net.sf.tweety.logics.el.parser

Class ModalParser

java.lang.Object

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

net.sf.tweety.logics.el.parser.ModalParser

public class ModalParser
extends Parser<ModalBeliefSet>

This class implements a parser for modal logic. The BNF for a modal knowledge base is given by (starting symbol is KB)

KB ::== SORTSDEC DECLAR FORMULAS
DECLAR ::== (FUNCTORDEC | PREDDEC)*
SORTSDEC ::== ( SORTNAME "=" "{" (CONSTANTNAME ("," CONSTANTNAME)*)? "}" "\n" )*
PREDDEC ::== "type" "(" PREDICATENAME ("(" SORTNAME ("," SORTNAME)* ")")? ")" "\n"
FUNCTORDEC ::== "type" "(" SORTNAME "=" FUNCTORNAME "(" (SORTNAME ("," SORTNAME)*)? ")" ")" "\n"
FORMULAS ::== ( "\n" FORMULA)*
FORMULA ::== ATOM | "forall" VARIABLENAME ":" "(" FORMULA ")" | "exists" VARIABLENAME ":" "(" FORMULA ")" |
"(" FORMULA ")" | "[]" "(" FORMULA ")" | "<>" "(" FORMULA ")" |
FORMULA "&&" FORMULA | FORMULA "||" FORMULA | "!" FORMULA | "+" | "-"
ATOM ::== PREDICATENAME ("(" TERM ("," TERM)* ")")?
TERM ::== VARIABLENAME | CONSTANTNAME | FUNCTORNAME "(" (TERM ("," TERM)*)? ")"

where SORTNAME, PREDICATENAME, CONSTANTNAME, VARIABLENAME, and FUNCTORNAME are sequences of
symbols from {a,...,z,A,...,Z,0,...,9} with a letter at the beginning.

Author:

Matthias Thimm, Anna Gessler

Field Summary

Fields

Modifier and Type	Field and Description
(package private) FolParser	folparser

Constructor Summary

Constructors

Constructor and Description
ModalParser()

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 modal formula from the stream.
FolSignature	getSignature() Returns the signature of this parser.
private RelationalFormula	parseAtomic(java.util.List<java.lang.Object> l) Parses a simple formula as a list of String tokens or formulas into a fol formula.
ModalBeliefSet	parseBeliefBase(java.io.Reader reader) Parses the given reader into a belief base of the given type.
private RelationalFormula	parseConjunction(java.util.List<java.lang.Object> l) Parses a simple conjunction as a list of String tokens or formulas into a fol formula.
private RelationalFormula	parseDisjunction(java.util.List<java.lang.Object> l) Parses a disjunction as a list of String tokens or formulas into a fol formula.
Formula	parseFormula(java.io.Reader reader) Parses the given reader into a formula of the given type.
private RelationalFormula	parseModalization(java.util.List<java.lang.Object> l)
private RelationalFormula	parseNegation(java.util.List<java.lang.Object> l) Parses a simple formula as a list of String tokens or formulas into a fol formula.
private RelationalFormula	parseQuantification(java.util.List<java.lang.Object> l)
private java.util.List<Term<?>>	parseTermlist(java.util.List<java.lang.Object> l)
void	setSignature(FolSignature signature) Sets the signature for this parser.

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

Field Detail

folparser

FolParser folparser

Constructor Detail

ModalParser

public ModalParser()

Method Detail

parseBeliefBase

public ModalBeliefSet parseBeliefBase(java.io.Reader reader)
                               throws java.io.IOException,
                                      ParserException

Description copied from class: Parser

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

Specified by:

parseBeliefBase in class Parser<ModalBeliefSet>

Parameters:

reader - a reader

Returns:

a belief base

Throws:

java.io.IOException

ParserException

parseFormula

public Formula parseFormula(java.io.Reader reader)
                     throws java.io.IOException,
                            ParserException

Description copied from class: Parser

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

Specified by:

parseFormula in class Parser<ModalBeliefSet>

Parameters:

reader - a reader

Returns:

a formula

Throws:

java.io.IOException

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 modal 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.

parseTermlist

private java.util.List<Term<?>> parseTermlist(java.util.List<java.lang.Object> l)

parseModalization

private RelationalFormula parseModalization(java.util.List<java.lang.Object> l)
                                     throws ParserException

Throws:

ParserException

parseQuantification

private RelationalFormula parseQuantification(java.util.List<java.lang.Object> l)

parseDisjunction

private RelationalFormula parseDisjunction(java.util.List<java.lang.Object> l)

Parses a disjunction as a list of String tokens or formulas into a fol 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 FolFormula.

Returns:

a FolFormula.

Throws:

ParserException - if the list could not be parsed.

parseConjunction

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

Parses a simple conjunction as a list of String tokens or formulas into a fol formula.

Parameters:

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

Returns:

a FolFormula.

Throws:

ParserException - if the list could not be parsed.

parseNegation

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

Parses a simple formula as a list of String tokens or formulas into a fol 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 FolFormula.

Returns:

a fol formula.

Throws:

ParserException - if the list could not be parsed.

parseAtomic

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

Parses a simple formula as a list of String tokens or formulas into a fol 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 an atom (a predicate with a list of terms).

Parameters:

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

Returns:

a fol formula.

Throws:

ParserException

setSignature

public void setSignature(FolSignature signature)

Sets the signature for this parser.

Parameters:

signature - a fol signature.

getSignature

public FolSignature getSignature()

Returns the signature of this parser.

Returns:

the signature of this parser.