mirror of
https://github.com/go-gitea/gitea.git
synced 2024-08-23 20:57:29 +02:00
1220 lines
30 KiB
Go
1220 lines
30 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package html
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import (
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"bytes"
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"errors"
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"io"
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"strconv"
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"strings"
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"golang.org/x/net/html/atom"
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)
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// A TokenType is the type of a Token.
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type TokenType uint32
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const (
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// ErrorToken means that an error occurred during tokenization.
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ErrorToken TokenType = iota
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// TextToken means a text node.
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TextToken
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// A StartTagToken looks like <a>.
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StartTagToken
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// An EndTagToken looks like </a>.
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EndTagToken
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// A SelfClosingTagToken tag looks like <br/>.
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SelfClosingTagToken
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// A CommentToken looks like <!--x-->.
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CommentToken
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// A DoctypeToken looks like <!DOCTYPE x>
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DoctypeToken
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)
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// ErrBufferExceeded means that the buffering limit was exceeded.
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var ErrBufferExceeded = errors.New("max buffer exceeded")
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// String returns a string representation of the TokenType.
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func (t TokenType) String() string {
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switch t {
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case ErrorToken:
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return "Error"
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case TextToken:
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return "Text"
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case StartTagToken:
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return "StartTag"
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case EndTagToken:
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return "EndTag"
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case SelfClosingTagToken:
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return "SelfClosingTag"
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case CommentToken:
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return "Comment"
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case DoctypeToken:
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return "Doctype"
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}
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return "Invalid(" + strconv.Itoa(int(t)) + ")"
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}
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// An Attribute is an attribute namespace-key-value triple. Namespace is
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// non-empty for foreign attributes like xlink, Key is alphabetic (and hence
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// does not contain escapable characters like '&', '<' or '>'), and Val is
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// unescaped (it looks like "a<b" rather than "a<b").
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//
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// Namespace is only used by the parser, not the tokenizer.
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type Attribute struct {
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Namespace, Key, Val string
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}
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// A Token consists of a TokenType and some Data (tag name for start and end
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// tags, content for text, comments and doctypes). A tag Token may also contain
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// a slice of Attributes. Data is unescaped for all Tokens (it looks like "a<b"
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// rather than "a<b"). For tag Tokens, DataAtom is the atom for Data, or
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// zero if Data is not a known tag name.
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type Token struct {
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Type TokenType
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DataAtom atom.Atom
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Data string
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Attr []Attribute
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}
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// tagString returns a string representation of a tag Token's Data and Attr.
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func (t Token) tagString() string {
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if len(t.Attr) == 0 {
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return t.Data
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}
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buf := bytes.NewBufferString(t.Data)
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for _, a := range t.Attr {
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buf.WriteByte(' ')
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buf.WriteString(a.Key)
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buf.WriteString(`="`)
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escape(buf, a.Val)
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buf.WriteByte('"')
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}
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return buf.String()
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}
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// String returns a string representation of the Token.
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func (t Token) String() string {
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switch t.Type {
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case ErrorToken:
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return ""
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case TextToken:
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return EscapeString(t.Data)
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case StartTagToken:
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return "<" + t.tagString() + ">"
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case EndTagToken:
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return "</" + t.tagString() + ">"
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case SelfClosingTagToken:
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return "<" + t.tagString() + "/>"
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case CommentToken:
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return "<!--" + t.Data + "-->"
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case DoctypeToken:
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return "<!DOCTYPE " + t.Data + ">"
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}
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return "Invalid(" + strconv.Itoa(int(t.Type)) + ")"
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}
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// span is a range of bytes in a Tokenizer's buffer. The start is inclusive,
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// the end is exclusive.
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type span struct {
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start, end int
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}
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// A Tokenizer returns a stream of HTML Tokens.
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type Tokenizer struct {
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// r is the source of the HTML text.
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r io.Reader
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// tt is the TokenType of the current token.
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tt TokenType
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// err is the first error encountered during tokenization. It is possible
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// for tt != Error && err != nil to hold: this means that Next returned a
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// valid token but the subsequent Next call will return an error token.
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// For example, if the HTML text input was just "plain", then the first
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// Next call would set z.err to io.EOF but return a TextToken, and all
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// subsequent Next calls would return an ErrorToken.
