diff options
author | Rob Pike <r@golang.org> | 2009-06-09 09:53:44 -0700 |
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committer | Rob Pike <r@golang.org> | 2009-06-09 09:53:44 -0700 |
commit | 7249ea4df2b4f12a4e7ed446f270cea87e4ffd34 (patch) | |
tree | 7032a11d0cac2ae4d3e90f7a189b575b5a50f848 /src/lib/xml/xml.go | |
parent | acf6ef7a82b3fe61516a1bac4563706552bdf078 (diff) | |
download | golang-7249ea4df2b4f12a4e7ed446f270cea87e4ffd34.tar.gz |
mv src/lib to src/pkg
tests: all.bash passes, gobuild still works, godoc still works.
R=rsc
OCL=30096
CL=30102
Diffstat (limited to 'src/lib/xml/xml.go')
-rw-r--r-- | src/lib/xml/xml.go | 426 |
1 files changed, 0 insertions, 426 deletions
diff --git a/src/lib/xml/xml.go b/src/lib/xml/xml.go deleted file mode 100644 index bd944337e..000000000 --- a/src/lib/xml/xml.go +++ /dev/null @@ -1,426 +0,0 @@ -// Copyright 2009 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. - -// NOTE(rsc): Actually, this package is just a description -// of an implementation that hasn't been written yet. - -// This package implements an XML parser but relies on -// clients to implement the parsing actions. - -// An XML document is a single XML element. -// -// An XML element is either a start tag and an end tag, -// like <tag>...</tag>, or a combined start/end tag <tag/>. -// The latter is identical in semantics to <tag></tag>, -// and this parser does not distinguish them. -// -// The start (or combined start/end) tag can have -// name="value" attributes inside the angle brackets after -// the tag name, as in <img src="http://google.com/icon.png" alt="Google">. -// Names are drawn from a fixed set of alphabetic letters; -// Values are strings quoted with single or double quotes. -// -// An element made up of distinct start and end tags can -// contain free-form text and other elements inside it, -// as in <a href="http://www.google.com">Google</a> -// or <b><a href="http://www.google.com">Google</a></b>. -// The former is an <a> element with the text "Google" inside it. -// The latter is a <b> element with that <a> element inside it. -// In general, an element can contain a sequence of elements -// and text inside it. In XML, white space inside an element is -// always counted as text--it is never discarded by the parser. -// XML parsers do translate \r and \r\n into \n in text. -// -// This parser reads an XML document and calls methods on a -// Builder interface object in response to the text. -// It calls the builder's StartElement, Text, and EndElement -// methods, mimicking the structure of the text. -// For example, the simple XML document: -// -// <a href="http://www.google.com"> -// <img src="http://www.google.com/icon.png" alt="Google" /> -// <br/></a> -// -// results in the following sequence of builder calls: -// -// StartElement("a", []Attr(Attr("href", "http://www.google.com"))); -// Text("\n\t"); -// StartElement("img", []Attr(Attr("src", "http://www.google.com/icon.png"), -// Attr("alt", "Google"))); -// EndElement("img"); -// Text("\n"); -// StartElement("br", []Attr()); -// EndElement("br"); -// EndElement("a"); -// -// There are, of course, a few more details, but the story so far -// should be enough for the majority of uses. The details are: -// -// * XML documents typically begin with an XML declaration line like -// <?xml version="1.0" encoding="UTF-8"?>. -// This line is strongly recommended, but not strictly required. -// It introduces the XML version and text encoding for the rest -// of the file. XML parsers are required to recognize UTF-8 and -// UTF-16. This parser only recognizes UTF-8 (for now?). -// -// * After the XML declaration comes an optional doctype declaration like -// <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" -// "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> -// The parser should pass this information on to the client in some -// form, but does not. It discards such lines. -// -// * The XML declaration line is an instance of a more general tag -// called a processing instruction, XML's #pragma. The general form is -// <?target text?