src/pkg/template/funcs.go - go - Git at Google

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package template

 import (
 	"bytes"
 	"fmt"
 	"io"
 	"os"
 	"reflect"
 	"strings"
 	"unicode"
 	"url"
 	"utf8"
 )

 // FuncMap is the type of the map defining the mapping from names to functions.
 // Each function must have either a single return value, or two return values of
 // which the second has type os.Error. If the second argument evaluates to non-nil
 // during execution, execution terminates and Execute returns an error.
 type FuncMap map[string]interface{}

 var builtins = FuncMap{
 	"and":      and,
 	"html":     HTMLEscaper,
 	"index":    index,
 	"js":       JSEscaper,
 	"len":      length,
 	"not":      not,
 	"or":       or,
 	"print":    fmt.Sprint,
 	"printf":   fmt.Sprintf,
 	"println":  fmt.Sprintln,
 	"urlquery": URLQueryEscaper,
 }

 var builtinFuncs = createValueFuncs(builtins)

 // createValueFuncs turns a FuncMap into a map[string]reflect.Value
 func createValueFuncs(funcMap FuncMap) map[string]reflect.Value {
 	m := make(map[string]reflect.Value)
 	addValueFuncs(m, funcMap)
 	return m
 }

 // addValueFuncs adds to values the functions in funcs, converting them to reflect.Values.
 func addValueFuncs(out map[string]reflect.Value, in FuncMap) {
 	for name, fn := range in {
 		v := reflect.ValueOf(fn)
 		if v.Kind() != reflect.Func {
 			panic("value for " + name + " not a function")
 		}
 		if !goodFunc(v.Type()) {
 			panic(fmt.Errorf("can't handle multiple results from method/function %q", name))
 		}
 		out[name] = v
 	}
 }

 // addFuncs adds to values the functions in funcs. It does no checking of the input -
 // call addValueFuncs first.
 func addFuncs(out, in FuncMap) {
 	for name, fn := range in {
 		out[name] = fn
 	}
 }

 // goodFunc checks that the function or method has the right result signature.
 func goodFunc(typ reflect.Type) bool {
 	// We allow functions with 1 result or 2 results where the second is an os.Error.
 	switch {
 	case typ.NumOut() == 1:
 		return true
 	case typ.NumOut() == 2 && typ.Out(1) == osErrorType:
 		return true
 	}
 	return false
 }

 // findFunction looks for a function in the template, set, and global map.
 func findFunction(name string, tmpl *Template, set *Set) (reflect.Value, bool) {
 	if tmpl != nil {
 		if fn := tmpl.execFuncs[name]; fn.IsValid() {
 			return fn, true
 		}
 	}
 	if set != nil {
 		if fn := set.execFuncs[name]; fn.IsValid() {
 			return fn, true
 		}
 	}
 	if fn := builtinFuncs[name]; fn.IsValid() {
 		return fn, true
 	}
 	return reflect.Value{}, false
 }

 // Indexing.

 // index returns the result of indexing its first argument by the following
 // arguments.  Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
 // indexed item must be a map, slice, or array.
 func index(item interface{}, indices ...interface{}) (interface{}, os.Error) {
 	v := reflect.ValueOf(item)
 	for _, i := range indices {
 		index := reflect.ValueOf(i)
 		var isNil bool
 		if v, isNil = indirect(v); isNil {
 			return nil, fmt.Errorf("index of nil pointer")
 		}
 		switch v.Kind() {
 		case reflect.Array, reflect.Slice:
 			var x int64
 			switch index.Kind() {
 			case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 				x = index.Int()
 			case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 				x = int64(index.Uint())
 			default:
 				return nil, fmt.Errorf("cannot index slice/array with type %s", index.Type())
 			}
 			if x < 0 || x >= int64(v.Len()) {
 				return nil, fmt.Errorf("index out of range: %d", x)
 			}
 			v = v.Index(int(x))
 		case reflect.Map:
 			if !index.Type().AssignableTo(v.Type().Key()) {
 				return nil, fmt.Errorf("%s is not index type for %s", index.Type(), v.Type())
 			}
 			if x := v.MapIndex(index); x.IsValid() {
 				v = x
 			} else {
 				v = reflect.Zero(v.Type().Key())
 			}
 		default:
 			return nil, fmt.Errorf("can't index item of type %s", index.Type())
 		}
 	}
 	return v.Interface(), nil
 }

