Package dev.zemco.codegame.execution.engine

Class ProgramExecutionEngine

java.lang.Object

dev.zemco.codegame.execution.engine.ProgramExecutionEngine

All Implemented Interfaces:

IExecutionEngine

public class ProgramExecutionEngine
extends Object
implements IExecutionEngine

Implementation of the execution engine that executes a program. The program is executed sequentially from the first instruction.

This implementation manages its own execution context that is retrievable using the getExecutionContext() method.

Author:

Erik Zemčík

Constructor Summary

Constructors

Constructor	Description
ProgramExecutionEngine(Program program, IMemory memory, IInputSource inputSource, IOutputSink outputSink)	Creates an instance of ProgramExecutionEngine that executes a given program.

Method Summary

Modifier and Type	Method	Description
IExecutionContext	getExecutionContext()	Returns the execution context managed by this engine.
Optional<InstructionDescriptor>	getNextInstructionDescriptor()	Returns a descriptor of the instruction that will be executed next by the engine.
void	jumpToLabel(String label)	Performs a jump to an instruction that is followed by the specified label.
void	step()	Executes a single instruction on the engine's execution context and moves to the next.

Methods inherited from class java.lang.Object

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

Constructor Details

ProgramExecutionEngine

public ProgramExecutionEngine(Program program,
 IMemory memory,
 IInputSource inputSource,
 IOutputSink outputSink)

Creates an instance of ProgramExecutionEngine that executes a given program. This new instance uses the provided components (memory, inputSource and outputSink) as a execution context.

Parameters:

program - program to execute

memory - memory to use during execution

inputSource - input source to use during execution

outputSink - output sink to use during execution

Throws:

IllegalArgumentException - if any parameter is null

Method Details

jumpToLabel

public void jumpToLabel(String label)

Performs a jump to an instruction that is followed by the specified label. This label must be known by the program, which is executed by the engine, and must be included in the map accessible using Program.getJumpLabelToLinePositionMap().

Specified by:

jumpToLabel in interface IExecutionEngine

Parameters:

label - label to jump to

Throws:

IllegalArgumentException - if label is null or empty

UnknownJumpLabelException - if label is not known by the program

getNextInstructionDescriptor

public Optional<InstructionDescriptor> getNextInstructionDescriptor()

Returns a descriptor of the instruction that will be executed next by the engine. This method returns an empty Optional if the engine has reached the end of the execution.

Specified by:

getNextInstructionDescriptor in interface IExecutionEngine

Returns:

instruction descriptor of the next instruction or an empty Optional

step

public void step()

Description copied from interface: IExecutionEngine

Executes a single instruction on the engine's execution context and moves to the next.

Specified by:

step in interface IExecutionEngine

getExecutionContext

public IExecutionContext getExecutionContext()

Returns the execution context managed by this engine.

Returns:

execution context managed by this engine