| // 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 "<!--" + EscapeString(t.Data) + "-->" |
| case DoctypeToken: |
| return "<!DOCTYPE " + EscapeString(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 |
| } |
| }() |
| |
| var dashCount int |
| beginning := true |
| for { |
| 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 || beginning { |
| 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 |
| beginning = false |
| } |
| } |
| |
| // 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 |
| } |