVersion        string // Project-Id-Version: PACKAGE VERSION
+	ReportMsgidBugsTo       string // Report-Msgid-Bugs-To: FIRST AUTHOR <EMAIL@ADDRESS>
+	POTCreationDate         string // POT-Creation-Date: YEAR-MO-DA HO:MI+ZONE
+	PORevisionDate          string // PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE
+	LastTranslator          string // Last-Translator: FIRST AUTHOR <EMAIL@ADDRESS>
+	LanguageTeam            string // Language-Team: golang-china
+	Language                string // Language: zh_CN
+	MimeVersion             string // MIME-Version: 1.0
+	ContentType             string // Content-Type: text/plain; charset=UTF-8
+	ContentTransferEncoding string // Content-Transfer-Encoding: 8bit
+	PluralForms             string // Plural-Forms: nplurals=2; plural=n == 1 ? 0 : 1;
+	XGenerator              string // X-Generator: Poedit 1.5.5
+	UnknowFields            map[string]string
+}
+
+func (p *Header) parseHeader(msg *Message) {
+	if msg.MsgId != "" || msg.MsgStr == "" {
+		return
+	}
+	lines := strings.Split(msg.MsgStr, "\n")
+	for i := 0; i < len(lines); i++ {
+		idx := strings.Index(lines[i], ":")
+		if idx < 0 {
+			continue
+		}
+		key := strings.TrimSpace(lines[i][:idx])
+		val := strings.TrimSpace(lines[i][idx+1:])
+		switch strings.ToUpper(key) {
+		case strings.ToUpper("Project-Id-Version"):
+			p.ProjectIdVersion = val
+		case strings.ToUpper("Report-Msgid-Bugs-To"):
+			p.ReportMsgidBugsTo = val
+		case strings.ToUpper("POT-Creation-Date"):
+			p.POTCreationDate = val
+		case strings.ToUpper("PO-Revision-Date"):
+			p.PORevisionDate = val
+		case strings.ToUpper("Last-Translator"):
+			p.LastTranslator = val
+		case strings.ToUpper("Language-Team"):
+			p.LanguageTeam = val
+		case strings.ToUpper("Language"):
+			p.Language = val
+		case strings.ToUpper("MIME-Version"):
+			p.MimeVersion = val
+		case strings.ToUpper("Content-Type"):
+			p.ContentType = val
+		case strings.ToUpper("Content-Transfer-Encoding"):
+			p.ContentTransferEncoding = val
+		case strings.ToUpper("Plural-Forms"):
+			p.PluralForms = val
+		case strings.ToUpper("X-Generator"):
+			p.XGenerator = val
+		default:
+			if p.UnknowFields == nil {
+				p.UnknowFields = make(map[string]string)
+			}
+			p.UnknowFields[key] = val
+		}
+	}
+	p.Comment = msg.Comment
+}
+
+// String returns the po format header string.
+func (p Header) String() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "%s", p.Comment.String())
+	fmt.Fprintf(&buf, `msgid ""`+"\n")
+	fmt.Fprintf(&buf, `msgstr ""`+"\n")
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Project-Id-Version", p.ProjectIdVersion)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Report-Msgid-Bugs-To", p.ReportMsgidBugsTo)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "POT-Creation-Date", p.POTCreationDate)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "PO-Revision-Date", p.PORevisionDate)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Last-Translator", p.LastTranslator)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Language-Team", p.LanguageTeam)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Language", p.Language)
+	if p.MimeVersion != "" {
+		fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "MIME-Version", p.MimeVersion)
+	}
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Content-Type", p.ContentType)
+	fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "Content-Transfer-Encoding", p.ContentTransferEncoding)
+	if p.XGenerator != "" {
+		fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", "X-Generator", p.XGenerator)
+	}
+	for k, v := range p.UnknowFields {
+		fmt.Fprintf(&buf, `"%s: %s\n"`+"\n", k, v)
+	}
+	return buf.String()
+}
@@ -0,0 +1,62 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"io"
+	"strings"
+)
+
+type lineReader struct {
+	lines []string
+	pos   int
+}
+
+func newLineReader(data string) *lineReader {
+	data = strings.Replace(data, "\r", "", -1)
+	lines := strings.Split(data, "\n")
+	return &lineReader{lines: lines}
+}
+
+func (r *lineReader) skipBlankLine() error {
+	for ; r.pos < len(r.lines); r.pos++ {
+		if strings.TrimSpace(r.lines[r.pos]) != "" {
+			break
+		}
+	}
+	if r.pos >= len(r.lines) {
+		return io.EOF
+	}
+	return nil
+}
+
+func (r *lineReader) currentPos() int {
+	return r.pos
+}
+
+func (r *lineReader) currentLine() (s string, pos int, err error) {
+	if r.pos >= len(r.lines) {
+		err = io.EOF
+		return
+	}
+	s, pos = r.lines[r.pos], r.pos
+	return
+}
+
+func (r *lineReader) readLine() (s string, pos int, err error) {
+	if r.pos >= len(r.lines) {
+		err = io.EOF
+		return
+	}
+	s, pos = r.lines[r.pos], r.pos
+	r.pos++
+	return
+}
+
+func (r *lineReader) unreadLine() {
+	if r.pos >= 0 {
+		r.pos--
+	}
+}
@@ -0,0 +1,193 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// A PO file is made up of many entries,
+// each entry holding the relation between an original untranslated string
+// and its corresponding translation.
