implement .repeats for maps.

Fixes #309.

R=rsc
CC=golang-dev
https://golang.org/cl/181044

src/pkg/template/template.go

@@ -833,41 +833,35 @@ func (t *Template) executeRepeated(r *repeatedElement, st *state) {
 	}
 	first := true
 
-	if array, ok := field.(reflect.ArrayOrSliceValue); ok {
-		for j := 0; j < array.Len(); j++ {
-			newst := st.clone(array.Elem(j))
-
-			// .alternates between elements
-			if !first && r.altstart >= 0 {
-				for i := r.altstart; i < r.altend; {
-					i = t.executeElement(i, newst)
-				}
-			}
-			first = false
-
-			for i := start; i < end; {
+	// Code common to all the loops.
+	loopBody := func(newst *state) {
+		// .alternates between elements
+		if !first && r.altstart >= 0 {
+			for i := r.altstart; i < r.altend; {
 				i = t.executeElement(i, newst)
 			}
 		}
+		first = false
+		for i := start; i < end; {
+			i = t.executeElement(i, newst)
+		}
+	}
+
+	if array, ok := field.(reflect.ArrayOrSliceValue); ok {
+		for j := 0; j < array.Len(); j++ {
+			loopBody(st.clone(array.Elem(j)))
+		}
+	} else if m, ok := field.(*reflect.MapValue); ok {
+		for _, key := range m.Keys() {
+			loopBody(st.clone(m.Elem(key)))
+		}
 	} else if ch := iter(field); ch != nil {
 		for {
 			e := ch.Recv()
 			if ch.Closed() {
 				break
 			}
-			newst := st.clone(e)
-
-			// .alternates between elements
-			if !first && r.altstart >= 0 {
-				for i := r.altstart; i < r.altend; {
-					i = t.executeElement(i, newst)
-				}
-			}
-			first = false
-
-			for i := start; i < end; {
-				i = t.executeElement(i, newst)
-			}
+			loopBody(st.clone(e))
 		}
 	} else {
 		t.execError(st, r.linenum, ".repeated: cannot repeat %s (type %s)",

src/pkg/template/template_test.go

@@ -42,6 +42,7 @@ type S struct {
 	false         bool
 	mp            map[string]string
 	innermap      U
+	stringmap     map[string]string
 	bytes         []byte
 }
 
@@ -314,12 +315,24 @@ var tests = []*Test{
 
 		out: "Ahoy!\n",
 	},
-
 	&Test{
 		in: "{innermap.mp.innerkey}\n",
 
 		out: "55\n",
 	},
+	&Test{
+		in: "{stringmap.stringkey1}\n",
+
+		out: "stringresult\n",
+	},
+	&Test{
+		in: "{.repeated section stringmap}\n" +
+			"{@}\n" +
+			"{.end}",
+
+		out: "stringresult\n" +
+			"stringresult\n",
+	},
 }
 
 func TestAll(t *testing.T) {
@@ -342,6 +355,9 @@ func TestAll(t *testing.T) {
 	s.mp["mapkey"] = "Ahoy!"
 	s.innermap.mp = make(map[string]int)
 	s.innermap.mp["innerkey"] = 55
+	s.stringmap = make(map[string]string)
+	s.stringmap["stringkey1"] = "stringresult" // the same value so repeated section is order-independent
+	s.stringmap["stringkey2"] = "stringresult"
 	s.bytes = strings.Bytes("hello")
 
 	var buf bytes.Buffer