Properly handle singular vs plural defaults for untranslated strings. Fixes #9

use kinako instead of anko

.travis.yml

@@ -0,0 +1,16 @@
+language: go
+
+go:
+  - 1.6
+  - 1.7
+  - 1.8
+  - tip
+
+before_install:
+  - go get -t -v ./...
+
+script: go test -v -race -coverprofile=coverage.txt -covermode=atomic .
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
+

Godeps/Godeps.json

@@ -0,0 +1,18 @@
+{
+	"ImportPath": "github.com/leonelquinteros/gotext",
+	"GoVersion": "devel +be9d7f6d87 Fri Jun 16 00:31:25 2017 +0000",
+	"Deps": [
+		{
+			"ImportPath": "github.com/mattn/kinako/ast",
+			"Rev": "fbc18625ec69b28ae03b4eea4c349f215840ee09"
+		},
+		{
+			"ImportPath": "github.com/mattn/kinako/parser",
+			"Rev": "fbc18625ec69b28ae03b4eea4c349f215840ee09"
+		},
+		{
+			"ImportPath": "github.com/mattn/kinako/vm",
+			"Rev": "fbc18625ec69b28ae03b4eea4c349f215840ee09"
+		}
+	]
+}

Godeps/Readme

@@ -0,0 +1,5 @@
+This directory tree is generated automatically by godep.
+
+Please do not edit.
+
+See https://github.com/tools/godep for more information.

README.md

@@ -1,24 +1,39 @@
+[![GitHub release](https://img.shields.io/github/release/leonelquinteros/gotext.svg)](https://github.com/leonelquinteros/gotext)
+[![MIT license](https://img.shields.io/badge/License-MIT-blue.svg)](LICENSE)
 [![GoDoc](https://godoc.org/github.com/leonelquinteros/gotext?status.svg)](https://godoc.org/github.com/leonelquinteros/gotext)
+[![Build Status](https://travis-ci.org/leonelquinteros/gotext.svg?branch=master)](https://travis-ci.org/leonelquinteros/gotext)
+[![codecov](https://codecov.io/gh/leonelquinteros/gotext/branch/master/graph/badge.svg)](https://codecov.io/gh/leonelquinteros/gotext)
+[![Go Report Card](https://goreportcard.com/badge/github.com/leonelquinteros/gotext)](https://goreportcard.com/report/github.com/leonelquinteros/gotext)
 
 # Gotext
 
-GNU gettext utilities for Go. 
-
-**Version: 0.9.0**
+[GNU gettext utilities](https://www.gnu.org/software/gettext) for Go. 
 
 
-#Features
+# Features
 
 - Implements GNU gettext support in native Go.
-- Safe for concurrent use accross multiple goroutines. 
+- Complete support for [PO files](https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html) including:
+  - Support for multiline strings and headers.
+  - Support for variables inside translation strings using Go's [fmt syntax](https://golang.org/pkg/fmt/).
+  - Support for [pluralization rules](https://www.gnu.org/software/gettext/manual/html_node/Translating-plural-forms.html).
+  - Support for [message contexts](https://www.gnu.org/software/gettext/manual/html_node/Contexts.html).
+- Thread-safe: This package is safe for concurrent use across multiple goroutines. 
 - It works with UTF-8 encoding as it's the default for Go language.
-- Unit tests available 
-- Language codes are automatically simplified from the form "en_UK" to "en" if the formed isn't available.
+- Unit tests available.
+- Language codes are automatically simplified from the form `en_UK` to `en` if the first isn't available.
 - Ready to use inside Go templates.
-- Support for pluralization rules.
-- Support for variables inside translation strings using Go's [fmt package syntax](https://golang.org/pkg/fmt/)
 
 
+# License
+
+[MIT license](LICENSE)
+
+
+# Documentation
+
+Refer to the Godoc package documentation at (https://godoc.org/github.com/leonelquinteros/gotext)
+
 
 # Installation 
 
@@ -31,42 +46,62 @@ go get github.com/leonelquinteros/gotext
 - No need for environment variables. Some naming conventions are applied but not needed.  
 
 
-# License
+#### Version vendoring
 
-[MIT license](LICENSE)
+Stable releases use [semantic versioning](http://semver.org/spec/v2.0.0.html) tagging on this repository.
+
+You can rely on this to use your preferred vendoring tool or to manually retrieve the corresponding release tag from the GitHub repository.
 
 
-# Documentation
+##### Vendoring with [gopkg.in](http://labix.org/gopkg.in)
 
-Refer to the Godoc package documentation at (https://godoc.org/github.com/leonelquinteros/gotext)
+[http://gopkg.in/leonelquinteros/gotext.v1](http://gopkg.in/leonelquinteros/gotext.v1)
+
+To get the latest v1 package stable release, execute:
+
+```
+go get gopkg.in/leonelquinteros/gotext.v1
+```
+
+To import this package, add the following line to your code:
+
+```go
+import "gopkg.in/leonelquinteros/gotext.v1"
+```
+
+Refer to it as gotext.
 
 
 # Locales directories structure
 
-The package will asume a directories structure starting with a base path that will be provided to the package configuration 
+The package will assume a directories structure starting with a base path that will be provided to the package configuration 
 or to object constructors depending on the use, but either will use the same convention to lookup inside the base path. 
 
 Inside the base directory where will be the language directories named using the language and country 2-letter codes (en_US, es_AR, ...). 
 All package functions can lookup after the simplified version for each language in case the full code isn't present but the more general language code exists. 
-So if the language set is "en_UK", but there is no directory named after that code and there is a directory named "en", 
+So if the language set is `en_UK`, but there is no directory named after that code and there is a directory named `en`, 
 all package functions will be able to resolve this generalization and provide translations for the more general library.  
 
 The language codes are assumed to be [ISO 639-1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) codes (2-letter codes). 
 That said, most functions will work with any coding standard as long the directory name matches the language code set on the configuration.
 
-A normal library directory structure may look like: 
+Then, there can be a `LC_MESSAGES` containing all PO files or the PO files themselves.  
+A library directory structure can look like: 
 
 ```
 /path/to/locales
 /path/to/locales/en_US
-/path/to/locales/en_US/default.po
-/path/to/locales/en_US/extras.po
+/path/to/locales/en_US/LC_MESSAGES
+/path/to/locales/en_US/LC_MESSAGES/default.po
+/path/to/locales/en_US/LC_MESSAGES/extras.po
 /path/to/locales/en_UK
-/path/to/locales/en_UK/default.po
-/path/to/locales/en_UK/extras.po
+/path/to/locales/en_UK/LC_MESSAGES
+/path/to/locales/en_UK/LC_MESSAGES/default.po
+/path/to/locales/en_UK/LC_MESSAGES/extras.po
 /path/to/locales/en_AU
-/path/to/locales/en_AU/default.po
-/path/to/locales/en_AU/extras.po
+/path/to/locales/en_AU/LC_MESSAGES
+/path/to/locales/en_AU/LC_MESSAGES/default.po
+/path/to/locales/en_AU/LC_MESSAGES/extras.po
 /path/to/locales/es
 /path/to/locales/es/default.po
 /path/to/locales/es/extras.po
@@ -84,9 +119,9 @@ And so on...
 
 # About translation function names
 
-The standard GNU gettext defines helper functions that maps to the gettext() function and it's widely adopted by most implementations. 
+The standard GNU gettext defines helper functions that maps to the `gettext()` function and it's widely adopted by most implementations. 
 
-The basic translation function is usually _() in the form: 
+The basic translation function is usually `_()` in the form: 
 
 ```
 _("Translate this")
@@ -109,8 +144,8 @@ func _(str string, vars ...interface{}) string {
 
 This is valid and can be used within a package.
 
-In normal conditions the Go compiler will optimize the calls to _() by replacing its content in place of the function call to reduce the function calling overhead. 
-This is a normal Go compiler behaviour.  
+In normal conditions the Go compiler will optimize the calls to `_()` by replacing its content in place of the function call to reduce the function calling overhead. 
+This is a normal Go compiler behavior.  
 
 
 
@@ -121,17 +156,20 @@ This is a normal Go compiler behaviour.
 For quick/simple translations you can use the package level functions directly.
 
 ```go
-import "github.com/leonelquinteros/gotext"
+import (
+    "fmt"
+    "github.com/leonelquinteros/gotext"
+)
 
 func main() {
     // Configure package
     gotext.Configure("/path/to/locales/root/dir", "en_UK", "domain-name")
     
     // Translate text from default domain
-    println(gotext.Get("My text on 'domain-name' domain"))
+    fmt.Println(gotext.Get("My text on 'domain-name' domain"))
     
     // Translate text from a different domain without reconfigure
-    println(gotext.GetD("domain2", "Another text on a different domain"))
+    fmt.Println(gotext.GetD("domain2", "Another text on a different domain"))
 }
 
 ```
@@ -142,7 +180,10 @@ All translation strings support dynamic variables to be inserted without transla
 Use the fmt.Printf syntax (from Go's "fmt" package) to specify how to print the non-translated variable inside the translation string. 
 
 ```go
-import "github.com/leonelquinteros/gotext"
+import (
+    "fmt"
+    "github.com/leonelquinteros/gotext"
+)
 
 func main() {
     // Configure package
@@ -152,7 +193,7 @@ func main() {
     name := "John"
     
     // Translate text with variables
-    println(gotext.Get("Hi, my name is %s", name))
+    fmt.Println(gotext.Get("Hi, my name is %s", name))
 }
 
 ```
@@ -164,7 +205,10 @@ When having multiple languages/domains/libraries at the same time, you can creat
 so you can handle each settings on their own.
 
 ```go
-import "github.com/leonelquinteros/gotext"
+import (
+    "fmt"
+    "github.com/leonelquinteros/gotext"
+)
 
 func main() {
     // Create Locale with library path and language code
@@ -174,18 +218,18 @@ func main() {
     l.AddDomain("default")
     
     // Translate text from default domain
-    println(l.Get("Translate this"))
+    fmt.Println(l.Get("Translate this"))
     
     // Load different domain
     l.AddDomain("translations")
     
     // Translate text from domain
-    println(l.GetD("translations", "Translate this"))
+    fmt.Println(l.GetD("translations", "Translate this"))
 }
 ```
 
 This is also helpful for using inside templates (from the "text/template" package), where you can pass the Locale object to the template.
-If you set the Locale object as "Loc" in the template, then the templace code would look like: 
+If you set the Locale object as "Loc" in the template, then the template code would look like: 
 
 ```
 {{ .Loc.Get "Translate this" }}
@@ -198,7 +242,10 @@ For when you need to work with PO files and strings,
 you can directly use the Po object to parse it and access the translations in there in the same way.
 
 ```go
-import "github.com/leonelquinteros/gotext"
+import (
+    "fmt"
+    "github.com/leonelquinteros/gotext"
+)
 
 func main() {
     // Set PO content
@@ -217,7 +264,7 @@ msgstr "This one sets the var: %s"
     po := new(Po)
     po.Parse(str)
     
-    println(po.Get("Translate this"))
+    fmt.Println(po.Get("Translate this"))
 }
 ```
 
@@ -225,13 +272,26 @@ msgstr "This one sets the var: %s"
 ## Use plural forms of translations
 
 PO format supports defining one or more plural forms for the same translation.
+Relying on the PO file headers, a Plural-Forms formula can be set on the translation file
+as defined in (https://www.gnu.org/savannah-checkouts/gnu/gettext/manual/html_node/Plural-forms.html)
+
+Plural formulas are parsed and evaluated using [Kinako](https://github.com/mattn/kinako)
 
 ```go
-import "github.com/leonelquinteros/gotext"
+import (
+    "fmt"
+    "github.com/leonelquinteros/gotext"
+)
 
 func main() {
     // Set PO content
     str := `
+msgid ""
+msgstr ""
+
+# Header below
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
 msgid "Translate this"
 msgstr "Translated text"
 
@@ -242,15 +302,14 @@ msgid "One with var: %s"
 msgid_plural "Several with vars: %s"
 msgstr[0] "This one is the singular: %s"
 msgstr[1] "This one is the plural: %s"
-msgstr[2] "And this is the second plural form: %s"
 `
     
     // Create Po object
     po := new(Po)
     po.Parse(str)
     
