' byte that, per above, we'd like to avoid escaping unless we have to.
+//
+// Studying the summary table (and T actions in its '>' column) closely, we
+// only need to escape in states 43, 44, 49, 51 and 52. State 43 is at the
+// start of the comment data. State 52 is after a '!'. The other three states
+// are after a '-'.
+//
+// Our algorithm is thus to escape every '&' and to escape '>' if and only if:
+// - The '>' is after a '!' or '-' (in the unescaped data) or
+// - The '>' is at the start of the comment data (after the opening ""
+ case DoctypeToken:
+ return ""
+ }
+ 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 "" that closes the next token. If
+ // non-empty, the subsequent call to Next will return a raw or RCDATA text
+ // token: one that treats "" 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 as
+// the text "foo". The default value is false, which means to recognize it as
+// a bogus comment "" 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 element
+// can contain a 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 "a<b>c</b>d "
+// yields a start tag token for "", a text token for "a<b>c</b>d", and
+// an end tag token for " ". There are no distinct start tag or end tag
+// tokens for the "" and " ".
+//
+// 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: 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() {
+ // When modifying this function, consider manually increasing the
+ // maxSuffixLen constant in func TestComments, from 6 to e.g. 9 or more.
+ // That increase should only be temporary, not committed, as it
+ // exponentially affects the test running time.
+
+ 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 {
+ z.data.end = z.calculateAbruptCommentDataEnd()
+ 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.calculateAbruptCommentDataEnd()
+ return
+ } else if c == '>' {
+ z.data.end = z.raw.end - len("--!>")
+ return
+ } else if c == '-' {
+ dashCount = 1
+ beginning = false
+ continue
+ }
+ }
+ }
+ dashCount = 0
+ beginning = false
+ }
+}
+
+func (z *Tokenizer) calculateAbruptCommentDataEnd() int {
+ raw := z.Raw()
+ const prefixLen = len("<!--")
+ if len(raw) >= prefixLen {
+ raw = raw[prefixLen:]
+ if hasSuffix(raw, "--!") {
+ return z.raw.end - 3
+ } else if hasSuffix(raw, "--") {
+ return z.raw.end - 2
+ } else if hasSuffix(raw, "-") {
+ return z.raw.end - 1
+ }
+ }
+ return z.raw.end
+}
+
+func hasSuffix(b []byte, suffix string) bool {
+ if len(b) < len(suffix) {
+ return false
+ }
+ b = b[len(b)-len(suffix):]
+ for i := range b {
+ if b[i] != suffix[i] {
+ return false
+ }
+ }
+ return true
+}
+
+// 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 '=':
+ if z.pendingAttr[0].start+1 == z.raw.end {
+ // WHATWG 13.2.5.32, if we see an equals sign before the attribute name
+ // begins, we treat it as a character in the attribute name and continue.
+ continue
+ }
+ fallthrough
+ case ' ', '\n', '\r', '\t', '\f', '/', '>':
+ // WHATWG 13.2.5.33 Attribute name state
+ // We need to reconsume the char in the after attribute name state to support the / character
+ 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 == '/' {
+ // WHATWG 13.2.5.34 After attribute name state
+ // U+002F SOLIDUS (/) - Switch to the self-closing start tag state.
+ 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
+ // MOD -- remove lower(s)
+ return s, z.nAttrReturned < len(z.attr)
+ // 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]
+ // MOD -- remove lower(s)
+ return key, unescape(convertNewlines(val), true), z.nAttrReturned < len(z.attr)
+ // 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
+}
+
+// lower lower-cases the A-Z bytes in b in-place, so that "aBc" becomes "abc".
+func lower(b []byte) []byte {
+ for i, c := range b {
+ if 'A' <= c && c <= 'Z' {
+ b[i] = c + 'a' - 'A'
+ }
+ }
+ return b
+}
+
+// unescapeEntity reads an entity like "<" from b[src:] and writes the
+// corresponding "<" to b[dst:], returning the incremented dst and src cursors.
+// Precondition: b[src] == '&' && dst <= src.
+// attribute should be true if parsing an attribute value.
+func unescapeEntity(b []byte, dst, src int, attribute bool) (dst1, src1 int) {
+ // https://html.spec.whatwg.org/multipage/syntax.html#consume-a-character-reference
+
+ // i starts at 1 because we already know that s[0] == '&'.
+ i, s := 1, b[src:]
+
+ if len(s) <= 1 {
+ b[dst] = b[src]
+ return dst + 1, src + 1
+ }
+
+ if s[i] == '#' {
+ if len(s) <= 3 { // We need to have at least "&#.".
