better html support.

turn on error reporting; not enough info otherwise.

R=r
DELTA=49  (43 added, 6 deleted, 0 changed)
OCL=27476
CL=27478

src/lib/template/format.go

@@ -12,12 +12,6 @@ import (
 	"reflect";
 )
 
-// HtmlFormatter formats arbitrary values for HTML
-// TODO: do something for real.
-func HtmlFormatter(w io.Write, value interface{}, format string) {
-	fmt.Fprint(w, value);
-}
-
 // StringFormatter formats into the default string representation.
 // It is stored under the name "str" and is the default formatter.
 // You can override the default formatter by storing your default
@@ -25,3 +19,36 @@ func HtmlFormatter(w io.Write, value interface{}, format string) {
 func StringFormatter(w io.Write, value interface{}, format string) {
 	fmt.Fprint(w, value);
 }
+
+
+var esc_amp = io.StringBytes("&")
+var esc_lt = io.StringBytes("<")
+var esc_gt = io.StringBytes(">")
+
+// HtmlEscape writes to w the properly escaped HTML equivalent
+// of the plain text data s.
+func HtmlEscape(w io.Write, s []byte) {
+	last := 0;
+	for i, c := range s {
+		if c == '&' || c == '<' || c == '>' {
+			w.Write(s[last:i]);
+			switch c {
+			case '&':
+				w.Write(esc_amp);
+			case '<':
+				w.Write(esc_lt);
+			case '>':
+				w.Write(esc_gt);
+			}
+			last = i+1;
+		}
+	}
+	w.Write(s[last:len(s)]);
+}
+
+// HtmlFormatter formats arbitrary values for HTML
+func HtmlFormatter(w io.Write, value interface{}, format string) {
+	var b io.ByteBuffer;
+	fmt.Fprint(&b, value);
+	HtmlEscape(w, b.Data());
+}

src/lib/template/template.go

@@ -67,6 +67,7 @@ type state struct {
 
 // Report error and stop generation.
 func (st *state) error(err *os.Error, args ...) {
+	fmt.Fprintf(os.Stderr, "template: %v%s\n", err, fmt.Sprint(args));
 	st.errorchan <- err;
 	sys.Goexit();
 }

src/lib/template/template_test.go

@@ -25,6 +25,7 @@ type T struct {
 type S struct {
 	header string;
 	integer int;
+	raw string;
 	data []T;
 	pdata []*T;
 	empty []*T;
@@ -161,7 +162,14 @@ var tests = []*Test {
 		"HEADER=78\n"
 		"Header=77\n"
 	},
-
+	
+	&Test{
+		"{raw}\n"
+		"{raw|html}\n",
+		
+		"&<>!@ #$%^\n"
+		"&amp;&lt;&gt;!@ #$%^\n"
+	},
 }
 
 func TestAll(t *testing.T) {
@@ -169,6 +177,7 @@ func TestAll(t *testing.T) {
 	// initialized by hand for clarity.
 	s.header = "Header";
 	s.integer = 77;
+	s.raw = "&<>!@ #$%^";
 	s.data = []T{ t1, t2 };
 	s.pdata = []*T{ &t1, &t2 };
 	s.empty = []*T{ };