 // Length

 // length returns the length of the item, with an error if it has no defined length.
 func length(item interface{}) (int, os.Error) {
 	v, isNil := indirect(reflect.ValueOf(item))
 	if isNil {
 		return 0, fmt.Errorf("len of nil pointer")
 	}
 	switch v.Kind() {
 	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
 		return v.Len(), nil
 	}
 	return 0, fmt.Errorf("len of type %s", v.Type())
 }

 // Boolean logic.

 func truth(a interface{}) bool {
 	t, _ := isTrue(reflect.ValueOf(a))
 	return t
 }

 // and computes the Boolean AND of its arguments, returning
 // the first false argument it encounters, or the last argument.
 func and(arg0 interface{}, args ...interface{}) interface{} {
 	if !truth(arg0) {
 		return arg0
 	}
 	for i := range args {
 		arg0 = args[i]
 		if !truth(arg0) {
 			break
 		}
 	}
 	return arg0
 }

 // or computes the Boolean OR of its arguments, returning
 // the first true argument it encounters, or the last argument.
 func or(arg0 interface{}, args ...interface{}) interface{} {
 	if truth(arg0) {
 		return arg0
 	}
 	for i := range args {
 		arg0 = args[i]
 		if truth(arg0) {
 			break
 		}
 	}
 	return arg0
 }

 // not returns the Boolean negation of its argument.
 func not(arg interface{}) (truth bool) {
 	truth, _ = isTrue(reflect.ValueOf(arg))
 	return !truth
 }

 // HTML escaping.

 var (
 	htmlQuot = []byte("&#34;") // shorter than "&quot;"
 	htmlApos = []byte("&#39;") // shorter than "&apos;"
 	htmlAmp  = []byte("&amp;")
 	htmlLt   = []byte("&lt;")
 	htmlGt   = []byte("&gt;")
 )

 // HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.
 func HTMLEscape(w io.Writer, b []byte) {
 	last := 0
 	for i, c := range b {
 		var html []byte
 		switch c {
 		case '"':
 			html = htmlQuot
 		case '\'':
 			html = htmlApos
 		case '&':
 			html = htmlAmp
 		case '<':
 			html = htmlLt
 		case '>':
 			html = htmlGt
 		default:
 			continue
 		}
 		w.Write(b[last:i])
 		w.Write(html)
 		last = i + 1
 	}
 	w.Write(b[last:])
 }

 // HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.
 func HTMLEscapeString(s string) string {
 	// Avoid allocation if we can.
 	if strings.IndexAny(s, `'"&<>`) < 0 {
 		return s
 	}
 	var b bytes.Buffer
 	HTMLEscape(&b, []byte(s))
 	return b.String()
 }

 // HTMLEscaper returns the escaped HTML equivalent of the textual
 // representation of its arguments.
 func HTMLEscaper(args ...interface{}) string {
 	ok := false
 	var s string
 	if len(args) == 1 {
 		s, ok = args[0].(string)
 	}
 	if !ok {
 		s = fmt.Sprint(args...)
 	}
 	return HTMLEscapeString(s)
 }

 // JavaScript escaping.

 var (
 	jsLowUni = []byte(`\u00`)
 	hex      = []byte("0123456789ABCDEF")

 	jsBackslash = []byte(`\\`)
 	jsApos      = []byte(`\'`)
 	jsQuot      = []byte(`\"`)
 	jsLt        = []byte(`\x3C`)
 	jsGt        = []byte(`\x3E`)
 )