>, where target is a name (like "xml") specifying -// the intended recipient of the instruction, and text is the -// instruction itself. This XML parser keeps the <?xml ...?> declaration -// to itself but passes along other processing instructions using -// the ProcInst method. Processing instructions can appear anywhere -// in an XML document. Most clients will simply ignore them. -// -// * An XML comment can appear anywhere in an XML document. -// Comments have the form <!--text-->. The XML parser passes -// them along by calling the Comment method. Again, most clients -// will simply ignore them. -// -// * Text inside an XML element must be escaped to avoid looking like -// a start/end tag. Specifically, the characters < and & must be -// written as < and &. An alternate quoting mechanism is to -// use the construct <![CDATA[...]]>. The quoted text ... can contain -// < characters, but not the sequence ]]>. Ampersands must still be -// escaped. For some reason, the existence of the CDATA quoting mechanism -// infects the processing of ordinary unquoted text, which is not allowed -// to contain the literal sequence ]]>. Instead, it would be written -// escaped, as in ]]>. The parser hides all these considerations -// from the library client -- it reports all text, regardless of original -// form and already unescaped, using the Text method. -// -// * A revision to XML 1.0 introduced the concept of name spaces -// for attribute and tag names. A start tag with an attribute -// xmlns:prefix="URL" introduces `prefix' as a shorthand -// for the name space whose identifier is URL. Inside the element -// with that start tag, an element name or attribute prefix:foo -// (as in <prefix:foo prefix:bar="baz">) is understood to refer -// to name `foo' in the name space denoted by `URL'. Although -// this is a shorthand, there is no canonical expansion. Thus: -// -// <tag xmlns:foo="http://google.com/foo" xmlns:bar="http://google.com/bar"> -// <foo:red bar:attr="value">text1</foo:red> -// <bar:red>text2</bar:red> -// </tag> -// -// and -// -// <tag xmlns:bar="http://google.com/foo" xmlns:foo="http://google.com/bar"> -// <bar:red foo:attr="value">text1</bar:red> -// <foo:red>text2</foo:red> -// </tag> -// -// are equivalent XML documents, and there is no canonical form. -// -// The special attribute xmlns="URL" sets the default name space -// for unprefixed tags (but not attribute names) to URL. -// Thus: -// -// <tag xmlns="http://google.com/foo" xmlns:bar="http://google.com/bar"> -// <red bar:attr="value">text1</red> -// <bar:red>text2</bar:red> -// </tag> -// -// is another XML document equivalent to the first two, and -// -// <tag xmlns:bar="http://google.com/foo" xmlns="http://google.com/bar"> -// <bar:red attr="value">text1</bar:red> -// <red>text2</red> -// </tag> -// -// would be equivalent, except that `attr' in attr="value" has no -// associated name space, in contrast to the previous three where it -// is in the http://google.com/bar name space. -// -// The XML parser hides these details from the client by passing -// a Name struct (ns + name pair) for tag and attribute names. -// Tags and attributes without a name space have ns == "". -// -// References: -// Annotated XML spec: http://www.xml.com/axml/testaxml.htm -// XML name spaces: http://www.w3.org/TR/REC-xml-names/ - -package xml - -import ( - "io"; - "os"; -) - -// XML name, annotated with name space URL -type Name struct { - ns, name string; -} - -// XML attribute (name=value). -type Attr struct { - name Name; - value string; -} - -// XML Builder - methods client provides to Parser. -// Parser calls methods on builder as it reads and parses XML. -// If a builder method returns an error, the parse stops. -type Builder interface { - // Called when an element starts. - // Attr is list of attributes given in the tag. - // <name attr.name=attr.value attr1.name=attr1.value ...