329 lines
9.1 KiB
Ragel
329 lines
9.1 KiB
Ragel
#include "lexer.h"
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VALUE oga_cLexer;
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%%machine lexer;
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/**
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* Calls a method defined in the Ruby side of the lexer. The String value is
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* created based on the values of `ts` and `te` and uses the encoding specified
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* in `encoding`.
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*
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* @example
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* rb_encoding *encoding = rb_enc_get(...);
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* liboga_xml_lexer_callback(self, "on_string", encoding, ts, te);
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*/
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void liboga_xml_lexer_callback(
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VALUE self,
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const char *name,
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rb_encoding *encoding,
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const char *ts,
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const char *te
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)
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{
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VALUE value = rb_enc_str_new(ts, te - ts, encoding);
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VALUE method = rb_intern(name);
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rb_funcall(self, method, 1, value);
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}
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/**
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* Calls a method defined in the Ruby side of the lexer without passing it any
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* arguments.
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*
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* @example
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* liboga_xml_lexer_callback_simple(self, "on_cdata_start");
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*/
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void liboga_xml_lexer_callback_simple(VALUE self, const char *name)
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{
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VALUE method = rb_intern(name);
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rb_funcall(self, method, 0);
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}
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%% write data;
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/**
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* Lexes the input String specified in the instance variable `@data`. Lexed
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* values have the same encoding as the input value. This instance variable
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* is set in the Ruby layer of the lexer.
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*
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* The Ragel loop dispatches method calls back to Ruby land to make it easier
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* to implement complex actions without having to fiddle around with C. This
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* introduces a small performance overhead compared to a pure C implementation.
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* However, this is worth the overhead due to it being much easier to maintain.
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*/
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VALUE oga_xml_lexer_advance(VALUE self)
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{
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/* Pull the data in from Ruby land. */
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VALUE data_ivar = rb_ivar_get(self, rb_intern("@data"));
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/* Make sure that all data passed back to Ruby has the proper encoding. */
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rb_encoding *encoding = rb_enc_get(data_ivar);
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char *data_str_val = StringValuePtr(data_ivar);
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const char *p = data_str_val;
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const char *pe = data_str_val + strlen(data_str_val);
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const char *eof = pe;
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const char *ts, *te;
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int act = 0;
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int cs = 0;
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int top = 0;
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/*
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Fixed stack size is enough since the lexer doesn't use that many nested
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fcalls.
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*/
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int stack[8];
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%% write init;
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%% write exec;
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return Qnil;
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}
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%%{
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newline = '\n' | '\r\n';
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whitespace = [ \t];
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identifier = [a-zA-Z0-9\-_:]+;
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# Strings
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#
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# Strings in HTML can either be single or double quoted. If a string
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# starts with one of these quotes it must be closed with the same type
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# of quote.
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dquote = '"';
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squote = "'";
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# Machine for processing double quoted strings.
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string_dquote := |*
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^dquote+ => {
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liboga_xml_lexer_callback(self, "on_string", encoding, ts, te);
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};
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dquote => { fret; };
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*|;
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# Machine for processing single quoted strings.
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string_squote := |*
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^squote+ => {
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liboga_xml_lexer_callback(self, "on_string", encoding, ts, te);
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};
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squote => { fret; };
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*|;
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# DOCTYPES
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#
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# http://www.w3.org/TR/html-markup/syntax.html#doctype-syntax
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#
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# These rules support the 3 flavours of doctypes:
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#
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# 1. Normal doctypes, as introduced in the HTML5 specification.
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# 2. Deprecated doctypes, the more verbose ones used prior to HTML5.
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# 3. Legacy doctypes
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#
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doctype_start = '<!DOCTYPE'i whitespace+;
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action start_doctype {
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liboga_xml_lexer_callback_simple(self, "on_doctype_start");
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fcall doctype;
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}
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# Machine for processing doctypes. Doctype values such as the public
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# and system IDs are treated as T_STRING tokens.
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doctype := |*
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'PUBLIC' | 'SYSTEM' => {
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liboga_xml_lexer_callback(self, "on_doctype_type", encoding, ts, te);
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};
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# Lex the public/system IDs as regular strings.
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dquote => { fcall string_dquote; };
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squote => { fcall string_squote; };
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# Whitespace inside doctypes is ignored since there's no point in
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# including it.
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whitespace;
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identifier => {
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liboga_xml_lexer_callback(self, "on_doctype_name", encoding, ts, te);
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};
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'>' => {
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liboga_xml_lexer_callback_simple(self, "on_doctype_end");
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fret;
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};
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*|;
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# CDATA
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#
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# http://www.w3.org/TR/html-markup/syntax.html#cdata-sections
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#
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# CDATA tags are broken up into 3 parts: the start, the content and the
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# end tag.
