oga/ext/ragel/base_lexer.rl

259 lines
6.9 KiB
Ragel

%%machine base_lexer;
%%{
##
# Base grammar for the XML lexer.
#
# This grammar is shared between the C and Java extensions. As a result of
# this you should **not** include language specific code in Ragel
# actions/callbacks.
#
# To call back in to Ruby you can use one of the following two functions:
#
# * callback
# * callback_simple
#
# The first function takes 5 arguments:
#
# * The name of the Ruby method to call.
# * The input data.
# * The encoding of the input data.
# * The start of the current buffer.
# * The end of the current buffer.
#
# The function callback_simple only takes one argument: the name of the
# method to call. This function should be used for callbacks that don't
# require any values.
#
# When you call a method in Ruby make sure that said method is defined as
# an instance method in the `Oga::XML::Lexer` class.
#
# ## Machine Transitions
#
# To transition from one machine to another always use `fnext` instead of
# `fcall` and `fret`. This removes the need for the code to keep track of a
# stack.
#
newline = '\n' | '\r\n';
whitespace = [ \t];
identifier = [a-zA-Z0-9\-_]+;
# Comments
#
# http://www.w3.org/TR/html-markup/syntax.html#comments
#
# Unlike the W3 specification these rules *do* allow character sequences
# such as `--` and `->`. Putting extra checks in for these sequences would
# actually make the rules/actions more complex.
#
comment_start = '<!--';
comment_end = '-->';
action start_comment {
mark = ts + 4;
fnext comment_body;
}
comment_body := |*
comment_end => {
callback("on_comment", data, encoding, mark, te - 3);
mark = 0;
fnext main;
};
any;
*|;
# CDATA
#
# http://www.w3.org/TR/html-markup/syntax.html#cdata-sections
#
# In HTML CDATA tags have no meaning/are not supported. Oga does
# support them but treats their contents as plain text.
#
cdata = '<![CDATA[' any* ']]>';
# Strings
#
# Strings in HTML can either be single or double quoted. If a string
# starts with one of these quotes it must be closed with the same type
# of quote.
#
dquote = '"';
squote = "'";
string_dquote = (dquote ^dquote+ dquote);
string_squote = (squote ^squote+ squote);
string = string_dquote | string_squote;
action emit_string {
callback("on_string", data, encoding, ts + 1, te - 1);
}
# DOCTYPES
#
# http://www.w3.org/TR/html-markup/syntax.html#doctype-syntax
#
# These rules support the 3 flavours of doctypes:
#
# 1. Normal doctypes, as introduced in the HTML5 specification.
# 2. Deprecated doctypes, the more verbose ones used prior to HTML5.
# 3. Legacy doctypes
#
doctype_start = '<!DOCTYPE'i whitespace+;
action start_doctype {
callback_simple("on_doctype_start");
fnext doctype;
}
# Machine for processing doctypes. Doctype values such as the public
# and system IDs are treated as T_STRING tokens.
doctype := |*
'PUBLIC' | 'SYSTEM' => {
callback("on_doctype_type", data, encoding, ts, te);
};
# Consumes everything between the [ and ]. Due to the use of :> the ]
# is not consumed by any+.
'[' any+ :> ']' => {
callback("on_doctype_inline", data, encoding, ts + 1, te - 1);
};
# Lex the public/system IDs as regular strings.
string => emit_string;
# Whitespace inside doctypes is ignored since there's no point in
# including it.
whitespace;
identifier => {
callback("on_doctype_name", data, encoding, ts, te);
};
'>' => {
callback_simple("on_doctype_end");
fnext main;
};
*|;
# XML declaration tags
#
# http://www.w3.org/TR/REC-xml/#sec-prolog-dtd
#
xml_decl_start = '<?xml';
xml_decl_end = '?>';
action start_xml_decl {
callback_simple("on_xml_decl_start");
fnext xml_decl;
}
# Machine that processes the contents of an XML declaration tag.
xml_decl := |*
xml_decl_end => {
callback_simple("on_xml_decl_end");
fnext main;
};
# Attributes and their values (e.g. version="1.0").
identifier => {
callback("on_attribute", data, encoding, ts, te);
};
string => emit_string;
any;
*|;
# Elements
#
# http://www.w3.org/TR/html-markup/syntax.html#syntax-elements
#
# Lexing of elements is broken up into different machines that handle the
# name/namespace, contents of the open tag and the body of an element. The
# body of an element is lexed using the `main` machine.
#
action start_element {
callback_simple("on_element_start");
fnext element_name;
}
# Machine used for lexing the name/namespace of an element.
element_name := |*
identifier ':' => {
callback("on_element_ns", data, encoding, ts, te - 1);
};
identifier => {
callback("on_element_name", data, encoding, ts, te);
fnext element_head;
};
*|;
# Machine used for processing the contents of an element's starting tag.
# This includes the name, namespace and attributes.
element_head := |*
whitespace | '=';
newline => {
callback_simple("advance_line");
};
# Attribute names and namespaces.
identifier ':' => {
callback("on_attribute_ns", data, encoding, ts, te - 1);
};
identifier => {
callback("on_attribute", data, encoding, ts, te);
};
# Attribute values.
string => emit_string;
# We're done with the open tag of the element.
'>' => {
callback_simple("on_element_open_end");
fnext main;
};
# Self closing tags.
'/>' => {
callback_simple("on_element_end");
fnext main;
};
*|;
# The main machine aka the entry point of Ragel.
main := |*
doctype_start => start_doctype;
xml_decl_start => start_xml_decl;
comment_start => start_comment;
cdata => {
callback("on_cdata", data, encoding, ts + 9, te - 3);
};
# The start of an element.
'<' => start_element;
# Regular closing tags.
'</' identifier (':' identifier)* '>' => {
callback_simple("on_element_end");
};
# Treat everything else, except for "<", as regular text. The "<" sign
# is used for tags so we can't emit text nodes for these characters.
^'<'+ => {
callback("on_text", data, encoding, ts, te);
};
*|;
}%%