diff options
Diffstat (limited to 'vendor/golang.org/x/net/html/token.go')
| -rw-r--r-- | vendor/golang.org/x/net/html/token.go | 1224 |
1 files changed, 1224 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/html/token.go b/vendor/golang.org/x/net/html/token.go new file mode 100644 index 00000000..877709f9 --- /dev/null +++ b/vendor/golang.org/x/net/html/token.go @@ -0,0 +1,1224 @@ +// Copyright 2010 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 html + +import ( + "bytes" + "errors" + "io" + "strconv" + "strings" + + "golang.org/x/net/html/atom" +) + +// A TokenType is the type of a Token. +type TokenType uint32 + +const ( + // ErrorToken means that an error occurred during tokenization. + ErrorToken TokenType = iota + // TextToken means a text node. + TextToken + // A StartTagToken looks like <a>. + StartTagToken + // An EndTagToken looks like </a>. + EndTagToken + // A SelfClosingTagToken tag looks like <br/>. + SelfClosingTagToken + // A CommentToken looks like <!--x-->. + CommentToken + // A DoctypeToken looks like <!DOCTYPE x> + DoctypeToken +) + +// ErrBufferExceeded means that the buffering limit was exceeded. +var ErrBufferExceeded = errors.New("max buffer exceeded") + +// String returns a string representation of the TokenType. +func (t TokenType) String() string { + switch t { + case ErrorToken: + return "Error" + case TextToken: + return "Text" + case StartTagToken: + return "StartTag" + case EndTagToken: + return "EndTag" + case SelfClosingTagToken: + return "SelfClosingTag" + case CommentToken: + return "Comment" + case DoctypeToken: + return "Doctype" + } + return "Invalid(" + strconv.Itoa(int(t)) + ")" +} + +// An Attribute is an attribute namespace-key-value triple. Namespace is +// non-empty for foreign attributes like xlink, Key is alphabetic (and hence +// does not contain escapable characters like '&', '<' or '>'), and Val is +// unescaped (it looks like "a<b" rather than "a<b"). +// +// Namespace is only used by the parser, not the tokenizer. +type Attribute struct { + Namespace, Key, Val string +} + +// A Token consists of a TokenType and some Data (tag name for start and end +// tags, content for text, comments and doctypes). A tag Token may also contain +// a slice of Attributes. Data is unescaped for all Tokens (it looks like "a<b" +// rather than "a<b"). For tag Tokens, DataAtom is the atom for Data, or +// zero if Data is not a known tag name. +type Token struct { + Type TokenType + DataAtom atom.Atom + Data string + Attr []Attribute +} + +// tagString returns a string representation of a tag Token's Data and Attr. +func (t Token) tagString() string { + if len(t.Attr) == 0 { + return t.Data + } + buf := bytes.NewBufferString(t.Data) + for _, a := range t.Attr { + buf.WriteByte(' ') + buf.WriteString(a.Key) + buf.WriteString(`="`) + escape(buf, a.Val) + buf.WriteByte('"') + } + return buf.String() +} + +// String returns a string representation of the Token. +func (t Token) String() string { + switch t.Type { + case ErrorToken: + return "" + case TextToken: + return EscapeString(t.Data) + case StartTagToken: + return "<" + t.tagString() + ">" + case EndTagToken: + return "</" + t.tagString() + ">" + case SelfClosingTagToken: + return "<" + t.tagString() + "/>" + case CommentToken: + return "<!--" + t.Data + "-->" + case DoctypeToken: + return "<!DOCTYPE " + t.Data + ">" + } + return "Invalid(" + strconv.Itoa(int(t.Type)) + ")" +} + +// span is a range of bytes in a Tokenizer's buffer. The start is inclusive, +// the end is exclusive. +type span struct { + start, end int +} + +// A Tokenizer returns a stream of HTML Tokens. +type Tokenizer struct { + // r is the source of the HTML text. + r io.Reader + // tt is the TokenType of the current token. + tt TokenType + // err is the first error encountered during tokenization. It is possible + // for tt != Error && err != nil to hold: this means that Next returned a + // valid token but the subsequent Next call will return an error token. + // For example, if the HTML text input was just "plain", then the first + // Next call would set z.err to io.EOF but return a TextToken, and all + // subsequent Next calls would return an ErrorToken. + // err is never reset. Once it becomes non-nil, it stays non-nil. + err error + // readErr is the error returned by the io.Reader r. It is separate from + // err because it is valid for an io.Reader to return (n int, err1 error) + // such that n > 0 && err1 != nil, and callers should always process the + // n > 0 bytes before considering the error err1. + readErr error + // buf[raw.start:raw.end] holds the raw bytes of the current token. + // buf[raw.end:] is buffered input that will yield future tokens. + raw span + buf []byte + // maxBuf limits the data buffered in buf. A value of 0 means unlimited. + maxBuf int + // buf[data.start:data.end] holds the raw bytes of the current token's data: + // a text token's text, a tag token's tag name, etc. + data span + // pendingAttr is the attribute key and value currently being tokenized. + // When complete, pendingAttr is pushed onto attr. nAttrReturned is + // incremented on each call to TagAttr. + pendingAttr [2]span + attr [][2]span + nAttrReturned int + // rawTag is the "script" in "</script>" that closes the next token. If + // non-empty, the subsequent call to Next will return a raw or RCDATA text + // token: one that treats "<p>" as text instead of an element. + // rawTag's contents are lower-cased. + rawTag string + // textIsRaw is whether the current text token's data is not escaped. + textIsRaw bool + // convertNUL is whether NUL bytes in the current token's data should + // be converted into \ufffd replacement characters. + convertNUL bool + // allowCDATA is whether CDATA sections are allowed in the current context. + allowCDATA bool +} + +// AllowCDATA sets whether or not the tokenizer recognizes <![CDATA[foo]]> as +// the text "foo". The default value is false, which means to recognize it as +// a bogus comment "<!-- [CDATA[foo]] -->" instead. +// +// Strictly speaking, an HTML5 compliant tokenizer should allow CDATA if and +// only if tokenizing foreign content, such as MathML and SVG. However, +// tracking foreign-contentness is difficult to do purely in the tokenizer, +// as opposed to the parser, due to HTML integration points: an <svg> element +// can contain a <foreignObject> that is foreign-to-SVG but not foreign-to- +// HTML. For strict compliance with the HTML5 tokenization algorithm, it is the +// responsibility of the user of a tokenizer to call AllowCDATA as appropriate. +// In practice, if using the tokenizer without caring whether MathML or SVG +// CDATA is text or comments, such as tokenizing HTML to find all the anchor +// text, it is acceptable to ignore this responsibility. +func (z *Tokenizer) AllowCDATA(allowCDATA bool) { + z.allowCDATA = allowCDATA +} + +// NextIsNotRawText instructs the tokenizer that the next token should not be +// considered as 'raw text'. Some elements, such as script and title elements, +// normally require the next token after the opening tag to be 'raw text' that +// has no child elements. For example, tokenizing "<title>a<b>c</b>d</title>" +// yields a start tag token for "<title>", a text token for "a<b>c</b>d", and +// an end tag token for "</title>". There are no distinct start tag or end tag +// tokens for the "<b>" and "</b>". +// +// This tokenizer implementation will generally look for raw text at the right +// times. Strictly speaking, an HTML5 compliant tokenizer should not look for +// raw text if in foreign content: <title> generally needs raw text, but a +// <title> inside an <svg> does not. Another example is that a <textarea> +// generally needs raw text, but a <textarea> is not allowed as an