lp.trans
Class Solver<M>

java.lang.Object
  lp.trans.Solver<M>

Direct Known Subclasses:

DlpSolver, EvolpSolver, LpSolver

public abstract class Solver<M>
extends Object

An abstract class that contains common functionality of classes used to compute stable models of grounded logic programs (LpSolver, DlpSolver and EvolpSolver). The inheriting classes differ in the way they interprete the resulting models (they may throw some computed atoms away or transform them to different atoms).

Version:

1.0.0

Author:

Martin Slota

See Also:

LpSolver, DlpSolver, EvolpSolver

Field Summary

private LparseWrapper	lw An LparseWrapper instance used to execute lparse before executing smodels.
private int	modelCount Number of models that were computed.
private LpPrinter<Writer>	printer The printer used to write a logic program to the LparseWrapper.
private SmodelsWrapper	sw An SmodelsWrapper instance used to compute the stable models.

Constructor Summary

Solver(LparseWrapper lparseWrapper, SmodelsWrapper smodelsWrapper)
Creates a new instance of that uses the given objects to invoke lparse and smodels when computing the stable models.

Method Summary

int	getModelCount() Returns the number of models that were computed.
protected static String	getNextModelString(BufferedReader smodelsOutput) Returns the string containing space-separated atoms in the next model computed by smodels.
protected abstract M	parseModel(String modelString) Parses modelString and returns the model that it represents.
void	setLparsePath(String lparsePath) Sets the path to lparse binary that is used to invoke lparse.
void	setModelLimit(int modelLimit) Sets the maximum number of stable models that should be computed by smodels.
void	setSmodelsPath(String smodelsPath) Sets the path to smodels binary that is used to invoke smodels.
void	solve(LogicProgram program, Consumer<M> consumer) Computes the stable models of the grounded logic program program and passes them to consumer.

Methods inherited from class java.lang.Object

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

Field Detail

lw

private final LparseWrapper lw

An LparseWrapper instance used to execute lparse before executing smodels.

sw

private final SmodelsWrapper sw

An SmodelsWrapper instance used to compute the stable models.

printer

private final LpPrinter<Writer> printer

The printer used to write a logic program to the LparseWrapper.

modelCount

private int modelCount

Number of models that were computed.

Constructor Detail

Solver

public Solver(LparseWrapper lparseWrapper,
              SmodelsWrapper smodelsWrapper)

Creates a new instance of that uses the given objects to invoke lparse and smodels when computing the stable models.

Parameters:

lparseWrapper - the object used to execute lparse

smodelsWrapper - the object used to execute smodels

Method Detail

setLparsePath

public void setLparsePath(String lparsePath)

Sets the path to lparse binary that is used to invoke lparse.

Parameters:

lparsePath - path to the lparse binary

Throws:

IllegalArgumentException - if lparsePath is null or an empty string

setSmodelsPath

public void setSmodelsPath(String smodelsPath)

Sets the path to smodels binary that is used to invoke smodels.

Parameters:

smodelsPath - path to the smodels binary

Throws:

IllegalArgumentException - if smodelsPath is null or an empty string

setModelLimit

public void setModelLimit(int modelLimit)

Sets the maximum number of stable models that should be computed by smodels. If set to zero, all models will be computed.

Parameters:

modelLimit - the maximum number of stable models that should be computed by smodels.

Throws:

IllegalArgumentException - if modelLimit is negative

solve

public void solve(LogicProgram program,
                  Consumer<M> consumer)

Computes the stable models of the grounded logic program program and passes them to consumer.

Parameters:

program - logic program whose stable models should be computed

consumer - object that processes the resulting models

Throws:

IllegalArgumentException - if program has not been grounded yet

IOException - (wrapped in an ExceptionAdapter) if an I/O error occurs while manipulating the standard input and output streams of an lparse process

WrapperException - if an error occurs while calling lparse or smodels, see LparseWrapper.waitFor() and SmodelsWrapper.waitFor().

LpParserException - if an error occurs while the resulting models are being converted to their object representation (probably indicates a bug in this class)

getModelCount

public int getModelCount()

Returns the number of models that were computed.

Returns:

as specified above

getNextModelString

protected static String getNextModelString(BufferedReader smodelsOutput)
                                    throws IOException

Returns the string containing space-separated atoms in the next model computed by smodels.

Parameters:

smodelsOutput - reader of the output of smodels

Returns:

as specified above

Throws:

IOException

parseModel

protected abstract M parseModel(String modelString)

Parses modelString and returns the model that it represents.

Parameters:

modelString - a string representation of a model returned by smodels

Returns:

the object representation of the model

Throws:

LpParserException - if an error occurs while the resulting models are being converted to their object representation (probably indicates a bug in this class)