+//
+// See http://www.gnu.org/software/gettext/manual/html_node/PO-Files.html
+type Message struct {
+	Comment               // Coments
+	MsgContext   string   // msgctxt context
+	MsgId        string   // msgid untranslated-string
+	MsgIdPlural  string   // msgid_plural untranslated-string-plural
+	MsgStr       string   // msgstr translated-string
+	MsgStrPlural []string // msgstr[0] translated-string-case-0
+}
+
+func (p *Message) less(q *Message) bool {
+	if p.Comment.less(&q.Comment) {
+		return true
+	}
+	if a, b := p.MsgContext, q.MsgContext; a != b {
+		return a < b
+	}
+	if a, b := p.MsgId, q.MsgId; a != b {
+		return a < b
+	}
+	if a, b := p.MsgIdPlural, q.MsgIdPlural; a != b {
+		return a < b
+	}
+	return false
+}
+
+func (p *Message) readPoEntry(r *lineReader) (err error) {
+	*p = Message{}
+	if err = r.skipBlankLine(); err != nil {
+		return
+	}
+	defer func(oldPos int) {
+		newPos := r.currentPos()
+		if newPos != oldPos && err == io.EOF {
+			err = nil
+		}
+	}(r.currentPos())
+
+	if err = p.Comment.readPoComment(r); err != nil {
+		return
+	}
+	for {
+		var s string
+		if s, _, err = r.currentLine(); err != nil {
+			return
+		}
+
+		if p.isInvalidLine(s) {
+			err = fmt.Errorf("gettext: line %d, %v", r.currentPos(), "invalid line")
+			return
+		}
+		if reComment.MatchString(s) || reBlankLine.MatchString(s) {
+			return
+		}
+
+		if err = p.readMsgContext(r); err != nil {
+			return
+		}
+		if err = p.readMsgId(r); err != nil {
+			return
+		}
+		if err = p.readMsgIdPlural(r); err != nil {
+			return
+		}
+		if err = p.readMsgStrOrPlural(r); err != nil {
+			return
+		}
+	}
+}
+
+func (p *Message) readMsgContext(r *lineReader) (err error) {
+	var s string
+	if s, _, err = r.currentLine(); err != nil {
+		return
+	}
+	if !reMsgContext.MatchString(s) {
+		return
+	}
+	p.MsgContext, err = p.readString(r)
+	return
+}
+
+func (p *Message) readMsgId(r *lineReader) (err error) {
+	var s string
+	if s, _, err = r.currentLine(); err != nil {
+		return
+	}
+	if !reMsgId.MatchString(s) {
+		return
+	}
+	p.MsgId, err = p.readString(r)
+	return
+}
+
+func (p *Message) readMsgIdPlural(r *lineReader) (err error) {
+	var s string
+	if s, _, err = r.currentLine(); err != nil {
+		return
+	}
+	if !reMsgIdPlural.MatchString(s) {
+		return
+	}
+	p.MsgIdPlural, err = p.readString(r)
+	return nil
+}
+
+func (p *Message) readMsgStrOrPlural(r *lineReader) (err error) {
+	var s string
+	if s, _, err = r.currentLine(); err != nil {
+		return
+	}
+	if !reMsgStr.MatchString(s) && !reMsgStrPlural.MatchString(s) {
+		return
+	}
+	if reMsgStrPlural.MatchString(s) {
+		left, right := strings.Index(s, `[`), strings.LastIndex(s, `]`)
+		idx, _ := strconv.Atoi(s[left+1 : right])
+		s, err = p.readString(r)
+		if n := len(p.MsgStrPlural); (idx + 1) > n {
+			p.MsgStrPlural = append(p.MsgStrPlural, make([]string, (idx+1)-n)...)