-    println(po.GetN("One with var: %s", "Several with vars: %s", 2, v))
-    // "And this is the second plural form: Variable"
+    fmt.Println(po.GetN("One with var: %s", "Several with vars: %s", 54, v))
+    // "This one is the plural: Variable"
 }
 ```
 

gotext.go

@@ -1,21 +1,22 @@
 /*
 Package gotext implements GNU gettext utilities.
 
-Version 0.9.0 (stable)
-
 For quick/simple translations you can use the package level functions directly.
 
-    import "github.com/leonelquinteros/gotext"
+    import (
+	    "fmt"
+	    "github.com/leonelquinteros/gotext"
+    )
 
     func main() {
         // Configure package
         gotext.Configure("/path/to/locales/root/dir", "en_UK", "domain-name")
 
         // Translate text from default domain
-        println(gotext.Get("My text on 'domain-name' domain"))
+        fmt.Println(gotext.Get("My text on 'domain-name' domain"))
 
         // Translate text from a different domain without reconfigure
-        println(gotext.GetD("domain2", "Another text on a different domain"))
+        fmt.Println(gotext.GetD("domain2", "Another text on a different domain"))
     }
 
 */
@@ -30,7 +31,7 @@ var (
 	language = "en_US"
 
 	// Path to library directory where all locale directories and translation files are.
-	library = "/tmp"
+	library = "/usr/local/share/locale"
 
 	// Storage for package level methods
 	storage *Locale
@@ -102,8 +103,7 @@ func Get(str string, vars ...interface{}) string {
 	return GetD(domain, str, vars...)
 }
 
-// GetN retrieves the (N)th plural form translation for the given string in the "default" domain.
-// If n == 0, usually the singular form of the string is returned as defined in the PO file.
+// GetN retrieves the (N)th plural form of translation for the given string in the "default" domain.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func GetN(str, plural string, n int, vars ...interface{}) string {
 	return GetND("default", str, plural, n, vars...)
@@ -112,10 +112,10 @@ func GetN(str, plural string, n int, vars ...interface{}) string {
 // GetD returns the corresponding translation in the given domain for a given string.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func GetD(dom, str string, vars ...interface{}) string {
-	return GetND(dom, str, str, 0, vars...)
+	return GetND(dom, str, str, 1, vars...)
 }
 
-// GetND retrieves the (N)th plural form translation in the given domain for a given string.
+// GetND retrieves the (N)th plural form of translation in the given domain for a given string.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func GetND(dom, str, plural string, n int, vars ...interface{}) string {
 	// Try to load default package Locale storage
@@ -124,3 +124,31 @@ func GetND(dom, str, plural string, n int, vars ...interface{}) string {
 	// Return translation
 	return storage.GetND(dom, str, plural, n, vars...)
 }
+
+// GetC uses the default domain globally set to return the corresponding translation of the given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func GetC(str, ctx string, vars ...interface{}) string {
+	return GetDC(domain, str, ctx, vars...)
+}
+
+// GetNC retrieves the (N)th plural form of translation for the given string in the given context in the "default" domain.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func GetNC(str, plural string, n int, ctx string, vars ...interface{}) string {
+	return GetNDC("default", str, plural, n, ctx, vars...)
+}
+
+// GetDC returns the corresponding translation in the given domain for the given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func GetDC(dom, str, ctx string, vars ...interface{}) string {
+	return GetNDC(dom, str, str, 1, ctx, vars...)
+}
+
+// GetNDC retrieves the (N)th plural form of translation in the given domain for a given string.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func GetNDC(dom, str, plural string, n int, ctx string, vars ...interface{}) string {
+	// Try to load default package Locale storage
+	loadStorage(false)
+
+	// Return translation
+	return storage.GetNDC(dom, str, plural, n, ctx, vars...)
+}

gotext_test.go

@@ -6,7 +6,220 @@ import (
 	"testing"
 )
 
+func TestGettersSetters(t *testing.T) {
+	SetDomain("test")
+	dom := GetDomain()
+
+	if dom != "test" {
+		t.Errorf("Expected GetDomain to return 'test', but got '%s'", dom)
+	}
+
+	SetLibrary("/tmp/test")
+	lib := GetLibrary()
+
+	if lib != "/tmp/test" {
+		t.Errorf("Expected GetLibrary to return '/tmp/test', but got '%s'", lib)
+	}
+
+	SetLanguage("es")
+	lang := GetLanguage()
+
+	if lang != "es" {
+		t.Errorf("Expected GetLanguage to return 'es', but got '%s'", lang)
+	}
+}
+
 func TestPackageFunctions(t *testing.T) {
+	// Set PO content
+	str := `
+# msgid ""
+# msgstr ""
+# Initial comment
+# Headers below
+"Language: en\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+# Some comment
+msgid "My text"
+msgstr "Translated text"
+
+# More comments
+msgid "Another string"
+msgstr ""
+
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular: %s"
+msgstr[1] "This one is the plural: %s"
+msgstr[2] "And this is the second plural form: %s"
+
+msgid "This one has invalid syntax translations"
+msgid_plural "Plural index"
+msgstr[abc] "Wrong index"
+msgstr[1 "Forgot to close brackets"
+msgstr[0] "Badly formatted string'
+
+msgid "Invalid formatted id[] with no translations
+
+msgctxt "Ctx"
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular in a Ctx context: %s"
+msgstr[1] "This one is the plural in a Ctx context: %s"
+
+msgid "Some random"
+msgstr "Some random translation"
+
+msgctxt "Ctx"
+msgid "Some random in a context"
+msgstr "Some random translation in a context"
+
+msgid "More"
+msgstr "More translation"
+
+msgid "Untranslated"
+msgid_plural "Several untranslated"
+msgstr[0] ""
+msgstr[1] ""
+
+	`
+
+	// Create Locales directory on default location
+	dirname := path.Clean("/tmp" + string(os.PathSeparator) + "en_US")
+	err := os.MkdirAll(dirname, os.ModePerm)
+	if err != nil {
+		t.Fatalf("Can't create test directory: %s", err.Error())
+	}
+
+	// Write PO content to default domain file
+	filename := path.Clean(dirname + string(os.PathSeparator) + "default.po")
+
+	f, err := os.Create(filename)
+	if err != nil {
+		t.Fatalf("Can't create test file: %s", err.Error())
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(str)
+	if err != nil {
+		t.Fatalf("Can't write to test file: %s", err.Error())
+	}
+
+	// Set package configuration
+	Configure("/tmp", "en_US", "default")
+
+	// Test translations
+	tr := Get("My text")
+	if tr != "Translated text" {
+		t.Errorf("Expected 'Translated text' but got '%s'", tr)
+	}
+
+	v := "Variable"
+	tr = Get("One with var: %s", v)
+	if tr != "This one is the singular: Variable" {
+		t.Errorf("Expected 'This one is the singular: Variable' but got '%s'", tr)
+	}
+
+	// Test plural
+	tr = GetN("One with var: %s", "Several with vars: %s", 2, v)
+	if tr != "This one is the plural: Variable" {
+		t.Errorf("Expected 'This one is the plural: Variable' but got '%s'", tr)
+	}
+
+	// Test context translations
+	tr = GetC("Some random in a context", "Ctx")
+	if tr != "Some random translation in a context" {
+		t.Errorf("Expected 'Some random translation in a context' but got '%s'", tr)
+	}
+
+	v = "Variable"
+	tr = GetC("One with var: %s", "Ctx", v)
+	if tr != "This one is the singular in a Ctx context: Variable" {
+		t.Errorf("Expected 'This one is the singular in a Ctx context: Variable' but got '%s'", tr)
+	}
+
+	tr = GetNC("One with var: %s", "Several with vars: %s", 19, "Ctx", v)
+	if tr != "This one is the plural in a Ctx context: Variable" {
+		t.Errorf("Expected 'This one is the plural in a Ctx context: Variable' but got '%s'", tr)
+	}
+}
+
+func TestUntranslated(t *testing.T) {
+	// Set PO content
+	str := `
+# msgid ""
+# msgstr ""
+# Initial comment
+# Headers below
+"Language: en\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+msgid "Untranslated"
+msgid_plural "Several untranslated"
+msgstr[0] ""
+msgstr[1] ""
+
+	`
+
+	// Create Locales directory on default location
+	dirname := path.Clean("/tmp" + string(os.PathSeparator) + "en_US")
+	err := os.MkdirAll(dirname, os.ModePerm)
+	if err != nil {
+		t.Fatalf("Can't create test directory: %s", err.Error())
+	}
+
+	// Write PO content to default domain file
+	filename := path.Clean(dirname + string(os.PathSeparator) + "default.po")
+
+	f, err := os.Create(filename)
+	if err != nil {
+		t.Fatalf("Can't create test file: %s", err.Error())
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(str)
+	if err != nil {
+		t.Fatalf("Can't write to test file: %s", err.Error())
+	}
+
+	// Set package configuration
+	Configure("/tmp", "en_US", "default")
+
+	// Test untranslated
+	tr := Get("Untranslated")
+	if tr != "Untranslated" {
+		t.Errorf("Expected 'Untranslated' but got '%s'", tr)
+	}
+	tr = GetN("Untranslated", "Several untranslated", 1)
+	if tr != "Untranslated" {
+		t.Errorf("Expected 'Untranslated' but got '%s'", tr)
+	}
+
+	tr = GetN("Untranslated", "Several untranslated", 2)
+	if tr != "Several untranslated" {
+		t.Errorf("Expected 'Several untranslated' but got '%s'", tr)
+	}
+
+	tr = GetD("default", "Untranslated")
+	if tr != "Untranslated" {
+		t.Errorf("Expected 'Untranslated' but got '%s'", tr)
+	}
+	tr = GetND("default", "Untranslated", "Several untranslated", 1)
+	if tr != "Untranslated" {
+		t.Errorf("Expected 'Untranslated' but got '%s'", tr)
+	}
+
+	tr = GetND("default", "Untranslated", "Several untranslated", 2)
+	if tr != "Several untranslated" {
+		t.Errorf("Expected 'Several untranslated' but got '%s'", tr)
+	}
+}
+
+func TestPackageRace(t *testing.T) {
 	// Set PO content
 	str := `# Some comment
 msgid "My text"
@@ -45,21 +258,22 @@ msgstr[2] "And this is the second plural form: %s"
 		t.Fatalf("Can't write to test file: %s", err.Error())
 	}
 
+	// Init sync channels
+	c1 := make(chan bool)
+	c2 := make(chan bool)
+
+	for i := 0; i < 100; i++ {
 		// Test translations
-	tr := Get("My text")
-	if tr != "Translated text" {
-		t.Errorf("Expected 'Translated text' but got '%s'", tr)
-	}
+		go func(done chan bool) {
+			Get("My text")
+			done <- true
+		}(c1)
 
-	v := "Variable"
-	tr = Get("One with var: %s", v)
-	if tr != "This one is the singular: Variable" {
-		t.Errorf("Expected 'This one is the singular: Variable' but got '%s'", tr)
-	}
+		go func(done chan bool) {
+			Get("My text")
+			done <- true
+		}(c2)
 
-	// Test plural
-	tr = GetN("One with var: %s", "Several with vars: %s", 2, v)
-	if tr != "And this is the second plural form: Variable" {
-		t.Errorf("Expected 'And this is the second plural form: Variable' but got '%s'", tr)
+		Get("My text")
 	}
 }

locale.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"sync"
 )
 
 /*
@@ -13,23 +14,26 @@ multiple languages at the same time by working with this object.
 
 Example:
 
-    import "github.com/leonelquinteros/gotext"
+    import (
+	    "fmt"
+	    "github.com/leonelquinteros/gotext"
+    )
 
     func main() {
         // Create Locale with library path and language code
         l := gotext.NewLocale("/path/to/i18n/dir", "en_US")
 
-        // Load domain '/path/to/i18n/dir/en_US/default.po'
+        // Load domain '/path/to/i18n/dir/en_US/LC_MESSAGES/default.po'
         l.AddDomain("default")
 
         // Translate text from default domain
-        println(l.Get("Translate this"))
+        fmt.Println(l.Get("Translate this"))
 
-        // Load different domain ('/path/to/i18n/dir/en_US/extras.po')
+        // Load different domain ('/path/to/i18n/dir/en_US/LC_MESSAGES/extras.po')
         l.AddDomain("extras")
 
         // Translate text from domain
-        println(l.GetD("extras", "Translate this"))
+        fmt.Println(l.GetD("extras", "Translate this"))
     }
 
 */
@@ -42,6 +46,9 @@ type Locale struct {
 
 	// List of available domains for this locale.
 	domains map[string]*Po
+
+	// Sync Mutex
+	sync.RWMutex
 }
 
 // NewLocale creates and initializes a new Locale object for a given language.
@@ -54,25 +61,43 @@ func NewLocale(p, l string) *Locale {
 	}
 }
 
+func (l *Locale) findPO(dom string) string {
+	filename := path.Join(l.path, l.lang, "LC_MESSAGES", dom+".po")
+	if _, err := os.Stat(filename); err == nil {
+		return filename
+	}
+
+	if len(l.lang) > 2 {
+		filename = path.Join(l.path, l.lang[:2], "LC_MESSAGES", dom+".po")
+		if _, err := os.Stat(filename); err == nil {
+			return filename
+		}
+	}
+
+	filename = path.Join(l.path, l.lang, dom+".po")
+	if _, err := os.Stat(filename); err == nil {
+		return filename
+	}
+
+	if len(l.lang) > 2 {
+		filename = path.Join(l.path, l.lang[:2], dom+".po")
+	}
+
+	return filename
+}
+
 // AddDomain creates a new domain for a given locale object and initializes the Po object.
 // If the domain exists, it gets reloaded.
 func (l *Locale) AddDomain(dom string) {
 	po := new(Po)
 
-	// Check for file.
-	filename := path.Clean(l.path + string(os.PathSeparator) + l.lang + string(os.PathSeparator) + dom + ".po")
-
-	// Try to use the generic language dir if the provided isn't available
-	if _, err := os.Stat(filename); err != nil {
-		if len(l.lang) > 2 {
-			filename = path.Clean(l.path + string(os.PathSeparator) + l.lang[:2] + string(os.PathSeparator) + dom + ".po")
-		}
-	}
-
 	// Parse file.
-	po.ParseFile(filename)
+	po.ParseFile(l.findPO(dom))
 
 	// Save new domain
+	l.Lock()
+	defer l.Unlock()
+
 	if l.domains == nil {
 		l.domains = make(map[string]*Po)
 	}
@@ -85,23 +110,25 @@ func (l *Locale) Get(str string, vars ...interface{}) string {
 	return l.GetD("default", str, vars...)
 }
 
