libgo/go/template/format.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Template library: default formatters
   6
   7 package template
   8
   9 import (
  10         "bytes"
  11         "fmt"
  12         "io"
  13 )
  14
  15 // StringFormatter formats into the default string representation.
  16 // It is stored under the name "str" and is the default formatter.
  17 // You can override the default formatter by storing your default
  18 // under the name "" in your custom formatter map.
  19 func StringFormatter(w io.Writer, value interface{}, format string) {
  20         if b, ok := value.([]byte); ok {
  21                 w.Write(b)
  22                 return
  23         }
  24         fmt.Fprint(w, value)
  25 }
  26
  27 var (
  28         esc_quot = []byte("&#34;") // shorter than "&quot;"
  29         esc_apos = []byte("&#39;") // shorter than "&apos;"
  30         esc_amp  = []byte("&amp;")
  31         esc_lt   = []byte("&lt;")
  32         esc_gt   = []byte("&gt;")
  33 )
  34
  35 // HTMLEscape writes to w the properly escaped HTML equivalent
  36 // of the plain text data s.
  37 func HTMLEscape(w io.Writer, s []byte) {
  38         var esc []byte
  39         last := 0
  40         for i, c := range s {
  41                 switch c {
  42                 case '"':
  43                         esc = esc_quot
  44                 case '\'':
  45                         esc = esc_apos
  46                 case '&':
  47                         esc = esc_amp
  48                 case '<':
  49                         esc = esc_lt
  50                 case '>':
  51                         esc = esc_gt
  52                 default:
  53                         continue
  54                 }
  55                 w.Write(s[last:i])
  56                 w.Write(esc)
  57                 last = i + 1
  58         }
  59         w.Write(s[last:])
  60 }
  61
  62 // HTMLFormatter formats arbitrary values for HTML
  63 func HTMLFormatter(w io.Writer, value interface{}, format string) {
  64         b, ok := value.([]byte)
  65         if !ok {
  66                 var buf bytes.Buffer
  67                 fmt.Fprint(&buf, value)
  68                 b = buf.Bytes()
  69         }
  70         HTMLEscape(w, b)
  71 }