406 lines
10 KiB
Ragel
406 lines
10 KiB
Ragel
%%machine base_lexer;
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%%{
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##
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# Base grammar for the XML lexer.
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#
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# This grammar is shared between the C and Java extensions. As a result of
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# this you should **not** include language specific code in Ragel
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# actions/callbacks.
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#
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# To call back in to Ruby you can use one of the following two functions:
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#
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# * callback
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# * callback_simple
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#
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# The first function takes 5 arguments:
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#
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# * The name of the Ruby method to call.
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# * The input data.
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# * The encoding of the input data.
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# * The start of the current buffer.
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# * The end of the current buffer.
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#
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# The function callback_simple only takes one argument: the name of the
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# method to call. This function should be used for callbacks that don't
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# require any values.
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#
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# When you call a method in Ruby make sure that said method is defined as
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# an instance method in the `Oga::XML::Lexer` class.
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#
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# The name of the callback to invoke should be an identifier starting with
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# "id_". The identifier should be defined in the associated C and Java code.
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# In case of C code its value should be a Symbol as a ID object, for Java
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# it should be a String. For example:
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#
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# ID id_foo = rb_intern("foo");
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#
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# And for Java:
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#
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# String id_foo = "foo";
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#
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# ## Machine Transitions
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#
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# To transition from one machine to another always use `fnext` instead of
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# `fcall` and `fret`. This removes the need for the code to keep track of a
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# stack.
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#
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newline = '\n' | '\r\n';
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action count_newlines {
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if ( fc == '\n' ) lines++;
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}
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whitespace = [ \t];
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ident_char = [a-zA-Z0-9\-_];
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identifier = ident_char+;
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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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# Unlike the W3 specification these rules *do* allow character sequences
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# such as `--` and `->`. Putting extra checks in for these sequences would
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# 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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comment = comment_start (any* -- comment_end) comment_end;
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action start_comment {
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callback(id_on_comment, data, encoding, ts + 4, te - 3);
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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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# 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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cdata = cdata_start (any* -- cdata_end) cdata_end;
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action start_cdata {
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callback(id_on_cdata, data, encoding, ts + 9, te - 3);
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}
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# Processing Instructions
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#
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# http://www.w3.org/TR/xpath/#section-Processing-Instruction-Nodes
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# http://en.wikipedia.org/wiki/Processing_Instruction
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#
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# These are tags meant to be used by parsers/libraries for custom behaviour.
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# One example are the tags used by PHP: <?php and ?>. Note that the XML
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# declaration tags (<?xml ?>) are not considered to be a processing
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# instruction.
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#
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proc_ins_start = '<?' identifier;
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proc_ins_end = '?>';
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action start_proc_ins {
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callback_simple(id_on_proc_ins_start);
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callback(id_on_proc_ins_name, data, encoding, ts + 2, te);
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mark = te;
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fnext proc_ins_body;
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}
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proc_ins_body := |*
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proc_ins_end => {
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callback(id_on_text, data, encoding, mark, ts);
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callback_simple(id_on_proc_ins_end);
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mark = 0;
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fnext main;
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};
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any;
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*|;
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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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#
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dquote = '"';
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squote = "'";
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action emit_string {
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callback(id_on_string_body, data, encoding, ts, te);
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if ( lines > 0 )
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{
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advance_line(lines);
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lines = 0;
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}
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}
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action start_string_squote {
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callback_simple(id_on_string_squote);
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fcall string_squote;
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}
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action start_string_dquote {
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callback_simple(id_on_string_dquote);
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fcall string_dquote;
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}
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string_squote := |*
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^squote* $count_newlines => emit_string;
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squote => {
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callback_simple(id_on_string_squote);
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fret;
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};
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*|;
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string_dquote := |*
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^dquote* $count_newlines => emit_string;
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dquote => {
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callback_simple(id_on_string_dquote);
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fret;
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};
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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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callback_simple(id_on_doctype_start);
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fnext doctype;
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}
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# Machine for processing inline rules of a doctype.