-// GetN retrieves the (N)th plural form translation for the given string in the "default" domain.
-// If n == 0, usually the singular form of the string is returned as defined in the PO file.
+// GetN retrieves the (N)th plural form of translation for the given string in the "default" domain.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func (l *Locale) GetN(str, plural string, n int, vars ...interface{}) string {
 	return l.GetND("default", str, plural, n, vars...)
 }
 
-// GetD returns the corresponding translation in the given domain for a given string.
+// GetD returns the corresponding translation in the given domain for the given string.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func (l *Locale) GetD(dom, str string, vars ...interface{}) string {
-	return l.GetND(dom, str, str, 0, vars...)
+	return l.GetND(dom, str, str, 1, vars...)
 }
 
-// GetND retrieves the (N)th plural form translation in the given domain for a given string.
-// If n == 0, usually the singular form of the string is returned as defined in the PO file.
+// GetND retrieves the (N)th plural form of translation in the given domain for the given string.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func (l *Locale) GetND(dom, str, plural string, n int, vars ...interface{}) string {
+	// Sync read
+	l.RLock()
+	defer l.RUnlock()
+
 	if l.domains != nil {
 		if _, ok := l.domains[dom]; ok {
 			if l.domains[dom] != nil {
@@ -113,3 +140,40 @@ func (l *Locale) GetND(dom, str, plural string, n int, vars ...interface{}) stri
 	// Return the same we received by default
 	return fmt.Sprintf(plural, vars...)
 }
+
+// GetC uses a domain "default" to return the corresponding translation of the given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func (l *Locale) GetC(str, ctx string, vars ...interface{}) string {
+	return l.GetDC("default", str, ctx, vars...)
+}
+
+// GetNC retrieves the (N)th plural form of translation for the given string in the given context in the "default" domain.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func (l *Locale) GetNC(str, plural string, n int, ctx string, vars ...interface{}) string {
+	return l.GetNDC("default", str, plural, n, ctx, vars...)
+}
+
+// GetDC returns the corresponding translation in the given domain for the given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func (l *Locale) GetDC(dom, str, ctx string, vars ...interface{}) string {
+	return l.GetNDC(dom, str, str, 1, ctx, vars...)
+}
+
+// GetNDC retrieves the (N)th plural form of translation in the given domain for the given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func (l *Locale) GetNDC(dom, str, plural string, n int, ctx string, vars ...interface{}) string {
+	// Sync read
+	l.RLock()
+	defer l.RUnlock()
+
+	if l.domains != nil {
+		if _, ok := l.domains[dom]; ok {
+			if l.domains[dom] != nil {
+				return l.domains[dom].GetNC(str, plural, n, ctx, vars...)
+			}
+		}
+	}
+
+	// Return the same we received by default
+	return fmt.Sprintf(plural, vars...)
+}

locale_test.go

@@ -7,6 +7,243 @@ import (
 )
 
 func TestLocale(t *testing.T) {
+	// Set PO content
+	str := `
+# msgid ""
+# msgstr ""
+# Initial comment
+# Headers below
+"Language: en\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+# Some comment
+msgid "My text"
+msgstr "Translated text"
+
+# More comments
+msgid "Another string"
+msgstr ""
+
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular: %s"
+msgstr[1] "This one is the plural: %s"
+msgstr[2] "And this is the second plural form: %s"
+
+msgid "This one has invalid syntax translations"
+msgid_plural "Plural index"
+msgstr[abc] "Wrong index"
+msgstr[1 "Forgot to close brackets"
+msgstr[0] "Badly formatted string'
+
+msgid "Invalid formatted id[] with no translations
+
+msgctxt "Ctx"
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular in a Ctx context: %s"
+msgstr[1] "This one is the plural in a Ctx context: %s"
+
+msgid "Some random"
+msgstr "Some random translation"
+
+msgctxt "Ctx"
+msgid "Some random in a context"
+msgstr "Some random translation in a context"
+
+msgid "More"
+msgstr "More translation"
+
+	`
+
+	// Create Locales directory with simplified language code
+	dirname := path.Join("/tmp", "en", "LC_MESSAGES")
+	err := os.MkdirAll(dirname, os.ModePerm)
+	if err != nil {
+		t.Fatalf("Can't create test directory: %s", err.Error())
+	}
+
+	// Write PO content to file
+	filename := path.Join(dirname, "my_domain.po")
+
+	f, err := os.Create(filename)
+	if err != nil {
+		t.Fatalf("Can't create test file: %s", err.Error())
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(str)
+	if err != nil {
+		t.Fatalf("Can't write to test file: %s", err.Error())
+	}
+
+	// Create Locale with full language code
+	l := NewLocale("/tmp", "en_US")
+
+	// Force nil domain storage
+	l.domains = nil
+
+	// Add domain
+	l.AddDomain("my_domain")
+
+	// Test translations
+	tr := l.GetD("my_domain", "My text")
+	if tr != "Translated text" {
+		t.Errorf("Expected 'Translated text' but got '%s'", tr)
+	}
+
+	v := "Variable"
+	tr = l.GetD("my_domain", "One with var: %s", v)
+	if tr != "This one is the singular: Variable" {
+		t.Errorf("Expected 'This one is the singular: Variable' but got '%s'", tr)
+	}
+
+	// Test plural
+	tr = l.GetND("my_domain", "One with var: %s", "Several with vars: %s", 7, v)
+	if tr != "This one is the plural: Variable" {
+		t.Errorf("Expected 'This one is the plural: Variable' but got '%s'", tr)
+	}
+
+	// Test context translations
+	v = "Test"
+	tr = l.GetDC("my_domain", "One with var: %s", "Ctx", v)
+	if tr != "This one is the singular in a Ctx context: Test" {
+		t.Errorf("Expected 'This one is the singular in a Ctx context: Test' but got '%s'", tr)
+	}
+
+	// Test plural
+	tr = l.GetNDC("my_domain", "One with var: %s", "Several with vars: %s", 3, "Ctx", v)
+	if tr != "This one is the plural in a Ctx context: Test" {
+		t.Errorf("Expected 'This one is the plural in a Ctx context: Test' but got '%s'", tr)
+	}
+
+	// Test last translation
+	tr = l.GetD("my_domain", "More")
+	if tr != "More translation" {
+		t.Errorf("Expected 'More translation' but got '%s'", tr)
+	}
+}
+
+func TestLocaleFails(t *testing.T) {
+	// Set PO content
+	str := `
+msgid ""
+msgstr ""
+# Initial comment
+# Headers below
+"Language: en\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+# Some comment
+msgid "My text"
+msgstr "Translated text"
+
+# More comments
+msgid "Another string"
+msgstr ""
+
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular: %s"
+msgstr[1] "This one is the plural: %s"
+msgstr[2] "And this is the second plural form: %s"
+
+msgid "This one has invalid syntax translations"
+msgid_plural "Plural index"
+msgstr[abc] "Wrong index"
+msgstr[1 "Forgot to close brackets"
+msgstr[0] "Badly formatted string'
+
+msgid "Invalid formatted id[] with no translations
+
+msgctxt "Ctx"
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular in a Ctx context: %s"
+msgstr[1] "This one is the plural in a Ctx context: %s"
+
+msgid "Some random"
+msgstr "Some random translation"
+
+msgctxt "Ctx"
+msgid "Some random in a context"
+msgstr "Some random translation in a context"
+
+msgid "More"
+msgstr "More translation"
+
+	`
+
+	// Create Locales directory with simplified language code
+	dirname := path.Join("/tmp", "en", "LC_MESSAGES")
+	err := os.MkdirAll(dirname, os.ModePerm)
+	if err != nil {
+		t.Fatalf("Can't create test directory: %s", err.Error())
+	}
+
+	// Write PO content to file
+	filename := path.Join(dirname, "my_domain.po")
+
+	f, err := os.Create(filename)
+	if err != nil {
+		t.Fatalf("Can't create test file: %s", err.Error())
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(str)
+	if err != nil {
+		t.Fatalf("Can't write to test file: %s", err.Error())
+	}
+
+	// Create Locale with full language code
+	l := NewLocale("/tmp", "en_US")
+
+	// Force nil domain storage
+	l.domains = nil
+
+	// Add domain
+	l.AddDomain("my_domain")
+
+	// Test non-existent "deafult" domain responses
+	tr := l.Get("My text")
+	if tr != "My text" {
+		t.Errorf("Expected 'My text' but got '%s'", tr)
+	}
+
+	v := "Variable"
+	tr = l.GetN("One with var: %s", "Several with vars: %s", 2, v)
+	if tr != "Several with vars: Variable" {
+		t.Errorf("Expected 'Several with vars: Variable' but got '%s'", tr)
+	}
+
+	// Test inexistent translations
+	tr = l.Get("This is a test")
+	if tr != "This is a test" {
+		t.Errorf("Expected 'This is a test' but got '%s'", tr)
+	}
+
+	tr = l.GetN("This is a test", "This are tests", 1)
+	if tr != "This are tests" {
+		t.Errorf("Expected 'This are tests' but got '%s'", tr)
+	}
+
+	// Test syntax error parsed translations
+	tr = l.Get("This one has invalid syntax translations")
+	if tr != "This one has invalid syntax translations" {
+		t.Errorf("Expected 'This one has invalid syntax translations' but got '%s'", tr)
+	}
+
+	tr = l.GetN("This one has invalid syntax translations", "This are tests", 1)
+	if tr != "This are tests" {
+		t.Errorf("Expected 'Plural index' but got '%s'", tr)
+	}
+}
+
+func TestLocaleRace(t *testing.T) {
 	// Set PO content
 	str := `# Some comment
 msgid "My text"
@@ -25,14 +262,14 @@ msgstr[2] "And this is the second plural form: %s"
 	`
 
 	// Create Locales directory with simplified language code
-	dirname := path.Clean("/tmp" + string(os.PathSeparator) + "en")
+	dirname := path.Join("/tmp", "es")
 	err := os.MkdirAll(dirname, os.ModePerm)
 	if err != nil {
 		t.Fatalf("Can't create test directory: %s", err.Error())
 	}
 
 	// Write PO content to file
-	filename := path.Clean(dirname + string(os.PathSeparator) + "my_domain.po")
+	filename := path.Join(dirname, "race.po")
 
 	f, err := os.Create(filename)
 	if err != nil {
@@ -46,26 +283,28 @@ msgstr[2] "And this is the second plural form: %s"
 	}
 
 	// Create Locale with full language code
-	l := NewLocale("/tmp", "en_US")
+	l := NewLocale("/tmp", "es")
 
-	// Add domain
-	l.AddDomain("my_domain")
+	// Init sync channels
+	ac := make(chan bool)
+	rc := make(chan bool)
 
-	// Test translations
-	tr := l.GetD("my_domain", "My text")
-	if tr != "Translated text" {
-		t.Errorf("Expected 'Translated text' but got '%s'", tr)
-	}
+	// Add domain in goroutine
+	go func(l *Locale, done chan bool) {
+		l.AddDomain("race")
+		done <- true
+	}(l, ac)
 
-	v := "Variable"
-	tr = l.GetD("my_domain", "One with var: %s", v)
-	if tr != "This one is the singular: Variable" {
-		t.Errorf("Expected 'This one is the singular: Variable' but got '%s'", tr)
-	}
+	// Get translations in goroutine
+	go func(l *Locale, done chan bool) {
+		l.GetD("race", "My text")
+		done <- true
+	}(l, rc)
 
-	// Test plural
-	tr = l.GetND("my_domain", "One with var: %s", "Several with vars: %s", 2, v)
-	if tr != "And this is the second plural form: Variable" {
-		t.Errorf("Expected 'And this is the second plural form: Variable' but got '%s'", tr)
-	}
+	// Get translations at top level
+	l.GetD("race", "My text")
+
+	// Wait for goroutines to finish
+	<-ac
+	<-rc
 }

po.go

@@ -1,8 +1,11 @@
 package gotext
 
 import (
+	"bufio"
 	"fmt"
+	"github.com/mattn/kinako/vm"
 	"io/ioutil"
+	"net/textproto"
 	"os"
 	"strconv"
 	"strings"
@@ -11,7 +14,7 @@ import (
 
 type translation struct {
 	id       string
-	pluralId string
+	pluralID string
 	trs      map[int]string
 }
 
@@ -25,8 +28,10 @@ func newTranslation() *translation {
 func (t *translation) get() string {
 	// Look for translation index 0
 	if _, ok := t.trs[0]; ok {
+		if t.trs[0] != "" {
 			return t.trs[0]
 		}
+	}
 
 	// Return unstranlated id by default
 	return t.id
@@ -35,21 +40,31 @@ func (t *translation) get() string {
 func (t *translation) getN(n int) string {
 	// Look for translation index
 	if _, ok := t.trs[n]; ok {
+		if t.trs[n] != "" {
 			return t.trs[n]
 		}
+	}
 
-	// Return unstranlated plural by default
-	return t.pluralId
+	// Return unstranlated singular if corresponding
+	if n == 0 {
+		return t.id
+	}
+
+	// Return untranslated plural by default
+	return t.pluralID
 }
 
 /*
 Po parses the content of any PO file and provides all the translation functions needed.
-It's the base object used by all packafe methods.
-And it's safe for concurrent use by multiple goroutines by using the sync package for write locking.
+It's the base object used by all package methods.
+And it's safe for concurrent use by multiple goroutines by using the sync package for locking.
 
 Example:
 
-    import "github.com/leonelquinteros/gotext"
+	import (
+		"fmt"
+		"github.com/leonelquinteros/gotext"
+	)
 
 	func main() {
 		// Create po object
@@ -59,18 +74,46 @@ Example:
 		po.ParseFile("/path/to/po/file/translations.po")
 
 		// Get translation
-        println(po.Get("Translate this"))
+		fmt.Println(po.Get("Translate this"))
 	}
 
 */
 type Po struct {
+	// Headers
+	RawHeaders string
+
+	// Language header
+	Language string
+
+	// Plural-Forms header
+	PluralForms string
+
+	// Parsed Plural-Forms header values
+	nplurals int
+	plural   string
+
 	// Storage
 	translations map[string]*translation
+	contexts     map[string]map[string]*translation
 
 	// Sync Mutex
 	sync.RWMutex
+
+	// Parsing buffers
+	trBuffer  *translation
+	ctxBuffer string
 }
 
+type parseState int
+
+const (
+	head parseState = iota
+	msgCtxt
+	msgID
+	msgIDPlural
+	msgStr
+)
+
 // ParseFile tries to read the file by its provided path (f) and parse its content as a .po file.
 func (po *Po) ParseFile(f string) {
 	// Check if file exists
@@ -95,97 +138,288 @@ func (po *Po) ParseFile(f string) {
 
 // Parse loads the translations specified in the provided string (str)
 func (po *Po) Parse(str string) {
-	if po.translations == nil {
