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-rw-r--r--vendor/golang.org/x/net/html/charset/charset.go257
1 files changed, 257 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/html/charset/charset.go b/vendor/golang.org/x/net/html/charset/charset.go
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--- /dev/null
+++ b/vendor/golang.org/x/net/html/charset/charset.go
@@ -0,0 +1,257 @@
+// Copyright 2013 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.
+
+// Package charset provides common text encodings for HTML documents.
+//
+// The mapping from encoding labels to encodings is defined at
+// https://encoding.spec.whatwg.org/.
+package charset // import "golang.org/x/net/html/charset"
+
+import (
+ "bytes"
+ "fmt"
+ "io"
+ "mime"
+ "strings"
+ "unicode/utf8"
+
+ "golang.org/x/net/html"
+ "golang.org/x/text/encoding"
+ "golang.org/x/text/encoding/charmap"
+ "golang.org/x/text/encoding/htmlindex"
+ "golang.org/x/text/transform"
+)
+
+// Lookup returns the encoding with the specified label, and its canonical
+// name. It returns nil and the empty string if label is not one of the
+// standard encodings for HTML. Matching is case-insensitive and ignores
+// leading and trailing whitespace. Encoders will use HTML escape sequences for
+// runes that are not supported by the character set.
+func Lookup(label string) (e encoding.Encoding, name string) {
+ e, err := htmlindex.Get(label)
+ if err != nil {
+ return nil, ""
+ }
+ name, _ = htmlindex.Name(e)
+ return &htmlEncoding{e}, name
+}
+
+type htmlEncoding struct{ encoding.Encoding }
+
+func (h *htmlEncoding) NewEncoder() *encoding.Encoder {
+ // HTML requires a non-terminating legacy encoder. We use HTML escapes to
+ // substitute unsupported code points.
+ return encoding.HTMLEscapeUnsupported(h.Encoding.NewEncoder())
+}
+
+// DetermineEncoding determines the encoding of an HTML document by examining
+// up to the first 1024 bytes of content and the declared Content-Type.
+//
+// See http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#determining-the-character-encoding
+func DetermineEncoding(content []byte, contentType string) (e encoding.Encoding, name string, certain bool) {
+ if len(content) > 1024 {
+ content = content[:1024]
+ }
+
+ for _, b := range boms {
+ if bytes.HasPrefix(content, b.bom) {
+ e, name = Lookup(b.enc)
+ return e, name, true
+ }
+ }
+
+ if _, params, err := mime.ParseMediaType(contentType); err == nil {
+ if cs, ok := params["charset"]; ok {
+ if e, name = Lookup(cs); e != nil {
+ return e, name, true
+ }
+ }
+ }
+
+ if len(content) > 0 {
+ e, name = prescan(content)
+ if e != nil {
+ return e, name, false
+ }
+ }
+
+ // Try to detect UTF-8.
+ // First eliminate any partial rune at the end.
+ for i := len(content) - 1; i >= 0 && i > len(content)-4; i-- {
+ b := content[i]
+ if b < 0x80 {
+ break
+ }
+ if utf8.RuneStart(b) {
+ content = content[:i]
+ break
+ }
+ }
+ hasHighBit := false
+ for _, c := range content {
+ if c >= 0x80 {
+ hasHighBit = true
+ break
+ }
+ }
+ if hasHighBit && utf8.Valid(content) {
+ return encoding.Nop, "utf-8", false
+ }
+
+ // TODO: change default depending on user's locale?
+ return charmap.Windows1252, "windows-1252", false
+}
+
+// NewReader returns an io.Reader that converts the content of r to UTF-8.
+// It calls DetermineEncoding to find out what r's encoding is.