 // JSEscape writes to w the escaped JavaScript equivalent of the plain text data b.
 func JSEscape(w io.Writer, b []byte) {
 	last := 0
 	for i := 0; i < len(b); i++ {
 		c := b[i]

 		if !jsIsSpecial(int(c)) {
 			// fast path: nothing to do
 			continue
 		}
 		w.Write(b[last:i])

 		if c < utf8.RuneSelf {
 			// Quotes, slashes and angle brackets get quoted.
 			// Control characters get written as \u00XX.
 			switch c {
 			case '\\':
 				w.Write(jsBackslash)
 			case '\'':
 				w.Write(jsApos)
 			case '"':
 				w.Write(jsQuot)
 			case '<':
 				w.Write(jsLt)
 			case '>':
 				w.Write(jsGt)
 			default:
 				w.Write(jsLowUni)
 				t, b := c>>4, c&0x0f
 				w.Write(hex[t : t+1])
 				w.Write(hex[b : b+1])
 			}
 		} else {
 			// Unicode rune.
 			rune, size := utf8.DecodeRune(b[i:])
 			if unicode.IsPrint(rune) {
 				w.Write(b[i : i+size])
 			} else {
 				// TODO(dsymonds): Do this without fmt?
 				fmt.Fprintf(w, "\\u%04X", rune)
 			}
 			i += size - 1
 		}
 		last = i + 1
 	}
 	w.Write(b[last:])
 }

 // JSEscapeString returns the escaped JavaScript equivalent of the plain text data s.
 func JSEscapeString(s string) string {
 	// Avoid allocation if we can.
 	if strings.IndexFunc(s, jsIsSpecial) < 0 {
 		return s
 	}
 	var b bytes.Buffer
 	JSEscape(&b, []byte(s))
 	return b.String()
 }

 func jsIsSpecial(rune int) bool {
 	switch rune {
 	case '\\', '\'', '"', '<', '>':
 		return true
 	}
 	return rune < ' ' || utf8.RuneSelf <= rune
 }

 // JSEscaper returns the escaped JavaScript equivalent of the textual
 // representation of its arguments.
 func JSEscaper(args ...interface{}) string {
 	ok := false
 	var s string
 	if len(args) == 1 {
 		s, ok = args[0].(string)
 	}
 	if !ok {
 		s = fmt.Sprint(args...)
 	}
 	return JSEscapeString(s)
 }

 // URLQueryEscaper returns the escaped value of the textual representation of
 // its arguments in a form suitable for embedding in a URL query.
 func URLQueryEscaper(args ...interface{}) string {
 	s, ok := "", false
 	if len(args) == 1 {
 		s, ok = args[0].(string)
 	}
 	if !ok {
 		s = fmt.Sprint(args...)
 	}
 	return url.QueryEscape(s)
 }
	// Copyright 2011 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package template

	import (
	"bytes"
	"fmt"
	"io"
	"os"
	"reflect"
	"strings"
	"unicode"
	"url"
	"utf8"
	)

	// FuncMap is the type of the map defining the mapping from names to functions.
	// Each function must have either a single return value, or two return values of
	// which the second has type os.Error. If the second argument evaluates to non-nil
	// during execution, execution terminates and Execute returns an error.
	type FuncMap map[string]interface{}

	var builtins = FuncMap{
	"and": and,
	"html": HTMLEscaper,
	"index": index,
	"js": JSEscaper,
	"len": length,
	"not": not,
	"or": or,
	"print": fmt.Sprint,
	"printf": fmt.Sprintf,
	"println": fmt.Sprintln,
	"urlquery": URLQueryEscaper,
	}

	var builtinFuncs = createValueFuncs(builtins)

	// createValueFuncs turns a FuncMap into a map[string]reflect.Value
	func createValueFuncs(funcMap FuncMap) map[string]reflect.Value {
	m := make(map[string]reflect.Value)
	addValueFuncs(m, funcMap)
	return m
	}

	// addValueFuncs adds to values the functions in funcs, converting them to reflect.Values.
	func addValueFuncs(out map[string]reflect.Value, in FuncMap) {
	for name, fn := range in {
	v := reflect.ValueOf(fn)
	if v.Kind() != reflect.Func {
	panic("value for " + name + " not a function")
	}
	if !goodFunc(v.Type()) {
	panic(fmt.Errorf("can't handle multiple results from method/function %q", name))
	}
	out[name] = v
	}
	}