immediate +// child of a <select>; in normal parsing, a <textarea> implies </select>, but +// one cannot close the implicit element when parsing a <select>'s InnerHTML. +// Similarly to AllowCDATA, tracking the correct moment to override raw-text- +// ness is difficult to do purely in the tokenizer, as opposed to the parser. +// For strict compliance with the HTML5 tokenization algorithm, it is the +// responsibility of the user of a tokenizer to call NextIsNotRawText as +// appropriate. In practice, like AllowCDATA, it is acceptable to ignore this +// responsibility for basic usage. +// +// Note that this 'raw text' concept is different from the one offered by the +// Tokenizer.Raw method. +func (z *Tokenizer) NextIsNotRawText() { + z.rawTag = "" +} + +// Err returns the error associated with the most recent ErrorToken token. +// This is typically io.EOF, meaning the end of tokenization. +func (z *Tokenizer) Err() error { + if z.tt != ErrorToken { + return nil + } + return z.err +} + +// readByte returns the next byte from the input stream, doing a buffered read +// from z.r into z.buf if necessary. z.buf[z.raw.start:z.raw.end] remains a contiguous byte +// slice that holds all the bytes read so far for the current token. +// It sets z.err if the underlying reader returns an error. +// Pre-condition: z.err == nil. +func (z *Tokenizer) readByte() byte { + if z.raw.end >= len(z.buf) { + // Our buffer is exhausted and we have to read from z.r. Check if the + // previous read resulted in an error. + if z.readErr != nil { + z.err = z.readErr + return 0 + } + // We copy z.buf[z.raw.start:z.raw.end] to the beginning of z.buf. If the length + // z.raw.end - z.raw.start is more than half the capacity of z.buf, then we + // allocate a new buffer before the copy. + c := cap(z.buf) + d := z.raw.end - z.raw.start + var buf1 []byte + if 2*d > c { + buf1 = make([]byte, d, 2*c) + } else { + buf1 = z.buf[:d] + } + copy(buf1, z.buf[z.raw.start:z.raw.end]) + if x := z.raw.start; x != 0 { + // Adjust the data/attr spans to refer to the same contents after the copy. + z.data.start -= x + z.data.end -= x + z.pendingAttr[0].start -= x + z.pendingAttr[0].end -= x + z.pendingAttr[1].start -= x + z.pendingAttr[1].end -= x + for i := range z.attr { + z.attr[i][0].start -= x + z.attr[i][0].end -= x + z.attr[i][1].start -= x + z.attr[i][1].end -= x + } + } + z.raw.start, z.raw.end, z.buf = 0, d, buf1[:d] + // Now that we have copied the live bytes to the start of the buffer, + // we read from z.r into the remainder. + var n int + n, z.readErr = readAtLeastOneByte(z.r, buf1[d:cap(buf1)]) + if n == 0 { + z.err = z.readErr + return 0 + } + z.buf = buf1[:d+n] + } + x := z.buf[z.raw.end] + z.raw.end++ + if z.maxBuf > 0 && z.raw.end-z.raw.start >= z.maxBuf { + z.err = ErrBufferExceeded + return 0 + } + return x +} + +// Buffered returns a slice containing data buffered but not yet tokenized. +func (z *Tokenizer) Buffered() []byte { + return z.buf[z.raw.end:] +} + +// readAtLeastOneByte wraps an io.Reader so that reading cannot return (0, nil). +// It returns io.ErrNoProgress if the underlying r.Read method returns (0, nil) +// too many times in succession. +func readAtLeastOneByte(r io.Reader, b []byte) (int, error) { + for i := 0; i < 100; i++ { + if n, err := r.Read(b); n != 0 || err != nil { + return n, err + } + } + return 0, io.ErrNoProgress +} + +// skipWhiteSpace skips past any white space. +func (z *Tokenizer) skipWhiteSpace() { + if z.err != nil { + return + } + for { + c := z.readByte() + if z.err != nil { + return + } + switch c { + case ' ', '\n', '\r', '\t', '\f': + // No-op. + default: + z.raw.end-- + return + } + } +} + +// readRawOrRCDATA reads until the next "</foo>", where "foo" is z.rawTag and +// is typically something like "script" or "textarea". +func (z *Tokenizer) readRawOrRCDATA() { + if z.rawTag == "script" { + z.readScript() + z.textIsRaw = true + z.rawTag = "" + return + } +loop: + for { + c := z.readByte() + if z.err != nil { + break loop + } + if c != '<' { + continue loop + } + c = z.readByte() + if z.err != nil { + break loop + } + if c != '/' { + z.raw.end-- + continue loop + } + if z.readRawEndTag() || z.err != nil { + break loop + } + } + z.data.end = z.raw.end + // A textarea's or title's RCDATA can contain escaped entities. + z.textIsRaw = z.rawTag != "textarea" && z.rawTag != "title" + z.rawTag = "" +} + +// readRawEndTag attempts to read a tag like "</foo>", where "foo" is z.rawTag. +// If it succeeds, it backs up the input position to reconsume the tag and +// returns true. Otherwise it returns false. The opening "</" has already been +// consumed. +func (z *Tokenizer) readRawEndTag() bool { + for i := 0; i < len(z.rawTag); i++ { + c := z.readByte() + if z.err != nil { + return false + } + if c != z.rawTag[i] && c != z.rawTag[i]-('a'-'A') { + z.raw.end-- + return false + } + } + c := z.readByte() + if z.err != nil { + return false + } + switch c { + case ' ', '\n', '\r', '\t', '\f', '/', '>': + // The 3 is 2 for the leading "</" plus 1 for the trailing character c. + z.raw.end -= 3 + len(z.rawTag) + return true + } + z.raw.end-- + return false +} + +// readScript reads until the next </script> tag, following the byzantine +// rules for escaping/hiding the closing tag. +func (z *Tokenizer) readScript() { + defer func() { + z.data.end = z.raw.end + }() + var c byte + +scriptData: + c = z.readByte() + if z.err != nil { + return + } + if c == '<' { + goto scriptDataLessThanSign + } + goto scriptData + +scriptDataLessThanSign: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '/': + goto scriptDataEndTagOpen + case '!': + goto scriptDataEscapeStart + } + z.raw.end-- + goto scriptData + +scriptDataEndTagOpen: + if z.readRawEndTag() || z.err != nil { + return + } + goto scriptData + +scriptDataEscapeStart: + c = z.readByte() + if z.err != nil { + return + } + if c == '-' { + goto scriptDataEscapeStartDash + } + z.raw.end-- + goto scriptData + +scriptDataEscapeStartDash: + c = z.readByte() + if z.err != nil { + return + } + if c == '-' { + goto scriptDataEscapedDashDash + } + z.raw.end-- + goto scriptData + +scriptDataEscaped: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '-': + goto scriptDataEscapedDash + case '<': + goto scriptDataEscapedLessThanSign + } + goto scriptDataEscaped + +scriptDataEscapedDash: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '-': + goto scriptDataEscapedDashDash + case '<': + goto scriptDataEscapedLessThanSign + } + goto scriptDataEscaped + +scriptDataEscapedDashDash: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '-': + goto scriptDataEscapedDashDash + case '<': + goto scriptDataEscapedLessThanSign + case '>': + goto scriptData + } + goto scriptDataEscaped + +scriptDataEscapedLessThanSign: + c = z.readByte() + if z.err != nil { + return + } + if c == '/' { + goto scriptDataEscapedEndTagOpen + } + if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' { + goto scriptDataDoubleEscapeStart + } + z.raw.end-- + goto scriptData + +scriptDataEscapedEndTagOpen: + if z.readRawEndTag() || z.err != nil { + return + } + goto scriptDataEscaped + +scriptDataDoubleEscapeStart: + z.raw.end-- + for i := 0; i < len("script"); i++ { + c = z.readByte() + if z.err != nil { + return + } + if c != "script"[i] && c != "SCRIPT"[i] { + z.raw.end-- + goto scriptDataEscaped + } + } + c = z.readByte() + if z.err != nil { + return + } + switch c { + case ' ', '\n', '\r', '\t', '\f', '/', '>': + goto scriptDataDoubleEscaped + } + z.raw.end-- + goto scriptDataEscaped + +scriptDataDoubleEscaped: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '-': + goto scriptDataDoubleEscapedDash + case '<': + goto scriptDataDoubleEscapedLessThanSign + } + goto scriptDataDoubleEscaped + +scriptDataDoubleEscapedDash: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '-': + goto scriptDataDoubleEscapedDashDash + case '<': + goto scriptDataDoubleEscapedLessThanSign + } + goto scriptDataDoubleEscaped + +scriptDataDoubleEscapedDashDash: + c = z.readByte() + if z.err != nil { + return + } + switch c { + case '-': + goto scriptDataDoubleEscapedDashDash + case '<': + goto scriptDataDoubleEscapedLessThanSign + case '>': + goto scriptData + } + goto scriptDataDoubleEscaped + +scriptDataDoubleEscapedLessThanSign: + c = z.readByte() + if z.err != nil { + return + } + if c == '/' { + goto scriptDataDoubleEscapeEnd + } + z.raw.end-- + goto scriptDataDoubleEscaped + +scriptDataDoubleEscapeEnd: + if z.readRawEndTag() { + z.raw.end += len("</script>") + goto scriptDataEscaped + } + if z.err != nil { + return + } + goto scriptDataDoubleEscaped +} + +// readComment reads the next comment token starting with "<!--". The opening +// "<!--" has already been consumed. +func (z *Tokenizer) readComment() { + z.data.start = z.raw.end + defer func() { + if z.data.end < z.data.start { + // It's a comment with no data, like <!-->. + z.data.end = z.data.start + } + }() + for dashCount := 2; ; { + c := z.readByte() + if z.err != nil { + // Ignore up to two dashes at EOF. + if dashCount > 2 { + dashCount = 2 + } + z.data.end = z.raw.end - dashCount + return + } + switch c { + case '-': + dashCount++ + continue + case '>': + if dashCount >= 2 { + z.data.end = z.raw.end - len("-->") + return + } + case '!': + if dashCount >= 2 { + c = z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return + } + if c == '>' { + z.data.end = z.raw.end - len("--!>") + return + } + } + } + dashCount = 0 + } +} + +// readUntilCloseAngle reads until the next ">". +func (z *Tokenizer) readUntilCloseAngle() { + z.data.start = z.raw.end + for { + c := z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return + } + if c == '>' { + z.data.end = z.raw.end - len(">") + return + } + } +} + +// readMarkupDeclaration reads the next token starting with "<!". It might be +// a "<!--comment-->", a "<!DOCTYPE foo>", a "<![CDATA[section]]>" or +// "<!a bogus comment". The opening "<!" has already been consumed. +func (z *Tokenizer) readMarkupDeclaration() TokenType { + z.data.start = z.raw.end + var c [2]byte + for i := 0; i < 2; i++ { + c[i] = z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return CommentToken + } + } + if c[0] == '-' && c[1] == '-' { + z.readComment() + return CommentToken + } + z.raw.end -= 2 + if z.readDoctype() { + return DoctypeToken + } + if z.allowCDATA && z.readCDATA() { + z.convertNUL = true + return TextToken + } + // It's a bogus comment. + z.readUntilCloseAngle() + return CommentToken +} + +// readDoctype attempts to read a doctype declaration and returns true if +// successful. The opening "<!" has already been consumed. +func (z *Tokenizer) readDoctype() bool { + const s = "DOCTYPE" + for i := 0; i < len(s); i++ { + c := z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return false + } + if c != s[i] && c != s[i]+('a'-'A') { + // Back up to read the fragment of "DOCTYPE" again. + z.raw.end = z.data.start + return false + } + } + if z.skipWhiteSpace(); z.err != nil { + z.data.start = z.raw.end + z.data.end = z.raw.end + return true + } + z.readUntilCloseAngle() + return true +} + +// readCDATA attempts to read a CDATA section and returns true if +// successful. The opening "<!" has already been consumed. +func (z *Tokenizer) readCDATA() bool { + const s = "[CDATA[" + for i := 0; i < len(s); i++ { + c := z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return false + } + if c != s[i] { + // Back up to read the fragment of "[CDATA[" again. + z.raw.end = z.data.start + return false + } + } + z.data.start = z.raw.end + brackets := 0 + for { + c := z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return true + } + switch c { + case ']': + brackets++ + case '>': + if brackets >= 2 { + z.data.end = z.raw.end - len("]]>") + return true + } + brackets = 0 + default: + brackets = 0 + } + } +} + +// startTagIn returns whether the start tag in z.buf[z.data.start:z.data.end] +// case-insensitively matches any element of ss. +func (z *Tokenizer) startTagIn(ss ...string) bool { +loop: + for _, s := range ss { + if z.data.end-z.data.start != len(s) { + continue loop + } + for i := 0; i < len(s); i++ { + c := z.buf[z.data.start+i] + if 'A' <= c && c <= 'Z' { + c += 'a' - 'A' + } + if c != s[i] { + continue loop + } + } + return true + } + return false +} + +// readStartTag reads the next start tag token. The opening "<a" has already +// been consumed, where 'a' means anything in [A-Za-z]. +func (z *Tokenizer) readStartTag() TokenType { + z.readTag(true) + if z.err != nil { + return ErrorToken + } + // Several tags flag the tokenizer's next token as raw. + c, raw := z.buf[z.data.start], false + if 'A' <= c && c <= 'Z' { + c += 'a' - 'A' + } + switch c { + case 'i': + raw = z.startTagIn("iframe") + case 'n': + raw = z.startTagIn("noembed", "noframes", "noscript") + case 'p': + raw = z.startTagIn("plaintext") + case 's': + raw = z.startTagIn("script", "style") + case 't': + raw = z.startTagIn("textarea", "title") + case 'x': + raw = z.startTagIn("xmp") + } + if raw { + z.rawTag = strings.ToLower(string(z.buf[z.data.start:z.data.end])) + } + // Look for a self-closing token like "<br/>". + if z.err == nil && z.buf[z.raw.end-2] == '/' { + return SelfClosingTagToken + } + return StartTagToken +} + +// readTag reads the next tag token and its attributes. If saveAttr, those +// attributes are saved in z.attr, otherwise z.attr is set to an empty slice. +// The opening "<a" or "</a" has already been consumed, where 'a' means anything +// in [A-Za-z]. +func (z *Tokenizer) readTag(saveAttr bool) { + z.attr = z.attr[:0] + z.nAttrReturned = 0 + // Read the tag name and attribute key/value pairs. + z.readTagName() + if z.skipWhiteSpace(); z.err != nil { + return + } + for { + c := z.readByte() + if z.err != nil || c == '>' { + break + } + z.raw.end-- + z.readTagAttrKey() + z.readTagAttrVal() + // Save pendingAttr if saveAttr and that attribute has a non-empty key. + if saveAttr && z.pendingAttr[0].start != z.pendingAttr[0].end { + z.attr = append(z.attr, z.pendingAttr) + } + if z.skipWhiteSpace(); z.err != nil { + break + } + } +} + +// readTagName sets z.data to the "div" in "<div k=v>". The reader (z.raw.end) +// is positioned such that the first byte of the tag name (the "d" in "<div") +// has already been consumed. +func (z *Tokenizer) readTagName() { + z.data.start = z.raw.end - 1 + for { + c := z.readByte() + if z.err != nil { + z.data.end = z.raw.end + return + } + switch c { + case ' ', '\n', '\r', '\t', '\f': + z.data.end = z.raw.end - 1 + return + case '/', '>': + z.raw.end-- + z.data.end = z.raw.end + return + } + } +} + +// readTagAttrKey sets z.pendingAttr[0] to the "k" in "<div k=v>". +// Precondition: z.err == nil. +func (z *Tokenizer) readTagAttrKey() { + z.pendingAttr[0].start = z.raw.end + for { + c := z.readByte() + if z.err != nil { + z.pendingAttr[0].end = z.raw.end + return + } + switch c { + case ' ', '\n', '\r', '\t', '\f', '/': + z.pendingAttr[0].end = z.raw.end - 1 + return + case '=', '>': + z.raw.end-- + z.pendingAttr[0].end = z.raw.end + return + } + } +} + +// readTagAttrVal sets z.pendingAttr[1] to the "v" in "<div k=v>". +func (z *Tokenizer) readTagAttrVal() { + z.pendingAttr[1].start = z.raw.end + z.pendingAttr[1].end = z.raw.end + if z.skipWhiteSpace(); z.err != nil { + return + } + c := z.readByte() + if z.err != nil { + return + } + if c != '=' { + z.raw.end-- + return + } + if z.skipWhiteSpace(); z.err != nil { + return + } + quote := z.readByte() + if z.err != nil { + return + } + switch quote { + case '>': + z.raw.end-- + return + + case '\'', '"': + z.pendingAttr[1].start = z.raw.end + for { + c := z.readByte() + if z.err != nil { + z.pendingAttr[1].end = z.raw.end + return + } + if c == quote { + z.pendingAttr[1].end = z.raw.end - 1 + return + } + } + + default: + z.pendingAttr[1].start = z.raw.end - 1 + for { + c := z.readByte() + if z.err != nil { + z.pendingAttr[1].end = z.raw.end + return + } + switch c { + case ' ', '\n', '\r', '\t', '\f': + z.pendingAttr[1].end = z.raw.end - 1 + return + case '>': + z.raw.end-- + z.pendingAttr[1].end = z.raw.end + return + } + } + } +} + +// Next scans the next token and returns its type. +func (z *Tokenizer) Next() TokenType { + z.raw.start = z.raw.end + z.data.start = z.raw.end + z.data.end = z.raw.end + if z.err != nil { + z.tt = ErrorToken + return z.tt + } + if z.rawTag != "" { + if z.rawTag == "plaintext" { + // Read everything up to EOF. + for z.err == nil { + z.readByte() + } + z.data.end = z.raw.end + z.textIsRaw = true + } else { + z.readRawOrRCDATA() + } + if z.data.end > z.data.start { + z.tt = TextToken + z.convertNUL = true + return z.tt + } + } + z.textIsRaw = false + z.convertNUL = false + +loop: + for { + c := z.readByte() + if z.err != nil { + break loop + } + if c != '<' { + continue loop + } + + // Check if the '<' we have just read is part of a tag, comment + // or doctype. If not, it's part of the accumulated text token. + c = z.readByte() + if z.err != nil { + break loop + } + var tokenType TokenType + switch { + case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z': + tokenType = StartTagToken + case c == '/': + tokenType = EndTagToken + case c == '!' || c == '?': + // We use CommentToken to mean any of "<!--actual comments-->", + // "<!DOCTYPE declarations>" and "<?xml processing instructions?>". + tokenType = CommentToken + default: + // Reconsume the current character. + z.raw.end-- + continue + } + + // We have a non-text token, but we might have accumulated some text + // before that. If so, we return the text first, and return the non- + // text token on the subsequent call to Next. + if x := z.raw.end - len("<a"); z.raw.start < x { + z.raw.end = x + z.data.end = x + z.tt = TextToken + return z.tt + } + switch tokenType { + case StartTagToken: + z.tt = z.readStartTag() + return z.tt + case EndTagToken: + c = z.readByte() + if z.err != nil { + break loop + } + if c == '>' { + // "</>" does not generate a token at all. Generate an empty comment + // to allow passthrough clients to pick up the data using Raw. + // Reset the tokenizer state and start again. + z.tt = CommentToken + return z.tt + } + if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' { + z.readTag(false) + if z.err != nil { + z.tt = ErrorToken + } else { + z.tt = EndTagToken + } + return z.tt + } + z.raw.end-- + z.readUntilCloseAngle() + z.tt = CommentToken + return z.tt + case CommentToken: + if c == '!' { + z.tt = z.readMarkupDeclaration() + return z.tt + } + z.raw.end-- + z.readUntilCloseAngle() + z.tt = CommentToken + return z.tt + } + } + if z.raw.start < z.raw.end { + z.data.end = z.raw.end + z.tt = TextToken + return z.tt + } + z.tt = ErrorToken + return z.tt +} + +// Raw returns the unmodified text of the current token. Calling Next, Token, +// Text, TagName or TagAttr may change the contents of the returned slice. +// +// The token stream's raw bytes partition the byte stream (up until an +// ErrorToken). There are no overlaps or gaps between two consecutive token's +// raw bytes. One implication is that the byte offset of the current token is +// the sum of the lengths of all previous tokens' raw bytes. +func (z *Tokenizer) Raw() []byte { + return z.buf[z.raw.start:z.raw.end] +} + +// convertNewlines converts "\r" and "\r\n" in s to "\n". +// The conversion happens in place, but the resulting slice may be shorter. +func convertNewlines(s []byte) []byte { + for i, c := range s { + if c != '\r' { + continue + } + + src := i + 1 + if src >= len(s) || s[src] != '\n' { + s[i] = '\n' + continue + } + + dst := i + for src < len(s) { + if s[src] == '\r' { + if src+1 < len(s) && s[src+1] == '\n' { + src++ + } + s[dst] = '\n' + } else { + s[dst] = s[src] + } + src++ + dst++ + } + return s[:dst] + } + return s +} + +var ( + nul = []byte("\x00") + replacement = []byte("\ufffd") +) + +// Text returns the unescaped text of a text, comment or doctype token. The +// contents of the returned slice may change on the next call to Next. +func (z *Tokenizer) Text() []byte { + switch z.tt { + case TextToken, CommentToken, DoctypeToken: + s := z.buf[z.data.start:z.data.end] + z.data.start = z.raw.end + z.data.end = z.raw.end + s = convertNewlines(s) + if (z.convertNUL || z.tt == CommentToken) && bytes.Contains(s, nul) { + s = bytes.Replace(s, nul, replacement, -1) + } + if !z.textIsRaw { + s = unescape(s, false) + } + return s + } + return nil +} + +// TagName returns the lower-cased name of a tag token (the `img` out of +// `<IMG SRC="foo">`) and whether the tag has attributes. +// The contents of the returned slice may change on the next call to Next. +func (z *Tokenizer) TagName() (name []byte, hasAttr bool) { + if z.data.start < z.data.end { + switch z.tt { + case StartTagToken, EndTagToken, SelfClosingTagToken: + s := z.buf[z.data.start:z.data.end] + z.data.start = z.raw.end + z.data.end = z.raw.end + return lower(s), z.nAttrReturned < len(z.attr) + } + } + return nil, false +} + +// TagAttr returns the lower-cased key and unescaped value of the next unparsed +// attribute for the current tag token and whether there are more attributes. +// The contents of the returned slices may change on the next call to Next. +func (z *Tokenizer) TagAttr() (key, val []byte, moreAttr bool) { + if z.nAttrReturned < len(z.attr) { + switch z.tt { + case StartTagToken, SelfClosingTagToken: + x := z.attr[z.nAttrReturned] + z.nAttrReturned++ + key = z.buf[x[0].start:x[0].end] + val = z.buf[x[1].start:x[1].end] + return lower(key), unescape(convertNewlines(val), true), z.nAttrReturned < len(z.attr) + } + } + return nil, nil, false +} + +// Token returns the current Token. The result's Data and Attr values remain +// valid after subsequent Next calls. +func (z *Tokenizer) Token() Token { + t := Token{Type: z.tt} + switch z.tt { + case TextToken, CommentToken, DoctypeToken: + t.Data = string(z.Text()) + case StartTagToken, SelfClosingTagToken, EndTagToken: + name, moreAttr := z.TagName() + for moreAttr { + var key, val []byte + key, val, moreAttr = z.TagAttr() + t.Attr = append(t.Attr, Attribute{"", atom.String(key), string(val)}) + } + if a := atom.Lookup(name); a != 0 { + t.DataAtom, t.Data = a, a.String() + } else { + t.DataAtom, t.Data = 0, string(name) + } + } + return t +} + +// SetMaxBuf sets a limit on the amount of data buffered during tokenization. +// A value of 0 means unlimited. +func (z *Tokenizer) SetMaxBuf(n int) { + z.maxBuf = n +} + +// NewTokenizer returns a new HTML Tokenizer for the given Reader. +// The input is assumed to be UTF-8 encoded. +func NewTokenizer(r io.Reader) *Tokenizer { + return NewTokenizerFragment(r, "") +} + +// NewTokenizerFragment returns a new HTML Tokenizer for the given Reader, for +// tokenizing an existing element's InnerHTML fragment. contextTag is that +// element's tag, such as "div" or "iframe". +// +// For example, how the InnerHTML "a<b" is tokenized depends on whether it is +// for a <p> tag or a <script> tag. +// +// The input is assumed to be UTF-8 encoded. +func NewTokenizerFragment(r io.Reader, contextTag string) *Tokenizer { + z := &Tokenizer{ + r: r, + buf: make([]byte, 0, 4096), + } + if contextTag != "" { + switch s := strings.ToLower(contextTag); s { + case "iframe", "noembed", "noframes", "noscript", "plaintext", "script", "style", "title", "textarea", "xmp": + z.rawTag = s + } + } + return z +} |