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// err is never reset. Once it becomes non-nil, it stays non-nil.
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err error
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// readErr is the error returned by the io.Reader r. It is separate from
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// err because it is valid for an io.Reader to return (n int, err1 error)
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// such that n > 0 && err1 != nil, and callers should always process the
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// n > 0 bytes before considering the error err1.
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readErr error
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// buf[raw.start:raw.end] holds the raw bytes of the current token.
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// buf[raw.end:] is buffered input that will yield future tokens.
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raw span
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buf []byte
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// maxBuf limits the data buffered in buf. A value of 0 means unlimited.
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maxBuf int
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// buf[data.start:data.end] holds the raw bytes of the current token's data:
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// a text token's text, a tag token's tag name, etc.
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data span
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// pendingAttr is the attribute key and value currently being tokenized.
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// When complete, pendingAttr is pushed onto attr. nAttrReturned is
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// incremented on each call to TagAttr.
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pendingAttr [2]span
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attr [][2]span
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nAttrReturned int
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// rawTag is the "script" in "</script>" that closes the next token. If
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// non-empty, the subsequent call to Next will return a raw or RCDATA text
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// token: one that treats "<p>" as text instead of an element.
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// rawTag's contents are lower-cased.
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rawTag string
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// textIsRaw is whether the current text token's data is not escaped.
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textIsRaw bool
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// convertNUL is whether NUL bytes in the current token's data should
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// be converted into \ufffd replacement characters.
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convertNUL bool
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// allowCDATA is whether CDATA sections are allowed in the current context.
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allowCDATA bool
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}
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// AllowCDATA sets whether or not the tokenizer recognizes <![CDATA[foo]]> as
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// the text "foo". The default value is false, which means to recognize it as
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// a bogus comment "<!-- [CDATA[foo]] -->" instead.
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//
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// Strictly speaking, an HTML5 compliant tokenizer should allow CDATA if and
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// only if tokenizing foreign content, such as MathML and SVG. However,
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// tracking foreign-contentness is difficult to do purely in the tokenizer,
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// as opposed to the parser, due to HTML integration points: an <svg> element
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// can contain a <foreignObject> that is foreign-to-SVG but not foreign-to-
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// HTML. For strict compliance with the HTML5 tokenization algorithm, it is the
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// responsibility of the user of a tokenizer to call AllowCDATA as appropriate.
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// In practice, if using the tokenizer without caring whether MathML or SVG
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// CDATA is text or comments, such as tokenizing HTML to find all the anchor
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// text, it is acceptable to ignore this responsibility.
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func (z *Tokenizer) AllowCDATA(allowCDATA bool) {
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z.allowCDATA = allowCDATA
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}
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// NextIsNotRawText instructs the tokenizer that the next token should not be
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// considered as 'raw text'. Some elements, such as script and title elements,
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// normally require the next token after the opening tag to be 'raw text' that
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// has no child elements. For example, tokenizing "<title>a<b>c</b>d</title>"
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// yields a start tag token for "<title>", a text token for "a<b>c</b>d", and
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// an end tag token for "</title>". There are no distinct start tag or end tag
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// tokens for the "<b>" and "</b>".
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//
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// This tokenizer implementation will generally look for raw text at the right
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// times. Strictly speaking, an HTML5 compliant tokenizer should not look for
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// raw text if in foreign content: <title> generally needs raw text, but a
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// <title> inside an <svg> does not. Another example is that a <textarea>
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// generally needs raw text, but a <textarea> is not allowed as an immediate
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// child of a <select>; in normal parsing, a <textarea> implies </select>, but
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// one cannot close the implicit element when parsing a <select>'s InnerHTML.
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// Similarly to AllowCDATA, tracking the correct moment to override raw-text-
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// ness is difficult to do purely in the tokenizer, as opposed to the parser.
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// For strict compliance with the HTML5 tokenization algorithm, it is the
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// responsibility of the user of a tokenizer to call NextIsNotRawText as
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// appropriate. In practice, like AllowCDATA, it is acceptable to ignore this
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// responsibility for basic usage.
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//
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// Note that this 'raw text' concept is different from the one offered by the
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// Tokenizer.Raw method.
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func (z *Tokenizer) NextIsNotRawText() {
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z.rawTag = ""
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}
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// Err returns the error associated with the most recent ErrorToken token.
