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/*******************************************************************************
* Copyright (c) 2009 Luaj.org. 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
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package org.luaj.vm2.compiler;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import org.luaj.vm2.Globals;
import org.luaj.vm2.LoadState;
import org.luaj.vm2.LocVars;
import org.luaj.vm2.Prototype;
import org.luaj.vm2.LuaString;
import org.luaj.vm2.LuaValue;


/** Class to dump a {@link Prototype} into an output stream, as part of compiling.
 * 
 * Generally, this class is not used directly, but rather indirectly via a command 
 * line interface tool such as {@link luac}.
 * 

 * A lua binary file is created via {@link DumpState#dump}:
 * 
 {@code
 * Globals globals = JsePlatform.standardGlobals();
 * Prototype p = globals.compilePrototype(new StringReader("print('hello, world')"), "main.lua");
 * ByteArrayOutputStream o = new ByteArrayOutputStream();
 * DumpState.dump(p, o, false);
 * byte[] lua_binary_file_bytes = o.toByteArray();
 * } 
 * 
 * The {@link LoadState} may be used directly to undump these bytes:
 *  {@code
 * Prototypep = LoadState.instance.undump(new ByteArrayInputStream(lua_binary_file_bytes), "main.lua");
 * LuaClosure c = new LuaClosure(p, globals);
 * c.call();
 * } 
 * 
 * 
 * More commonly, the {@link Globals#undumper} may be used to undump them:
 *  {@code
 * Prototype p = globals.loadPrototype(new ByteArrayInputStream(lua_binary_file_bytes), "main.lua", "b");
 * LuaClosure c = new LuaClosure(p, globals);
 * c.call();
 * } 
 * 
 * @see luac
 * @see LoadState
 * @see Globals
 * @see Prototype
 */
public class DumpState {

	/** set true to allow integer compilation */
	public static boolean ALLOW_INTEGER_CASTING = false;
	
	/** format corresponding to non-number-patched lua, all numbers are floats or doubles */
	public static final int NUMBER_FORMAT_FLOATS_OR_DOUBLES    = 0;

	/** format corresponding to non-number-patched lua, all numbers are ints */
	public static final int NUMBER_FORMAT_INTS_ONLY            = 1;
	
	/** format corresponding to number-patched lua, all numbers are 32-bit (4 byte) ints */
	public static final int NUMBER_FORMAT_NUM_PATCH_INT32      = 4;
	
	/** default number format */
	public static final int NUMBER_FORMAT_DEFAULT = NUMBER_FORMAT_FLOATS_OR_DOUBLES;

	// header fields
	private boolean IS_LITTLE_ENDIAN = false;
	private int NUMBER_FORMAT = NUMBER_FORMAT_DEFAULT;
	private int SIZEOF_LUA_NUMBER = 8;
	private static final int SIZEOF_INT = 4;
	private static final int SIZEOF_SIZET = 4;
	private static final int SIZEOF_INSTRUCTION = 4;

	DataOutputStream writer;
	boolean strip;
	int status;

	public DumpState(OutputStream w, boolean strip) {
		this.writer = new DataOutputStream( w );
		this.strip = strip;
		this.status = 0;
	}

	void dumpBlock(final byte[] b, int size) throws IOException {
		writer.write(b, 0, size);
	}

	void dumpChar(int b) throws IOException {
		writer.write( b );
	}

	void dumpInt(int x) throws IOException {
		if ( IS_LITTLE_ENDIAN ) {
			writer.writeByte(x&0xff);
			writer.writeByte((x>>8)&0xff);
			writer.writeByte((x>>16)&0xff);
			writer.writeByte((x>>24)&0xff);
		} else {
			writer.writeInt(x);
		}
	}
	
	void dumpString(LuaString s) throws IOException {
		final int len = s.len().toint();
		dumpInt( len+1 );
		s.write( writer, 0, len );
		writer.write( 0 );
	}
	
	void dumpDouble(double d) throws IOException {
		long l = Double.doubleToLongBits(d);
		if ( IS_LITTLE_ENDIAN ) {
			dumpInt( (int) l );
			dumpInt( (int) (l>>32) );
		} else {
			writer.writeLong(l);
		}
	}

	void dumpCode( final Prototype f ) throws IOException {
		final int[] code = f.code;
		int n = code.length;
		dumpInt( n );
		for ( int i=0; i