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doctype_inline := |*
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^']'* $count_newlines => {
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callback(id_on_doctype_inline, data, encoding, ts, te);
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if ( lines > 0 )
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{
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advance_line(lines);
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lines = 0;
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}
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};
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']' => { fnext 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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callback(id_on_doctype_type, data, encoding, ts, te);
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};
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# Starts a set of inline doctype rules.
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'[' => { fnext doctype_inline; };
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# Lex the public/system IDs as regular strings.
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squote => start_string_squote;
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dquote => start_string_dquote;
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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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callback(id_on_doctype_name, data, encoding, ts, te);
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};
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'>' => {
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callback_simple(id_on_doctype_end);
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fnext main;
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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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callback_simple(id_on_xml_decl_start);
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fnext 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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callback_simple(id_on_xml_decl_end);
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fnext main;
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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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callback(id_on_attribute, data, encoding, ts, te);
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};
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squote => start_string_squote;
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dquote => start_string_dquote;
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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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# Lexing of elements is broken up into different machines that handle the
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# name/namespace, contents of the open tag and the body of an element. The
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# body of an element is lexed using the `main` machine.
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#
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element_start = '<' ident_char;
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element_end = '</' identifier (':' identifier)* '>';
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action start_element {
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callback_simple(id_on_element_start);
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fhold;
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fnext element_name;
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}
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action close_element {
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callback_simple(id_on_element_end);
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}
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# Machine used for lexing the name/namespace of an element.
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element_name := |*
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identifier ':' => {
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callback(id_on_element_ns, data, encoding, ts, te - 1);
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};
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identifier => {
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callback(id_on_element_name, data, encoding, ts, te);
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fnext element_head;
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};
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*|;
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# Machine used for processing the contents of an element's starting tag.
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# This includes the name, namespace and attributes.
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element_head := |*
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whitespace | '=';
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newline => {
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callback_simple(id_advance_line);
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};
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# Attribute names and namespaces.
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identifier ':' => {
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callback(id_on_attribute_ns, data, encoding, ts, te - 1);
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};
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identifier => {
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callback(id_on_attribute, data, encoding, ts, te);
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};
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# Attribute values.
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squote => start_string_squote;
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dquote => start_string_dquote;
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# We're done with the open tag of the element.
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'>' => {
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callback_simple(id_on_element_open_end);
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fnext main;
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};
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# Self closing tags.
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'/>' => {
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callback_simple(id_on_element_end);
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fnext main;
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};
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*|;
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# Text
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#
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# http://www.w3.org/TR/xml/#syntax
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# http://www.w3.org/TR/html-markup/syntax.html#text-syntax
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#
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# Text content is everything leading up to certain special tags such as "</"
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# and "<?".
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action start_text {
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fhold;
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fnext text;
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}
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# These characters terminate a T_TEXT sequence and instruct Ragel to jump
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# back to the main machine.
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#
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# Note that this only works if each sequence is exactly 2 characters
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# long. Because of this "<!" is used instead of "<!--".
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terminate_text = '</' | '<!' | '<?' | element_start;
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allowed_text = (any* -- terminate_text) $count_newlines;
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text := |*
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terminate_text | allowed_text => {
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callback(id_on_text, data, encoding, ts, te);
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if ( lines > 0 )
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{
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advance_line(lines);
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lines = 0;
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}
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fnext main;
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};
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# Text followed by a special tag, such as "foo<!--"
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allowed_text %{ mark = p; } terminate_text => {
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callback(id_on_text, data, encoding, ts, mark);
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p = mark - 1;
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mark = 0;
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if ( lines > 0 )
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{
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advance_line(lines);
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lines = 0;
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}
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fnext main;
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};
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*|;
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# The main machine aka the entry point of Ragel.
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main := |*
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doctype_start => start_doctype;
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xml_decl_start => start_xml_decl;
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comment => start_comment;
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cdata => start_cdata;
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proc_ins_start => start_proc_ins;
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element_start => start_element;
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element_end => close_element;
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any => start_text;
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*|;
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}%%
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