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// This is typically io.EOF, meaning the end of tokenization.
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func (z *Tokenizer) Err() error {
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if z.tt != ErrorToken {
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return nil
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}
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return z.err
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}
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// readByte returns the next byte from the input stream, doing a buffered read
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// from z.r into z.buf if necessary. z.buf[z.raw.start:z.raw.end] remains a contiguous byte
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// slice that holds all the bytes read so far for the current token.
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// It sets z.err if the underlying reader returns an error.
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// Pre-condition: z.err == nil.
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func (z *Tokenizer) readByte() byte {
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if z.raw.end >= len(z.buf) {
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// Our buffer is exhausted and we have to read from z.r. Check if the
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// previous read resulted in an error.
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if z.readErr != nil {
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z.err = z.readErr
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return 0
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}
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// We copy z.buf[z.raw.start:z.raw.end] to the beginning of z.buf. If the length
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// z.raw.end - z.raw.start is more than half the capacity of z.buf, then we
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// allocate a new buffer before the copy.
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c := cap(z.buf)
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d := z.raw.end - z.raw.start
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var buf1 []byte
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if 2*d > c {
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buf1 = make([]byte, d, 2*c)
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} else {
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buf1 = z.buf[:d]
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}
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copy(buf1, z.buf[z.raw.start:z.raw.end])
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if x := z.raw.start; x != 0 {
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// Adjust the data/attr spans to refer to the same contents after the copy.
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z.data.start -= x
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z.data.end -= x
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z.pendingAttr[0].start -= x
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z.pendingAttr[0].end -= x
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z.pendingAttr[1].start -= x
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z.pendingAttr[1].end -= x
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for i := range z.attr {
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z.attr[i][0].start -= x
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z.attr[i][0].end -= x
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z.attr[i][1].start -= x
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z.attr[i][1].end -= x
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}
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}
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z.raw.start, z.raw.end, z.buf = 0, d, buf1[:d]
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// Now that we have copied the live bytes to the start of the buffer,
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// we read from z.r into the remainder.
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var n int
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n, z.readErr = readAtLeastOneByte(z.r, buf1[d:cap(buf1)])
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if n == 0 {
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z.err = z.readErr
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return 0
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}
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z.buf = buf1[:d+n]
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}
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x := z.buf[z.raw.end]
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z.raw.end++
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if z.maxBuf > 0 && z.raw.end-z.raw.start >= z.maxBuf {
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z.err = ErrBufferExceeded
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return 0
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}
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return x
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}
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// Buffered returns a slice containing data buffered but not yet tokenized.
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func (z *Tokenizer) Buffered() []byte {
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return z.buf[z.raw.end:]
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}
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// readAtLeastOneByte wraps an io.Reader so that reading cannot return (0, nil).
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// It returns io.ErrNoProgress if the underlying r.Read method returns (0, nil)
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// too many times in succession.
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func readAtLeastOneByte(r io.Reader, b []byte) (int, error) {
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for i := 0; i < 100; i++ {
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n, err := r.Read(b)
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if n != 0 || err != nil {
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return n, err
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}
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}
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return 0, io.ErrNoProgress
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}
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// skipWhiteSpace skips past any white space.
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func (z *Tokenizer) skipWhiteSpace() {
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if z.err != nil {
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return
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}
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for {
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c := z.readByte()
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if z.err != nil {
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return
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}
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switch c {
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case ' ', '\n', '\r', '\t', '\f':
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// No-op.
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default:
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z.raw.end--
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return
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}
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}
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}
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// readRawOrRCDATA reads until the next "</foo>", where "foo" is z.rawTag and
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// is typically something like "script" or "textarea".
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func (z *Tokenizer) readRawOrRCDATA() {
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if z.rawTag == "script" {
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z.readScript()
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z.textIsRaw = true
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z.rawTag = ""
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return
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}
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loop:
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for {
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c := z.readByte()
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if z.err != nil {
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break loop
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}
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if c != '<' {
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continue loop
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}
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c = z.readByte()
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if z.err != nil {
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break loop
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}
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if c != '/' {
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continue loop
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}
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if z.readRawEndTag() || z.err != nil {
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break loop
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}
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}
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z.data.end = z.raw.end
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// A textarea's or title's RCDATA can contain escaped entities.