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#
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# In HTML CDATA tags have no meaning/are not supported. Oga does
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# support them but treats their contents as plain text.
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#
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cdata_start = '<![CDATA[';
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cdata_end = ']]>';
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action start_cdata {
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liboga_xml_lexer_callback_simple(self, "on_cdata_start");
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fcall cdata;
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}
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# Machine that for processing the contents of CDATA tags. Everything
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# inside a CDATA tag is treated as plain text.
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cdata := |*
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any* cdata_end => {
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liboga_xml_lexer_callback(self, "on_text", encoding, ts, te - 3);
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liboga_xml_lexer_callback_simple(self, "on_cdata_end");
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fret;
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};
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*|;
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# Comments
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#
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# http://www.w3.org/TR/html-markup/syntax.html#comments
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#
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# Comments are lexed into 3 parts: the start tag, the content and the
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# end tag.
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#
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# Unlike the W3 specification these rules *do* allow character
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# sequences such as `--` and `->`. Putting extra checks in for these
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# sequences would actually make the rules/actions more complex.
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#
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comment_start = '<!--';
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comment_end = '-->';
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action start_comment {
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liboga_xml_lexer_callback_simple(self, "on_comment_start");
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fcall comment;
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}
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# Machine used for processing the contents of a comment. Everything
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# inside a comment is treated as plain text (similar to CDATA tags).
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comment := |*
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any* comment_end => {
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liboga_xml_lexer_callback(self, "on_text", encoding, ts, te - 3);
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liboga_xml_lexer_callback_simple(self, "on_comment_end");
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fret;
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};
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*|;
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# XML declaration tags
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#
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# http://www.w3.org/TR/REC-xml/#sec-prolog-dtd
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#
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xml_decl_start = '<?xml';
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xml_decl_end = '?>';
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action start_xml_decl {
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liboga_xml_lexer_callback_simple(self, "on_xml_decl_start");
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fcall xml_decl;
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}
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# Machine that processes the contents of an XML declaration tag.
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xml_decl := |*
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xml_decl_end => {
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liboga_xml_lexer_callback_simple(self, "on_xml_decl_end");
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fret;
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};
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# Attributes and their values (e.g. version="1.0").
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identifier => {
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liboga_xml_lexer_callback(self, "on_attribute", encoding, ts, te);
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};
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dquote => { fcall string_dquote; };
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squote => { fcall string_squote; };
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any;
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*|;
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# Elements
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#
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# http://www.w3.org/TR/html-markup/syntax.html#syntax-elements
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#
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# Action that creates the tokens for the opening tag, name and
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# namespace (if any). Remaining work is delegated to a dedicated
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# machine.
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action start_element {
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liboga_xml_lexer_callback(self, "on_element_start", encoding, ts + 1, te);
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fcall element_head;
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}
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element_start = '<' identifier;
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# Machine used for processing the characters inside a element head. An
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# element head is everything between `<NAME` (where NAME is the element
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# name) and `>`.
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#
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# For example, in `<p foo="bar">` the element head is ` foo="bar"`.
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#
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element_head := |*
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whitespace | '=';
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newline => {
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liboga_xml_lexer_callback_simple(self, "on_newline");
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};
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# Attribute names.
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identifier => {
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liboga_xml_lexer_callback(self, "on_attribute", encoding, ts, te);
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};
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# Attribute values.
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dquote => { fcall string_dquote; };
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squote => { fcall string_squote; };
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# The closing character of the open tag.
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('>' | '/') => {
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fhold;
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fret;
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};
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*|;
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main := |*
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element_start => start_element;
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doctype_start => start_doctype;
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cdata_start => start_cdata;
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comment_start => start_comment;
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xml_decl_start => start_xml_decl;
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# Enter the body of the tag. If HTML mode is enabled and the current
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# element is a void element we'll close it and bail out.
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'>' => {
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liboga_xml_lexer_callback_simple(self, "on_element_open_end");
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};
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# Regular closing tags.
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'</' identifier '>' => {
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liboga_xml_lexer_callback_simple(self, "on_element_end");
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};
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# Self closing elements that are not handled by the HTML mode.
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'/>' => {
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liboga_xml_lexer_callback_simple(self, "on_element_end");
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};
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# Note that this rule should be declared at the very bottom as it
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# will otherwise take precedence over the other rules.
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^('<' | '>')+ => {
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liboga_xml_lexer_callback(self, "on_text", encoding, ts, te);
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};
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*|;
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}%%
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void Init_liboga_xml_lexer()
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{
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oga_cLexer = rb_define_class_under(oga_mXML, "Lexer", rb_cObject);
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rb_define_method(oga_cLexer, "advance_native", oga_xml_lexer_advance, 0);
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}
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