1 files changed, 63 insertions, 0 deletions
diff --git a/src/pkg/exp/template/funcs.go b/src/pkg/exp/template/funcs.go
new file mode 100644
index 0000000000..88f82f3b2c
--- /dev/null
+++ b/src/pkg/exp/template/funcs.go
@@ -0,0 +1,63 @@
+// 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 (
+	"fmt"
+	"reflect"
+)
+
+// 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.
+type FuncMap map[string]interface{}
+
+var funcs = map[string]reflect.Value{
+	"printf": reflect.ValueOf(fmt.Sprintf),
+}
+
+// addFuncs adds to values the functions in funcs, converting them to reflect.Values.
+func addFuncs(values map[string]reflect.Value, funcMap FuncMap) {
+	for name, fn := range funcMap {
+		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))
+		}
+		values[name] = v
+	}
+}
+
+// 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.funcs[name]; fn.IsValid() {
+			return fn, true
+		}
+	}
+	if set != nil {
+		if fn := set.funcs[name]; fn.IsValid() {
+			return fn, true
+		}
+	}
+	if fn := funcs[name]; fn.IsValid() {
+		return fn, true
+	}
+	return reflect.Value{}, false
+}