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Source file 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"
)

// 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) {
    if b, ok := value.([]byte); ok {
        w.Write(b)
        return
    }
    fmt.Fprint(w, value)
}

var (
    esc_quot = []byte(""") // shorter than """
    esc_apos = []byte("'") // shorter than "'"
    esc_amp  = []byte("&")
    esc_lt   = []byte("<")
    esc_gt   = []byte(">")
)

// 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:])
}

// 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())
}