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#######################################################################
# Name: simple.py
# Purpose: Simple language based on example from pyPEG
# Author: Igor R. Dejanovic <igor DOT dejanovic AT gmail DOT com>
# Copyright: (c) 2009-2015 Igor R. Dejanovic <igor DOT dejanovic AT gmail DOT com>
# License: MIT License
#
# This example demonstrates grammar definition using python constructs.
# It is taken and adapted from pyPEG project (see http://www.fdik.org/pyPEG/).
#######################################################################
from __future__ import unicode_literals
import os
from arpeggio import *
from arpeggio import RegExMatch as _
# Grammar
def comment(): return [_(r"//.*"), _(r"/\*.*\*/")]
def literal(): return _(r'\d*\.\d*|\d+|".*?"')
def symbol(): return _(r"\w+")
def operator(): return _(r"\+|\-|\*|\/|\=\=")
def operation(): return symbol, operator, [literal, functioncall]
def expression(): return [literal, operation, functioncall]
def expressionlist(): return expression, ZeroOrMore(",", expression)
def returnstatement(): return Kwd("return"), expression
def ifstatement(): return Kwd("if"), "(", expression, ")", block, Kwd("else"), block
def statement(): return [ifstatement, returnstatement], ";"
def block(): return "{", OneOrMore(statement), "}"
def parameterlist(): return "(", symbol, ZeroOrMore(",", symbol), ")"
def functioncall(): return symbol, "(", expressionlist, ")"
def function(): return Kwd("function"), symbol, parameterlist, block
def simpleLanguage(): return function
def main(debug=False):
# Load test program from file
current_dir = os.path.dirname(__file__)
test_program = open(os.path.join(current_dir, 'program.simple')).read()
# Parser instantiation. simpleLanguage is the definition of the root rule
# and comment is a grammar rule for comments.
parser = ParserPython(simpleLanguage, comment, debug=debug)
parse_tree = parser.parse(test_program)
if __name__ == "__main__":
# In debug mode dot (graphviz) files for parser model
# and parse tree will be created for visualization.
# Checkout current folder for .dot files.
main(debug=True)
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