Package org.tweetyproject.logics.fol.parser

Class FolParser

java.lang.Object

org.tweetyproject.commons.Parser<FolBeliefSet,FolFormula>

org.tweetyproject.logics.fol.parser.FolParser

public class FolParser
extends Parser<FolBeliefSet,FolFormula>

This class implements a parser for first-order logic. The BNF for a first-order 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 | FORMULA "<=>" FORMULA | FORMULA "==" FORMULA | FORMULA "/==" FORMULA |
FORMULA "^^" FORMULA
ATOM ::== PREDICATENAME ("(" TERM ("," TERM)* ")")?
TERM ::== VARIABLENAME | CONSTANTNAME | FUNCTORNAME "(" (TERM ("," TERM)*)? ")"

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

Note: Equality/Inequality predicates (== and /==) can only be parsed if the parser is given a FolSignature
with the containsEquality attribute enabled (which is not the case by default).

Author:

Matthias Thimm, Anna Gessler

Constructor Summary

Constructors

Constructor	Description
FolParser()	Creates a new FolParser
FolParser(boolean ignoreUndeclaredConstants)	Creates a new FolParser

Method Summary

Modifier and Type	Method	Description
FolSignature	getSignature()	Returns the signature of this parser.
Map<String,Variable>	getVariables()	returns variables
FolBeliefSet	parseBeliefBase(Reader reader)	Parses the given reader into a belief base of the given type.
FolFormula	parseFormula(Reader reader)	Parses the given reader into a formula of the given type.
FolSignature	parseSignature(String s)	This function parses only the sorts declaration and type declaration parts of a belief base.
void	parseSortDeclaration(String s, FolSignature sig)	Parses a sort declaration of the form "SORTNAME "=" "{" (CONSTANTNAME ("," CONSTANTNAME)*)? "}"" and modifies the given signature accordingly.
void	parseTypeDeclaration(String s, FolSignature sig)	Parses a predicate declaration of the form "type" "(" PREDICATENAME "(" (SORTNAME ("," SORTNAME)*)? ")" ")" or a functor declaration of the form "type" "(" SORTNAME "=" FUNCTORNAME "(" (SORTNAME ("," SORTNAME)*)? ")" ")" and modifies the given signature accordingly.
void	setSignature(FolSignature signature)	Sets the signature for this parser.
void	setVariables(Map<String,Variable> variables)	sets variables

Methods inherited from class org.tweetyproject.commons.Parser

isNumeric, parseBeliefBase, parseBeliefBaseFromFile, parseFormula, parseFormulaFromFile, parseListOfBeliefBases, parseListOfBeliefBases, parseListOfBeliefBasesFromFile, parseListOfBeliefBasesFromFile

Methods inherited from class java.lang.Object

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

Constructor Details

FolParser

public FolParser()

Creates a new FolParser

FolParser

public FolParser(boolean ignoreUndeclaredConstants)

Creates a new FolParser

Parameters:

ignoreUndeclaredConstants - Do not raise exceptions when encountering new constants, all new constants are treated as THING

Method Details

parseBeliefBase

public FolBeliefSet parseBeliefBase(Reader reader)
                             throws 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<FolBeliefSet,FolFormula>

Parameters:

reader - a reader

Returns:

a belief base

Throws:

IOException - if some IO issue occurred.

ParserException - some parsing exceptions may be added here.

parseSortDeclaration

public void parseSortDeclaration(String s,
 FolSignature sig)
                          throws ParserException

Parses a sort declaration of the form "SORTNAME "=" "{" (CONSTANTNAME ("," CONSTANTNAME)*)? "}"" and modifies the given signature accordingly.

Parameters:

s - a string

sig - a signature

Throws:

ParserException - if parsing fails

parseTypeDeclaration

public void parseTypeDeclaration(String s,
 FolSignature sig)
                          throws ParserException

Parses a predicate declaration of the form "type" "(" PREDICATENAME "(" (SORTNAME ("," SORTNAME)*)? ")" ")" or a functor declaration of the form "type" "(" SORTNAME "=" FUNCTORNAME "(" (SORTNAME ("," SORTNAME)*)? ")" ")" and modifies the given signature accordingly.

Parameters:

s - a string

sig - a signature

Throws:

ParserException - if parsing fails

parseFormula

public FolFormula parseFormula(Reader reader)
                        throws IOException,
ParserException

Description copied from class: Parser

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

Specified by:

parseFormula in class Parser<FolBeliefSet,FolFormula>

Parameters:

reader - a reader

Returns:

a formula

Throws:

IOException - if some IO issue occurred.

ParserException - some parsing exceptions may be added here.

parseSignature

public FolSignature parseSignature(String s)

This function parses only the sorts declaration and type declaration parts of a belief base.

Parameters:

s - the signature as a string

Returns:

the parsed fol signature

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.

getVariables

public Map<String,Variable> getVariables()

returns variables

Returns:

variables

setVariables

public void setVariables(Map<String,Variable> variables)

sets variables

Parameters:

variables - variables to be set