Package net.sf.tweety.logics.pl.parser

Class PlParser

java.lang.Object

net.sf.tweety.commons.Parser<PlBeliefSet,PlFormula>

net.sf.tweety.logics.pl.parser.PlParser

public class PlParser
extends Parser<PlBeliefSet,PlFormula>

This class implements a parser for propositional logic. The BNF for a propositional belief set is given by (starting symbol is FORMULASET)

FORMULASET ::== FORMULA ( "\n" FORMULA )*
FORMULA ::== PROPOSITION | "(" FORMULA ")" | FORMULA ">>" FORMULA | FORMULA "||" FORMULA | FORMULA "=>" FORMULA | FORMULA "<=>" FORMULA | "!" FORMULA | "+" | "-"

PROPOSITION is a sequence of characters excluding |,&,!,(,),=,<,> and whitespace characters.

Author:

Matthias Thimm, Bastian Wolf

Constructor Summary

Constructors

Constructor	Description
PlParser()

Method Summary

Modifier and Type	Method	Description
private void	consumeToken(java.util.Stack<java.lang.Object> stack, int c)	This method reads one token from the given reader and appropriately constructs a propositional formula from the stream.
private PlFormula	parseAtomic(java.util.List<java.lang.Object> l)	Parses a simple formula as a list of String tokens or formulas into a propositional formula.
PlBeliefSet	parseBeliefBase(java.io.Reader reader)	Parses the given reader into a belief base of the given type.
private PlFormula	parseConjunction(java.util.List<java.lang.Object> l)	Parses a simple formula as a list of String tokens or formulas into a propositional formula.
private PlFormula	parseDisjunction(java.util.List<java.lang.Object> l)	Parses a simple formula as a list of String tokens or formulas into a propositional formula.
private PlFormula	parseEquivalence(java.util.List<java.lang.Object> l)	Parses a simple formula as a list of String tokens or formulas into a propositional formula.
PlFormula	parseFormula(java.io.Reader reader)	Parses the given reader into a formula of the given type.
private PlFormula	parseImplication(java.util.List<java.lang.Object> l)	Parses a simple formula as a list of String tokens or formulas into a propositional formula.
private PlFormula	parseNegation(java.util.List<java.lang.Object> l)	Parses a simple formula as a list of String tokens or formulas into a propositional formula.

Methods inherited from class net.sf.tweety.commons.Parser

isNumeric, parseBeliefBase, parseBeliefBaseFromFile, parseFormula, parseFormulaFromFile

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PlParser

public PlParser()

Method Detail

parseBeliefBase

public PlBeliefSet parseBeliefBase(java.io.Reader reader)
                            throws ParserException

Description copied from class: Parser

Parses the given reader into a belief base of the given type.

Specified by:

parseBeliefBase in class Parser<PlBeliefSet,PlFormula>

Parameters:

reader - a reader

Returns:

a belief base

Throws:

ParserException - some parsing exceptions may be added here.

parseFormula

public PlFormula parseFormula(java.io.Reader reader)
                       throws ParserException

Description copied from class: Parser

Parses the given reader into a formula of the given type.

Specified by:

parseFormula in class Parser<PlBeliefSet,PlFormula>

Parameters:

reader - a reader

Returns:

a formula

Throws:

ParserException - some parsing exceptions may be added here.

consumeToken

private void consumeToken(java.util.Stack<java.lang.Object> stack,
                          int c)
                   throws ParserException

This method reads one token from the given reader and appropriately constructs a propositional formula from the stream.

Parameters:

stack - a stack used for monitoring the read items.

c - a token from a stream.

Throws:

ParserException - in case of parser errors.

parseEquivalence

private PlFormula parseEquivalence(java.util.List<java.lang.Object> l)

Parses a simple formula as a list of String tokens or formulas into a propositional formula. This method expects no parentheses in the list and as such treats the formula as a equivalence.

Parameters:

l - a list objects, either String tokens or objects of type PlFormula.

Returns:

a PlFormula.

Throws:

ParserException - if the list could not be parsed.

parseImplication

private PlFormula parseImplication(java.util.List<java.lang.Object> l)

Parses a simple formula as a list of String tokens or formulas into a propositional formula. This method expects no parentheses in the list and as such treats the formula as a implication.

Parameters:

l - a list objects, either String tokens or objects of type PlFormula.

Returns:

a PlFormula.

Throws:

ParserException - if the list could not be parsed.

parseDisjunction

private PlFormula parseDisjunction(java.util.List<java.lang.Object> l)
                            throws ParserException

Parses a simple formula as a list of String tokens or formulas into a propositional formula. This method expects no parentheses in the list and as such treats the formula as a disjunction.

Parameters:

l - a list objects, either String tokens or objects of type PropositionalFormula.

Returns:

a propositional formula.

Throws:

ParserException - if the list could not be parsed.

parseConjunction

private PlFormula parseConjunction(java.util.List<java.lang.Object> l)
                            throws ParserException

Parses a simple formula as a list of String tokens or formulas into a propositional formula. This method expects no parentheses and no disjunctions in the list and as such treats the formula as a conjunction.

Parameters:

l - a list objects, either String tokens or objects of type PropositionalFormula.

Returns:

a propositional formula.

Throws:

ParserException - if the list could not be parsed.

parseNegation

private PlFormula parseNegation(java.util.List<java.lang.Object> l)
                         throws ParserException

Parses a simple formula as a list of String tokens or formulas into a propositional formula. This method expects no parentheses, no disjunctions, and no conjunctions in the list and as such treats the formula as a negation.

Parameters:

l - a list objects, either String tokens or objects of type PropositionalFormula.

Returns:

a propositional formula.

Throws:

ParserException - if the list could not be parsed.

parseAtomic

private PlFormula parseAtomic(java.util.List<java.lang.Object> l)
                       throws ParserException

Parses a simple formula as a list of String tokens or formulas into a propositional formula. This method expects no parentheses, no disjunctions, no conjunctions, and no negation in the list and as such treats the formula as an atomic construct, either a contradiction, a tautology, or a proposition.

Parameters:

l - a list objects, either String tokens or objects of type PropositionalFormula.

Returns:

a propositional formula.

Throws:

ParserException - if parsing fails