+	// Lock while parsing
 	po.Lock()
+	defer po.Unlock()
+
+	// Init storage
+	if po.translations == nil {
 		po.translations = make(map[string]*translation)
-		po.Unlock()
+		po.contexts = make(map[string]map[string]*translation)
 	}
 
+	// Get lines
 	lines := strings.Split(str, "\n")
 
-	tr := newTranslation()
+	// Init buffer
+	po.trBuffer = newTranslation()
+	po.ctxBuffer = ""
 
+	state := head
 	for _, l := range lines {
 		// Trim spaces
 		l = strings.TrimSpace(l)
 
-		// Skip empty lines
-		if l == "" {
+		// Skip invalid lines
+		if !po.isValidLine(l) {
 			continue
 		}
 
-		// Skip invalid lines
-		if !strings.HasPrefix(l, "msgid") && !strings.HasPrefix(l, "msgid_plural") && !strings.HasPrefix(l, "msgstr") {
+		// Buffer context and continue
+		if strings.HasPrefix(l, "msgctxt") {
+			po.parseContext(l)
+			state = msgCtxt
 			continue
 		}
 
 		// Buffer msgid and continue
 		if strings.HasPrefix(l, "msgid") && !strings.HasPrefix(l, "msgid_plural") {
-			// Save current translation buffer.
-			po.Lock()
-			po.translations[tr.id] = tr
-			po.Unlock()
-
-			// Flush buffer
-			tr = newTranslation()
-
-			// Set id
-			tr.id, _ = strconv.Unquote(strings.TrimSpace(strings.TrimPrefix(l, "msgid")))
-
-			// Loop
+			po.parseID(l)
+			state = msgID
 			continue
 		}
 
 		// Check for plural form
 		if strings.HasPrefix(l, "msgid_plural") {
-			tr.pluralId, _ = strconv.Unquote(strings.TrimSpace(strings.TrimPrefix(l, "msgid_plural")))
-
-			// Loop
+			po.parsePluralID(l)
+			state = msgIDPlural
 			continue
 		}
 
 		// Save translation
 		if strings.HasPrefix(l, "msgstr") {
-			l = strings.TrimSpace(strings.TrimPrefix(l, "msgstr"))
-
-			// Check for indexed translation forms
-			if strings.HasPrefix(l, "[") {
-				in := strings.Index(l, "]")
-				if in == -1 {
-					// Skip wrong index formatting
+			po.parseMessage(l)
+			state = msgStr
 			continue
 		}
 
-				// Parse index
-				i, err := strconv.Atoi(l[1:in])
-				if err != nil {
-					// Skip wrong index formatting
+		// Multi line strings and headers
+		if strings.HasPrefix(l, "\"") && strings.HasSuffix(l, "\"") {
+			state = po.parseString(l, state)
 			continue
 		}
-
-				// Parse translation string
-				tr.trs[i], _ = strconv.Unquote(strings.TrimSpace(l[in+1:]))
-
-				// Loop
-				continue
-			}
-
-			// Save single translation form under 0 index
-			tr.trs[0], _ = strconv.Unquote(l)
-		}
 	}
 
 	// Save last translation buffer.
-	if tr.id != "" {
-		po.Lock()
-		po.translations[tr.id] = tr
-		po.Unlock()
+	po.saveBuffer()
+
+	// Parse headers
+	po.parseHeaders()
+}
+
+// saveBuffer takes the context and translation buffers
+// and saves it on the translations collection
+func (po *Po) saveBuffer() {
+	// If we have something to save...
+	if po.trBuffer.id != "" {
+		// With no context...
+		if po.ctxBuffer == "" {
+			po.translations[po.trBuffer.id] = po.trBuffer
+		} else {
+			// With context...
+			if _, ok := po.contexts[po.ctxBuffer]; !ok {
+				po.contexts[po.ctxBuffer] = make(map[string]*translation)
 			}
+			po.contexts[po.ctxBuffer][po.trBuffer.id] = po.trBuffer
+		}
+
+		// Flush buffer
+		po.trBuffer = newTranslation()
+		po.ctxBuffer = ""
+	}
+}
+
+// parseContext takes a line starting with "msgctxt",
+// saves the current translation buffer and creates a new context.
+func (po *Po) parseContext(l string) {
+	// Save current translation buffer.
+	po.saveBuffer()
+
+	// Buffer context
+	po.ctxBuffer, _ = strconv.Unquote(strings.TrimSpace(strings.TrimPrefix(l, "msgctxt")))
+}
+
+// parseID takes a line starting with "msgid",
+// saves the current translation and creates a new msgid buffer.
+func (po *Po) parseID(l string) {
+	// Save current translation buffer.
+	po.saveBuffer()
+
+	// Set id
+	po.trBuffer.id, _ = strconv.Unquote(strings.TrimSpace(strings.TrimPrefix(l, "msgid")))
+}
+
+// parsePluralID saves the plural id buffer from a line starting with "msgid_plural"
+func (po *Po) parsePluralID(l string) {
+	po.trBuffer.pluralID, _ = strconv.Unquote(strings.TrimSpace(strings.TrimPrefix(l, "msgid_plural")))
+}
+
+// parseMessage takes a line starting with "msgstr" and saves it into the current buffer.
+func (po *Po) parseMessage(l string) {
+	l = strings.TrimSpace(strings.TrimPrefix(l, "msgstr"))
+
+	// Check for indexed translation forms
+	if strings.HasPrefix(l, "[") {
+		idx := strings.Index(l, "]")
+		if idx == -1 {
+			// Skip wrong index formatting
+			return
+		}
+
+		// Parse index
+		i, err := strconv.Atoi(l[1:idx])
+		if err != nil {
+			// Skip wrong index formatting
+			return
+		}
+
+		// Parse translation string
+		po.trBuffer.trs[i], _ = strconv.Unquote(strings.TrimSpace(l[idx+1:]))
+
+		// Loop
+		return
+	}
+
+	// Save single translation form under 0 index
+	po.trBuffer.trs[0], _ = strconv.Unquote(l)
+}
+
+// parseString takes a well formatted string without prefix
+// and creates headers or attach multi-line strings when corresponding
+func (po *Po) parseString(l string, state parseState) parseState {
+	switch state {
+	case msgStr:
+		// Check for multiline from previously set msgid
+		if po.trBuffer.id != "" {
+			// Append to last translation found
+			uq, _ := strconv.Unquote(l)
+			po.trBuffer.trs[len(po.trBuffer.trs)-1] += uq
+
+		}
+	case msgID:
+		// Multiline msgid - Append to current id
+		uq, _ := strconv.Unquote(l)
+		po.trBuffer.id += uq
+	case msgIDPlural:
+		// Multiline msgid - Append to current id
+		uq, _ := strconv.Unquote(l)
+		po.trBuffer.pluralID += uq
+	case msgCtxt:
+		// Multiline context - Append to current context
+		ctxt, _ := strconv.Unquote(l)
+		po.ctxBuffer += ctxt
+	default:
+		// Otherwise is a header
+		h, _ := strconv.Unquote(strings.TrimSpace(l))
+		po.RawHeaders += h
+		return head
+	}
+
+	return state
+}
+
+// isValidLine checks for line prefixes to detect valid syntax.
+func (po *Po) isValidLine(l string) bool {
+	// Skip empty lines
+	if l == "" {
+		return false
+	}
+
+	// Check prefix
+	if !strings.HasPrefix(l, "\"") && !strings.HasPrefix(l, "msgctxt") && !strings.HasPrefix(l, "msgid") && !strings.HasPrefix(l, "msgid_plural") && !strings.HasPrefix(l, "msgstr") {
+		return false
+	}
+
+	return true
+}
+
+// parseHeaders retrieves data from previously parsed headers
+func (po *Po) parseHeaders() {
+	// Make sure we end with 2 carriage returns.
+	po.RawHeaders += "\n\n"
+
+	// Read
+	reader := bufio.NewReader(strings.NewReader(po.RawHeaders))
+	tp := textproto.NewReader(reader)
+
+	mimeHeader, err := tp.ReadMIMEHeader()
+	if err != nil {
+		return
+	}
+
+	// Get/save needed headers
+	po.Language = mimeHeader.Get("Language")
+	po.PluralForms = mimeHeader.Get("Plural-Forms")
+
+	// Parse Plural-Forms formula
+	if po.PluralForms == "" {
+		return
+	}
+
+	// Split plural form header value
+	pfs := strings.Split(po.PluralForms, ";")
+
+	// Parse values
+	for _, i := range pfs {
+		vs := strings.SplitN(i, "=", 2)
+		if len(vs) != 2 {
+			continue
+		}
+
+		switch strings.TrimSpace(vs[0]) {
+		case "nplurals":
+			po.nplurals, _ = strconv.Atoi(vs[1])
+
+		case "plural":
+			po.plural = vs[1]
+		}
+	}
+}
+
+// pluralForm calculates the plural form index corresponding to n.
+// Returns 0 on error
+func (po *Po) pluralForm(n int) int {
+	po.RLock()
+	defer po.RUnlock()
+
+	// Failsafe
+	if po.nplurals < 1 {
+		return 0
+	}
+	if po.plural == "" {
+		return 0
+	}
+
+	// Init compiler
+	env := vm.NewEnv()
+	env.Define("n", n)
+
+	plural, err := env.Execute(po.plural)
+	if err != nil {
+		return 0
+	}
+	if plural.Type().Name() == "bool" {
+		if plural.Bool() {
+			return 1
+		}
+		// Else
+		return 0
+	}
+
+	if int(plural.Int()) > po.nplurals {
+		return 0
+	}
+
+	return int(plural.Int())
 }
 
 // Get retrieves the corresponding translation for the given string.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func (po *Po) Get(str string, vars ...interface{}) string {
+	// Sync read
+	po.RLock()
+	defer po.RUnlock()
+
 	if po.translations != nil {
 		if _, ok := po.translations[str]; ok {
 			return fmt.Sprintf(po.translations[str].get(), vars...)
@@ -196,16 +430,66 @@ func (po *Po) Get(str string, vars ...interface{}) string {
 	return fmt.Sprintf(str, vars...)
 }
 
-// GetN retrieves the (N)th plural form translation for the given string.
-// If n == 0, usually the singular form of the string is returned as defined in the PO file.
+// GetN retrieves the (N)th plural form of translation for the given string.
 // Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
 func (po *Po) GetN(str, plural string, n int, vars ...interface{}) string {
+	// Sync read
+	po.RLock()
+	defer po.RUnlock()
+
 	if po.translations != nil {
 		if _, ok := po.translations[str]; ok {
-			return fmt.Sprintf(po.translations[str].getN(n), vars...)
+			return fmt.Sprintf(po.translations[str].getN(po.pluralForm(n)), vars...)
 		}
 	}
 
-	// Return the plural string we received by default
+	if n == 1 {
+		return fmt.Sprintf(str, vars...)
+	}
+
+	return fmt.Sprintf(plural, vars...)
+}
+
+// GetC retrieves the corresponding translation for a given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func (po *Po) GetC(str, ctx string, vars ...interface{}) string {
+	// Sync read
+	po.RLock()
+	defer po.RUnlock()
+
+	if po.contexts != nil {
+		if _, ok := po.contexts[ctx]; ok {
+			if po.contexts[ctx] != nil {
+				if _, ok := po.contexts[ctx][str]; ok {
+					return fmt.Sprintf(po.contexts[ctx][str].get(), vars...)
+				}
+			}
+		}
+	}
+
+	// Return the string we received by default
+	return fmt.Sprintf(str, vars...)
+}
+
+// GetNC retrieves the (N)th plural form of translation for the given string in the given context.
+// Supports optional parameters (vars... interface{}) to be inserted on the formatted string using the fmt.Printf syntax.
+func (po *Po) GetNC(str, plural string, n int, ctx string, vars ...interface{}) string {
+	// Sync read
+	po.RLock()
+	defer po.RUnlock()
+
+	if po.contexts != nil {
+		if _, ok := po.contexts[ctx]; ok {
+			if po.contexts[ctx] != nil {
+				if _, ok := po.contexts[ctx][str]; ok {
+					return fmt.Sprintf(po.contexts[ctx][str].getN(po.pluralForm(n)), vars...)
+				}
+			}
+		}
+	}
+
+	if n == 1 {
+		return fmt.Sprintf(str, vars...)
+	}
 	return fmt.Sprintf(plural, vars...)
 }

po_test.go

@@ -7,6 +7,438 @@ import (
 )
 
 func TestPo(t *testing.T) {
+	// Set PO content
+	str := `
+# Initial comment
+# Headers below
+"Language: en\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+# Some comment
+msgid "My text"
+msgstr "Translated text"
+
+# More comments
+msgid "Another string"
+msgstr ""
+
+# Multi-line msgid
+msgid "multi"
+"line"
+"id"
+msgstr "id with multiline content"
+
+# Multi-line msgid_plural
+msgid "multi"
+"line"
+"plural"
+"id"
+msgstr "plural id with multiline content"
+
+#Multi-line string
+msgid "Multi-line"
+msgstr "Multi "
+"line"
+
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular: %s"
+msgstr[1] "This one is the plural: %s"
+msgstr[2] "And this is the second plural form: %s"
+
+msgid "This one has invalid syntax translations"
+msgid_plural "Plural index"
+msgstr[abc] "Wrong index"
+msgstr[1 "Forgot to close brackets"
+msgstr[0] "Badly formatted string'
+
+msgid "Invalid formatted id[] with no translations
+
+msgctxt "Ctx"
+msgid "One with var: %s"
+msgid_plural "Several with vars: %s"
+msgstr[0] "This one is the singular in a Ctx context: %s"
+msgstr[1] "This one is the plural in a Ctx context: %s"
+
+msgid "Some random"
+msgstr "Some random translation"
+
+msgctxt "Ctx"
+msgid "Some random in a context"
+msgstr "Some random translation in a context"
+
+msgid "Empty translation"
+msgstr ""
+
+msgid "Empty plural form singular"
+msgid_plural "Empty plural form"
+msgstr[0] "Singular translated"
+msgstr[1] "
+
+msgid "More"
+msgstr "More translation"
+"
+	`
+
+	// Write PO content to file
+	filename := path.Clean(os.TempDir() + string(os.PathSeparator) + "default.po")
+
+	f, err := os.Create(filename)
+	if err != nil {
+		t.Fatalf("Can't create test file: %s", err.Error())
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(str)
+	if err != nil {
+		t.Fatalf("Can't write to test file: %s", err.Error())
+	}
+
+	// Create po object
+	po := new(Po)
+
+	// Try to parse a directory
+	po.ParseFile(path.Clean(os.TempDir()))
+
+	// Parse file
+	po.ParseFile(filename)
+
+	// Test translations
+	tr := po.Get("My text")
+	if tr != "Translated text" {
+		t.Errorf("Expected 'Translated text' but got '%s'", tr)
+	}
+
+	v := "Variable"
+	tr = po.Get("One with var: %s", v)
+	if tr != "This one is the singular: Variable" {
+		t.Errorf("Expected 'This one is the singular: Variable' but got '%s'", tr)
+	}
+
+	// Test multi-line id
+	tr = po.Get("multilineid")
+	if tr != "id with multiline content" {
+		t.Errorf("Expected 'id with multiline content' but got '%s'", tr)
+	}
+
+	// Test multi-line plural id
+	tr = po.Get("multilinepluralid")
+	if tr != "plural id with multiline content" {
+		t.Errorf("Expected 'plural id with multiline content' but got '%s'", tr)
+	}
+
+	// Test multi-line
+	tr = po.Get("Multi-line")
+	if tr != "Multi line" {
+		t.Errorf("Expected 'Multi line' but got '%s'", tr)
+	}
+
+	// Test plural
+	tr = po.GetN("One with var: %s", "Several with vars: %s", 2, v)
+	if tr != "This one is the plural: Variable" {
+		t.Errorf("Expected 'This one is the plural: Variable' but got '%s'", tr)
+	}
+
+	// Test inexistent translations
+	tr = po.Get("This is a test")
+	if tr != "This is a test" {
+		t.Errorf("Expected 'This is a test' but got '%s'", tr)
+	}
+
+	tr = po.GetN("This is a test", "This are tests", 100)
+	if tr != "This are tests" {
+		t.Errorf("Expected 'This are tests' but got '%s'", tr)
