net.sf.tweety.action.query.parser

Class ActionQueryParser

java.lang.Object

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

net.sf.tweety.action.query.parser.ActionQueryParser

public class ActionQueryParser
extends Parser<SActionQuerySet>

This class implements a parser for action queries in S. The BNF of such queries is given by: (starting symbol is KB)
KB ::== QUERY1 ("\n" QUERY1)*
QUERY1 ::== QUERY ( "requires" REQUIREMENTS )?
QUERY ::== PROPOSITION | QUERY "&&" QUERY | QUERY "||" QUERY | "!" QUERY | "(" QUERY ")" | "+" | "-"
PROPOSITION ::== HOLDSQUERY | ALWAYSQUERY | NECESSARILYQUERY
HOLDSQUERY ::== "holds" "[" STATEFORMULA "]"
ALWAYSQUERY ::== "always" "[" STATEFORMULA "]"
NECESSARILYQUERY ::== "necessarily" "[" STATEFORMULA "]" "after" ACTIONS
ACTIONS ::== ACTION ( ";" ACTION )*
ACTION ::== "{" ACTIONNAME ("," ACTIONNAME)* "}"
REQUIREMENTS ::== REQUIREMENT ("," REQUIREMENT)*
REQUIREMENT ::== (VARIABLENAME "<>" VARIABLENAME | VARIABLENAME "<>" CONSTANTNAME)*

where STATEFORMULA is an unquantified first-order formula without functors,
and VARIABLENAME, CONSTANTNAME are sequences of symbols
from {a,...,z,A,...,Z,0,...,9} with a letter at the beginning.

Author:

Sebastian Homann, Tim Janus (change constant LogicalSymbols to dynamic)

Field Summary

Fields

Modifier and Type	Field and Description
private ActionSignature	signature

Constructor Summary

Constructors

Constructor and Description
ActionQueryParser(ActionSignature signature)

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 FolAction	parseAction(java.util.List<java.lang.Object> l) Parses a list of actionnames or a list of actions.
private SActionQuery	parseActionFormula(java.util.Stack<java.lang.Object> stack) Parses a simple formula as a list of string tokens or formulas into an action query.
private FOLAtom	parseActionName(java.lang.String s)
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.
SActionQuerySet	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.
SActionQuery	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

Field Detail

signature

private ActionSignature signature

Constructor Detail

ActionQueryParser

public ActionQueryParser(ActionSignature signature)

Method Detail

parseBeliefBase

public SActionQuerySet parseBeliefBase(java.io.Reader reader)

Description copied from class: Parser

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

Specified by:

parseBeliefBase in class Parser<SActionQuerySet>

Parameters:

reader - a reader

Returns:

a belief base

parseFormula

public SActionQuery 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<SActionQuerySet>

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 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.

parseAction

private FolAction parseAction(java.util.List<java.lang.Object> l)
                       throws ParserException,
                              java.io.IOException

Parses a list of actionnames or a list of actions. Actions are strings of the form ACTIONNAME ("," ACTIONNAME)* into an action.

Parameters:

s - String

Returns:

an Action.

Throws:

ParserException

java.io.IOException

parseActionName

private FOLAtom parseActionName(java.lang.String s)
                         throws ParserException,
                                java.io.IOException

Throws:

ParserException

java.io.IOException

parseActionFormula

private SActionQuery parseActionFormula(java.util.Stack<java.lang.Object> stack)
                                 throws ParserException

Parses a simple formula as a list of string tokens or formulas into an action query. This method expects a list of requirements at the end of the list.

Parameters:

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

Throws:

ParserException

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