+		}
+		p.MsgStrPlural[idx] = s
+	} else {
+		p.MsgStr, err = p.readString(r)
+	}
+	return nil
+}
+
+func (p *Message) readString(r *lineReader) (msg string, err error) {
+	var s string
+	if s, _, err = r.readLine(); err != nil {
+		return
+	}
+	msg += decodePoString(s)
+	for {
+		if s, _, err = r.readLine(); err != nil {
+			return
+		}
+		if !reStringLine.MatchString(s) {
+			r.unreadLine()
+			break
+		}
+		msg += decodePoString(s)
+	}
+	return
+}
+
+// String returns the po format entry string.
+func (p Message) String() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "%s", p.Comment.String())
+	if p.MsgContext != "" {
+		fmt.Fprintf(&buf, "msgctxt %s", encodePoString(p.MsgContext))
+	}
+	fmt.Fprintf(&buf, "msgid %s", encodePoString(p.MsgId))
+	if p.MsgIdPlural != "" {
+		fmt.Fprintf(&buf, "msgid_plural %s", encodePoString(p.MsgIdPlural))
+	}
+	if len(p.MsgStrPlural) == 0 {
+		if p.MsgStr != "" {
+			fmt.Fprintf(&buf, "msgstr %s", encodePoString(p.MsgStr))
+		} else {
+			fmt.Fprintf(&buf, "msgstr %s", `""`+"\n")
+		}
+	} else {
+		for i := 0; i < len(p.MsgStrPlural); i++ {
+			if p.MsgStrPlural[i] != "" {
+				fmt.Fprintf(&buf, "msgstr[%d] %s", i, encodePoString(p.MsgStrPlural[i]))
+			} else {
+				fmt.Fprintf(&buf, "msgstr[%d] %s", i, `""`+"\n")
+			}
+		}
+	}
+	return buf.String()
+}
@@ -0,0 +1,58 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"regexp"
+)
+
+var (
+	reComment                = regexp.MustCompile(`^#`)              // #
+	reExtractedComments      = regexp.MustCompile(`^#\.`)            // #.
+	reReferenceComments      = regexp.MustCompile(`^#:`)             // #:
+	reFlagsComments          = regexp.MustCompile(`^#,`)             // #, fuzzy,c-format
+	rePrevMsgContextComments = regexp.MustCompile(`^#\|\s+msgctxt`)  // #| msgctxt
+	rePrevMsgIdComments      = regexp.MustCompile(`^#\|\s+msgid`)    // #| msgid
+	reStringLineComments     = regexp.MustCompile(`^#\|\s+".*"\s*$`) // #| "message"
+
+	reMsgContext   = regexp.MustCompile(`^msgctxt\s+".*"\s*$`)            // msgctxt
+	reMsgId        = regexp.MustCompile(`^msgid\s+".*"\s*$`)              // msgid
+	reMsgIdPlural  = regexp.MustCompile(`^msgid_plural\s+".*"\s*$`)       // msgid_plural
+	reMsgStr       = regexp.MustCompile(`^msgstr\s*".*"\s*$`)             // msgstr
+	reMsgStrPlural = regexp.MustCompile(`^msgstr\s*(\[\d+\])\s*".*"\s*$`) // msgstr[0]
+	reStringLine   = regexp.MustCompile(`^\s*".*"\s*$`)                   // "message"
+	reBlankLine    = regexp.MustCompile(`^\s*$`)                          //
+)
+
+func (p *Message) isInvalidLine(s string) bool {
+	if reComment.MatchString(s) {
+		return false
+	}
+	if reBlankLine.MatchString(s) {
+		return false
+	}
+
+	if reMsgContext.MatchString(s) {
+		return false
+	}
+	if reMsgId.MatchString(s) {
+		return false
+	}
+	if reMsgIdPlural.MatchString(s) {
+		return false
+	}
+	if reMsgStr.MatchString(s) {
+		return false
+	}
+	if reMsgStrPlural.MatchString(s) {
+		return false
+	}
+
+	if reStringLine.MatchString(s) {
+		return false
+	}
+
+	return true
+}
@@ -0,0 +1,114 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package po
+
+import (
+	"bytes"
+	"strings"
+)
+
+func decodePoString(text string) string {
+	lines := strings.Split(text, "\n")
+	for i := 0; i < len(lines); i++ {
+		left := strings.Index(lines[i], `"`)
+		right := strings.LastIndex(lines[i], `"`)
+		if left < 0 || right < 0 || left == right {
+			lines[i] = ""
+			continue
+		}
+		line := lines[i][left+1 : right]
+		data := make([]byte, 0, len(line))
+		for i := 0; i < len(line); i++ {
+			if line[i] != '\\' {
+				data = append(data, line[i])
+				continue
+			}
+			if i+1 >= len(line) {
+				break
+			}
+			switch line[i+1] {
+			case 'n': // \\n -> \n
+				data = append(data, '\n')
+				i++
+			case 't': // \\t -> \n
+				data = append(data, '\t')
+				i++
+			case '\\': // \\\ -> ?