+func NewReader(r io.Reader, contentType string) (io.Reader, error) {
+ preview := make([]byte, 1024)
+ n, err := io.ReadFull(r, preview)
+ switch {
+ case err == io.ErrUnexpectedEOF:
+ preview = preview[:n]
+ r = bytes.NewReader(preview)
+ case err != nil:
+ return nil, err
+ default:
+ r = io.MultiReader(bytes.NewReader(preview), r)
+ }
+
+ if e, _, _ := DetermineEncoding(preview, contentType); e != encoding.Nop {
+ r = transform.NewReader(r, e.NewDecoder())
+ }
+ return r, nil
+}
+
+// NewReaderLabel returns a reader that converts from the specified charset to
+// UTF-8. It uses Lookup to find the encoding that corresponds to label, and
+// returns an error if Lookup returns nil. It is suitable for use as
+// encoding/xml.Decoder's CharsetReader function.
+func NewReaderLabel(label string, input io.Reader) (io.Reader, error) {
+ e, _ := Lookup(label)
+ if e == nil {
+ return nil, fmt.Errorf("unsupported charset: %q", label)
+ }
+ return transform.NewReader(input, e.NewDecoder()), nil
+}
+
+func prescan(content []byte) (e encoding.Encoding, name string) {
+ z := html.NewTokenizer(bytes.NewReader(content))
+ for {
+ switch z.Next() {
+ case html.ErrorToken:
+ return nil, ""
+
+ case html.StartTagToken, html.SelfClosingTagToken:
+ tagName, hasAttr := z.TagName()
+ if !bytes.Equal(tagName, []byte("meta")) {
+ continue
+ }
+ attrList := make(map[string]bool)
+ gotPragma := false
+
+ const (
+ dontKnow = iota
+ doNeedPragma
+ doNotNeedPragma
+ )
+ needPragma := dontKnow
+
+ name = ""
+ e = nil
+ for hasAttr {
+ var key, val []byte
+ key, val, hasAttr = z.TagAttr()
+ ks := string(key)
+ if attrList[ks] {
+ continue
+ }
+ attrList[ks] = true
+ for i, c := range val {
+ if 'A' <= c && c <= 'Z' {
+ val[i] = c + 0x20
+ }
+ }
+
+ switch ks {
+ case "http-equiv":
+ if bytes.Equal(val, []byte("content-type")) {
+ gotPragma = true
+ }
+
+ case "content":
+ if e == nil {
+ name = fromMetaElement(string(val))
+ if name != "" {
+ e, name = Lookup(name)
+ if e != nil {
+ needPragma = doNeedPragma
+ }
+ }
+ }
+
+ case "charset":
+ e, name = Lookup(string(val))
+ needPragma = doNotNeedPragma
+ }
+ }
+
+ if needPragma == dontKnow || needPragma == doNeedPragma && !gotPragma {
+ continue
+ }
+
+ if strings.HasPrefix(name, "utf-16") {
+ name = "utf-8"
+ e = encoding.Nop
+ }
+
+ if e != nil {
+ return e, name
+ }
+ }
+ }
+}
+
+func fromMetaElement(s string) string {
+ for s != "" {
+ csLoc := strings.Index(s, "charset")
+ if csLoc == -1 {
+ return ""
+ }
+ s = s[csLoc+len("charset"):]
+ s = strings.TrimLeft(s, " \t\n\f\r")
+ if !strings.HasPrefix(s, "=") {
+ continue
+ }
+ s = s[1:]
+ s = strings.TrimLeft(s, " \t\n\f\r")
+ if s == "" {
+ return ""
+ }
+ if q := s[0]; q == '"' || q == '\'' {
+ s = s[1:]
+ closeQuote := strings.IndexRune(s, rune(q))
+ if closeQuote == -1 {
+ return ""
+ }
+ return s[:closeQuote]
+ }
+
+ end := strings.IndexAny(s, "; \t\n\f\r")
+ if end == -1 {
+ end = len(s)
+ }
+ return s[:end]
+ }
+ return ""
+}
+
+var boms = []struct {
+ bom []byte
+ enc string
+}{
+ {[]byte{0xfe, 0xff}, "utf-16be"},
+ {[]byte{0xff, 0xfe}, "utf-16le"},
+ {[]byte{0xef, 0xbb, 0xbf}, "utf-8"},
+}