From 6312ad4bf7e48347539eb5b4c5075e447d8142f3 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Fri, 26 Jan 2018 12:18:59 +0100 Subject: Add verndor --- vendor/golang.org/x/net/html/doc.go | 106 ++++++++++++++++++++++++++++++++++++ 1 file changed, 106 insertions(+) create mode 100644 vendor/golang.org/x/net/html/doc.go (limited to 'vendor/golang.org/x/net/html/doc.go') diff --git a/vendor/golang.org/x/net/html/doc.go b/vendor/golang.org/x/net/html/doc.go new file mode 100644 index 0000000..822ed42 --- /dev/null +++ b/vendor/golang.org/x/net/html/doc.go @@ -0,0 +1,106 @@ +// 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 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.ErrorToken { + // ... + 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.ErrorToken { + // Returning io.EOF indicates success. + return z.Err() + } + 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 html.ErrorToken: + return z.Err() + case html.TextToken: + if depth > 0 { + // emitBytes should copy the []byte it receives, + // if it doesn't process it immediately. + emitBytes(z.Text()) + } + case html.StartTagToken, html.EndTagToken: + tn, _ := z.TagName() + if len(tn) == 1 && tn[0] == 'a' { + if tt == html.StartTagToken { + depth++ + } else { + depth-- + } + } + } + } + +Parsing is done by calling Parse with an io.Reader, which returns the root of +the parse tree (the document element) as a *Node. It is the caller's +responsibility to ensure that the Reader provides UTF-8 encoded HTML. For +example, to process each anchor node in depth-first order: + + doc, err := html.Parse(r) + if err != nil { + // ... + } + var f func(*html.Node) + f = func(n *html.Node) { + if n.Type == html.ElementNode && n.Data == "a" { + // Do something with n... + } + for c := n.FirstChild; c != nil; c = c.NextSibling { + f(c) + } + } + f(doc) + +The relevant specifications include: +https://html.spec.whatwg.org/multipage/syntax.html and +https://html.spec.whatwg.org/multipage/syntax.html#tokenization +*/ +package html // import "golang.org/x/net/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): Does a DOM API belong in this package or a separate one? +// TODO(nigeltao): How does parsing interact with a JavaScript engine? -- cgit v1.2.3