hash/adler32\
hash/crc32\
hash/crc64\
+ html\
http\
http/pprof\
image\
--- /dev/null
+# 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.
+
+include ../../Make.$(GOARCH)
+
+TARG=html
+GOFILES=\
+ doc.go\
+ entity.go\
+ escape.go\
+ token.go\
+
+include ../../Make.pkg
--- /dev/null
+// 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.
+
+/*
+The html package implements an HTML5-compliant tokenizer and parser.
+
+Tokenization is done by creating a Tokenizer for an io.Reader r. It is the
+caller's responsibility to ensure that r provides UTF-8 encoded HTML.
+
+ z := html.NewTokenizer(r)
+
+Given a Tokenizer z, the HTML is tokenized by repeatedly calling z.Next(),
+which parses the next token and returns its type, or an error:
+
+ for {
+ tt := z.Next()
+ if tt == html.Error {
+ // ...
+ return ...
+ }
+ // Process the current token.
+ }
+
+There are two APIs for retrieving the current token. The high-level API is to
+call Token; the low-level API is to call Text or TagName / TagAttr. Both APIs
+allow optionally calling Raw after Next but before Token, Text, TagName, or
+TagAttr. In EBNF notation, the valid call sequence per token is:
+
+ Next {Raw} [ Token | Text | TagName {TagAttr} ]
+
+Token returns an independent data structure that completely describes a token.
+Entities (such as "<") are unescaped, tag names and attribute keys are
+lower-cased, and attributes are collected into a []Attribute. For example:
+
+ for {
+ if z.Next() == html.Error {
+ // Returning os.EOF indicates success.
+ return z.Error()
+ }
+ emitToken(z.Token())
+ }
+
+The low-level API performs fewer allocations and copies, but the contents of
+the []byte values returned by Text, TagName and TagAttr may change on the next
+call to Next. For example, to extract an HTML page's anchor text:
+
+ depth := 0
+ for {
+ tt := z.Next()
+ switch tt {
+ case Error:
+ return z.Error()
+ case Text:
+ if depth > 0 {
+ // emitBytes should copy the []byte it receives,
+ // if it doesn't process it immediately.
+ emitBytes(z.Text())
+ }
+ case StartTag, EndTag:
+ tn, _ := z.TagName()
+ if len(tn) == 1 && tn[0] == 'a' {
+ if tt == StartTag {
+ depth++
+ } else {
+ depth--
+ }
+ }
+ }
+ }
+
+The relevant specifications include:
+http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html and
+http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html
+*/
+package html
+
+// The tokenization algorithm implemented by this package is not a line-by-line
+// transliteration of the relatively verbose state-machine in the WHATWG
+// specification. A more direct approach is used instead, where the program
+// counter implies the state, such as whether it is tokenizing a tag or a text
+// node. Specification compliance is verified by checking expected and actual
+// outputs over a test suite rather than aiming for algorithmic fidelity.
+
+// TODO(nigeltao): Implement a parser, not just a tokenizer.
+// TODO(nigeltao): Does a DOM API belong in this package or a separate one?
+// TODO(nigeltao): How does parsing interact with a JavaScript engine?
--- /dev/null
+// 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 (
+ "utf8"
+)
+
+// entity is a map from HTML entity names to their values. The semicolon matters:
+// http://www.whatwg.org/specs/web-apps/current-work/multipage/named-character-references.html
+// lists both "amp" and "amp;" as two separate entries.
+//
+// TODO(nigeltao): Take the complete map from the HTML5 spec section 10.5 "Named character references".
+// http://www.whatwg.org/specs/web-apps/current-work/multipage/named-character-references.html
+// Note that the HTML5 list is larger than the HTML4 list at
+// http://www.w3.org/TR/html4/sgml/entities.html
+var entity = map[string]int{
+ "aacute": '\U000000E1',
+ "aacute;": '\U000000E1',
+ "amp;": '\U00000026',
+ "apos;": '\U00000027',
+ "gt;": '\U0000003E',
+ "lt;": '\U0000003C',
+ "quot;": '\U00000022',
+}
+
+func init() {
+ // We verify that the length of UTF-8 encoding of each value is <= 1 + len(key).
+ // The +1 comes from the leading "&". This property implies that the length of
+ // unescaped text is <= the length of escaped text.
