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Luaj 3.0-beta1 for the jse platform
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/*******************************************************************************
* Copyright (c) 2008 LuaJ. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
******************************************************************************/
package org.luaj.vm2.script;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptException;
import javax.script.SimpleScriptContext;

import org.luaj.vm2.LoadState;
import org.luaj.vm2.Lua;
import org.luaj.vm2.LuaClosure;
import org.luaj.vm2.LuaError;
import org.luaj.vm2.LuaFunction;
import org.luaj.vm2.LuaValue;
import org.luaj.vm2.Prototype;
import org.luaj.vm2.lib.jse.JsePlatform;

/**
 * 
 * @author jim_roseborough
 */
public class LuaScriptEngine implements ScriptEngine, Compilable {
    
	private static final String __ENGINE_VERSION__   = Lua._VERSION;
    private static final String __NAME__             = "Luaj";
    private static final String __SHORT_NAME__       = "Luaj";
    private static final String __LANGUAGE__         = "lua";
    private static final String __LANGUAGE_VERSION__ = "5.1";
    private static final String __ARGV__             = "arg";
    private static final String __FILENAME__         = "?";
    
    private static final ScriptEngineFactory myFactory = new LuaScriptEngineFactory();
    
    private ScriptContext defaultContext;

    private final LuaValue _G;

    public LuaScriptEngine() {

        // create globals
        _G = JsePlatform.standardGlobals();
    	
    	// set up context
    	ScriptContext ctx = new SimpleScriptContext();
    	ctx.setBindings(createBindings(), ScriptContext.ENGINE_SCOPE);
        setContext(ctx);
        
        // set special values
        put(LANGUAGE_VERSION, __LANGUAGE_VERSION__);
        put(LANGUAGE, __LANGUAGE__);
        put(ENGINE, __NAME__);
        put(ENGINE_VERSION, __ENGINE_VERSION__);
        put(ARGV, __ARGV__);
        put(FILENAME, __FILENAME__);
        put(NAME, __SHORT_NAME__);
        put("THREADING", null);
    }
    
    
    public Object eval(String script) throws ScriptException {
        return eval(new StringReader(script));
    }
    
    public Object eval(String script, ScriptContext context) throws ScriptException {
    	return eval(new StringReader(script), context);
    }
    
    public Object eval(String script, Bindings bindings) throws ScriptException {
        return eval(new StringReader(script), bindings);
    }
    
    public Object eval(Reader reader) throws ScriptException {
        return eval(reader, getContext());
    }
    
    public Object eval(Reader reader, ScriptContext scriptContext) throws ScriptException {
    	return compile(reader).eval(scriptContext);
    }
    
    public Object eval(Reader reader, Bindings bindings) throws ScriptException {
    	ScriptContext c = getContext();
        Bindings current = c.getBindings(ScriptContext.ENGINE_SCOPE);
        c.setBindings(bindings, ScriptContext.ENGINE_SCOPE);
        Object result = eval(reader);
        c.setBindings(current, ScriptContext.ENGINE_SCOPE);
        return result;
    }
    
    public void put(String key, Object value) {
		Bindings b = getBindings(ScriptContext.ENGINE_SCOPE);
		((LuaBindings)b).put(key, value);
    }
    
    public Object get(String key) {
		Bindings b = getBindings(ScriptContext.ENGINE_SCOPE);
		return ((LuaBindings)b).get(key);
    }

    public Bindings getBindings(int scope) {
        return getContext().getBindings(scope);
    }
    
    public void setBindings(Bindings bindings, int scope) {
        getContext().setBindings(bindings, scope);
    }
    
    public Bindings createBindings() {
        return new LuaBindings( _G );
    }
    
    public ScriptContext getContext() {
        return defaultContext;
    }
    
    public void setContext(ScriptContext context) {
        defaultContext = context;
    }
    
    public ScriptEngineFactory getFactory() {
        return myFactory;
    }

	public CompiledScript compile(String script) throws ScriptException {
		return compile(new StringReader(script));
	}

