lp.trans
Class LpGrounder

java.lang.Object
  lp.trans.Grounder<LogicProgram>
      lp.trans.LpGrounder

public class LpGrounder
extends Grounder<LogicProgram>

Creates a grounded version of a normal logic program. This means that the resulting program output has the same stable models as the original program and output.isGround() returns true. The transformation is performed using LparseWrapper and can be executed by calling the Grounder.ground(Object) method. Lparse warnings (see LparseWrapper.getWarnings()) issued during the grounding process are translated into GrounderMessages and can be retrieved through the Grounder.getWarnings() method.

Version:

1.0.0

Author:

Martin Slota

See Also:

LparseWrapper, LpSolver

Field Summary

private LpParser	parser Used to parse lparse's output.
private LpPrinter<Writer>	pp An instance of LpPrettyPrinter that is used to create the lparse input with the original (non-ground) program.

Constructor Summary

LpGrounder()
Creates a new instance of LpGrounder that creates its own LparseWrapper instance using its default constructors.

LpGrounder(LparseWrapper wrapper)
Creates a new instance of LpGrounder that uses the given object to invoke lparse and process its output.

Method Summary

protected GrounderMessage	makeGrounderMessage(LparseMessage message, LogicProgram inputProgram) Creates an error message based on lparseMessage from lparse and the input program.
protected LogicProgram	parseOutput(String program) Parses the given lparse output and returns the grounded program.
protected void	printProgram(LogicProgram inputProgram, Writer writer) Prints inputProgram in a form that is groundable by lparse (as long as the programmer didn't break the constraints imposed by lparse).

Methods inherited from class lp.trans.Grounder

getWarnings, ground, setLparsePath

Methods inherited from class java.lang.Object

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

Field Detail

pp

private final LpPrinter<Writer> pp

An instance of LpPrettyPrinter that is used to create the lparse input with the original (non-ground) program.

parser

private final LpParser parser

Used to parse lparse's output.

Constructor Detail

LpGrounder

public LpGrounder()

Creates a new instance of LpGrounder that creates its own LparseWrapper instance using its default constructors.

LpGrounder

public LpGrounder(LparseWrapper wrapper)

Creates a new instance of LpGrounder that uses the given object to invoke lparse and process its output.

Parameters:

wrapper - the object used to execute lparse, parse its warnings and/or errors and create corresponding LparseMessage objects

Method Detail

printProgram

protected void printProgram(LogicProgram inputProgram,
                            Writer writer)

Prints inputProgram in a form that is groundable by lparse (as long as the programmer didn't break the constraints imposed by lparse).

Specified by:

printProgram in class Grounder<LogicProgram>

Parameters:

inputProgram - the (ungrounded) input program

writer - a Writer to write to

makeGrounderMessage

protected GrounderMessage makeGrounderMessage(LparseMessage message,
                                              LogicProgram inputProgram)

Creates an error message based on lparseMessage from lparse and the input program.

Specified by:

makeGrounderMessage in class Grounder<LogicProgram>

Parameters:

message - the error or warning message issued by lparse

inputProgram - the input program

Returns:

an enhanced message containing a reference to the problematic rule

parseOutput

protected LogicProgram parseOutput(String program)

Parses the given lparse output and returns the grounded program.

Specified by:

parseOutput in class Grounder<LogicProgram>

Parameters:

program - the lparse output

Returns:

the grounded program