JsEngine.java

package com.drawbridge.jsengine;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import com.drawbridge.dm.DMImageFactory.DMImage;
import com.drawbridge.dm.DMPanel;
import com.drawbridge.jsengine.ast.DBParser;
import com.drawbridge.jsengine.ast.ParserListener;
import com.drawbridge.jsengine.jsobjects.Colour;
import com.drawbridge.jsengine.jsobjects.JSImage;
import com.drawbridge.jsengine.jsobjects.JSNativeFunction;
import com.drawbridge.jsengine.jsobjects.JSNumber;
import com.drawbridge.text.TextPanel;
import com.drawbridge.utils.Utils;
import com.drawbridge.vl.VLPanel;
import com.google.caja.ancillary.linter.LintHelper;

public class JsEngine
{

	/**
	 * List of listeners that need to be notified when the model is updated
	 */
	private List<JSEngineListener>	mListeners;
	private final Scope				mGlobalScope;
	private static JsEngine			mInstance			= null;
	private final String			mScaffoldCode;
	public final Integer			mScaffoldLines;
	private int						mContinueASTExecutionRequests;
	private final Runnable			mExecutionRunnable;
	private Thread					mExecutionThread	= null;

	public static JsEngine getInstance()
	{
		if (mInstance != null)
		{
			return mInstance;
		} else
		{
			mInstance = new JsEngine();
			return mInstance;
		}
	}

	public JsEngine() {
		mListeners = new ArrayList<JSEngineListener>();
		mGlobalScope = new Scope(this, null);
		mScaffoldCode = Utils.loadTextFromPackagedFile("/SimpleTweeningJS/stubs.js");
		mScaffoldLines = Utils.getNumberOfLinesFromPackagedFile("/SimpleTweeningJS/stubs.js");

		mExecutionRunnable = new Runnable()
		{

			@Override
			public void run()
			{
				while (mContinueASTExecutionRequests > 0)
				{
					mContinueASTExecutionRequests = 0;

					getGlobalScope().resetVariables();

					// Load any existing DMImages into JS Memory
					loadDMImagesIntoJSEngine();
					try
					{
						DBParser.getInstance();
						DBParser.getInstance().evaluate();
					} catch (Exception e)
					{
						e.printStackTrace();
					}
					try
					{
						Thread.sleep(30);
					} catch (InterruptedException e)
					{
						e.printStackTrace();
					}
				}
			}

		};
	}

	public synchronized Scope getGlobalScope()
	{
		return mGlobalScope;
	}

	public synchronized void addModelListener(JSEngineListener listener)
	{
		mListeners.add(listener);
	}

	/**
	 * Updates listeners that a scope has changed has changed
	 * 
	 * @param child
	 *            - the scope the change affects new JSImage(
	 * @param source
	 *            - where the change was made
	 */
	private synchronized void notifyModelListeners(Scope child, JSEngineListener source)
	{
		synchronized (mListeners)
		{
			for (JSEngineListener name : mListeners)
			{
				if (!name.equals(source))
				{
					name.modelChange(child);
				}
			}
		}
	}

	public void childChanged(Scope scope, JSEngineListener source)
	{
		notifyModelListeners(scope, source);
	}

	public interface JSEngineListener
	{

		/**
		 * Whenever the main model changes, each subscriber gets notified
		 * 
		 * @param scope
		 * @param source
		 */
		public void modelChange(Scope scope);

	}

	/**
	 * Executes code in the JSEngine. If evaluate is false, the code is simply parsed and pushed to listeners
	 * 
	 * @param sourceListener
	 * @param code
	 * @param evaluate
	 */
	public void executeCode(ParserListener sourceListener, String code, boolean evaluate)
	{
		Utils.out.println(getClass(), "Execute Code from " + ((sourceListener != null) ? sourceListener.getClass().getSimpleName() : "Utils") + (evaluate? "evaluating" : " not evaluating"));
		LinkedList<ParserListener> listeners = new LinkedList<ParserListener>();
		if (TextPanel.hasInstance())
			listeners.add(TextPanel.getInstance());
		if (VLPanel.hasInstance())
			listeners.add(VLPanel.getInstance().mCanvas.getModel());

		DBParser.getInstance().setParams(sourceListener, listeners, mGlobalScope, code);
		long before = System.currentTimeMillis();
		DBParser.getInstance().parse();

		if (evaluate)
		{
			getGlobalScope().resetVariables();

			// Load any existing DMImages into JS Memory
			loadDMImagesIntoJSEngine();
			try
			{
				DBParser.getInstance().evaluate();
			} catch (Exception e)
			{
				e.printStackTrace();
			}
			JsEngine.getInstance().getGlobalScope().printScopeDeep(0);
		}

		LintHelper lh = new LintHelper();
		String fullCode = mScaffoldCode + code;
		lh.runTest(mScaffoldLines, fullCode);
		Utils.out.println(fullCode);
		long after = System.currentTimeMillis();//INVALID_ASSIGNMENT
		long difference = after - before;
		Utils.out.println(getClass(), "Time taken to executeCode: " + difference + " milliseconds");
	}

	/**
	 * Adds the code to an execution queue, which is executed according to how fast executions take. It then takes the
	 * next to be processed
	 * 
	 * @param sourceListener
	 * @param code
	 */
	public void requestExecutionOfModifiedAST()
	{
		mContinueASTExecutionRequests++;
		// Utils.out.println("Requested:" + mNumberRequested + ", processed:" +
		// mNumberProcessed);
		// If thread isn't working, start it
		if (mExecutionThread != null && mExecutionThread.isAlive())
		{
			// it will process if it has time
		}
		else
		{
			mExecutionThread = new Thread(mExecutionRunnable);
			mExecutionThread.start();
		}
	}

	// Push info from model into JSEngine
	public void loadDMImagesIntoJSEngine()
	{
		LinkedList<DMImage> images = DMPanel.getInstance().mModel.getModelObjects();
		for (int i = 0; i < images.size(); i++)
		{
			JSImage newImage = new JSImage(images.get(i));
			String name = "image" + i;
			SymbolTableEntry entry = new SymbolTableEntry(newImage);
			JsEngine.getInstance().getGlobalScope().declareVariable(null, name, entry);
		}
		JsEngine.getInstance().getGlobalScope().declareVariable(null, "WIDTH", new SymbolTableEntry(new JSNumber(DMPanel.getInstance().getWidth())));
		JsEngine.getInstance().getGlobalScope().declareVariable(null, "HEIGHT", new SymbolTableEntry(new JSNumber(DMPanel.getInstance().getHeight())));
		JsEngine.getInstance().getGlobalScope().declareVariable(null, "loadImage", new SymbolTableEntry(new JSNativeFunction(null, "loadImage", new Class<?>[] { JSNumber.class, JSNumber.class, JSNumber.class, JSNumber.class, JSNumber.class })));

		JsEngine.getInstance().getGlobalScope().declareVariable(null, "setTimeToDestination", new SymbolTableEntry(new JSNativeFunction(null, "setTimeToDestination", new Class<?>[] { JSNumber.class })));

		JsEngine.getInstance().getGlobalScope().declareVariable(null, "Colour", new SymbolTableEntry(new Colour()));

	}

}