logic_inference.py

import os
import random
import re
import shutil

from pyke import knowledge_engine


class PykeProgram:
    def __init__(
        self, logic_program: str, dataset_name='ProntoQA', workspace_mount_path='./'
    ) -> None:
        self.logic_program = logic_program
        self.flag = self.parse_logic_program()
        self.dataset_name = dataset_name
        self.cache_dir = os.path.join(workspace_mount_path, '.cache_program')

        # prepare the files for facts and rules
        try:
            self.create_fact_file(self.Facts)
            self.create_rule_file(self.Rules)
            self.flag = True
        except Exception:
            self.flag = False

        self.answer_map = {
            'ProntoQA': self.answer_map_prontoqa,
            'ProofWriter': self.answer_map_proofwriter,
        }

    def parse_logic_program(self):
        keywords = ['Query:', 'Rules:', 'Facts:', 'Predicates:']
        program_str = self.logic_program
        for keyword in keywords:
            try:
                program_str, segment_list = self._parse_segment(program_str, keyword)
                setattr(self, keyword[:-1], segment_list)
            except Exception:
                setattr(self, keyword[:-1], None)

        return self.validate_program()

    def _parse_segment(self, program_str, key_phrase):
        remain_program_str, segment = program_str.split(key_phrase)
        segment_list = segment.strip().split('\n')
        for i in range(len(segment_list)):
            segment_list[i] = segment_list[i].split(':::')[0].strip()
        return remain_program_str, segment_list

    # check if the program is valid; if not, try to fix it
    def validate_program(self):
        if self.Rules is not None and self.Facts is not None:
            if not self.Rules[0] == '' and not self.Facts[0] == '':
                return True
        # try to fix the program
        tmp_rules = []
        tmp_facts = []
        statements = self.Facts if self.Facts is not None else self.Rules
        if statements is None:
            return False

        for fact in statements:
            if fact.find('>>>') >= 0:  # this is a rule
                tmp_rules.append(fact)
            else:
                tmp_facts.append(fact)
        self.Rules = tmp_rules
        self.Facts = tmp_facts
        return False

    def create_fact_file(self, facts):
        with open(os.path.join(self.cache_dir, 'facts.kfb'), 'w') as f:
            for fact in facts:
                # check for invalid facts
                if not fact.find('$x') >= 0:
                    f.write(fact + '\n')

    def create_rule_file(self, rules):
        pyke_rules = []
        for idx, rule in enumerate(rules):
            pyke_rules.append(self.parse_forward_rule(idx + 1, rule))

        with open(os.path.join(self.cache_dir, 'rules.krb'), 'w') as f:
            f.write('\n\n'.join(pyke_rules))

    # example rule: Furry($x, True) && Quite($x, True) >>> White($x, True)
    def parse_forward_rule(self, f_index, rule):
        premise, conclusion = rule.split('>>>')
        premise = premise.strip()
        # split the premise into multiple facts if needed
        premise = premise.split('&&')
        premise_list = [p.strip() for p in premise]

        conclusion = conclusion.strip()
        # split the conclusion into multiple facts if needed
        conclusion = conclusion.split('&&')
        conclusion_list = [c.strip() for c in conclusion]

        # create the Pyke rule
        pyke_rule = f"""fact{f_index}\n\tforeach"""
        for p in premise_list:
            pyke_rule += f"""\n\t\tfacts.{p}"""
        pyke_rule += """\n\tassert"""
        for c in conclusion_list:
            pyke_rule += f"""\n\t\tfacts.{c}"""
        return pyke_rule

    """
    for example: Is Marvin from Mars?
    Query: FromMars(Marvin, $label)
    """

    def check_specific_predicate(self, subject_name, predicate_name, engine):
        results = []
        with engine.prove_goal(
            f'facts.{predicate_name}({subject_name}, $label)'
        ) as gen:
            for vars, plan in gen:
                results.append(vars['label'])

        with engine.prove_goal(
            f'rules.{predicate_name}({subject_name}, $label)'
        ) as gen:
            for vars, plan in gen:
                results.append(vars['label'])

        if len(results) == 1:
            return results[0]
        elif len(results) == 2:
            return results[0] and results[1]
        elif len(results) == 0:
            return None

    """
    Input Example: Metallic(Wren, False)
    """

    def parse_query(self, query):
        pattern = r'(\w+)\(([^,]+),\s*([^)]+)\)'
        match = re.match(pattern, query)
        if match:
            function_name = match.group(1)
            arg1 = match.group(2)
            arg2 = match.group(3)
            arg2 = True if arg2 == 'True' else False
            return function_name, arg1, arg2
        else:
            raise ValueError(f'Invalid query: {query}')

    def execute_program(self):
        # delete the compiled_krb dir
        complied_krb_dir = './models/compiled_krb'
        if os.path.exists(complied_krb_dir):
            print('removing compiled_krb')
            # os.system(f'rm -rf {complied_krb_dir}/*')
            shutil.rmtree(complied_krb_dir)

        # absolute_path = os.path.abspath(complied_krb_dir)
        # print(absolute_path)
        try:
            engine = knowledge_engine.engine(self.cache_dir)
            engine.reset()
            engine.activate('rules')
            engine.get_kb('facts')

            # parse the logic query into pyke query
            predicate, subject, value_to_check = self.parse_query(self.Query[0])
            result = self.check_specific_predicate(subject, predicate, engine)
            answer = self.answer_map[self.dataset_name](result, value_to_check)
        except Exception as err:
            return None, err

        return answer, ''

    def answer_mapping(self, answer):
        return answer

    def answer_map_prontoqa(self, result, value_to_check):
        if result == value_to_check:
            return 'A'
        else:
            return 'B'

    def answer_map_proofwriter(self, result, value_to_check):
        if result is None:
            return 'C'
        elif result == value_to_check:
            return 'A'
        else:
            return 'B'


class LogicInferenceEngine:
    def __init__(self):
        self.dataset_name = os.environ.get('DATASET_NAME', 'ProofWriter')
        self.workspace_mount_path = '/workspace'

    def random_backup(self):
        if self.dataset_name == 'ProntoQA':
            return random.choice(['A', 'B'])
        elif self.dataset_name == 'ProofWriter':
            return random.choice(['A', 'B', 'C'])

    def safe_execute_program(self, logic_program):
        program = PykeProgram(
            logic_program, self.dataset_name, self.workspace_mount_path
        )
        # cannot parse the program
        if not program.flag:
            answer = self.random_backup()
            return answer, 'parsing error', ''
        # execute the program
        answer, error_message = program.execute_program()
        # not executable
        if answer is None:
            answer = self.random_backup()
            return answer, 'execution error', error_message
        # successfully executed
        answer = program.answer_mapping(answer)
        return answer, 'success', ''