+				data = append(data, '\\')
+				i++
+			}
+		}
+		lines[i] = string(data)
+	}
+	return strings.Join(lines, "")
+}
+
+func encodePoString(text string) string {
+	var buf bytes.Buffer
+	lines := strings.Split(text, "\n")
+	for i := 0; i < len(lines); i++ {
+		if lines[i] == "" {
+			if i != len(lines)-1 {
+				buf.WriteString(`"\n"` + "\n")
+			}
+			continue
+		}
+		buf.WriteRune('"')
+		for _, r := range lines[i] {
+			switch r {
+			case '\\':
+				buf.WriteString(`\\`)
+			case '"':
+				buf.WriteString(`\"`)
+			case '\n':
+				buf.WriteString(`\n`)
+			case '\t':
+				buf.WriteString(`\t`)
+			default:
+				buf.WriteRune(r)
+			}
+		}
+		if i < len(lines)-1 {
+			buf.WriteString(`\n"` + "\n")
+		} else {
+			buf.WriteString(`"` + "\n")
+		}
+	}
+	return buf.String()
+}
+
+func encodeCommentPoString(text string) string {
+	var buf bytes.Buffer
+	lines := strings.Split(text, "\n")
+	if len(lines) > 1 {
+		buf.WriteString(`""` + "\n")
+	}
+	for i := 0; i < len(lines); i++ {
+		if len(lines) > 0 {
+			buf.WriteString("#| ")
+		}
+		buf.WriteRune('"')
+		for _, r := range lines[i] {
+			switch r {
+			case '\\':
+				buf.WriteString(`\\`)
+			case '"':
+				buf.WriteString(`\"`)
+			case '\n':
+				buf.WriteString(`\n`)
+			case '\t':
+				buf.WriteString(`\t`)
+			default:
+				buf.WriteRune(r)
+			}
+		}
+		if i < len(lines)-1 {
+			buf.WriteString(`\n"` + "\n")
+		} else {
+			buf.WriteString(`"`)
+		}
+	}
+	return buf.String()
+}
@@ -0,0 +1,175 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"encoding/json"
+
+	"github.com/chai2010/gettext-go/mo"
+	"github.com/chai2010/gettext-go/plural"
+	"github.com/chai2010/gettext-go/po"
+)
+
+var nilTranslator = &translator{
+	MessageMap:    make(map[string]mo.Message),
+	PluralFormula: plural.Formula("??"),
+}
+
+type translator struct {
+	MessageMap    map[string]mo.Message
+	PluralFormula func(n int) int
+}
+
+func newMoTranslator(name string, data []byte) (*translator, error) {
+	var (
+		f   *mo.File
+		err error
+	)
+	if len(data) != 0 {
+		f, err = mo.Load(data)
+	} else {
+		f, err = mo.LoadFile(name)
+	}
+	if err != nil {
+		return nil, err
+	}
+	var tr = &translator{
+		MessageMap: make(map[string]mo.Message),
+	}
+	for _, v := range f.Messages {
+		tr.MessageMap[tr.makeMapKey(v.MsgContext, v.MsgId)] = v
+	}
+	if lang := f.MimeHeader.Language; lang != "" {
+		tr.PluralFormula = plural.Formula(lang)
+	} else {
+		tr.PluralFormula = plural.Formula("??")
+	}
+	return tr, nil
+}
+
+func newPoTranslator(name string, data []byte) (*translator, error) {
+	var (
+		f   *po.File
+		err error
+	)
+	if len(data) != 0 {
+		f, err = po.Load(data)
+	} else {
+		f, err = po.LoadFile(name)
+	}
+	if err != nil {
+		return nil, err
+	}
+	var tr = &translator{
+		MessageMap: make(map[string]mo.Message),
+	}
+	for _, v := range f.Messages {
+		tr.MessageMap[tr.makeMapKey(v.MsgContext, v.MsgId)] = mo.Message{
+			MsgContext:   v.MsgContext,
+			MsgId:        v.MsgId,
+			MsgIdPlural:  v.MsgIdPlural,
+			MsgStr:       v.MsgStr,
+			MsgStrPlural: v.MsgStrPlural,
+		}
+	}
+	if lang := f.MimeHeader.Language; lang != "" {
+		tr.PluralFormula = plural.Formula(lang)
+	} else {
+		tr.PluralFormula = plural.Formula("??")