+ for k, v := range entity {
+ if 1+len(k) < utf8.RuneLen(v) {
+ panic("escaped entity &" + k + " is shorter than its UTF-8 encoding " + string(v))
+ }
+ }
+}
--- /dev/null
+// 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 (
+ "strings"
+ "utf8"
+)
+
+// unescapeEntity reads an entity like "<" from b[src:] and writes the
+// corresponding "<" to b[dst:], returning the incremented dst and src cursors.
+// Precondition: src[0] == '&' && dst <= src.
+func unescapeEntity(b []byte, dst, src int) (dst1, src1 int) {
+ // TODO(nigeltao): Check that this entity substitution algorithm matches the spec:
+ // http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#consume-a-character-reference
+ // TODO(nigeltao): Handle things like "中" or "中".
+
+ // i starts at 1 because we already know that s[0] == '&'.
+ i, s := 1, b[src:]
+ 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' {
+ continue
+ }
+ if c != ';' {
+ i--
+ }
+ x := entity[string(s[1:i])]
+ if x != 0 {
+ return dst + utf8.EncodeRune(x, b[dst:]), src + i
+ }
+ break
+ }
+ 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".
+func unescape(b []byte) []byte {
+ for i, c := range b {
+ if c == '&' {
+ dst, src := unescapeEntity(b, i, i)
+ for src < len(b) {
+ c := b[src]
+ if c == '&' {
+ dst, src = unescapeEntity(b, dst, src)
+ } else {
+ b[dst] = c
+ dst, src = dst+1, src+1
+ }
+ }
+ return b[0:dst]
+ }
+ }
+ return b
+}
+
+// EscapeString escapes special characters like "<" to become "<". It
+// escapes only five such characters: amp, apos, lt, gt and quot.
+// UnescapeString(EscapeString(s)) == s always holds, but the converse isn't
+// always true.
+func EscapeString(s string) string {
+ // TODO(nigeltao): Do this much more efficiently.
+ s = strings.Replace(s, `&`, `&`, -1)
+ s = strings.Replace(s, `'`, `'`, -1)
+ s = strings.Replace(s, `<`, `<`, -1)
+ s = strings.Replace(s, `>`, `>`, -1)
+ s = strings.Replace(s, `"`, `"`, -1)
+ return s
+}
+
+// UnescapeString unescapes entities like "<" to become "<". It unescapes a
+// larger range of entities than EscapeString escapes. For example, "á"
+// unescapes to "รก", as does "á" and "&xE1;".
+// UnescapeString(EscapeString(s)) == s always holds, but the converse isn't
+// always true.
+func UnescapeString(s string) string {
+ for _, c := range s {
+ if c == '&' {
+ return string(unescape([]byte(s)))
+ }
+ }
+ return s
+}
--- /dev/null
+// 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 (
+ "io"
+ "log"
+ "os"
+ "strconv"
+)
+
+func init() {
+ // TODO(nigeltao): Remove this when ready.
+ log.Stderr("The html package is incomplete; do not use for production software.")
+}
+
+// A TokenType is the type of a Token.
+type TokenType int
+
+const (
+ // Error means that an error occurred during tokenization.
+ Error TokenType = iota
+ // Text means a text node.
+ Text
+ // A StartTag looks like <a>.
+ StartTag
+ // An EndTag looks like </a>.
+ EndTag
+ // A SelfClosingTag tag looks like <br/>.
+ SelfClosingTag
+)
+
+// String returns a string representation of the TokenType.
+func (t TokenType) String() string {
+ switch t {
+ case Error:
+ return "Error"
+ case Text:
+ return "Text"
+ case StartTag:
+ return "StartTag"
+ case EndTag:
+ return "EndTag"
+ case SelfClosingTag:
+ return "SelfClosingTag"
+ }
+ return "Invalid(" + strconv.Itoa(int(t)) + ")"
+}
+
+// An Attribute is an attribute key-value pair. 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").
+type Attribute struct {
+ Key, Val string
+}
+
+// A Token consists of a TokenType and some Data (tag name for start and end
+// tags, content for text). A tag Token may also contain a slice of Attributes.
+// Data is unescaped for both tag and text Tokens (it looks like "a<b" rather
+// than "a<b").
+type Token struct {
+ Type TokenType
+ Data string
+ Attr []Attribute
+}
+
+// tagString returns a string representation of a tag Token's Data and Attr.
+func (t Token) tagString() string {
+ // TODO(nigeltao): Don't use string concatenation; it is inefficient.
