add go1.2 template funcs eq, ge, gt, le, lt, ne to beego

@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"reflect"
 	"regexp"
 	"strings"
 )
@@ -33,13 +34,19 @@ func init() {
 	beegoTplFuncMap["htmlquote"] = Htmlquote
 	beegoTplFuncMap["htmlunquote"] = Htmlunquote
 	beegoTplFuncMap["renderform"] = RenderForm
+
+	// go1.2 added template funcs
+	// Comparisons
+	beegoTplFuncMap["eq"] = eq // ==
+	beegoTplFuncMap["ge"] = ge // >=
+	beegoTplFuncMap["gt"] = gt // >
+	beegoTplFuncMap["le"] = le // <=
+	beegoTplFuncMap["lt"] = lt // <
+	beegoTplFuncMap["ne"] = ne // !=
 }
 
 // AddFuncMap let user to register a func in the template
 func AddFuncMap(key string, funname interface{}) error {
-	if _, ok := beegoTplFuncMap[key]; ok {
-		return errors.New("funcmap already has the key")
-	}
 	beegoTplFuncMap[key] = funname
 	return nil
 }
@@ -219,3 +226,156 @@ func _getTemplate(t0 *template.Template, root string, submods [][]string, others
 	}
 	return
 }
+
+// go1.2 added template funcs. begin
+var (
+	errBadComparisonType = errors.New("invalid type for comparison")
+	errBadComparison     = errors.New("incompatible types for comparison")
+	errNoComparison      = errors.New("missing argument for comparison")
+)
+
+type kind int
+
+const (
+	invalidKind kind = iota
+	boolKind
+	complexKind
+	intKind
+	floatKind
+	integerKind
+	stringKind
+	uintKind
+)
+
+func basicKind(v reflect.Value) (kind, error) {
+	switch v.Kind() {
+	case reflect.Bool:
+		return boolKind, nil
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return intKind, nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return uintKind, nil
+	case reflect.Float32, reflect.Float64:
+		return floatKind, nil
+	case reflect.Complex64, reflect.Complex128:
+		return complexKind, nil
+	case reflect.String:
+		return stringKind, nil
+	}
+	return invalidKind, errBadComparisonType
+}
+
+// eq evaluates the comparison a == b || a == c || ...
+func eq(arg1 interface{}, arg2 ...interface{}) (bool, error) {
+	v1 := reflect.ValueOf(arg1)
+	k1, err := basicKind(v1)
+	if err != nil {
+		return false, err
+	}
+	if len(arg2) == 0 {
+		return false, errNoComparison
+	}
+	for _, arg := range arg2 {
+		v2 := reflect.ValueOf(arg)
+		k2, err := basicKind(v2)
+		if err != nil {
+			return false, err
+		}
+		if k1 != k2 {
+			return false, errBadComparison
+		}
+		truth := false
+		switch k1 {
+		case boolKind:
+			truth = v1.Bool() == v2.Bool()
+		case complexKind:
+			truth = v1.Complex() == v2.Complex()
+		case floatKind:
+			truth = v1.Float() == v2.Float()
+		case intKind:
+			truth = v1.Int() == v2.Int()
+		case stringKind:
+			truth = v1.String() == v2.String()
+		case uintKind:
+			truth = v1.Uint() == v2.Uint()
+		default:
+			panic("invalid kind")
+		}
+		if truth {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+// ne evaluates the comparison a != b.
+func ne(arg1, arg2 interface{}) (bool, error) {
+	// != is the inverse of ==.
+	equal, err := eq(arg1, arg2)
+	return !equal, err
+}
+
+// lt evaluates the comparison a < b.
+func lt(arg1, arg2 interface{}) (bool, error) {
+	v1 := reflect.ValueOf(arg1)
+	k1, err := basicKind(v1)
+	if err != nil {
+		return false, err
+	}
+	v2 := reflect.ValueOf(arg2)
+	k2, err := basicKind(v2)
+	if err != nil {
+		return false, err
+	}
+	if k1 != k2 {
+		return false, errBadComparison
+	}
+	truth := false
+	switch k1 {
+	case boolKind, complexKind:
+		return false, errBadComparisonType
+	case floatKind:
+		truth = v1.Float() < v2.Float()
+	case intKind:
+		truth = v1.Int() < v2.Int()
+	case stringKind:
+		truth = v1.String() < v2.String()
+	case uintKind:
+		truth = v1.Uint() < v2.Uint()
+	default:
+		panic("invalid kind")
+	}
+	return truth, nil
+}
+
+// le evaluates the comparison <= b.
+func le(arg1, arg2 interface{}) (bool, error) {
+	// <= is < or ==.
+	lessThan, err := lt(arg1, arg2)
+	if lessThan || err != nil {
+		return lessThan, err
+	}
+	return eq(arg1, arg2)
+}
+
+// gt evaluates the comparison a > b.
+func gt(arg1, arg2 interface{}) (bool, error) {
+	// > is the inverse of <=.
+	lessOrEqual, err := le(arg1, arg2)
+	if err != nil {
+		return false, err
+	}
+	return !lessOrEqual, nil
+}
+
+// ge evaluates the comparison a >= b.
+func ge(arg1, arg2 interface{}) (bool, error) {
+	// >= is the inverse of <.
+	lessThan, err := lt(arg1, arg2)
+	if err != nil {
+		return false, err
+	}
+	return !lessThan, nil
+}
+
+// go1.2 added template funcs. end