	// addFuncs adds to values the functions in funcs. It does no checking of the input -
	// call addValueFuncs first.
	func addFuncs(out, in FuncMap) {
	for name, fn := range in {
	out[name] = fn
	}
	}

	// goodFunc checks that the function or method has the right result signature.
	func goodFunc(typ reflect.Type) bool {
	// We allow functions with 1 result or 2 results where the second is an os.Error.
	switch {
	case typ.NumOut() == 1:
	return true
	case typ.NumOut() == 2 && typ.Out(1) == osErrorType:
	return true
	}
	return false
	}

	// findFunction looks for a function in the template, set, and global map.
	func findFunction(name string, tmpl Template, set Set) (reflect.Value, bool) {
	if tmpl != nil {
	if fn := tmpl.execFuncs[name]; fn.IsValid() {
	return fn, true
	}
	}
	if set != nil {
	if fn := set.execFuncs[name]; fn.IsValid() {
	return fn, true
	}
	}
	if fn := builtinFuncs[name]; fn.IsValid() {
	return fn, true
	}
	return reflect.Value{}, false
	}

	// Indexing.

	// index returns the result of indexing its first argument by the following
	// arguments. Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
	// indexed item must be a map, slice, or array.
	func index(item interface{}, indices ...interface{}) (interface{}, os.Error) {
	v := reflect.ValueOf(item)
	for _, i := range indices {
	index := reflect.ValueOf(i)
	var isNil bool
	if v, isNil = indirect(v); isNil {
	return nil, fmt.Errorf("index of nil pointer")
	}
	switch v.Kind() {
	case reflect.Array, reflect.Slice:
	var x int64
	switch index.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	x = index.Int()
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
	x = int64(index.Uint())
	default:
	return nil, fmt.Errorf("cannot index slice/array with type %s", index.Type())
	}
	if x < 0 \|\| x >= int64(v.Len()) {
	return nil, fmt.Errorf("index out of range: %d", x)
	}
	v = v.Index(int(x))
	case reflect.Map:
	if !index.Type().AssignableTo(v.Type().Key()) {
	return nil, fmt.Errorf("%s is not index type for %s", index.Type(), v.Type())
	}
	if x := v.MapIndex(index); x.IsValid() {
	v = x
	} else {
	v = reflect.Zero(v.Type().Key())
	}
	default:
	return nil, fmt.Errorf("can't index item of type %s", index.Type())
	}
	}
	return v.Interface(), nil
	}

	// Length

	// length returns the length of the item, with an error if it has no defined length.
	func length(item interface{}) (int, os.Error) {
	v, isNil := indirect(reflect.ValueOf(item))
	if isNil {
	return 0, fmt.Errorf("len of nil pointer")
	}
	switch v.Kind() {
	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
	return v.Len(), nil
	}
	return 0, fmt.Errorf("len of type %s", v.Type())
	}

	// Boolean logic.

	func truth(a interface{}) bool {
	t, _ := isTrue(reflect.ValueOf(a))
	return t
	}

	// and computes the Boolean AND of its arguments, returning
	// the first false argument it encounters, or the last argument.
	func and(arg0 interface{}, args ...interface{}) interface{} {
	if !truth(arg0) {
	return arg0
	}
	for i := range args {
	arg0 = args[i]
	if !truth(arg0) {
	break
	}
	}
	return arg0
	}

	// or computes the Boolean OR of its arguments, returning
	// the first true argument it encounters, or the last argument.
	func or(arg0 interface{}, args ...interface{}) interface{} {
	if truth(arg0) {
	return arg0
	}
	for i := range args {
	arg0 = args[i]
	if truth(arg0) {
	break
	}
	}
	return arg0
	}

	// not returns the Boolean negation of its argument.
	func not(arg interface{}) (truth bool) {
	truth, _ = isTrue(reflect.ValueOf(arg))
	return !truth
	}

	// HTML escaping.

	var (
	htmlQuot = []byte(""") // shorter than """
	htmlApos = []byte("'") // shorter than "'"
	htmlAmp = []byte("&")
	htmlLt = []byte("<")
	htmlGt = []byte(">")
	)

	// HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.
	func HTMLEscape(w io.Writer, b []byte) {
	last := 0
	for i, c := range b {
	var html []byte
	switch c {
	case '"':
	html = htmlQuot
	case '\'':
	html = htmlApos
	case '&':
	html = htmlAmp
	case '<':
	html = htmlLt
	case '>':
	html = htmlGt
	default:
	continue
	}
	w.Write(b[last:i])
	w.Write(html)
	last = i + 1
	}
	w.Write(b[last:])
	}

	// HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.
	func HTMLEscapeString(s string) string {
	// Avoid allocation if we can.
	if strings.IndexAny(s, `'"&<>`) < 0 {
	return s
	}
	var b bytes.Buffer
	HTMLEscape(&b, []byte(s))
	return b.String()
	}

	// HTMLEscaper returns the escaped HTML equivalent of the textual
	// representation of its arguments.
	func HTMLEscaper(args ...interface{}) string {
	ok := false
	var s string
	if len(args) == 1 {
	s, ok = args[0].(string)
	}
	if !ok {
	s = fmt.Sprint(args...)
	}
	return HTMLEscapeString(s)
	}

	// JavaScript escaping.

	var (
	jsLowUni = []byte(`\u00`)
	hex = []byte("0123456789ABCDEF")

	jsBackslash = []byte(`\\`)
	jsApos = []byte(`\'`)
	jsQuot = []byte(`\"`)
	jsLt = []byte(`\x3C`)
	jsGt = []byte(`\x3E`)
	)

	// JSEscape writes to w the escaped JavaScript equivalent of the plain text data b.
	func JSEscape(w io.Writer, b []byte) {
	last := 0
	for i := 0; i < len(b); i++ {
	c := b[i]

	if !jsIsSpecial(int(c)) {
	// fast path: nothing to do
	continue
	}
	w.Write(b[last:i])

	if c < utf8.RuneSelf {
	// Quotes, slashes and angle brackets get quoted.
	// Control characters get written as \u00XX.
	switch c {
	case '\\':
	w.Write(jsBackslash)
	case '\'':
	w.Write(jsApos)
	case '"':
	w.Write(jsQuot)
	case '<':
	w.Write(jsLt)
	case '>':
	w.Write(jsGt)
	default:
	w.Write(jsLowUni)
	t, b := c>>4, c&0x0f
	w.Write(hex[t : t+1])
	w.Write(hex[b : b+1])
	}
	} else {
	// Unicode rune.
	rune, size := utf8.DecodeRune(b[i:])
	if unicode.IsPrint(rune) {
	w.Write(b[i : i+size])
	} else {
	// TODO(dsymonds): Do this without fmt?
	fmt.Fprintf(w, "\\u%04X", rune)
	}
	i += size - 1
	}
	last = i + 1
	}
	w.Write(b[last:])
	}

	// JSEscapeString returns the escaped JavaScript equivalent of the plain text data s.
	func JSEscapeString(s string) string {
	// Avoid allocation if we can.
	if strings.IndexFunc(s, jsIsSpecial) < 0 {
	return s
	}
	var b bytes.Buffer
	JSEscape(&b, []byte(s))
	return b.String()
	}

	func jsIsSpecial(rune int) bool {
	switch rune {
	case '\\', '\'', '"', '<', '>':
	return true
	}
	return rune < ' ' \|\| utf8.RuneSelf <= rune
	}

	// JSEscaper returns the escaped JavaScript equivalent of the textual
	// representation of its arguments.
	func JSEscaper(args ...interface{}) string {
	ok := false
	var s string
	if len(args) == 1 {
	s, ok = args[0].(string)
	}
	if !ok {
	s = fmt.Sprint(args...)
	}
	return JSEscapeString(s)
	}

	// URLQueryEscaper returns the escaped value of the textual representation of
	// its arguments in a form suitable for embedding in a URL query.
	func URLQueryEscaper(args ...interface{}) string {
	s, ok := "", false
	if len(args) == 1 {
	s, ok = args[0].(string)
	}
	if !ok {
	s = fmt.Sprint(args...)
	}
	return url.QueryEscape(s)
	}