+ s := string(t.Data)
+ for _, a := range t.Attr {
+ s += ` ` + a.Key + `="` + EscapeString(a.Val) + `"`
+ }
+ return s
+}
+
+// String returns a string representation of the Token.
+func (t Token) String() string {
+ switch t.Type {
+ case Error:
+ return ""
+ case Text:
+ return EscapeString(t.Data)
+ case StartTag:
+ return "<" + t.tagString() + ">"
+ case EndTag:
+ return "</" + t.tagString() + ">"
+ case SelfClosingTag:
+ return "<" + t.tagString() + "/>"
+ }
+ return "Invalid(" + strconv.Itoa(int(t.Type)) + ")"
+}
+
+// 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 most recently read token. If tt == Error
+ // then err is the error associated with trying to read that token.
+ tt TokenType
+ err os.Error
+ // buf[p0:p1] holds the raw data of the most recent token.
+ // buf[p1:] is buffered input that will yield future tokens.
+ p0, p1 int
+ buf []byte
+}
+
+// Error returns the error associated with the most recent Error token. This is
+// typically os.EOF, meaning the end of tokenization.
+func (z *Tokenizer) Error() os.Error {
+ if z.tt != Error {
+ return nil
+ }
+ return z.err
+}
+
+// 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.p0:z.p1]
+}
+
+// readByte returns the next byte from the input stream, doing a buffered read
+// from z.r into z.buf if necessary. z.buf[z.p0:z.p1] remains a contiguous byte
+// slice that holds all the bytes read so far for the current token.
+func (z *Tokenizer) readByte() (byte, os.Error) {
+ if z.p1 >= len(z.buf) {
+ // Our buffer is exhausted and we have to read from z.r.
+ // We copy z.buf[z.p0:z.p1] to the beginning of z.buf. If the length
+ // z.p1 - z.p0 is more than half the capacity of z.buf, then we
+ // allocate a new buffer before the copy.
+ c := cap(z.buf)
+ d := z.p1 - z.p0
+ var buf1 []byte
+ if 2*d > c {
+ buf1 = make([]byte, d, 2*c)
+ } else {
+ buf1 = z.buf[0:d]
+ }
+ copy(buf1, z.buf[z.p0:z.p1])
+ z.p0, z.p1, z.buf = 0, d, buf1[0:d]
+ // Now that we have copied the live bytes to the start of the buffer,
+ // we read from z.r into the remainder.
+ n, err := z.r.Read(buf1[d:cap(buf1)])
+ if err != nil {
+ return 0, err
+ }
+ z.buf = buf1[0 : d+n]
+ }
+ x := z.buf[z.p1]
+ z.p1++
+ return x, nil
+}
+
+// readTo keeps reading bytes until x is found.
+func (z *Tokenizer) readTo(x uint8) os.Error {
+ for {
+ c, err := z.readByte()
+ if err != nil {
+ return err
+ }
+ switch c {
+ case x:
+ return nil
+ case '\\':
+ _, err = z.readByte()
+ if err != nil {
+ return err
+ }
+ }
+ }
+ panic("unreachable")
+}
+
+// nextTag returns the next TokenType starting from the tag open state.
+func (z *Tokenizer) nextTag() (tt TokenType, err os.Error) {
+ c, err := z.readByte()
+ if err != nil {
+ return Error, err
+ }
+ switch {
+ case c == '/':
+ tt = EndTag
+ // Lower-cased characters are more common in tag names, so we check for them first.
+ case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z':
+ tt = StartTag
+ case c == '!':
+ return Error, os.NewError("html: TODO(nigeltao): implement comments")
+ case c == '?':
+ return Error, os.NewError("html: TODO(nigeltao): implement XML processing instructions")
+ default:
+ return Error, os.NewError("html: TODO(nigeltao): handle malformed tags")
+ }
+ for {
+ c, err := z.readByte()
+ if err != nil {
+ return Text, err
+ }
+ switch c {
+ case '"':
+ err = z.readTo('"')
+ if err != nil {
+ return Text, err
+ }
+ case '\'':
+ err = z.readTo('\'')
+ if err != nil {
+ return Text, err
+ }
+ case '>':
+ if z.buf[z.p1-2] == '/' && tt == StartTag {
+ return SelfClosingTag, nil
+ }
+ return tt, nil
+ }
+ }
+ panic("unreachable")
+}
+
+// Next scans the next token and returns its type.