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z.textIsRaw = z.rawTag != "textarea" && z.rawTag != "title"
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z.rawTag = ""
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}
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// readRawEndTag attempts to read a tag like "</foo>", where "foo" is z.rawTag.
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// If it succeeds, it backs up the input position to reconsume the tag and
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// returns true. Otherwise it returns false. The opening "</" has already been
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// consumed.
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func (z *Tokenizer) readRawEndTag() bool {
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for i := 0; i < len(z.rawTag); i++ {
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c := z.readByte()
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if z.err != nil {
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return false
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}
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if c != z.rawTag[i] && c != z.rawTag[i]-('a'-'A') {
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z.raw.end--
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return false
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}
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}
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c := z.readByte()
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if z.err != nil {
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return false
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}
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switch c {
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case ' ', '\n', '\r', '\t', '\f', '/', '>':
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// The 3 is 2 for the leading "</" plus 1 for the trailing character c.
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z.raw.end -= 3 + len(z.rawTag)
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return true
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}
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z.raw.end--
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return false
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}
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// readScript reads until the next </script> tag, following the byzantine
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// rules for escaping/hiding the closing tag.
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func (z *Tokenizer) readScript() {
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defer func() {
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z.data.end = z.raw.end
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}()
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var c byte
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scriptData:
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c = z.readByte()
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if z.err != nil {
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return
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}
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if c == '<' {
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goto scriptDataLessThanSign
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}
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goto scriptData
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scriptDataLessThanSign:
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c = z.readByte()
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if z.err != nil {
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return
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}
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switch c {
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case '/':
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goto scriptDataEndTagOpen
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case '!':
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goto scriptDataEscapeStart
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}
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z.raw.end--
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goto scriptData
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scriptDataEndTagOpen:
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if z.readRawEndTag() || z.err != nil {
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return
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}
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goto scriptData
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|
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scriptDataEscapeStart:
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c = z.readByte()
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if z.err != nil {
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return
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}
|
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if c == '-' {
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goto scriptDataEscapeStartDash
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}
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z.raw.end--
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goto scriptData
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|
|
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scriptDataEscapeStartDash:
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c = z.readByte()
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if z.err != nil {
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return
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}
|
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if c == '-' {
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goto scriptDataEscapedDashDash
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}
|
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z.raw.end--
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goto scriptData
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|
|
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scriptDataEscaped:
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c = z.readByte()
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if z.err != nil {
|
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return
|
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}
|
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switch c {
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case '-':
|
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goto scriptDataEscapedDash
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case '<':
|
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goto scriptDataEscapedLessThanSign
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}
|
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goto scriptDataEscaped
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|
|
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scriptDataEscapedDash:
|
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c = z.readByte()
|
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if z.err != nil {
|
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return
|
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}
|
|
switch c {
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case '-':
|
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goto scriptDataEscapedDashDash
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|
case '<':
|
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goto scriptDataEscapedLessThanSign
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|
}
|
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goto scriptDataEscaped
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|
|
|
scriptDataEscapedDashDash:
|
|
c = z.readByte()
|
|
if z.err != nil {
|
|
return
|
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}
|
|
switch c {
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|
case '-':
|
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goto scriptDataEscapedDashDash
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|
case '<':
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goto scriptDataEscapedLessThanSign
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case '>':
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goto scriptData
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}
|
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goto scriptDataEscaped
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|
|
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scriptDataEscapedLessThanSign:
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c = z.readByte()
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if z.err != nil {
|
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return
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}
|
|
if c == '/' {
|
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goto scriptDataEscapedEndTagOpen
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}
|
|
if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' {
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goto scriptDataDoubleEscapeStart
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|
}
|
|
z.raw.end--
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goto scriptData
|
|
|
|
scriptDataEscapedEndTagOpen:
|
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if z.readRawEndTag() || z.err != nil {
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return
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}
|
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goto scriptDataEscaped
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|
|
|
scriptDataDoubleEscapeStart:
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z.raw.end--
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for i := 0; i < len("script"); i++ {
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c = z.readByte()
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if z.err != nil {
|
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return
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}
|
|
if c != "script"[i] && c != "SCRIPT"[i] {
|
|
z.raw.end--
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goto scriptDataEscaped
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}
|
|
}
|
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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.
|
|
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 next 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
|
|
}
|