net.sf.tweety.logics.pl.parser

Class PlParser

java.lang.Object

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

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

public class PlParser
extends Parser<PlBeliefSet>

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 | "+" | "-"

PROPOSITION is a sequence of symbols from {a,...,z,A,...,Z,0,...,9,_}.

Author:

Matthias Thimm, Bastian Wolf

Constructor Summary

Constructors

Constructor and Description
PlParser()

Method Summary

Modifier and Type	Method and 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 PropositionalFormula	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 PropositionalFormula	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 PropositionalFormula	parseDisjunction(java.util.List<java.lang.Object> l) Parses a simple formula as a list of String tokens or formulas into a propositional formula.
PropositionalFormula	parseFormula(java.io.Reader reader) Parses the given reader into a formula of the given type.
private PropositionalFormula	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>

Parameters:

reader - a reader

Returns:

a belief base

Throws:

ParserException

parseFormula

public PropositionalFormula 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>

Parameters:

reader - a reader

Returns:

a formula

Throws:

ParserException

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.

parseDisjunction

private PropositionalFormula 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 PropositionalFormula 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 PropositionalFormula 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 PropositionalFormula 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