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gnu.prolog.vm.interpreter
Class ExecutionState

java.lang.Object
 extended by gnu.prolog.vm.interpreter.ExecutionState

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public class ExecutionState
extends Object

execution state class

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Field Summary
Term[]	args arguments
static int	BACKTRACK instruction return code indicating need for backtracking
Term[]	environment current environment
Interpreter	interpreter current interpreter
static int	JUMP instruction return code indicating success.
int	jumpPosition current position
static int	NEXT instruction return code indicating success.
List<Term>	pushdown pushdown stack, used for unification and calls
static int	RETURN instruction return code indicating success.
BacktrackInfo	startBacktrackInfo current backtrack info, only active on backtracking

Constructor Summary
ExecutionState()

Method Summary
CallBacktrackInfo	getCallBacktrackInfo(int codePosition, Term[] args, PrologCode code, CompoundTermTag tag) get BacktrackInfo for call instruction.
EnterBacktrackInfo	getEnterBacktrackInfo() get enter backtrack info
Term	getEnvironment(int environmentIndex) get term from environment
LeaveBacktrackInfo	getLeaveBacktrackInfo() get leave backtrack info
RetryBacktrackInfo	getRetryBacktrackInfo(int retryPosition) get BacktrackInfo for try family instructions.
BacktrackInfo	peekBacktrackInfo() peek backtrack info w/o popping it
BacktrackInfo	popBacktrackInfo() pop backtrack info from stack
Term	popPushDown() pop term from pushdown stack
void	pushBacktrackInfo(BacktrackInfo cbi) push backtrack info to stack
void	pushPushDown(Term term) push term to pushdown stack
void	putEnvironment(int environmentIndex, Term term) put term to environment

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BACKTRACK

public static final int BACKTRACK

instruction return code indicating need for backtracking

See Also:

Constant Field Values

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NEXT

public static final int NEXT

instruction return code indicating success. backtrack information may or not be created

See Also:

Constant Field Values

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JUMP

public static final int JUMP

instruction return code indicating success. jump to position in instruction pointer needed

See Also:

Constant Field Values

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RETURN

public static final int RETURN

instruction return code indicating success. return from function needed.

See Also:

Constant Field Values

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interpreter

public Interpreter interpreter

current interpreter

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startBacktrackInfo

public BacktrackInfo startBacktrackInfo

current backtrack info, only active on backtracking

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environment

public Term[] environment

current environment

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pushdown

public List<Term> pushdown

pushdown stack, used for unification and calls

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jumpPosition

public int jumpPosition

current position

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args

public Term[] args

arguments

Constructor Detail

ExecutionState

public ExecutionState()

Method Detail

popBacktrackInfo

public BacktrackInfo popBacktrackInfo()

pop backtrack info from stack

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peekBacktrackInfo

public BacktrackInfo peekBacktrackInfo()

peek backtrack info w/o popping it

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pushBacktrackInfo

public void pushBacktrackInfo(BacktrackInfo cbi)

push backtrack info to stack

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getCallBacktrackInfo

public CallBacktrackInfo getCallBacktrackInfo(int codePosition,
 Term[] args,
 PrologCode code,
 CompoundTermTag tag)

get BacktrackInfo for call instruction.

Parameters:

codePosition -

args -

code -

tag -

Returns:

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getRetryBacktrackInfo

public RetryBacktrackInfo getRetryBacktrackInfo(int retryPosition)

get BacktrackInfo for try family instructions.

Parameters:

retryPosition -

Returns:

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popPushDown

public Term popPushDown()

pop term from pushdown stack

Returns:

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pushPushDown

public void pushPushDown(Term term)

push term to pushdown stack

Parameters:

term -

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getEnvironment

public Term getEnvironment(int environmentIndex)

get term from environment

Parameters:

environmentIndex -

Returns:

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putEnvironment

public void putEnvironment(int environmentIndex,
 Term term)

put term to environment

Parameters:

environmentIndex -

term -

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getLeaveBacktrackInfo

public LeaveBacktrackInfo getLeaveBacktrackInfo()

get leave backtrack info

Returns:

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getEnterBacktrackInfo

public EnterBacktrackInfo getEnterBacktrackInfo()

get enter backtrack info

Returns:

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Overview Package Class Use Tree Deprecated Index Help		GNU Prolog for Java
PREV CLASS NEXT CLASS	FRAMES NO FRAMES All Classes
SUMMARY: NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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