Sheerka/src/evaluators/DefConceptEvaluator.py

from common.global_symbols import NotInit
from core.ExecutionContext import ContextActions, ExecutionContext
from core.ReturnValue import ReturnValue
from core.concept import DefinitionType
from core.error import ErrorContext, SheerkaException
from evaluators.base_evaluator import EvaluatorEvalResult, EvaluatorMatchResult, OneReturnValueEvaluator
from parsers.BnfDefinitionParser import BnfDefinitionParser
from parsers.ConceptDefinitionParser import ConceptDefinition
from parsers.parser_utils import ParsingException
from parsers.tokenizer import TokenKind, Tokenizer

NAMES_TOKEN_TYPES = {TokenKind.IDENTIFIER,
                     TokenKind.STRING}
CONCEPT_PARTS_TO_USE = [
    "body",
    "where",
    "pre",
    "post",
    "ret",
]


class DefConceptEvaluator(OneReturnValueEvaluator):
    """
    This evaluator create the definition of a new concept
    after it is recognized by the RecognizeDefConcept parser
    """

    NAME = "DefConcept"

    def __init__(self):
        super().__init__(self.NAME, ContextActions.EVALUATION, 50)

    def matches(self, context: ExecutionContext,
                return_value: ReturnValue) -> EvaluatorMatchResult:
        return EvaluatorMatchResult(return_value.status and isinstance(return_value.value, ConceptDefinition))

    def eval(self, context: ExecutionContext,
             evaluation_context: object,
             return_value: ReturnValue) -> EvaluatorEvalResult:

        try:
            concept_def = return_value.value
            variables = self._get_variables(context, concept_def)
            parameters = None

            if concept_def.definition_type == DefinitionType.BNF:
                self._validate_bnf(context, concept_def)

            ret_val = context.sheerka.define_new_concept(context,
                                                         concept_def.name,
                                                         False,
                                                         False,
                                                         concept_def.body,
                                                         concept_def.where,
                                                         concept_def.pre,
                                                         concept_def.post,
                                                         concept_def.ret,
                                                         concept_def.definition,
                                                         concept_def.definition_type,
                                                         concept_def.auto_eval,
                                                         variables=variables,
                                                         parameters=parameters)

            if ret_val.status:
                new = ReturnValue(self.NAME, True, ret_val.value, parents=[return_value])
                return EvaluatorEvalResult([new], [return_value])
            else:
                error_ret_val = ReturnValue(self.NAME, False, ret_val.value, [return_value])
                return EvaluatorEvalResult([error_ret_val], [])

        except ParsingException as ex:
            error_context = ErrorContext(self.NAME, context, ex.error)
            error_ret_val = ReturnValue(self.NAME, False, error_context, [return_value])
            return EvaluatorEvalResult([error_ret_val], [])

    def _get_variables(self, context: ExecutionContext, concept_def: ConceptDefinition):
        variables_found = set()  # list of names, there is no tuple
        definition = concept_def.definition or concept_def.name
        possible_vars_from_name = self._get_possible_vars_from_def(context, definition)

        possible_vars_from_name_as_set = set(possible_vars_from_name)
        for part in CONCEPT_PARTS_TO_USE:
            # if these possibles variables are referenced in other parts of the definition, they may be variables
            part_value = getattr(concept_def, part)
            if part_value == "":
                continue

            possible_vars_from_part = self._get_possible_vars_from_part(context, part_value)
            variables_found.update(possible_vars_from_name_as_set & possible_vars_from_part)

        # add variables from add_var
        if concept_def.def_var:
            variables_found.update(concept_def.def_var)

        with_default_value = [v if isinstance(v, tuple) else (v, NotInit) for v in variables_found]

        # variables are sorted
        sorted_vars = []
        for possible_var in possible_vars_from_name:
            for found in with_default_value:
                if possible_var == found[0]:
                    sorted_vars.append(found)

        return sorted_vars

    @staticmethod
    def _get_possible_vars_from_def(context, definition):
        """

        :param context:
        :type context:
        :param definition:
        :type definition:
        :return: list of names
        :rtype:
        """
        names = (str(t.value) for t in Tokenizer(definition) if t.type in NAMES_TOKEN_TYPES)
        possible_vars = filter(lambda x: not context.sheerka.is_a_concept_name(x), names)

        return list(possible_vars)

    @staticmethod
    def _get_possible_vars_from_part(context, part):
        """

        :param context:
        :type context:
        :param part:
        :type part:
        :return:
        :rtype:
        """
        # not the final implementation
        # In the final impl,
        #   we first need to check if the part is a concept call (rather than a concept name)
        names = (str(t.value) for t in Tokenizer(part) if t.type in NAMES_TOKEN_TYPES)
        possible_vars = filter(lambda x: not context.sheerka.is_a_concept_name(x), names)

        return set(possible_vars)

    @staticmethod
    def _validate_bnf(context, definition):
        parser = BnfDefinitionParser(context, definition.definition, definition.name)
        parser.parse()
        if parser.error_sink:
            raise ParsingException(parser.error_sink[0])

        return True