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Basic boilerplate for Ragel and Ruby, extracted from Oga.
# Since public domain doesn't exist everywhere in the world and people might
# actually want to use this snippet here's the license (you can leave out
# the lines preceding it):
#
# Copyright (c) 2014, Yorick Peterse
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
%%machine lexer; # %
module MyProject
class Lexer
%% write data; # %
# Lazy way of forwarding instance method calls used internally by Ragel
# to their corresponding class methods.
private_methods.grep(/^_lexer_/).each do |name|
define_method(name) do
return self.class.send(name)
end
private(name)
end
##
# @param [String] data The data to lex.
#
def initialize(data)
@data = data.unpack('U*')
reset
end
##
# Resets the internal state of the lexer. Typically you don't need to
# call this method yourself as its called by #lex after lexing a given
# String.
#
def reset
@line = 1
@ts = nil
@te = nil
@tokens = []
@stack = []
@top = 0
@cs = self.class.lexer_start
@act = 0
@eof = @data.length
@p = 0
@pe = @eof
end
##
# Lexes the supplied String and returns an Array of tokens. Each token is
# an Array in the following format:
#
# [TYPE, VALUE]
#
# The type is a symbol, the value is either nil or a String.
#
# This method resets the internal state of the lexer after consuming the
# input.
#
# @param [String] data The string to consume.
# @return [Array]
# @see #advance
#
def lex
tokens = []
while token = advance
tokens << token
end
reset
return tokens
end
##
# Advances through the input and generates the corresponding tokens.
#
# This method does *not* reset the internal state of the lexer.
#
# @param [String] data The String to consume.
# @return [Array]
#
def advance
%% write exec; # % fix highlight
return @tokens.shift
end
private
##
# @param [Fixnum] amount The amount of lines to advance.
#
def advance_line(amount = 1)
@line += amount
end
##
# Emits a token who's value is based on the supplied start/stop position.
#
# @param [Symbol] type The token type.
# @param [Fixnum] start
# @param [Fixnum] stop
#
# @see #text
# @see #add_token
#
def emit(type, start = @ts, stop = @te)
value = text(start, stop)
add_token(type, value)
end
##
# Returns the text of the current buffer based on the supplied start and
# stop position.
#
# By default `@ts` and `@te` are used as the start/stop position.
#
# @param [Fixnum] start
# @param [Fixnum] stop
# @return [String]
#
def text(start = @ts, stop = @te)
return @data[start...stop].pack('U*')
end
##
# Adds a token with the given type and value to the list.
#
# @param [Symbol] type The token type.
# @param [String] value The token value.
#
def add_token(type, value = nil)
token = [type, value, @line]
@tokens << token
end
%%{
# Use instance variables for `ts` and friends.
access @;
getkey (@data[@p] || 0);
variable p @p;
variable pe @pe;
variable eof @eof;
newline = '\n' | '\r\n';
whitespace = [ \t];
main := |*
# Note that this rule should be declared at the very bottom as it
# will otherwise take precedence over the other rules.
any => {
};
*|;
}%%
end # Lexer
end # MyProject
@YorickPeterse

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YorickPeterse commented Apr 14, 2014

Note that I honestly don't give a crap about the license for this. You can dump it wherever you like or simply not include it.

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