DeterministicGenerator.py

# -*- coding: utf-8 -*-
# @copyright: MIT License
#   Copyright (c) 2018 syntactic (Pastèque Ho)
#   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
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#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# @summary: This file generates all strings described by a non-recursive JSGF grammar.
#   Run it by entering into the command line: python DeterministicGenerator.py <grammarFile>
#   where <grammarFile> is the path to the JSGF grammar.
# @since: 2014/06/02

"""
This file deterministically generates strings from a JSGF Grammar, whether there are \
        weights defined in rules or not. It requires one argument: the path to the JSGF\
        Grammar file. You can run this on the included grammar IdeasNonRecursive.gram:\


        ``python DeterministicGenerator.py IdeasNonRecursive.gram``

This will generate all strings defined by the public rules of IdeasNonRecursive.gram.\
        It is important that the grammar used by the generator is not recursive (rules \
        should not directly or indirectly reference themselves), so that the generator\
        terminates. Otherwise, you may get a maximum recursion depth exceeded error or \
        a segmentation fault. 
"""

import sys, itertools
import JSGFParser as parser
import JSGFGrammar as gram


def combineSets(listOfSets):
    """
    Combines sets of strings by taking the cross product of the sets and \
            concatenating the elements in the resulting tuples

    :param listOfSets: 2-D list of strings
    :returns: a list of strings
    """
    totalCrossProduct = ['']
    for i in range(len(listOfSets)):
        currentProduct = []
        for crossProduct in itertools.product(totalCrossProduct, listOfSets[i]):
            currentProduct.append((crossProduct[0].strip() + ' ' + crossProduct[1].strip()).strip())
        totalCrossProduct = currentProduct
    return totalCrossProduct

def processSequence(seq):
    """
    Combines adjacent elements in a sequence
    """
    componentSets = []
    for component in seq:
        componentSets.append(processRHS(component))
    return combineSets(componentSets)


def processNonTerminal(nt):
    """
    Finds the rule expansion for a nonterminal and returns its expansion.
    """
    return processRHS(grammar.getRHS(nt))

def processDisjunction(disj):
    """
    Returns the string representations of a set of alternatives

    :returns: list of strings, where each string is each alternative
    """
    disjunctExpansions = []
    if type(disj.disjuncts[0]) is tuple:
        disjuncts = map(lambda x : x[0], disj.disjuncts)
    else:
        disjuncts = disj.disjuncts
    for disjunct in disjuncts:
        disjunctExpansions.extend(processRHS(disjunct))
    return disjunctExpansions

def processOptional(opt):
    """
    Returns the string representations of an optional grouping

    :type opt: JSGFOptional
    :returns: list of strings, including an empty string
    """
    optional = ['']
    optional.extend(processRHS(opt.option))
    return optional

def processRHS(rhs):
    """
    Depending on the type of the argument, calls the corresponding
    function to deal with that type.

    :param rhs: portion of JSGF rule
    :type rhs: either a JSGF Expression, list, or string
    :returns: list of strings
    """
    if type(rhs) is list:
        return processSequence(rhs)
    elif isinstance(rhs, gram.Disjunction):
        return processDisjunction(rhs)
    elif isinstance(rhs, gram.Optional):
        return processOptional(rhs)
    elif isinstance(rhs, gram.NonTerminal):
        return processNonTerminal(rhs)
    elif type(rhs) is str:
        return [rhs]


if __name__ == '__main__':
    fileStream = open(sys.argv[1])
    grammar = parser.getGrammarObject(fileStream)
    for rule in grammar.publicRules:
        expansions = processRHS(rule.rhs)
        for expansion in expansions:
            print expansion