+	}
+
+	// Test syntax error parsed translations
+	tr = po.Get("This one has invalid syntax translations")
+	if tr != "This one has invalid syntax translations" {
+		t.Errorf("Expected 'This one has invalid syntax translations' but got '%s'", tr)
+	}
+
+	tr = po.GetN("This one has invalid syntax translations", "This are tests", 4)
+	if tr != "Plural index" {
+		t.Errorf("Expected 'Plural index' but got '%s'", tr)
+	}
+
+	// Test context translations
+	v = "Test"
+	tr = po.GetC("One with var: %s", "Ctx", v)
+	if tr != "This one is the singular in a Ctx context: Test" {
+		t.Errorf("Expected 'This one is the singular in a Ctx context: Test' but got '%s'", tr)
+	}
+
+	// Test plural
+	tr = po.GetNC("One with var: %s", "Several with vars: %s", 17, "Ctx", v)
+	if tr != "This one is the plural in a Ctx context: Test" {
+		t.Errorf("Expected 'This one is the plural in a Ctx context: Test' but got '%s'", tr)
+	}
+
+	// Test default plural vs singular return responses
+	tr = po.GetN("Original", "Original plural", 4)
+	if tr != "Original plural" {
+		t.Errorf("Expected 'Original plural' but got '%s'", tr)
+	}
+	tr = po.GetN("Original", "Original plural", 1)
+	if tr != "Original" {
+		t.Errorf("Expected 'Original' but got '%s'", tr)
+	}
+
+	// Test empty translation strings
+	tr = po.Get("Empty translation")
+	if tr != "Empty translation" {
+		t.Errorf("Expected 'Empty translation' but got '%s'", tr)
+	}
+
+	tr = po.Get("Empty plural form singular")
+	if tr != "Singular translated" {
+		t.Errorf("Expected 'Singular translated' but got '%s'", tr)
+	}
+
+	tr = po.GetN("Empty plural form singular", "Empty plural form", 1)
+	if tr != "Singular translated" {
+		t.Errorf("Expected 'Singular translated' but got '%s'", tr)
+	}
+
+	tr = po.GetN("Empty plural form singular", "Empty plural form", 2)
+	if tr != "Empty plural form" {
+		t.Errorf("Expected 'Empty plural form' but got '%s'", tr)
+	}
+
+	// Test last translation
+	tr = po.Get("More")
+	if tr != "More translation" {
+		t.Errorf("Expected 'More translation' but got '%s'", tr)
+	}
+}
+
+func TestPoHeaders(t *testing.T) {
+	// Set PO content
+	str := `
+# Initial comment
+# Headers below
+"Language: en\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+# Some comment
+msgid "Example"
+msgstr "Translated example"
+	`
+
+	// Create po object
+	po := new(Po)
+
+	// Parse
+	po.Parse(str)
+
+	// Check headers expected
+	if po.Language != "en" {
+		t.Errorf("Expected 'Language: en' but got '%s'", po.Language)
+	}
+
+	// Check headers expected
+	if po.PluralForms != "nplurals=2; plural=(n != 1);" {
+		t.Errorf("Expected 'Plural-Forms: nplurals=2; plural=(n != 1);' but got '%s'", po.PluralForms)
+	}
+}
+
+func TestPluralFormsSingle(t *testing.T) {
+	// Single form
+	str := `
+"Plural-Forms: nplurals=1; plural=0;"
+
+# Some comment
+msgid "Singular"
+msgid_plural "Plural"
+msgstr[0] "Singular form"
+msgstr[1] "Plural form 1"
+msgstr[2] "Plural form 2"
+msgstr[3] "Plural form 3"
+	`
+
+	// Create po object
+	po := new(Po)
+
+	// Parse
+	po.Parse(str)
+
+	// Check plural form
+	n := po.pluralForm(0)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(0), got %d", n)
+	}
+	n = po.pluralForm(1)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(1), got %d", n)
+	}
+	n = po.pluralForm(2)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(2), got %d", n)
+	}
+	n = po.pluralForm(3)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(3), got %d", n)
+	}
+	n = po.pluralForm(50)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(50), got %d", n)
+	}
+}
+
+func TestPluralForms2(t *testing.T) {
+	// 2 forms
+	str := `
+"Plural-Forms: nplurals=2; plural=n != 1;"
+
+# Some comment
+msgid "Singular"
+msgid_plural "Plural"
+msgstr[0] "Singular form"
+msgstr[1] "Plural form 1"
+msgstr[2] "Plural form 2"
+msgstr[3] "Plural form 3"
+	`
+
+	// Create po object
+	po := new(Po)
+
+	// Parse
+	po.Parse(str)
+
+	// Check plural form
+	n := po.pluralForm(0)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(0), got %d", n)
+	}
+	n = po.pluralForm(1)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(1), got %d", n)
+	}
+	n = po.pluralForm(2)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(2), got %d", n)
+	}
+	n = po.pluralForm(3)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(3), got %d", n)
+	}
+}
+
+func TestPluralForms3(t *testing.T) {
+	// 3 forms
+	str := `
+"Plural-Forms: nplurals=3; plural=n%10==1 && n%100!=11 ? 0 : n != 0 ? 1 : 2;"
+
+# Some comment
+msgid "Singular"
+msgid_plural "Plural"
+msgstr[0] "Singular form"
+msgstr[1] "Plural form 1"
+msgstr[2] "Plural form 2"
+msgstr[3] "Plural form 3"
+	`
+
+	// Create po object
+	po := new(Po)
+
+	// Parse
+	po.Parse(str)
+
+	// Check plural form
+	n := po.pluralForm(0)
+	if n != 2 {
+		t.Errorf("Expected 2 for pluralForm(0), got %d", n)
+	}
+	n = po.pluralForm(1)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(1), got %d", n)
+	}
+	n = po.pluralForm(2)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(2), got %d", n)
+	}
+	n = po.pluralForm(3)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(3), got %d", n)
+	}
+	n = po.pluralForm(100)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(100), got %d", n)
+	}
+	n = po.pluralForm(49)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(3), got %d", n)
+	}
+}
+
+func TestPluralFormsSpecial(t *testing.T) {
+	// 3 forms special
+	str := `
+"Plural-Forms: nplurals=3;"
+"plural=(n==1) ? 0 : (n>=2 && n<=4) ? 1 : 2;"
+
+# Some comment
+msgid "Singular"
+msgid_plural "Plural"
+msgstr[0] "Singular form"
+msgstr[1] "Plural form 1"
+msgstr[2] "Plural form 2"
+msgstr[3] "Plural form 3"
+	`
+
+	// Create po object
+	po := new(Po)
+
+	// Parse
+	po.Parse(str)
+
+	// Check plural form
+	n := po.pluralForm(1)
+	if n != 0 {
+		t.Errorf("Expected 0 for pluralForm(1), got %d", n)
+	}
+	n = po.pluralForm(2)
+	if n != 1 {
+		t.Errorf("Expected 1 for pluralForm(2), got %d", n)
+	}
+	n = po.pluralForm(4)
+	if n != 1 {
+		t.Errorf("Expected 4 for pluralForm(4), got %d", n)
+	}
+	n = po.pluralForm(0)
+	if n != 2 {
+		t.Errorf("Expected 2 for pluralForm(2), got %d", n)
+	}
+	n = po.pluralForm(1000)
+	if n != 2 {
+		t.Errorf("Expected 2 for pluralForm(1000), got %d", n)
+	}
+}
+
+func TestTranslationObject(t *testing.T) {
+	tr := newTranslation()
+	str := tr.get()
+
+	if str != "" {
+		t.Errorf("Expected '' but got '%s'", str)
+	}
+
+	// Set id
+	tr.id = "Text"
+
+	// Get again
+	str = tr.get()
+
+	if str != "Text" {
+		t.Errorf("Expected 'Text' but got '%s'", str)
+	}
+}
+
+func TestPoRace(t *testing.T) {
 	// Set PO content
 	str := `# Some comment
 msgid "My text"
@@ -23,39 +455,30 @@ msgstr[1] "This one is the plural: %s"
 msgstr[2] "And this is the second plural form: %s"
 
 	`
-	// Write PO content to file
-	filename := path.Clean(os.TempDir() + string(os.PathSeparator) + "default.po")
 
-	f, err := os.Create(filename)
-	if err != nil {
-		t.Fatalf("Can't create test file: %s", err.Error())
-	}
-	defer f.Close()
-
-	_, err = f.WriteString(str)
-	if err != nil {
-		t.Fatalf("Can't write to test file: %s", err.Error())
-	}
-
-	// Parse po file
+	// Create Po object
 	po := new(Po)
-	po.ParseFile(filename)
 
-	// Test translations
-	tr := po.Get("My text")
-	if tr != "Translated text" {
-		t.Errorf("Expected 'Translated text' but got '%s'", tr)
-	}
+	// Create sync channels
+	pc := make(chan bool)
+	rc := make(chan bool)
 
-	v := "Variable"
-	tr = po.Get("One with var: %s", v)
-	if tr != "This one is the singular: Variable" {
-		t.Errorf("Expected 'This one is the singular: Variable' but got '%s'", tr)
-	}
+	// Parse po content in a goroutine
+	go func(po *Po, done chan bool) {
+		po.Parse(str)
+		done <- true
+	}(po, pc)
 
-	// Test plural
-	tr = po.GetN("One with var: %s", "Several with vars: %s", 2, v)
-	if tr != "And this is the second plural form: Variable" {
-		t.Errorf("Expected 'And this is the second plural form: Variable' but got '%s'", tr)
-	}
+	// Read some translation on a goroutine
+	go func(po *Po, done chan bool) {
+		po.Get("My text")
+		done <- true
+	}(po, rc)
+
+	// Read something at top level
+	po.Get("My text")
+
+	// Wait for goroutines to finish
+	<-pc
+	<-rc
 }

vendor/github.com/mattn/kinako/ast/expr.go

@@ -0,0 +1,104 @@
+package ast
+
+type Token struct {
+	Tok int
+	Lit string
+}
+
+// Position provides interface to store code locations.
+type Position struct {
+	Line   int
+	Column int
+}
+
+// Expr provides all of interfaces for expression.
+type Expr interface {
+	expr()
+}
+
+// ExprImpl provide commonly implementations for Expr.
+type ExprImpl struct {
+}
+
+// expr provide restraint interface.
+func (x *ExprImpl) expr() {}
+
+// NumberExpr provide Number expression.
+type NumberExpr struct {
+	ExprImpl
+	Lit string
+}
+
+// UnaryExpr provide unary minus expression. ex: -1, ^1, ~1.
+type UnaryExpr struct {
+	ExprImpl
+	Operator string
+	Expr     Expr
+}
+
+// IdentExpr provide identity expression.
+type IdentExpr struct {
+	ExprImpl
+	Lit string
+}
+
+// Stmt provides all of interfaces for statement.
+type Stmt interface {
+	stmt()
+}
+
+// StmtImpl provide commonly implementations for Stmt..
+type StmtImpl struct {
+}
+
+// stmt provide restraint interface.
+func (x *StmtImpl) stmt() {}
+
+// LetsStmt provide multiple statement of let.
+type LetsStmt struct {
+	StmtImpl
+	Lhss     []Expr
+	Operator string
+	Rhss     []Expr
+}
+
+// StringExpr provide String expression.
+type StringExpr struct {
+	ExprImpl
+	Lit string
+}
+
+type TernaryOpExpr struct {
+	ExprImpl
+	Expr Expr
+	Lhs  Expr
+	Rhs  Expr
+}
+
+// ParenExpr provide parent block expression.
+type ParenExpr struct {
+	ExprImpl
+	SubExpr Expr
+}
+
+// BinOpExpr provide binary operator expression.
+type BinOpExpr struct {
+	ExprImpl
+	Lhs      Expr
+	Operator string
+	Rhs      Expr
+}
+
+// ExprStmt provide expression statement.
+type ExprStmt struct {
+	StmtImpl
+	Expr Expr
+}
+
+// LetStmt provide statement of let.
+type LetStmt struct {
+	StmtImpl
+	Lhs      Expr
+	Operator string
+	Rhs      Expr
+}

vendor/github.com/mattn/kinako/parser/Makefile

@@ -0,0 +1,4 @@
+all : parser.go
+
+parser.go : parser.go.y
+	goyacc -o $@ parser.go.y

vendor/github.com/mattn/kinako/parser/lexer.go

@@ -0,0 +1,427 @@
+package parser
+
+import (
+	"errors"
+	"fmt"
+	"unicode"
+
+	"github.com/mattn/kinako/ast"
+)
+
+const (
+	EOF = -1   // End of file.
+	EOL = '\n' // End of line.
+)
+
+// Error provides a convenient interface for handling runtime error.
+// It can be Error inteface with type cast which can call Pos().
+type Error struct {
+	Message  string
+	Filename string
+	Fatal    bool
+}
+
+// Error returns the error message.
+func (e *Error) Error() string {
+	return e.Message
+}
+
+// Scanner stores informations for lexer.
+type Scanner struct {
+	src      []rune
+	offset   int
+	lineHead int
+	line     int
+}
+
+// Init resets code to scan.
+func (s *Scanner) Init(src string) {
+	s.src = []rune(src)
+}
+
+// Scan analyses token, and decide identify or literals.
+func (s *Scanner) Scan() (tok int, lit string, pos ast.Position, err error) {
+retry:
+	s.skipBlank()
+	pos = s.pos()
+	switch ch := s.peek(); {
+	case isLetter(ch):
+		tok = IDENT
+		lit, err = s.scanIdentifier()
+		if err != nil {
+			return
+		}
+	case isDigit(ch):
+		tok = NUMBER
+		lit, err = s.scanNumber()
+		if err != nil {
+			return
+		}
+	case ch == '"':
+		tok = STRING
+		lit, err = s.scanString('"')
+		if err != nil {
+			return
+		}
+	case ch == '\'':
+		tok = STRING
+		lit, err = s.scanString('\'')
+		if err != nil {
+			return
+		}
+	case ch == '`':
+		tok = STRING
+		lit, err = s.scanRawString()
+		if err != nil {
+			return
+		}
+	default:
+		switch ch {
+		case EOF:
+			tok = EOF
+		case '#':
+			for !isEOL(s.peek()) {
+				s.next()
+			}
+			goto retry
+		case '!':
+			s.next()
+			switch s.peek() {
+			case '=':
+				tok = NEQ
+				lit = "!="
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
+		case '=':
+			s.next()
+			switch s.peek() {
+			case '=':
+				tok = EQEQ
+				lit = "=="
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
+		case '+':
+			tok = int(ch)
+			lit = string(ch)
+		case '-':
+			tok = int(ch)
+			lit = string(ch)
+		case '*':
+			tok = int(ch)
+			lit = string(ch)
+		case '/':
+			tok = int(ch)
+			lit = string(ch)
+		case '>':
+			s.next()
+			switch s.peek() {
+			case '=':
+				tok = GE
+				lit = ">="
+			case '>':
+				tok = SHIFTRIGHT
+				lit = ">>"
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
+		case '<':
+			s.next()
+			switch s.peek() {
+			case '=':
+				tok = LE
+				lit = "<="
+			case '<':
+				tok = SHIFTLEFT
+				lit = "<<"
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
+		case '|':
+			s.next()
+			switch s.peek() {
+			case '|':
+				tok = OROR
+				lit = "||"
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
+		case '&':
+			s.next()
+			switch s.peek() {
+			case '&':
+				tok = ANDAND
+				lit = "&&"
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
+		case '.':
+			tok = int(ch)
+			lit = string(ch)
+		case '\n':
+			tok = int(ch)
+			lit = string(ch)
+		case '(', ')', ':', ';', '%', '?', '{', '}', ',', '[', ']', '^':
+			tok = int(ch)
+			lit = string(ch)
+		default:
+			err = fmt.Errorf(`syntax error "%s"`, string(ch))
+			tok = int(ch)
+			lit = string(ch)
+			return
+		}
+		s.next()
+	}
+	return
+}
+
+// isLetter returns true if the rune is a letter for identity.
+func isLetter(ch rune) bool {
+	return unicode.IsLetter(ch) || ch == '_'
+}
+
+// isDigit returns true if the rune is a number.
+func isDigit(ch rune) bool {
+	return '0' <= ch && ch <= '9'
+}
+