+func (z *Tokenizer) Next() TokenType {
+ if z.err != nil {
+ z.tt = Error
+ return z.tt
+ }
+ z.p0 = z.p1
+ c, err := z.readByte()
+ if err != nil {
+ z.tt, z.err = Error, err
+ return z.tt
+ }
+ if c == '<' {
+ z.tt, z.err = z.nextTag()
+ return z.tt
+ }
+ for {
+ c, err := z.readByte()
+ if err != nil {
+ z.tt, z.err = Error, err
+ if err == os.EOF {
+ z.tt = Text
+ }
+ return z.tt
+ }
+ if c == '<' {
+ z.p1--
+ z.tt = Text
+ return z.tt
+ }
+ }
+ panic("unreachable")
+}
+
+// trim returns the largest j such that z.buf[i:j] contains only white space,
+// or only white space plus the final ">" or "/>" of the raw data.
+func (z *Tokenizer) trim(i int) int {
+ k := z.p1
+ for ; i < k; i++ {
+ switch z.buf[i] {
+ case ' ', '\n', '\t', '\f':
+ continue
+ case '>':
+ if i == k-1 {
+ return k
+ }
+ case '/':
+ if i == k-2 {
+ return k
+ }
+ }
+ return i
+ }
+ return k
+}
+
+// lower finds the largest alphabetic [a-zA-Z]* word at the start of z.buf[i:]
+// and returns that word lower-cased, as well as the trimmed cursor location
+// after that word.
+func (z *Tokenizer) lower(i int) ([]byte, int) {
+ i0 := i
+loop:
+ for ; i < z.p1; i++ {
+ c := z.buf[i]
+ // TODO(nigeltao): Check what '0' <= c && c <= '9' should do.
+ switch {
+ case 'A' <= c && c <= 'Z':
+ z.buf[i] = c + 'a' - 'A'
+ case 'a' <= c && c <= 'z':
+ // No-op.
+ default:
+ break loop
+ }
+ }
+ return z.buf[i0:i], z.trim(i)
+}
+
+// Text returns the raw data after unescaping.
+// The contents of the returned slice may change on the next call to Next.
+func (z *Tokenizer) Text() []byte {
+ s := unescape(z.Raw())
+ z.p0 = z.p1
+ return s
+}
+
+// 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, remaining bool) {
+ i := z.p0 + 1
+ if i >= z.p1 {
+ z.p0 = z.p1
+ return nil, false
+ }
+ if z.buf[i] == '/' {
+ i++
+ }
+ name, z.p0 = z.lower(i)
+ remaining = z.p0 != z.p1
+ return
+}
+
+// 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, remaining bool) {
+ key, i := z.lower(z.p0)
+ // Get past the "=\"".
+ if i == z.p1 || z.buf[i] != '=' {
+ return
+ }
+ i = z.trim(i + 1)
+ if i == z.p1 || z.buf[i] != '"' {
+ return
+ }
+ i = z.trim(i + 1)
+ // Copy and unescape everything up to the closing '"'.
+ dst, src := i, i
+loop:
+ for src < z.p1 {
+ c := z.buf[src]
+ switch c {
+ case '"':
+ src++
+ break loop
+ case '&':
+ dst, src = unescapeEntity(z.buf, dst, src)
+ case '\\':
+ if src == z.p1 {
+ z.buf[dst] = '\\'
+ dst++
+ } else {
+ z.buf[dst] = z.buf[src+1]
+ dst, src = dst+1, src+2
+ }
+ default:
+ z.buf[dst] = c
+ dst, src = dst+1, src+1
+ }
+ }
+ val, z.p0 = z.buf[i:dst], z.trim(src)
+ remaining = z.p0 != z.p1
+ return
+}
+
+// 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 Text:
+ t.Data = string(z.Text())
+ case StartTag, EndTag, SelfClosingTag:
+ var (
+ attr []Attribute
+ a int
+ )
+ name, remaining := z.TagName()
+ for remaining {
+ var key, val []byte
+ key, val, remaining = z.TagAttr()
+ if a == len(attr) {
+ // Grow the attr slice.
+ n := 4 + 2*a
+ attr1 := make([]Attribute, n, n)
+ copy(attr1, attr)
+ attr = attr1
+ }
+ attr[a] = Attribute{string(key), string(val)}
+ a++
+ }
+ t.Data = string(name)
+ t.Attr = attr[0:a]
+ }
+ return t
+}
+
+// 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 &Tokenizer{
+ r: r,
+ buf: make([]byte, 0, 4096),
+ }
+}
--- /dev/null
+// 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"
+ "os"
+ "testing"
+)
+
+type tokenTest struct {
+ // A short description of the test case.
