code review 27110043: go.net/html/charset: new package

html/charset/encoding.go

+// Package charset provides common text encodings for HTML documents.
+//
+// The mapping from encoding labels to encodings is defined
+// at http://encoding.spec.whatwg.org.
+package charset
+
+import (
+        "errors"
+        "strings"
+
+        "code.google.com/p/go.text/encoding"
+        "code.google.com/p/go.text/transform"
+)
+
+// Encoding returns the encoding with the specified label, or nil if label is
+// not one of the standard encodings for HTML. Matching is case-insensitive
+// and ignores leading and trailing whitespace.
+func Encoding(label string) encoding.Encoding {
+        label = strings.ToLower(strings.Trim(label, "\t\n\r\f "))
+        return encodings[label]
+}
+
+type utf8Encoding struct{}
+
+func (utf8Encoding) NewDecoder() transform.Transformer {
+        return transform.Nop
+}
+
+func (utf8Encoding) NewEncoder() transform.Transformer {
+        return transform.Nop
+}
+
+var ErrReplacementEncoding = errors.New("charset: ISO-2022-CN and ISO-2022-KR are obsolete encodings for HTML")
+
+type errorTransformer struct {
+        err error
+}
+
+func (t errorTransformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+        return 0, 0, t.err
+}
+
+type replacementEncoding struct{}
+
+func (replacementEncoding) NewDecoder() transform.Transformer {
+        return errorTransformer{ErrReplacementEncoding}
+}
+
+func (replacementEncoding) NewEncoder() transform.Transformer {
+        return transform.Nop
+}