+// isHex returns true if the rune is a hex digits.
+func isHex(ch rune) bool {
+	return ('0' <= ch && ch <= '9') || ('a' <= ch && ch <= 'f') || ('A' <= ch && ch <= 'F')
+}
+
+// isEOL returns true if the rune is at end-of-line or end-of-file.
+func isEOL(ch rune) bool {
+	return ch == '\n' || ch == -1
+}
+
+// isBlank returns true if the rune is empty character..
+func isBlank(ch rune) bool {
+	return ch == ' ' || ch == '\t' || ch == '\r'
+}
+
+// peek returns current rune in the code.
+func (s *Scanner) peek() rune {
+	if s.reachEOF() {
+		return EOF
+	}
+	return s.src[s.offset]
+}
+
+// next moves offset to next.
+func (s *Scanner) next() {
+	if !s.reachEOF() {
+		if s.peek() == '\n' {
+			s.lineHead = s.offset + 1
+			s.line++
+		}
+		s.offset++
+	}
+}
+
+// current returns the current offset.
+func (s *Scanner) current() int {
+	return s.offset
+}
+
+// offset sets the offset value.
+func (s *Scanner) set(o int) {
+	s.offset = o
+}
+
+// back moves back offset once to top.
+func (s *Scanner) back() {
+	s.offset--
+}
+
+// reachEOF returns true if offset is at end-of-file.
+func (s *Scanner) reachEOF() bool {
+	return len(s.src) <= s.offset
+}
+
+// pos returns the position of current.
+func (s *Scanner) pos() ast.Position {
+	return ast.Position{Line: s.line + 1, Column: s.offset - s.lineHead + 1}
+}
+
+// skipBlank moves position into non-black character.
+func (s *Scanner) skipBlank() {
+	for isBlank(s.peek()) {
+		s.next()
+	}
+}
+
+// scanIdentifier returns identifier begining at current position.
+func (s *Scanner) scanIdentifier() (string, error) {
+	var ret []rune
+	for {
+		if !isLetter(s.peek()) && !isDigit(s.peek()) {
+			break
+		}
+		ret = append(ret, s.peek())
+		s.next()
+	}
+	return string(ret), nil
+}
+
+// scanNumber returns number begining at current position.
+func (s *Scanner) scanNumber() (string, error) {
+	var ret []rune
+	ch := s.peek()
+	ret = append(ret, ch)
+	s.next()
+	if ch == '0' && s.peek() == 'x' {
+		ret = append(ret, s.peek())
+		s.next()
+		for isHex(s.peek()) {
+			ret = append(ret, s.peek())
+			s.next()
+		}
+	} else {
+		for isDigit(s.peek()) || s.peek() == '.' {
+			ret = append(ret, s.peek())
+			s.next()
+		}
+		if s.peek() == 'e' {
+			ret = append(ret, s.peek())
+			s.next()
+			if isDigit(s.peek()) || s.peek() == '+' || s.peek() == '-' {
+				ret = append(ret, s.peek())
+				s.next()
+				for isDigit(s.peek()) || s.peek() == '.' {
+					ret = append(ret, s.peek())
+					s.next()
+				}
+			}
+			for isDigit(s.peek()) || s.peek() == '.' {
+				ret = append(ret, s.peek())
+				s.next()
+			}
+		}
+		if isLetter(s.peek()) {
+			return "", errors.New("identifier starts immediately after numeric literal")
+		}
+	}
+	return string(ret), nil
+}
+
+// scanRawString returns raw-string starting at current position.
+func (s *Scanner) scanRawString() (string, error) {
+	var ret []rune
+	for {
+		s.next()
+		if s.peek() == EOF {
+			return "", errors.New("unexpected EOF")
+			break
+		}
+		if s.peek() == '`' {
+			s.next()
+			break
+		}
+		ret = append(ret, s.peek())
+	}
+	return string(ret), nil
+}
+
+// scanString returns string starting at current position.
+// This handles backslash escaping.
+func (s *Scanner) scanString(l rune) (string, error) {
+	var ret []rune
+eos:
+	for {
+		s.next()
+		switch s.peek() {
+		case EOL:
+			return "", errors.New("unexpected EOL")
+		case EOF:
+			return "", errors.New("unexpected EOF")
+		case l:
+			s.next()
+			break eos
+		case '\\':
+			s.next()
+			switch s.peek() {
+			case 'b':
+				ret = append(ret, '\b')
+				continue
+			case 'f':
+				ret = append(ret, '\f')
+				continue
+			case 'r':
+				ret = append(ret, '\r')
+				continue
+			case 'n':
+				ret = append(ret, '\n')
+				continue
+			case 't':
+				ret = append(ret, '\t')
+				continue
+			}
+			ret = append(ret, s.peek())
+			continue
+		default:
+			ret = append(ret, s.peek())
+		}
+	}
+	return string(ret), nil
+}
+
+// Lexer provides inteface to parse codes.
+type Lexer struct {
+	s     *Scanner
+	lit   string
+	pos   ast.Position
+	e     error
+	stmts []ast.Stmt
+}
+
+// Lex scans the token and literals.
+func (l *Lexer) Lex(lval *yySymType) int {
+	tok, lit, pos, err := l.s.Scan()
+	if err != nil {
+		l.e = &Error{Message: fmt.Sprintf("%s", err.Error()), Fatal: true}
+	}
+	lval.tok = ast.Token{Tok: tok, Lit: lit}
+	l.lit = lit
+	l.pos = pos
+	return tok
+}
+
+// Error sets parse error.
+func (l *Lexer) Error(msg string) {
+	l.e = &Error{Message: msg, Fatal: false}
+}
+
+// Parser provides way to parse the code using Scanner.
+func Parse(s *Scanner) ([]ast.Stmt, error) {
+	l := Lexer{s: s}
+	if yyParse(&l) != 0 {
+		return nil, l.e
+	}
+	return l.stmts, l.e
+}
+
+func EnableErrorVerbose() {
+	yyErrorVerbose = true
+}
+
+// ParserSrc provides way to parse the code from source.
+func ParseSrc(src string) ([]ast.Stmt, error) {
+	scanner := &Scanner{
+		src: []rune(src),
+	}
+	return Parse(scanner)
+}

vendor/github.com/mattn/kinako/parser/parser.go

@@ -0,0 +1,752 @@
+//line parser.go.y:2
+package parser
+
+import __yyfmt__ "fmt"
+
+//line parser.go.y:2
+import (
+	"github.com/mattn/kinako/ast"
+)
+
+//line parser.go.y:15
+type yySymType struct {
+	yys       int
+	compstmt  []ast.Stmt
+	stmts     []ast.Stmt
+	stmt      ast.Stmt
+	expr      ast.Expr
+	tok       ast.Token
+	term      ast.Token
+	terms     ast.Token
+	opt_terms ast.Token
+}
+
+const IDENT = 57346
+const NUMBER = 57347
+const STRING = 57348
+const EQEQ = 57349
+const NEQ = 57350
+const GE = 57351
+const LE = 57352
+const OROR = 57353
+const ANDAND = 57354
+const POW = 57355
+const SHIFTLEFT = 57356
+const SHIFTRIGHT = 57357
+const PLUSPLUS = 57358
+const MINUSMINUS = 57359
+const UNARY = 57360
+
+var yyToknames = [...]string{
+	"$end",
+	"error",
+	"$unk",
+	"IDENT",
+	"NUMBER",
+	"STRING",
+	"EQEQ",
+	"NEQ",
+	"GE",
+	"LE",
+	"OROR",
+	"ANDAND",
+	"POW",
+	"'='",
+	"'?'",
+	"':'",
+	"','",
+	"'>'",
+	"'<'",
+	"SHIFTLEFT",
+	"SHIFTRIGHT",
+	"'+'",
+	"'-'",
+	"PLUSPLUS",
+	"MINUSMINUS",
+	"'*'",
+	"'/'",
+	"'%'",
+	"UNARY",
+	"'!'",
+	"'^'",
+	"'('",
+	"')'",
+	"'|'",
+	"'&'",
+	"';'",
+	"'\\n'",
+}
+var yyStatenames = [...]string{}
+
+const yyEofCode = 1
+const yyErrCode = 2
+const yyInitialStackSize = 16
+
+//line parser.go.y:194
+
+//line yacctab:1
+var yyExca = [...]int{
+	-1, 1,
+	1, -1,
+	-2, 0,
+	-1, 49,
+	7, 0,
+	8, 0,
+	-2, 20,
+	-1, 50,
+	7, 0,
+	8, 0,
+	-2, 21,
+}
+
+const yyNprod = 36
+const yyPrivate = 57344
+
+var yyTokenNames []string
+var yyStates []string
+
+const yyLast = 249
+
+var yyAct = [...]int{
+
+	9, 6, 7, 33, 35, 4, 22, 23, 3, 18,
+	24, 25, 26, 37, 38, 39, 2, 40, 33, 35,
+	17, 42, 43, 44, 45, 46, 47, 48, 49, 50,
+	51, 52, 53, 54, 55, 56, 57, 58, 27, 28,
+	30, 32, 34, 36, 8, 1, 21, 60, 0, 29,
+	31, 0, 0, 22, 23, 5, 0, 24, 25, 26,
+	19, 61, 0, 41, 0, 33, 35, 27, 28, 30,
+	32, 34, 36, 0, 19, 21, 0, 0, 29, 31,
+	0, 0, 22, 23, 0, 0, 24, 25, 26, 0,
+	0, 0, 0, 59, 33, 35, 27, 28, 30, 32,
+	34, 36, 0, 20, 21, 0, 0, 29, 31, 0,
+	0, 22, 23, 0, 0, 24, 25, 26, 0, 0,
+	0, 0, 0, 33, 35, 27, 28, 30, 32, 34,
+	36, 0, 0, 21, 0, 0, 29, 31, 0, 0,
+	22, 23, 0, 0, 24, 25, 26, 0, 0, 0,
+	0, 0, 33, 35, 27, 28, 30, 32, 0, 36,
+	0, 0, 0, 0, 0, 29, 31, 0, 0, 22,
+	23, 0, 0, 24, 25, 26, 27, 28, 30, 32,
+	0, 33, 35, 0, 0, 0, 0, 29, 31, 0,
+	0, 22, 23, 0, 0, 24, 25, 26, 30, 32,
+	10, 11, 15, 33, 35, 0, 0, 29, 31, 0,
+	0, 22, 23, 0, 0, 24, 25, 26, 0, 12,
+	10, 11, 15, 33, 35, 0, 13, 14, 16, 24,
+	25, 26, 6, 7, 0, 0, 0, 33, 35, 12,
+	0, 0, 0, 0, 0, 0, 13, 14, 16,
+}
+var yyPact = [...]int{
+
+	-35, -1000, 216, -35, -35, -1000, -1000, -1000, -1000, 89,
+	-1000, -1000, 216, 216, 216, -1000, 216, -1000, 196, -1000,
+	216, 216, 216, 216, 216, 216, 216, 216, 216, 216,
+	216, 216, 216, 216, 216, 216, 216, -31, -31, -31,
+	60, -1000, 118, 31, 203, 203, -31, -31, -31, 189,
+	189, -16, -16, -16, -16, 118, 147, 118, 169, -1000,
+	216, 118,
+}
+var yyPgo = [...]int{
+
+	0, 45, 8, 44, 0, 16, 5, 55,
+}
+var yyR1 = [...]int{
+
+	0, 1, 1, 2, 2, 3, 3, 4, 4, 4,
+	4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+	4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+	5, 5, 6, 6, 7, 7,
+}
+var yyR2 = [...]int{
+
+	0, 1, 2, 2, 3, 3, 1, 1, 1, 2,
+	2, 2, 1, 5, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	0, 1, 1, 2, 1, 1,
+}
+var yyChk = [...]int{
+
+	-1000, -1, -5, -2, -6, -7, 36, 37, -3, -4,
+	4, 5, 23, 30, 31, 6, 32, -5, -6, -7,
+	14, 15, 22, 23, 26, 27, 28, 7, 8, 18,
+	9, 19, 10, 34, 11, 35, 12, -4, -4, -4,
+	-4, -3, -4, -4, -4, -4, -4, -4, -4, -4,
+	-4, -4, -4, -4, -4, -4, -4, -4, -4, 33,
+	16, -4,
+}
+var yyDef = [...]int{
+
+	30, -2, 1, 30, 31, 32, 34, 35, 3, 6,
+	7, 8, 0, 0, 0, 12, 0, 2, 31, 33,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 9, 10, 11,
+	0, 4, 5, 0, 15, 16, 17, 18, 19, -2,
+	-2, 22, 23, 24, 25, 26, 27, 28, 29, 14,
+	0, 13,
+}
+var yyTok1 = [...]int{
+
+	1, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	37, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 30, 3, 3, 3, 28, 35, 3,
+	32, 33, 26, 22, 17, 23, 3, 27, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 16, 36,
+	19, 14, 18, 15, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 31, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 34,
+}
+var yyTok2 = [...]int{
+
+	2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
+	12, 13, 20, 21, 24, 25, 29,
+}
+var yyTok3 = [...]int{
+	0,
+}
+
+var yyErrorMessages = [...]struct {
+	state int
+	token int
+	msg   string
+}{}
+
+//line yaccpar:1
+
+/*	parser for yacc output	*/
+
+var (
+	yyDebug        = 0
+	yyErrorVerbose = false
+)
+
+type yyLexer interface {
+	Lex(lval *yySymType) int
+	Error(s string)
+}
+
+type yyParser interface {
+	Parse(yyLexer) int
+	Lookahead() int
+}
+
+type yyParserImpl struct {
+	lval  yySymType
+	stack [yyInitialStackSize]yySymType
+	char  int
+}
+
+func (p *yyParserImpl) Lookahead() int {
+	return p.char
+}
+
+func yyNewParser() yyParser {
+	return &yyParserImpl{}
+}
+
+const yyFlag = -1000
+
+func yyTokname(c int) string {
+	if c >= 1 && c-1 < len(yyToknames) {
+		if yyToknames[c-1] != "" {
+			return yyToknames[c-1]
+		}
+	}
+	return __yyfmt__.Sprintf("tok-%v", c)
+}
+
+func yyStatname(s int) string {
+	if s >= 0 && s < len(yyStatenames) {
+		if yyStatenames[s] != "" {
+			return yyStatenames[s]
+		}
+	}
+	return __yyfmt__.Sprintf("state-%v", s)
+}
+
+func yyErrorMessage(state, lookAhead int) string {
+	const TOKSTART = 4
+
+	if !yyErrorVerbose {
+		return "syntax error"
+	}
+
+	for _, e := range yyErrorMessages {
+		if e.state == state && e.token == lookAhead {
+			return "syntax error: " + e.msg
+		}
+	}
+
+	res := "syntax error: unexpected " + yyTokname(lookAhead)
+
+	// To match Bison, suggest at most four expected tokens.
+	expected := make([]int, 0, 4)
+
+	// Look for shiftable tokens.
+	base := yyPact[state]
+	for tok := TOKSTART; tok-1 < len(yyToknames); tok++ {
+		if n := base + tok; n >= 0 && n < yyLast && yyChk[yyAct[n]] == tok {
+			if len(expected) == cap(expected) {
+				return res
+			}
+			expected = append(expected, tok)
+		}
+	}
+
+	if yyDef[state] == -2 {
+		i := 0
+		for yyExca[i] != -1 || yyExca[i+1] != state {
+			i += 2
+		}
+
+		// Look for tokens that we accept or reduce.
+		for i += 2; yyExca[i] >= 0; i += 2 {
+			tok := yyExca[i]
+			if tok < TOKSTART || yyExca[i+1] == 0 {
+				continue
+			}
+			if len(expected) == cap(expected) {
+				return res
+			}
+			expected = append(expected, tok)
+		}
+
+		// If the default action is to accept or reduce, give up.
+		if yyExca[i+1] != 0 {
+			return res
+		}
+	}
+
+	for i, tok := range expected {
+		if i == 0 {
+			res += ", expecting "
+		} else {
+			res += " or "
+		}
+		res += yyTokname(tok)
+	}
+	return res
+}
+
+func yylex1(lex yyLexer, lval *yySymType) (char, token int) {
+	token = 0
+	char = lex.Lex(lval)
+	if char <= 0 {
+		token = yyTok1[0]
+		goto out
+	}
+	if char < len(yyTok1) {
+		token = yyTok1[char]
+		goto out
+	}
+	if char >= yyPrivate {
+		if char < yyPrivate+len(yyTok2) {
+			token = yyTok2[char-yyPrivate]
+			goto out
+		}
+	}
+	for i := 0; i < len(yyTok3); i += 2 {
+		token = yyTok3[i+0]
+		if token == char {
+			token = yyTok3[i+1]
+			goto out
+		}
+	}
+
+out:
+	if token == 0 {
+		token = yyTok2[1] /* unknown char */
+	}
+	if yyDebug >= 3 {
+		__yyfmt__.Printf("lex %s(%d)\n", yyTokname(token), uint(char))
+	}
+	return char, token
+}
+
+func yyParse(yylex yyLexer) int {
+	return yyNewParser().Parse(yylex)
+}
+
+func (yyrcvr *yyParserImpl) Parse(yylex yyLexer) int {
+	var yyn int
+	var yyVAL yySymType
+	var yyDollar []yySymType
+	_ = yyDollar // silence set and not used
+	yyS := yyrcvr.stack[:]
+
+	Nerrs := 0   /* number of errors */
+	Errflag := 0 /* error recovery flag */
+	yystate := 0
+	yyrcvr.char = -1
+	yytoken := -1 // yyrcvr.char translated into internal numbering
+	defer func() {
+		// Make sure we report no lookahead when not parsing.
+		yystate = -1
+		yyrcvr.char = -1
+		yytoken = -1
+	}()
+	yyp := -1
+	goto yystack
+
+ret0:
+	return 0
+
+ret1:
+	return 1
+
+yystack:
+	/* put a state and value onto the stack */
+	if yyDebug >= 4 {
+		__yyfmt__.Printf("char %v in %v\n", yyTokname(yytoken), yyStatname(yystate))
+	}
+
+	yyp++
+	if yyp >= len(yyS) {
+		nyys := make([]yySymType, len(yyS)*2)
+		copy(nyys, yyS)
+		yyS = nyys
+	}
+	yyS[yyp] = yyVAL
+	yyS[yyp].yys = yystate
+
+yynewstate:
+	yyn = yyPact[yystate]
+	if yyn <= yyFlag {
+		goto yydefault /* simple state */
+	}
+	if yyrcvr.char < 0 {
+		yyrcvr.char, yytoken = yylex1(yylex, &yyrcvr.lval)
+	}
+	yyn += yytoken
+	if yyn < 0 || yyn >= yyLast {
+		goto yydefault
+	}
+	yyn = yyAct[yyn]
+	if yyChk[yyn] == yytoken { /* valid shift */