+ b[dst] = b[src]
+ return dst + 1, src + 1
+ }
+ i++
+ c := s[i]
+ hex := false
+ if c == 'x' || c == 'X' {
+ hex = true
+ i++
+ }
+
+ x := '\x00'
+ for i < len(s) {
+ c = s[i]
+ i++
+ if hex {
+ if '0' <= c && c <= '9' {
+ x = 16*x + rune(c) - '0'
+ continue
+ } else if 'a' <= c && c <= 'f' {
+ x = 16*x + rune(c) - 'a' + 10
+ continue
+ } else if 'A' <= c && c <= 'F' {
+ x = 16*x + rune(c) - 'A' + 10
+ continue
+ }
+ } else if '0' <= c && c <= '9' {
+ x = 10*x + rune(c) - '0'
+ continue
+ }
+ if c != ';' {
+ i--
+ }
+ break
+ }
+
+ if i <= 3 { // No characters matched.
+ b[dst] = b[src]
+ return dst + 1, src + 1
+ }
+
+ if 0x80 <= x && x <= 0x9F {
+ // Replace characters from Windows-1252 with UTF-8 equivalents.
+ x = replacementTable[x-0x80]
+ } else if x == 0 || (0xD800 <= x && x <= 0xDFFF) || x > 0x10FFFF {
+ // Replace invalid characters with the replacement character.
+ x = '\uFFFD'
+ }
+
+ return dst + utf8.EncodeRune(b[dst:], x), src + i
+ }
+
+ // Consume the maximum number of characters possible, with the
+ // consumed characters matching one of the named references.
+
+ for i < len(s) {
+ c := s[i]
+ i++
+ // Lower-cased characters are more common in entities, so we check for them first.
+ if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9' {
+ continue
+ }
+ if c != ';' {
+ i--
+ }
+ break
+ }
+
+ entityName := string(s[1:i])
+ if entityName == "" {
+ // No-op.
+ } else if attribute && entityName[len(entityName)-1] != ';' && len(s) > i && s[i] == '=' {
+ // No-op.
+ } else if x := entity[entityName]; x != 0 {
+ return dst + utf8.EncodeRune(b[dst:], x), src + i
+ } else if x := entity2[entityName]; x[0] != 0 {
+ dst1 := dst + utf8.EncodeRune(b[dst:], x[0])
+ return dst1 + utf8.EncodeRune(b[dst1:], x[1]), src + i
+ } else if !attribute {
+ maxLen := len(entityName) - 1
+ if maxLen > longestEntityWithoutSemicolon {
+ maxLen = longestEntityWithoutSemicolon
+ }
+ for j := maxLen; j > 1; j-- {
+ if x := entity[entityName[:j]]; x != 0 {
+ return dst + utf8.EncodeRune(b[dst:], x), src + j + 1
+ }
+ }
+ }
+
+ dst1, src1 = dst+i, src+i
+ copy(b[dst:dst1], b[src:src1])
+ return dst1, src1
+}
+
+// unescape unescapes b's entities in-place, so that "a<b" becomes "a<b".
+// attribute should be true if parsing an attribute value.
+func unescape(b []byte, attribute bool) []byte {
+ for i, c := range b {
+ if c == '&' {
+ dst, src := unescapeEntity(b, i, i, attribute)
+ for src < len(b) {
+ c := b[src]
+ if c == '&' {
+ dst, src = unescapeEntity(b, dst, src, attribute)
+ } else {
+ b[dst] = c
+ dst, src = dst+1, src+1
+ }
+ }
+ return b[0:dst]
+ }
+ }
+ return b
+}
+
+// These replacements permit compatibility with old numeric entities that
+// assumed Windows-1252 encoding.
+// https://html.spec.whatwg.org/multipage/syntax.html#consume-a-character-reference
+var replacementTable = [...]rune{
+ '\u20AC', // First entry is what 0x80 should be replaced with.
+ '\u0081',
+ '\u201A',
+ '\u0192',
+ '\u201E',
+ '\u2026',
+ '\u2020',
+ '\u2021',
+ '\u02C6',
+ '\u2030',
+ '\u0160',
+ '\u2039',
+ '\u0152',
+ '\u008D',
+ '\u017D',
+ '\u008F',
+ '\u0090',
+ '\u2018',
+ '\u2019',
+ '\u201C',
+ '\u201D',
+ '\u2022',
+ '\u2013',
+ '\u2014',
+ '\u02DC',
+ '\u2122',
+ '\u0161',
+ '\u203A',
+ '\u0153',
+ '\u009D',
+ '\u017E',
+ '\u0178', // Last entry is 0x9F.
+ // 0x00->'\uFFFD' is handled programmatically.
+ // 0x0D->'\u000D' is a no-op.
+}