go/src/pkg/template/format.go

// Copyright 2009 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.

// Template library: default formatters

package template

import (
	"bytes";
	"fmt";
	"io";
	"strings";
)

// 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
// under the name "" in your custom formatter map.
func StringFormatter(w io.Writer, value interface{}, format string) {
	fmt.Fprint(w, value);
}

var (
	esc_quot	= strings.Bytes(""");	// shorter than """
	esc_apos	= strings.Bytes("'");	// shorter than "'"
	esc_amp		= strings.Bytes("&");
	esc_lt		= strings.Bytes("<");
	esc_gt		= strings.Bytes(">");
)

// HTMLEscape writes to w the properly escaped HTML equivalent
// of the plain text data s.
func HTMLEscape(w io.Writer, s []byte) {
	var esc []byte;
	last := 0;
	for i, c := range s {
		switch c {
		case '"':
			esc = esc_quot;
		case '\'':
			esc = esc_apos;
		case '&':
			esc = esc_amp;
		case '<':
			esc = esc_lt;
		case '>':
			esc = esc_gt;
		default:
			continue;
		}
		w.Write(s[last:i]);
		w.Write(esc);
		last = i+1;
	}
	w.Write(s[last:len(s)]);
}

// HTMLFormatter formats arbitrary values for HTML
func HTMLFormatter(w io.Writer, value interface{}, format string) {
	var b bytes.Buffer;
	fmt.Fprint(&b, value);
	HTMLEscape(w, b.Bytes());
}