+		yyrcvr.char = -1
+		yytoken = -1
+		yyVAL = yyrcvr.lval
+		yystate = yyn
+		if Errflag > 0 {
+			Errflag--
+		}
+		goto yystack
+	}
+
+yydefault:
+	/* default state action */
+	yyn = yyDef[yystate]
+	if yyn == -2 {
+		if yyrcvr.char < 0 {
+			yyrcvr.char, yytoken = yylex1(yylex, &yyrcvr.lval)
+		}
+
+		/* look through exception table */
+		xi := 0
+		for {
+			if yyExca[xi+0] == -1 && yyExca[xi+1] == yystate {
+				break
+			}
+			xi += 2
+		}
+		for xi += 2; ; xi += 2 {
+			yyn = yyExca[xi+0]
+			if yyn < 0 || yyn == yytoken {
+				break
+			}
+		}
+		yyn = yyExca[xi+1]
+		if yyn < 0 {
+			goto ret0
+		}
+	}
+	if yyn == 0 {
+		/* error ... attempt to resume parsing */
+		switch Errflag {
+		case 0: /* brand new error */
+			yylex.Error(yyErrorMessage(yystate, yytoken))
+			Nerrs++
+			if yyDebug >= 1 {
+				__yyfmt__.Printf("%s", yyStatname(yystate))
+				__yyfmt__.Printf(" saw %s\n", yyTokname(yytoken))
+			}
+			fallthrough
+
+		case 1, 2: /* incompletely recovered error ... try again */
+			Errflag = 3
+
+			/* find a state where "error" is a legal shift action */
+			for yyp >= 0 {
+				yyn = yyPact[yyS[yyp].yys] + yyErrCode
+				if yyn >= 0 && yyn < yyLast {
+					yystate = yyAct[yyn] /* simulate a shift of "error" */
+					if yyChk[yystate] == yyErrCode {
+						goto yystack
+					}
+				}
+
+				/* the current p has no shift on "error", pop stack */
+				if yyDebug >= 2 {
+					__yyfmt__.Printf("error recovery pops state %d\n", yyS[yyp].yys)
+				}
+				yyp--
+			}
+			/* there is no state on the stack with an error shift ... abort */
+			goto ret1
+
+		case 3: /* no shift yet; clobber input char */
+			if yyDebug >= 2 {
+				__yyfmt__.Printf("error recovery discards %s\n", yyTokname(yytoken))
+			}
+			if yytoken == yyEofCode {
+				goto ret1
+			}
+			yyrcvr.char = -1
+			yytoken = -1
+			goto yynewstate /* try again in the same state */
+		}
+	}
+
+	/* reduction by production yyn */
+	if yyDebug >= 2 {
+		__yyfmt__.Printf("reduce %v in:\n\t%v\n", yyn, yyStatname(yystate))
+	}
+
+	yynt := yyn
+	yypt := yyp
+	_ = yypt // guard against "declared and not used"
+
+	yyp -= yyR2[yyn]
+	// yyp is now the index of $0. Perform the default action. Iff the
+	// reduced production is ε, $1 is possibly out of range.
+	if yyp+1 >= len(yyS) {
+		nyys := make([]yySymType, len(yyS)*2)
+		copy(nyys, yyS)
+		yyS = nyys
+	}
+	yyVAL = yyS[yyp+1]
+
+	/* consult goto table to find next state */
+	yyn = yyR1[yyn]
+	yyg := yyPgo[yyn]
+	yyj := yyg + yyS[yyp].yys + 1
+
+	if yyj >= yyLast {
+		yystate = yyAct[yyg]
+	} else {
+		yystate = yyAct[yyj]
+		if yyChk[yystate] != -yyn {
+			yystate = yyAct[yyg]
+		}
+	}
+	// dummy call; replaced with literal code
+	switch yynt {
+
+	case 1:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:43
+		{
+			yyVAL.compstmt = nil
+		}
+	case 2:
+		yyDollar = yyS[yypt-2 : yypt+1]
+		//line parser.go.y:47
+		{
+			yyVAL.compstmt = yyDollar[1].stmts
+		}
+	case 3:
+		yyDollar = yyS[yypt-2 : yypt+1]
+		//line parser.go.y:53
+		{
+			yyVAL.stmts = []ast.Stmt{yyDollar[2].stmt}
+			if l, ok := yylex.(*Lexer); ok {
+				l.stmts = yyVAL.stmts
+			}
+		}
+	case 4:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:60
+		{
+			if yyDollar[3].stmt != nil {
+				yyVAL.stmts = append(yyDollar[1].stmts, yyDollar[3].stmt)
+				if l, ok := yylex.(*Lexer); ok {
+					l.stmts = yyVAL.stmts
+				}
+			}
+		}
+	case 5:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:71
+		{
+			yyVAL.stmt = &ast.LetStmt{Lhs: yyDollar[1].expr, Operator: "=", Rhs: yyDollar[3].expr}
+		}
+	case 6:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:75
+		{
+			yyVAL.stmt = &ast.ExprStmt{Expr: yyDollar[1].expr}
+		}
+	case 7:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:81
+		{
+			yyVAL.expr = &ast.IdentExpr{Lit: yyDollar[1].tok.Lit}
+		}
+	case 8:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:85
+		{
+			yyVAL.expr = &ast.NumberExpr{Lit: yyDollar[1].tok.Lit}
+		}
+	case 9:
+		yyDollar = yyS[yypt-2 : yypt+1]
+		//line parser.go.y:89
+		{
+			yyVAL.expr = &ast.UnaryExpr{Operator: "-", Expr: yyDollar[2].expr}
+		}
+	case 10:
+		yyDollar = yyS[yypt-2 : yypt+1]
+		//line parser.go.y:93
+		{
+			yyVAL.expr = &ast.UnaryExpr{Operator: "!", Expr: yyDollar[2].expr}
+		}
+	case 11:
+		yyDollar = yyS[yypt-2 : yypt+1]
+		//line parser.go.y:97
+		{
+			yyVAL.expr = &ast.UnaryExpr{Operator: "^", Expr: yyDollar[2].expr}
+		}
+	case 12:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:101
+		{
+			yyVAL.expr = &ast.StringExpr{Lit: yyDollar[1].tok.Lit}
+		}
+	case 13:
+		yyDollar = yyS[yypt-5 : yypt+1]
+		//line parser.go.y:105
+		{
+			yyVAL.expr = &ast.TernaryOpExpr{Expr: yyDollar[1].expr, Lhs: yyDollar[3].expr, Rhs: yyDollar[5].expr}
+		}
+	case 14:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:109
+		{
+			yyVAL.expr = &ast.ParenExpr{SubExpr: yyDollar[2].expr}
+		}
+	case 15:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:113
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "+", Rhs: yyDollar[3].expr}
+		}
+	case 16:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:117
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "-", Rhs: yyDollar[3].expr}
+		}
+	case 17:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:121
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "*", Rhs: yyDollar[3].expr}
+		}
+	case 18:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:125
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "/", Rhs: yyDollar[3].expr}
+		}
+	case 19:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:129
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "%", Rhs: yyDollar[3].expr}
+		}
+	case 20:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:133
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "==", Rhs: yyDollar[3].expr}
+		}
+	case 21:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:137
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "!=", Rhs: yyDollar[3].expr}
+		}
+	case 22:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:141
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: ">", Rhs: yyDollar[3].expr}
+		}
+	case 23:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:145
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: ">=", Rhs: yyDollar[3].expr}
+		}
+	case 24:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:149
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "<", Rhs: yyDollar[3].expr}
+		}
+	case 25:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:153
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "<=", Rhs: yyDollar[3].expr}
+		}
+	case 26:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:157
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "|", Rhs: yyDollar[3].expr}
+		}
+	case 27:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:161
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "||", Rhs: yyDollar[3].expr}
+		}
+	case 28:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:165
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "&", Rhs: yyDollar[3].expr}
+		}
+	case 29:
+		yyDollar = yyS[yypt-3 : yypt+1]
+		//line parser.go.y:169
+		{
+			yyVAL.expr = &ast.BinOpExpr{Lhs: yyDollar[1].expr, Operator: "&&", Rhs: yyDollar[3].expr}
+		}
+	case 32:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:179
+		{
+		}
+	case 33:
+		yyDollar = yyS[yypt-2 : yypt+1]
+		//line parser.go.y:182
+		{
+		}
+	case 34:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:187
+		{
+		}
+	case 35:
+		yyDollar = yyS[yypt-1 : yypt+1]
+		//line parser.go.y:190
+		{
+		}
+	}
+	goto yystack /* stack new state and value */
+}

vendor/github.com/mattn/kinako/parser/parser.go.y

@@ -0,0 +1,195 @@
+%{
+package parser
+
+import (
+	"github.com/mattn/kinako/ast"
+)
+
+%}
+
+%type<compstmt> compstmt
+%type<stmts> stmts
+%type<stmt> stmt
+%type<expr> expr
+
+%union{
+	compstmt               []ast.Stmt
+	stmts                  []ast.Stmt
+	stmt                   ast.Stmt
+	expr                   ast.Expr
+	tok                    ast.Token
+	term                   ast.Token
+	terms                  ast.Token
+	opt_terms              ast.Token
+}
+
+%token<tok> IDENT NUMBER STRING EQEQ NEQ GE LE OROR ANDAND POW
+
+%right '='
+%right '?' ':'
+%left OROR
+%left ANDAND
+%left IDENT
+%nonassoc EQEQ NEQ ','
+%left '>' GE '<' LE SHIFTLEFT SHIFTRIGHT
+
+%left '+' '-' PLUSPLUS MINUSMINUS
+%left '*' '/' '%'
+%right UNARY
+
+%%
+
+compstmt : opt_terms
+	{
+		$$ = nil
+	}
+	| stmts opt_terms
+	{
+		$$ = $1
+	}
+
+stmts :
+	opt_terms stmt
+	{
+		$$ = []ast.Stmt{$2}
+		if l, ok := yylex.(*Lexer); ok {
+			l.stmts = $$
+		}
+	}
+	| stmts terms stmt
+	{
+		if $3 != nil {
+			$$ = append($1, $3)
+			if l, ok := yylex.(*Lexer); ok {
+				l.stmts = $$
+			}
+		}
+	}
+
+stmt :
+	expr '=' expr
+	{
+		$$ = &ast.LetStmt{Lhs: $1, Operator: "=", Rhs: $3}
+	}
+	| expr
+	{
+		$$ = &ast.ExprStmt{Expr: $1}
+	}
+
+expr :
+	IDENT
+	{
+		$$ = &ast.IdentExpr{Lit: $1.Lit}
+	}
+	| NUMBER
+	{
+		$$ = &ast.NumberExpr{Lit: $1.Lit}
+	}
+	| '-' expr %prec UNARY
+	{
+		$$ = &ast.UnaryExpr{Operator: "-", Expr: $2}
+	}
+	| '!' expr %prec UNARY
+	{
+		$$ = &ast.UnaryExpr{Operator: "!", Expr: $2}
+	}
+	| '^' expr %prec UNARY
+	{
+		$$ = &ast.UnaryExpr{Operator: "^", Expr: $2}
+	}
+	| STRING
+	{
+		$$ = &ast.StringExpr{Lit: $1.Lit}
+	}
+	| expr '?' expr ':' expr
+	{
+		$$ = &ast.TernaryOpExpr{Expr: $1, Lhs: $3, Rhs: $5}
+	}
+	| '(' expr ')'
+	{
+		$$ = &ast.ParenExpr{SubExpr: $2}
+	}
+	| expr '+' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "+", Rhs: $3}
+	}
+	| expr '-' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "-", Rhs: $3}
+	}
+	| expr '*' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "*", Rhs: $3}
+	}
+	| expr '/' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "/", Rhs: $3}
+	}
+	| expr '%' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "%", Rhs: $3}
+	}
+	| expr EQEQ expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "==", Rhs: $3}
+	}
+	| expr NEQ expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "!=", Rhs: $3}
+	}
+	| expr '>' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: ">", Rhs: $3}
+	}
+	| expr GE expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: ">=", Rhs: $3}
+	}
+	| expr '<' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "<", Rhs: $3}
+	}
+	| expr LE expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "<=", Rhs: $3}
+	}
+	| expr '|' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "|", Rhs: $3}
+	}
+	| expr OROR expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "||", Rhs: $3}
+	}
+	| expr '&' expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "&", Rhs: $3}
+	}
+	| expr ANDAND expr
+	{
+		$$ = &ast.BinOpExpr{Lhs: $1, Operator: "&&", Rhs: $3}
+	}
+
+opt_terms : /* none */
+	| terms
+	;
+
+
+terms : term
+	{
+	}
+	| terms term
+	{
+	}
+	;
+
+term : ';'
+	{
+	}
+	| '\n'
+	{
+	}
+	;
+
+%%
+

vendor/github.com/mattn/kinako/vm/env.go

@@ -0,0 +1,258 @@
+package vm
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+	"sync"
+
+	"github.com/mattn/kinako/parser"
+)
+
+// Env provides interface to run VM. This mean function scope and blocked-scope.
+// If stack goes to blocked-scope, it will make new Env.
+type Env struct {
+	name      string
+	env       map[string]reflect.Value
+	typ       map[string]reflect.Type
+	parent    *Env
+	interrupt *bool
+	sync.RWMutex
+}
+
+// NewEnv creates new global scope.
+func NewEnv() *Env {
+	b := false
+
+	return &Env{
+		env:       make(map[string]reflect.Value),
+		typ:       make(map[string]reflect.Type),
+		parent:    nil,
+		interrupt: &b,
+	}
+}
+
+// NewEnv creates new child scope.
+func (e *Env) NewEnv() *Env {
+	return &Env{
+		env:       make(map[string]reflect.Value),
+		typ:       make(map[string]reflect.Type),
+		parent:    e,
+		name:      e.name,
+		interrupt: e.interrupt,
+	}
+}
+
+func NewPackage(n string) *Env {
+	b := false
+
+	return &Env{
+		env:       make(map[string]reflect.Value),
+		typ:       make(map[string]reflect.Type),
+		parent:    nil,
+		name:      n,
+		interrupt: &b,
+	}
+}
+
+func (e *Env) NewPackage(n string) *Env {
+	return &Env{
+		env:       make(map[string]reflect.Value),
+		typ:       make(map[string]reflect.Type),
+		parent:    e,
+		name:      n,
+		interrupt: e.interrupt,
+	}
+}
+
+// Destroy deletes current scope.
+func (e *Env) Destroy() {
+	e.Lock()
+	defer e.Unlock()
+
+	if e.parent == nil {
+		return
+	}
+	for k, v := range e.parent.env {
+		if v.IsValid() && v.Interface() == e {
+			delete(e.parent.env, k)
+		}
+	}
+	e.parent = nil
+	e.env = nil
+}
+
+// NewModule creates new module scope as global.
+func (e *Env) NewModule(n string) *Env {
+	m := &Env{
+		env:    make(map[string]reflect.Value),
+		parent: e,
+		name:   n,
+	}
+	e.Define(n, m)
+	return m
+}
+
+// SetName sets a name of the scope. This means that the scope is module.
+func (e *Env) SetName(n string) {
+	e.Lock()
+	e.name = n
+	e.Unlock()
+}
+
+// GetName returns module name.
+func (e *Env) GetName() string {
+	e.RLock()
+	defer e.RUnlock()
+
+	return e.name
+}
+
+// Addr returns pointer value which specified symbol. It goes to upper scope until
+// found or returns error.
+func (e *Env) Addr(k string) (reflect.Value, error) {
+	e.RLock()
+	defer e.RUnlock()
+
+	if v, ok := e.env[k]; ok {
+		return v.Addr(), nil
+	}
+	if e.parent == nil {
+		return NilValue, fmt.Errorf("Undefined symbol '%s'", k)
+	}
+	return e.parent.Addr(k)
+}
+
+// Type returns type which specified symbol. It goes to upper scope until
+// found or returns error.
+func (e *Env) Type(k string) (reflect.Type, error) {
+	e.RLock()
+	defer e.RUnlock()
+
