nltk.sem.logic.LogicParser

Class LogicParser

A lambda calculus expression parser.

Instance Methods

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__init__(self)

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parse(self, data)
Parse the expression.

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process(self, data)
Put whitespace between symbols to make parsing easier

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get_all_symbols(self)
This method exists to be overridden

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inRange(self, location)
Return TRUE if the given location is within the buffer

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token(self, location=None)
Get the next waiting token.

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isvariable(self, tok)

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parse_Expression(self, allow_adjuncts=True)
Parse the next complete expression from the stream and return it.

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handle(self, tok)
This method is intended to be overridden for logics that use different operators or expressions

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handle_negation(self)

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make_NegatedExpression(self, expression)

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handle_variable(self, tok)

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handle_lambda(self, tok)

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get_QuantifiedExpression_factory(self, tok)
This method serves as a hook for other logic parsers that have different quantifiers

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handle_quant(self, tok)

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handle_open(self, tok)

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attempt_EqualityExpression(self, expression)
Attempt to make a boolean expression.

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make_EqualityExpression(self, first, second)
This method serves as a hook for other logic parsers that have different equality expression classes

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attempt_BooleanExpression(self, expression)
Attempt to make a boolean expression.

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get_BooleanExpression_factory(self)
This method serves as a hook for other logic parsers that have different boolean operators

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make_BooleanExpression(self, type, first, second)
This method exists to be overridden by parsers with more complex logic for creating BooleanExpressions

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attempt_ApplicationExpression(self, expression)
Attempt to make an application expression.

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make_ApplicationExpression(self, function, argument)

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make_VariableExpression(self, name)

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make_LambdaExpression(self, variable, term)

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assertToken(self, tok, expected)

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__repr__(self)

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parse(self, data)

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Parse the expression.

Parameters:

data - str for the input to be parsed

Returns:

a parsed Expression

token(self, location=None)

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Get the next waiting token. If a location is given, then return the token at currentIndex+location without advancing currentIndex; setting it gives lookahead/lookback capability.

attempt_EqualityExpression(self, expression)

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Attempt to make a boolean expression. If the next token is a boolean operator, then a BooleanExpression will be returned. Otherwise, the parameter will be returned.

attempt_BooleanExpression(self, expression)

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Attempt to make a boolean expression. If the next token is a boolean operator, then a BooleanExpression will be returned. Otherwise, the parameter will be returned.

attempt_ApplicationExpression(self, expression)

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Attempt to make an application expression. The next tokens are a list of arguments in parens, then the argument expression is a function being applied to the arguments. Otherwise, return the argument expression.