	public CompiledScript compile(Reader reader) throws ScriptException {
		try {
	    	InputStream ris = new Utf8Encoder(reader);
	    	try {
	    		final LuaFunction f = LoadState.load(ris, "script", null);
	    		if ( f.isclosure() ) {
	    			LuaClosure c = f.checkclosure();
	    			final Prototype p = c.p;
					return new CompiledScript() {
						public Object eval(ScriptContext context) throws ScriptException {
					        Bindings b = context.getBindings(ScriptContext.ENGINE_SCOPE);
					        LuaBindings lb = (LuaBindings) b;
							LuaClosure c = new LuaClosure( p, lb.env );
							return c.invoke(LuaValue.NONE);
						}
						public ScriptEngine getEngine() {
							return LuaScriptEngine.this;
						}
					};
	    		} else {
	    			final Class c = f.getClass();
					return new CompiledScript() {
						public Object eval(ScriptContext context) throws ScriptException {
					        Bindings b = context.getBindings(ScriptContext.ENGINE_SCOPE);
					        LuaBindings lb = (LuaBindings) b;
					        LuaFunction lf;
							try {
						        lf = (LuaFunction) c.newInstance();
							} catch (Exception e) {
								throw new ScriptException("instantiation failed: "+e.toString());
							}
					        lf.setfenv(lb.env);
							return lf.invoke(LuaValue.NONE);
						}
						public ScriptEngine getEngine() {
							return LuaScriptEngine.this;
						}
					};	    			
	    		}
			} catch ( LuaError lee ) {
				throw new ScriptException(lee.getMessage() );
			} finally { 
				ris.close();
			}
		} catch ( Throwable t ) {
			throw new ScriptException("eval threw "+t.toString());
		}
	}
	
	// ------ lua bindings -----
	private static final class LuaBindings implements Bindings {
		private LuaValue env;
		private LuaValue mt;
		private LuaBindings( LuaValue _G ) {
			mt = LuaValue.tableOf();
			mt.set( LuaValue.INDEX, _G );
			clear();
		}
		public void clear() {
			env = LuaValue.tableOf();
			env.setmetatable(mt);
		}
		private Object toJava(LuaValue v) {
			switch ( v.type() ) {
			case LuaValue.TNIL: return null;
			case LuaValue.TSTRING: return v.tojstring();
			case LuaValue.TUSERDATA: return v.checkuserdata(Object.class);
			case LuaValue.TNUMBER: return v.isinttype()? new Integer(v.toint()): new Double(v.todouble());
			default: 
				throw new java.lang.UnsupportedOperationException(
					"LuaBindings cannot convert lua type '"+v.typename()+"' to Java");
			}
		}
		private LuaValue toLua(Object javaValue) {
			if ( javaValue instanceof Number ) {
				return LuaValue.valueOf(((Number)javaValue).doubleValue());
			} else if ( javaValue instanceof String ) {
				return LuaValue.valueOf(javaValue.toString());
			} else if ( javaValue == null ) {
				return LuaValue.NIL; 
			} else {
				return LuaValue.userdataOf(javaValue);
			}
		}
		public boolean containsKey(Object key) {
			return ! env.get(toLua(key)).isnil();
		}
		public Object get(Object key) {
			return toJava(env.get(toLua(key)));
		}
		public Object put(String name, Object value) {
			LuaValue key = toLua(name);
			Object result = toJava(env.get(key));
			env.set(key, toLua(value));
			return result;
		}
		public void putAll(Map toMerge) {
			for ( Iterator it=toMerge.entrySet().iterator(); it.hasNext(); ) {
				Map.Entry e = (Map.Entry) it.next();
				put( e.getKey(), e.getValue() );
			}
		}
		public Object remove(Object javakey) {
			LuaValue key = toLua(javakey);
			Object result = toJava(env.get(key));
			env.set(key, LuaValue.NIL);
			return result;
		}
		public boolean containsValue(Object value) {
			throw new java.lang.UnsupportedOperationException(
				"containsValue() not supported for LuaBindings");
		}
		public Set> entrySet() {
			throw new java.lang.UnsupportedOperationException(
				"entrySet() not supported for LuaBindings");
		}
		public boolean isEmpty() {
			throw new java.lang.UnsupportedOperationException(
				"isEmpty() not supported for LuaBindings");
		}
		public Set keySet() {
			throw new java.lang.UnsupportedOperationException(
				"keySet() not supported for LuaBindings");
		}
		public int size() {
			throw new java.lang.UnsupportedOperationException(
				"size() not supported for LuaBindings");
		}
		public Collection