+	if v, ok := e.typ[k]; ok {
+		return v, nil
+	}
+	if e.parent == nil {
+		return NilType, fmt.Errorf("Undefined type '%s'", k)
+	}
+	return e.parent.Type(k)
+}
+
+// Get returns value which specified symbol. It goes to upper scope until
+// found or returns error.
+func (e *Env) Get(k string) (reflect.Value, error) {
+	e.RLock()
+	defer e.RUnlock()
+
+	if v, ok := e.env[k]; ok {
+		return v, nil
+	}
+	if e.parent == nil {
+		return NilValue, fmt.Errorf("Undefined symbol '%s'", k)
+	}
+	return e.parent.Get(k)
+}
+
+// Set modifies value which specified as symbol. It goes to upper scope until
+// found or returns error.
+func (e *Env) Set(k string, v interface{}) error {
+	e.Lock()
+	defer e.Unlock()
+
+	if _, ok := e.env[k]; ok {
+		val, ok := v.(reflect.Value)
+		if !ok {
+			val = reflect.ValueOf(v)
+		}
+		e.env[k] = val
+		return nil
+	}
+	if e.parent == nil {
+		return fmt.Errorf("Unknown symbol '%s'", k)
+	}
+	return e.parent.Set(k, v)
+}
+
+// DefineGlobal defines symbol in global scope.
+func (e *Env) DefineGlobal(k string, v interface{}) error {
+	if e.parent == nil {
+		return e.Define(k, v)
+	}
+	return e.parent.DefineGlobal(k, v)
+}
+
+// DefineType defines type which specifis symbol in global scope.
+func (e *Env) DefineType(k string, t interface{}) error {
+	if strings.Contains(k, ".") {
+		return fmt.Errorf("Unknown symbol '%s'", k)
+	}
+	global := e
+	keys := []string{k}
+
+	e.RLock()
+	for global.parent != nil {
+		if global.name != "" {
+			keys = append(keys, global.name)
+		}
+		global = global.parent
+	}
+	e.RUnlock()
+
+	for i, j := 0, len(keys)-1; i < j; i, j = i+1, j-1 {
+		keys[i], keys[j] = keys[j], keys[i]
+	}
+
+	typ, ok := t.(reflect.Type)
+	if !ok {
+		typ = reflect.TypeOf(t)
+	}
+
+	global.Lock()
+	global.typ[strings.Join(keys, ".")] = typ
+	global.Unlock()
+
+	return nil
+}
+
+// Define defines symbol in current scope.
+func (e *Env) Define(k string, v interface{}) error {
+	if strings.Contains(k, ".") {
+		return fmt.Errorf("Unknown symbol '%s'", k)
+	}
+	val, ok := v.(reflect.Value)
+	if !ok {
+		val = reflect.ValueOf(v)
+	}
+
+	e.Lock()
+	e.env[k] = val
+	e.Unlock()
+
+	return nil
+}
+
+// String return the name of current scope.
+func (e *Env) String() string {
+	e.RLock()
+	defer e.RUnlock()
+
+	return e.name
+}
+
+// Dump show symbol values in the scope.
+func (e *Env) Dump() {
+	e.RLock()
+	for k, v := range e.env {
+		fmt.Printf("%v = %#v\n", k, v)
+	}
+	e.RUnlock()
+}
+
+// Execute parses and runs source in current scope.
+func (e *Env) Execute(src string) (reflect.Value, error) {
+	stmts, err := parser.ParseSrc(src)
+	if err != nil {
+		return NilValue, err
+	}
+	return Run(stmts, e)
+}

vendor/github.com/mattn/kinako/vm/vm.go

@@ -0,0 +1,409 @@
+package vm
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"github.com/mattn/kinako/ast"
+)
+
+var (
+	NilValue   = reflect.ValueOf((*interface{})(nil))
+	NilType    = reflect.TypeOf((*interface{})(nil))
+	TrueValue  = reflect.ValueOf(true)
+	FalseValue = reflect.ValueOf(false)
+)
+
+// Error provides a convenient interface for handling runtime error.
+// It can be Error interface with type cast which can call Pos().
+type Error struct {
+	Message string
+}
+
+var (
+	BreakError     = errors.New("Unexpected break statement")
+	ContinueError  = errors.New("Unexpected continue statement")
+	ReturnError    = errors.New("Unexpected return statement")
+	InterruptError = errors.New("Execution interrupted")
+)
+
+// Error returns the error message.
+func (e *Error) Error() string {
+	return e.Message
+}
+
+// Func is function interface to reflect functions internaly.
+type Func func(args ...reflect.Value) (reflect.Value, error)
+
+func (f Func) String() string {
+	return fmt.Sprintf("[Func: %p]", f)
+}
+
+func ToFunc(f Func) reflect.Value {
+	return reflect.ValueOf(f)
+}
+
+// Run executes statements in the specified environment.
+func Run(stmts []ast.Stmt, env *Env) (reflect.Value, error) {
+	rv := NilValue
+	var err error
+	for _, stmt := range stmts {
+		rv, err = RunSingleStmt(stmt, env)
+		if err != nil {
+			return rv, err
+		}
+	}
+	return rv, nil
+}
+
+// Interrupts the execution of any running statements in the specified environment.
+//
+// Note that the execution is not instantly aborted: after a call to Interrupt,
+// the current running statement will finish, but the next statement will not run,
+// and instead will return a NilValue and an InterruptError.
+func Interrupt(env *Env) {
+	env.Lock()
+	*(env.interrupt) = true
+	env.Unlock()
+}
+
+// RunSingleStmt executes one statement in the specified environment.
+func RunSingleStmt(stmt ast.Stmt, env *Env) (reflect.Value, error) {
+	env.Lock()
+	if *(env.interrupt) {
+		*(env.interrupt) = false
+		env.Unlock()
+
+		return NilValue, InterruptError
+	}
+	env.Unlock()
+
+	switch stmt := stmt.(type) {
+	case *ast.ExprStmt:
+		rv, err := invokeExpr(stmt.Expr, env)
+		if err != nil {
+			return rv, err
+		}
+		return rv, nil
+	case *ast.LetStmt:
+		rv := NilValue
+		var err error
+		rv, err = invokeExpr(stmt.Rhs, env)
+		if err != nil {
+			return rv, err
+		}
+		_, err = invokeLetExpr(stmt.Lhs, rv, env)
+		if err != nil {
+			return rv, err
+		}
+		return rv, nil
+	default:
+		return NilValue, errors.New("unknown statement")
+	}
+}
+
+// toString converts all reflect.Value-s into string.
+func toString(v reflect.Value) string {
+	if v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+	if v.Kind() == reflect.String {
+		return v.String()
+	}
+	if !v.IsValid() {
+		return "nil"
+	}
+	return fmt.Sprint(v.Interface())
+}
+
+// toBool converts all reflect.Value-s into bool.
+func toBool(v reflect.Value) bool {
+	if v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+
+	switch v.Kind() {
+	case reflect.Float32, reflect.Float64:
+		return v.Float() != 0.0
+	case reflect.Int, reflect.Int32, reflect.Int64:
+		return v.Int() != 0
+	case reflect.Bool:
+		return v.Bool()
+	case reflect.String:
+		if v.String() == "true" {
+			return true
+		}
+		if toInt64(v) != 0 {
+			return true
+		}
+	}
+	return false
+}
+
+// toFloat64 converts all reflect.Value-s into float64.
+func toFloat64(v reflect.Value) float64 {
+	if v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+	switch v.Kind() {
+	case reflect.Float32, reflect.Float64:
+		return v.Float()
+	case reflect.Int, reflect.Int32, reflect.Int64:
+		return float64(v.Int())
+	}
+	return 0.0
+}
+
+func isNil(v reflect.Value) bool {
+	if !v.IsValid() || v.Kind().String() == "unsafe.Pointer" {
+		return true
+	}
+	if (v.Kind() == reflect.Interface || v.Kind() == reflect.Ptr) && v.IsNil() {
+		return true
+	}
+	return false
+}
+
+func isNum(v reflect.Value) bool {
+	switch v.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.Float32, reflect.Float64:
+		return true
+	}
+	return false
+}
+
+// equal returns true when lhsV and rhsV is same value.
+func equal(lhsV, rhsV reflect.Value) bool {
+	lhsIsNil, rhsIsNil := isNil(lhsV), isNil(rhsV)
+	if lhsIsNil && rhsIsNil {
+		return true
+	}
+	if (!lhsIsNil && rhsIsNil) || (lhsIsNil && !rhsIsNil) {
+		return false
+	}
+	if lhsV.Kind() == reflect.Interface || lhsV.Kind() == reflect.Ptr {
+		lhsV = lhsV.Elem()
+	}
+	if rhsV.Kind() == reflect.Interface || rhsV.Kind() == reflect.Ptr {
+		rhsV = rhsV.Elem()
+	}
+	if !lhsV.IsValid() || !rhsV.IsValid() {
+		return true
+	}
+	if isNum(lhsV) && isNum(rhsV) {
+		if rhsV.Type().ConvertibleTo(lhsV.Type()) {
+			rhsV = rhsV.Convert(lhsV.Type())
+		}
+	}
+	if lhsV.CanInterface() && rhsV.CanInterface() {
+		return reflect.DeepEqual(lhsV.Interface(), rhsV.Interface())
+	}
+	return reflect.DeepEqual(lhsV, rhsV)
+}
+
+// toInt64 converts all reflect.Value-s into int64.
+func toInt64(v reflect.Value) int64 {
+	if v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+	switch v.Kind() {
+	case reflect.Float32, reflect.Float64:
+		return int64(v.Float())
+	case reflect.Int, reflect.Int32, reflect.Int64:
+		return v.Int()
+	case reflect.String:
+		s := v.String()
+		var i int64
+		var err error
+		if strings.HasPrefix(s, "0x") {
+			i, err = strconv.ParseInt(s, 16, 64)
+		} else {
+			i, err = strconv.ParseInt(s, 10, 64)
+		}
+		if err == nil {
+			return int64(i)
+		}
+	}
+	return 0
+}
+
+func invokeLetExpr(expr ast.Expr, rv reflect.Value, env *Env) (reflect.Value, error) {
+	switch lhs := expr.(type) {
+	case *ast.IdentExpr:
+		if env.Set(lhs.Lit, rv) != nil {
+			if strings.Contains(lhs.Lit, ".") {
+				return NilValue, fmt.Errorf("Undefined symbol '%s'", lhs.Lit)
+			}
+			env.Define(lhs.Lit, rv)
+		}
+		return rv, nil
+	}
+	return NilValue, errors.New("Invalid operation")
+}
+
+// invokeExpr evaluates one expression.
+func invokeExpr(expr ast.Expr, env *Env) (reflect.Value, error) {
+	switch e := expr.(type) {
+	case *ast.NumberExpr:
+		if strings.Contains(e.Lit, ".") || strings.Contains(e.Lit, "e") {
+			v, err := strconv.ParseFloat(e.Lit, 64)
+			if err != nil {
+				return NilValue, err
+			}
+			return reflect.ValueOf(float64(v)), nil
+		}
+		var i int64
+		var err error
+		if strings.HasPrefix(e.Lit, "0x") {
+			i, err = strconv.ParseInt(e.Lit[2:], 16, 64)
+		} else {
+			i, err = strconv.ParseInt(e.Lit, 10, 64)
+		}
+		if err != nil {
+			return NilValue, err
+		}
+		return reflect.ValueOf(i), nil
+	case *ast.IdentExpr:
+		return env.Get(e.Lit)
+	case *ast.StringExpr:
+		return reflect.ValueOf(e.Lit), nil
+	case *ast.UnaryExpr:
+		v, err := invokeExpr(e.Expr, env)
+		if err != nil {
+			return v, err
+		}
+		switch e.Operator {
+		case "-":
+			if v.Kind() == reflect.Float64 {
+				return reflect.ValueOf(-v.Float()), nil
+			}
+			return reflect.ValueOf(-v.Int()), nil
+		case "^":
+			return reflect.ValueOf(^toInt64(v)), nil
+		case "!":
+			return reflect.ValueOf(!toBool(v)), nil
+		default:
+			return NilValue, errors.New("Unknown operator ''")
+		}
+	case *ast.ParenExpr:
+		v, err := invokeExpr(e.SubExpr, env)
+		if err != nil {
+			return v, err
+		}
+		return v, nil
+	case *ast.BinOpExpr:
+		lhsV := NilValue
+		rhsV := NilValue
+		var err error
+
+		lhsV, err = invokeExpr(e.Lhs, env)
+		if err != nil {
+			return lhsV, err
+		}
+		if lhsV.Kind() == reflect.Interface {
+			lhsV = lhsV.Elem()
+		}
+		if e.Rhs != nil {
+			rhsV, err = invokeExpr(e.Rhs, env)
+			if err != nil {
+				return rhsV, err
+			}
+			if rhsV.Kind() == reflect.Interface {
+				rhsV = rhsV.Elem()
+			}
+		}
+		switch e.Operator {
+		case "+":
+			if lhsV.Kind() == reflect.String || rhsV.Kind() == reflect.String {
+				return reflect.ValueOf(toString(lhsV) + toString(rhsV)), nil
+			}
+			if (lhsV.Kind() == reflect.Array || lhsV.Kind() == reflect.Slice) && (rhsV.Kind() != reflect.Array && rhsV.Kind() != reflect.Slice) {
+				return reflect.Append(lhsV, rhsV), nil
+			}
+			if (lhsV.Kind() == reflect.Array || lhsV.Kind() == reflect.Slice) && (rhsV.Kind() == reflect.Array || rhsV.Kind() == reflect.Slice) {
+				return reflect.AppendSlice(lhsV, rhsV), nil
+			}
+			if lhsV.Kind() == reflect.Float64 || rhsV.Kind() == reflect.Float64 {
+				return reflect.ValueOf(toFloat64(lhsV) + toFloat64(rhsV)), nil
+			}
+			return reflect.ValueOf(toInt64(lhsV) + toInt64(rhsV)), nil
+		case "-":
+			if lhsV.Kind() == reflect.Float64 || rhsV.Kind() == reflect.Float64 {
+				return reflect.ValueOf(toFloat64(lhsV) - toFloat64(rhsV)), nil
+			}
+			return reflect.ValueOf(toInt64(lhsV) - toInt64(rhsV)), nil
+		case "*":
+			if lhsV.Kind() == reflect.String && (rhsV.Kind() == reflect.Int || rhsV.Kind() == reflect.Int32 || rhsV.Kind() == reflect.Int64) {
+				return reflect.ValueOf(strings.Repeat(toString(lhsV), int(toInt64(rhsV)))), nil
+			}
+			if lhsV.Kind() == reflect.Float64 || rhsV.Kind() == reflect.Float64 {
+				return reflect.ValueOf(toFloat64(lhsV) * toFloat64(rhsV)), nil
+			}
+			return reflect.ValueOf(toInt64(lhsV) * toInt64(rhsV)), nil
+		case "/":
+			return reflect.ValueOf(toFloat64(lhsV) / toFloat64(rhsV)), nil
+		case "%":
+			return reflect.ValueOf(toInt64(lhsV) % toInt64(rhsV)), nil
+		case "==":
+			return reflect.ValueOf(equal(lhsV, rhsV)), nil
+		case "!=":
+			return reflect.ValueOf(equal(lhsV, rhsV) == false), nil
+		case ">":
+			return reflect.ValueOf(toFloat64(lhsV) > toFloat64(rhsV)), nil
+		case ">=":
+			return reflect.ValueOf(toFloat64(lhsV) >= toFloat64(rhsV)), nil
+		case "<":
+			return reflect.ValueOf(toFloat64(lhsV) < toFloat64(rhsV)), nil
+		case "<=":
+			return reflect.ValueOf(toFloat64(lhsV) <= toFloat64(rhsV)), nil
+		case "|":
+			return reflect.ValueOf(toInt64(lhsV) | toInt64(rhsV)), nil
+		case "||":
+			if toBool(lhsV) {
+				return lhsV, nil
+			}
+			return rhsV, nil
+		case "&":
+			return reflect.ValueOf(toInt64(lhsV) & toInt64(rhsV)), nil
+		case "&&":
+			if toBool(lhsV) {
+				return rhsV, nil
+			}
+			return lhsV, nil
+		case "**":
+			if lhsV.Kind() == reflect.Float64 {
+				return reflect.ValueOf(math.Pow(toFloat64(lhsV), toFloat64(rhsV))), nil
+			}
+			return reflect.ValueOf(int64(math.Pow(toFloat64(lhsV), toFloat64(rhsV)))), nil
+		case ">>":
+			return reflect.ValueOf(toInt64(lhsV) >> uint64(toInt64(rhsV))), nil
+		case "<<":
+			return reflect.ValueOf(toInt64(lhsV) << uint64(toInt64(rhsV))), nil
+		default:
+			return NilValue, errors.New("Unknown operator")
+		}
+	case *ast.TernaryOpExpr:
+		rv, err := invokeExpr(e.Expr, env)
+		if err != nil {
+			return rv, err
+		}
+		if toBool(rv) {
+			lhsV, err := invokeExpr(e.Lhs, env)
+			if err != nil {
+				return lhsV, err
+			}
+			return lhsV, nil
+		}
+		rhsV, err := invokeExpr(e.Rhs, env)
+		if err != nil {
+			return rhsV, err
+		}
+		return rhsV, nil
+	default:
+		return NilValue, errors.New("Unknown expression")
+	}
+}