> - // <name attr.name=attr.value attr1.name=attr1.value ... /> - // xmlns and xmlns:foo attributes are handled internally - // and not passed through to StartElement. - StartElement(name Name, attr []Attr) os.Error; - - // Called when an element ends. - // </name> - // <name ... /> - EndElement(name Name) os.Error; - - // Called for non-empty character data string inside element. - // Can be called multiple times between elements. - // text - // <![CDATA[text]]> - Text(text []byte) os.Error; - - // Called when a comment is found in the XML. - // <!-- text --> - Comment(text []byte) os.Error; - - // Called for a processing instruction - // <?target text?> - ProcInst(target string, text []byte) os.Error; -} - -// Default builder. Implements no-op Builder methods. -// Embed this in your own Builders to handle the calls -// you don't care about (e.g., Comment, ProcInst). -type BaseBuilder struct { -} - -func (b *BaseBuilder) StartElement(name Name, attr []Attr) os.Error { - return nil; -} - -func (b *BaseBuilder) EndElement(name Name) os.Error { - return nil; -} - -func (b *BaseBuilder) Text(text []byte) os.Error { - return nil; -} - -func (b *BaseBuilder) Comment(text []byte) os.Error { - return nil; -} - -func (b *BaseBuilder) ProcInst(target string, text []byte) os.Error { - return nil; -} - -// XML Parser. Calls Builder methods as it parses. -func Parse(r io.Read, b Builder) os.Error { - return os.NewError("unimplemented"); -} - -// Channel interface to XML parser: create a new channel, -// go ParseTokens(r, c), and then read from the channel -// until TokenEnd. This variant has the benefit that -// the process reading the channel can be a recursive -// function instead of a set of callbacks, but it has the -// drawback that the channel interface cannot signal an -// error to cause the parser to stop early. - -// An XML parsing token. -const ( - TokenStartElement = 1 + iota; - TokenEndElement; - TokenText; - TokenComment; - TokenProcInst; - TokenEnd; -) - -type Token struct { - Kind int; // TokenStartElement, TokenEndElement, etc. - Name Name; // name (TokenStartElement, TokenEndElement) - Attr []Attr; // attributes (TokenStartElement) - Target string; // target (TokenProcessingInstruction) - Text []byte; // text (TokenCharData, TokenComment, etc.) - Err os.Error; // error (TokenEnd) -} - -type ChanBuilder chan Token; - -func (c ChanBuilder) StartElement(name Name, attr []Attr) os.Error { - var t Token; - t.Kind = TokenStartElement; - t.Name = name; - t.Attr = attr; - c <- t; - return nil; -} - -func (c ChanBuilder) EndElement(name Name) os.Error { - var t Token; - t.Kind = TokenEndElement; - t.Name = name; - c <- t; - return nil; -} - -func (c ChanBuilder) Text(text []byte) os.Error { - var t Token; - t.Kind = TokenText; - t.Text = text; - c <- t; - return nil; -} - -func (c ChanBuilder) Comment(text []byte) os.Error { - var t Token; - t.Kind = TokenComment; - t.Text = text; - c <- t; - return nil; -} - -func (c ChanBuilder) ProcInst(target string, text []byte) os.Error { - var t Token; - t.Kind = TokenProcInst; - t.Target = target; - t.Text = text; - c <- t; - return nil; -} - -func ParseToChan(r io.Read, c chan Token) { - var t Token; - t.Kind = TokenEnd; - t.Err = Parse(r, ChanBuilder(c)); - c <- t; -} - - -// scribbled notes based on XML spec. - -// document is -// xml decl? -// doctype decl? -// element -// -// if xml decl is present, must be first. after that, -// can have comments and procinsts scattered throughout, -// even after the element is done. -// -// xml decl is: -// -// <\?xml version='[a-zA-Z0-9_.:\-]+'( encoding='[A-Za-z][A-Za-z0-9._\-]*')? -// ( standalone='(yes|no)')? ?\?> -// -// spaces denote [ \r\t\n]+. -// written with '' above but can use "" too. -// -// doctype decl might as well be <!DOCTYPE[^>]*> -// -// procinst is <\?name( .*?)\?>. name cannot be [Xx][Mm][Ll]. -// -// comment is <!--(.*?)-->. -// -// tags are: -// <name( attrib)* ?> start tag -// <name( attrib)* ?