+	}
+	return tr, nil
+}
+
+func newJsonTranslator(lang, name string, jsonData []byte) (*translator, error) {
+	var msgList []struct {
+		MsgContext  string   `json:"msgctxt"`      // msgctxt context
+		MsgId       string   `json:"msgid"`        // msgid untranslated-string
+		MsgIdPlural string   `json:"msgid_plural"` // msgid_plural untranslated-string-plural
+		MsgStr      []string `json:"msgstr"`       // msgstr translated-string
+	}
+	if err := json.Unmarshal(jsonData, &msgList); err != nil {
+		return nil, err
+	}
+
+	var tr = &translator{
+		MessageMap:    make(map[string]mo.Message),
+		PluralFormula: plural.Formula(lang),
+	}
+
+	for _, v := range msgList {
+		var v_MsgStr string
+		var v_MsgStrPlural = v.MsgStr
+
+		if len(v.MsgStr) != 0 {
+			v_MsgStr = v.MsgStr[0]
+		}
+
+		tr.MessageMap[tr.makeMapKey(v.MsgContext, v.MsgId)] = mo.Message{
+			MsgContext:   v.MsgContext,
+			MsgId:        v.MsgId,
+			MsgIdPlural:  v.MsgIdPlural,
+			MsgStr:       v_MsgStr,
+			MsgStrPlural: v_MsgStrPlural,
+		}
+	}
+	return tr, nil
+}
+
+func (p *translator) PGettext(msgctxt, msgid string) string {
+	return p.findMsgStr(msgctxt, msgid)
+}
+
+func (p *translator) PNGettext(msgctxt, msgid, msgidPlural string, n int) string {
+	n = p.PluralFormula(n)
+	if ss := p.findMsgStrPlural(msgctxt, msgid, msgidPlural); len(ss) != 0 {
+		if n >= len(ss) {
+			n = len(ss) - 1
+		}
+		if ss[n] != "" {
+			return ss[n]
+		}
+	}
+	if msgidPlural != "" && n > 0 {
+		return msgidPlural
+	}
+	return msgid
+}
+
+func (p *translator) findMsgStr(msgctxt, msgid string) string {
+	key := p.makeMapKey(msgctxt, msgid)
+	if v, ok := p.MessageMap[key]; ok {
+		if v.MsgStr != "" {
+			return v.MsgStr
+		}
+	}
+	return msgid
+}
+
+func (p *translator) findMsgStrPlural(msgctxt, msgid, msgidPlural string) []string {
+	key := p.makeMapKey(msgctxt, msgid)
+	if v, ok := p.MessageMap[key]; ok {
+		if len(v.MsgIdPlural) != 0 {
+			if len(v.MsgStrPlural) != 0 {
+				return v.MsgStrPlural
+			} else {
+				return nil
+			}
+		} else {
+			if len(v.MsgStr) != 0 {
+				return []string{v.MsgStr}
+			} else {
+				return nil
+			}
+		}
+	}
+	return nil
+}
+
+func (p *translator) makeMapKey(msgctxt, msgid string) string {
+	if msgctxt != "" {
+		return msgctxt + mo.EotSeparator + msgid
+	}
+	return msgid
+}
@@ -0,0 +1,34 @@
+// Copyright 2013 ChaiShushan <chaishushan{AT}gmail.com>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gettext
+
+import (
+	"os"
+	"strings"
+)
+
+func getDefaultLanguage() string {
+	if v := os.Getenv("LC_MESSAGES"); v != "" {
+		return simplifiedLanguage(v)
+	}
+	if v := os.Getenv("LANG"); v != "" {
+		return simplifiedLanguage(v)
+	}
+	return "default"
+}
+
+func simplifiedLanguage(lang string) string {
+	// en_US/en_US.UTF-8/zh_CN/zh_TW/el_GR@euro/...
+	if idx := strings.Index(lang, ":"); idx != -1 {
+		lang = lang[:idx]
+	}
+	if idx := strings.Index(lang, "@"); idx != -1 {
+		lang = lang[:idx]
+	}
+	if idx := strings.Index(lang, "."); idx != -1 {
+		lang = lang[:idx]
+	}
+	return strings.TrimSpace(lang)
+}