+ desc string
+ // The HTML to parse.
+ html string
+ // The string representations of the expected tokens.
+ tokens []string
+}
+
+var tokenTests = []tokenTest{
+ // A single text node. The tokenizer should not break text nodes on whitespace,
+ // nor should it normalize whitespace within a text node.
+ tokenTest{
+ "text",
+ "foo bar",
+ []string{
+ "foo bar",
+ },
+ },
+ // An entity.
+ tokenTest{
+ "entity",
+ "one < two",
+ []string{
+ "one < two",
+ },
+ },
+ // A start, self-closing and end tag. The tokenizer does not care if the start
+ // and end tokens don't match; that is the job of the parser.
+ tokenTest{
+ "tags",
+ "<a>b<c/>d</e>",
+ []string{
+ "<a>",
+ "b",
+ "<c/>",
+ "d",
+ "</e>",
+ },
+ },
+ // An attribute with a backslash.
+ tokenTest{
+ "backslash",
+ `<p id="a\"b">`,
+ []string{
+ `<p id="a"b">`,
+ },
+ },
+ // Entities, tag name and attribute key lower-casing, and whitespace
+ // normalization within a tag.
+ tokenTest{
+ "tricky",
+ "<p \t\n iD=\"a"B\" foo=\"bar\"><EM>te<&;xt</em></p>",
+ []string{
+ `<p id="a"B" foo="bar">`,
+ "<em>",
+ "te<&;xt",
+ "</em>",
+ "</p>",
+ },
+ },
+ // A non-existant entity. Tokenizing and converting back to a string should
+ // escape the "&" to become "&".
+ tokenTest{
+ "noSuchEntity",
+ `<a b="c&noSuchEntity;d"><&alsoDoesntExist;&`,
+ []string{
+ `<a b="c&noSuchEntity;d">`,
+ "<&alsoDoesntExist;&",
+ },
+ },
+}
+
+func TestTokenizer(t *testing.T) {
+loop:
+ for _, tt := range tokenTests {
+ z := NewTokenizer(bytes.NewBuffer([]byte(tt.html)))
+ for i, s := range tt.tokens {
+ if z.Next() == Error {
+ t.Errorf("%s token %d: want %q got error %v", tt.desc, i, s, z.Error())
+ continue loop
+ }
+ actual := z.Token().String()
+ if s != actual {
+ t.Errorf("%s token %d: want %q got %q", tt.desc, i, s, actual)
+ continue loop
+ }
+ }
+ z.Next()
+ if z.Error() != os.EOF {
+ t.Errorf("%s: want EOF got %q", tt.desc, z.Token().String())
+ }
+ }
+}
+
+func TestUnescapeEscape(t *testing.T) {
+ ss := []string{
+ ``,
+ `abc def`,
+ `a & b`,
+ `a&b`,
+ `a & b`,
+ `"`,
+ `"`,
+ `"<&>"`,
+ `"<&>"`,
+ `3&5==1 && 0<1, "0<1", a+acute=á`,
+ }
+ for _, s := range ss {
+ if s != UnescapeString(EscapeString(s)) {
+ t.Errorf("s != UnescapeString(EscapeString(s)), s=%q", s)
+ }
+ }
+}
+
+func TestBufAPI(t *testing.T) {
+ s := "0<a>1</a>2<b>3<a>4<a>5</a>6</b>7</a>8<a/>9"
+ z := NewTokenizer(bytes.NewBuffer([]byte(s)))
+ result := bytes.NewBuffer(nil)
+ depth := 0
+loop:
+ for {
+ tt := z.Next()
+ switch tt {
+ case Error:
+ if z.Error() != os.EOF {
+ t.Error(z.Error())
+ }
+ break loop
+ case Text:
+ if depth > 0 {
+ result.Write(z.Text())
+ }
+ case StartTag, EndTag:
+ tn, _ := z.TagName()
+ if len(tn) == 1 && tn[0] == 'a' {
+ if tt == StartTag {
+ depth++
+ } else {
+ depth--
+ }
+ }
+ }
+ }
+ u := "14567"
+ v := string(result.Bytes())
+ if u != v {
+ t.Errorf("TestBufAPI: want %q got %q", u, v)
+ }
+}