/> combined start/end tag -// </name ?> end tag -// (the " ?" is an optional space, not a literal question mark.) -// -// plain text is [^<&]* except cannot contain "]]>". -// can also have escaped characters: -// &#[0-9]+; -// &#x[0-9A-Fa-f]+; -// &name; -// -// can use <![CDATA[.*?]]> to avoid escaping < characters. -// -// must rewrite \r and \r\n into \n in text. -// -// names are Unicode. valid chars listed below. -// -// attrib is name="value" or name='value'. -// can have spaces around =. -// attribute value text is [^<&"]* for appropriate ". -// can also use the &...; escape sequences above. -// cannot use <![CDATA[...]]>. -// -// xmlns attributes are name=value where name has form xmlns:name -// (i.e., xmlns:123 is not okay, because 123 is not a name; xmlns:a123 is ok). -// sub-name must not start with : either. -// -// name is first(second)*. -// -// first is -// -// 003A 04D0-04EB 0A59-0A5C 0C35-0C39 0F49-0F69 1E00-1E9B -// 0041-005A 04EE-04F5 0A5E 0C60-0C61 10A0-10C5 1EA0-1EF9 -// 005F 04F8-04F9 0A72-0A74 0C85-0C8C 10D0-10F6 1F00-1F15 -// 0061-007A 0531-0556 0A85-0A8B 0C8E-0C90 1100 1F18-1F1D -// 00C0-00D6 0559 0A8D 0C92-0CA8 1102-1103 1F20-1F45 -// 00D8-00F6 0561-0586 0A8F-0A91 0CAA-0CB3 1105-1107 1F48-1F4D -// 00F8-00FF 05D0-05EA 0A93-0AA8 0CB5-0CB9 1109 1F50-1F57 -// 0100-0131 05F0-05F2 0AAA-0AB0 0CDE 110B-110C 1F59 -// 0134-013E 0621-063A 0AB2-0AB3 0CE0-0CE1 110E-1112 1F5B -// 0141-0148 0641-064A 0AB5-0AB9 0D05-0D0C 113C 1F5D -// 014A-017E 0671-06B7 0ABD 0D0E-0D10 113E 1F5F-1F7D -// 0180-01C3 06BA-06BE 0AE0 0D12-0D28 1140 1F80-1FB4 -// 01CD-01F0 06C0-06CE 0B05-0B0C 0D2A-0D39 114C 1FB6-1FBC -// 01F4-01F5 06D0-06D3 0B0F-0B10 0D60-0D61 114E 1FBE -// 01FA-0217 06D5 0B13-0B28 0E01-0E2E 1150 1FC2-1FC4 -// 0250-02A8 06E5-06E6 0B2A-0B30 0E30 1154-1155 1FC6-1FCC -// 02BB-02C1 0905-0939 0B32-0B33 0E32-0E33 1159 1FD0-1FD3 -// 0386 093D 0B36-0B39 0E40-0E45 115F-1161 1FD6-1FDB -// 0388-038A 0958-0961 0B3D 0E81-0E82 1163 1FE0-1FEC -// 038C 0985-098C 0B5C-0B5D 0E84 1165 1FF2-1FF4 -// 038E-03A1 098F-0990 0B5F-0B61 0E87-0E88 1167 1FF6-1FFC -// 03A3-03CE 0993-09A8 0B85-0B8A 0E8A 1169 2126 -// 03D0-03D6 09AA-09B0 0B8E-0B90 0E8D 116D-116E 212A-212B -// 03DA 09B2 0B92-0B95 0E94-0E97 1172-1173 212E -// 03DC 09B6-09B9 0B99-0B9A 0E99-0E9F 1175 2180-2182 -// 03DE 09DC-09DD 0B9C 0EA1-0EA3 119E 3007 -// 03E0 09DF-09E1 0B9E-0B9F 0EA5 11A8 3021-3029 -// 03E2-03F3 09F0-09F1 0BA3-0BA4 0EA7 11AB 3041-3094 -// 0401-040C 0A05-0A0A 0BA8-0BAA 0EAA-0EAB 11AE-11AF 30A1-30FA -// 040E-044F 0A0F-0A10 0BAE-0BB5 0EAD-0EAE 11B7-11B8 3105-312C -// 0451-045C 0A13-0A28 0BB7-0BB9 0EB0 11BA 4E00-9FA5 -// 045E-0481 0A2A-0A30 0C05-0C0C 0EB2-0EB3 11BC-11C2 AC00-D7A3 -// 0490-04C4 0A32-0A33 0C0E-0C10 0EBD 11EB -// 04C7-04C8 0A35-0A36 0C12-0C28 0EC0-0EC4 11F0 -// 04CB-04CC 0A38-0A39 0C2A-0C33 0F40-0F47 11F9 -// -// second is first plus -// -// 002D 06DD-06DF 09E6-09EF 0B56-0B57 0D3E-0D43 0F3E -// 002E 06E0-06E4 0A02 0B66-0B6F 0D46-0D48 0F3F -// 0030-0039 06E7-06E8 0A3C 0B82-0B83 0D4A-0D4D 0F71-0F84 -// 00B7 06EA-06ED 0A3E 0BBE-0BC2 0D57 0F86-0F8B -// 02D0 06F0-06F9 0A3F 0BC6-0BC8 0D66-0D6F 0F90-0F95 -// 02D1 0901-0903 0A40-0A42 0BCA-0BCD 0E31 0F97 -// 0300-0345 093C 0A47-0A48 0BD7 0E34-0E3A 0F99-0FAD -// 0360-0361 093E-094C 0A4B-0A4D 0BE7-0BEF 0E46 0FB1-0FB7 -// 0387 094D 0A66-0A6F 0C01-0C03 0E47-0E4E 0FB9 -// 0483-0486 0951-0954 0A70-0A71 0C3E-0C44 0E50-0E59 20D0-20DC -// 0591-05A1 0962-0963 0A81-0A83 0C46-0C48 0EB1 20E1 -// 05A3-05B9 0966-096F 0ABC 0C4A-0C4D 0EB4-0EB9 3005 -// 05BB-05BD 0981-0983 0ABE-0AC5 0C55-0C56 0EBB-0EBC 302A-302F -// 05BF 09BC 0AC7-0AC9 0C66-0C6F 0EC6 3031-3035 -// 05C1-05C2 09BE 0ACB-0ACD 0C82-0C83 0EC8-0ECD 3099 -// 05C4 09BF 0AE6-0AEF 0CBE-0CC4 0ED0-0ED9 309A -// 0640 09C0-09C4 0B01-0B03 0CC6-0CC8 0F18-0F19 309D-309E -// 064B-0652 09C7-09C8 0B3C 0CCA-0CCD 0F20-0F29 30FC-30FE -// 0660-0669 09CB-09CD 0B3E-0B43 0CD5-0CD6 0F35 -// 0670 09D7 0B47-0B48 0CE6-0CEF 0F37 -// 06D6-06DC 09E2-09E3 0B4B-0B4D 0D02-0D03 0F39 - |