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/*******************************************************************************
* Copyright (c) 2010 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
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*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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package org.luaj.vm2.lua2java;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.luaj.vm2.Lua;
import org.luaj.vm2.ast.Block;
import org.luaj.vm2.ast.Chunk;
import org.luaj.vm2.ast.FuncBody;
import org.luaj.vm2.ast.NameScope;
import org.luaj.vm2.ast.Variable;
import org.luaj.vm2.ast.Visitor;
import org.luaj.vm2.ast.Exp.BinopExp;
import org.luaj.vm2.ast.Exp.VarargsExp;
import org.luaj.vm2.ast.Stat.Return;
import org.luaj.vm2.lib.LibFunction;


public class JavaScope extends NameScope {

	private static final int MAX_CONSTNAME_LEN = 8;
	public static final Set SPECIALS = new HashSet();

	private static final String[] specials = {
			// keywords used by our code generator
			"name", 	"opcode",	"env",	// "arg", 
			
			// java keywords
			"abstract", "continue", "for",  	"new",		"switch",
			"assert", 	"default", 	"goto", 	"package", 	"synchronized",
			"boolean", 	"do", 		"if", 		"private", 	"this",
			"break", 	"double", 	"implements", "protected", 	"throw",
			"byte", 	"else", 	"import", 	"public", 	"throws",
			"case", 	"enum", 	"instanceof", "return", "transient",
			"catch", 	"extends", 	"int", 		"short", 	"try",
			"char", 	"final", 	"interface", "static", 	"void",
			"class", 	"finally", 	"long", 	"strictfp", "volatile",
			"const", 	"float", 	"native", 	"super", 	"while",
			
			// java literals
			"false", 	"null",		"true",	
	};
	
	static {
		for ( int i=0; i staticnames;
	final Set javanames = new HashSet();
	final Map astele2javaname = new HashMap();
	
	private JavaScope(Set staticnames, JavaScope outerScope) {		
		super(outerScope);	
		this.staticnames = staticnames;
	}
	
	public static JavaScope newJavaScope(Chunk chunk) {
		return new JavaScope(new HashSet(), null).initialize(chunk.block, -1);
	}
	
	public JavaScope pushJavaScope(FuncBody body) {
		return new JavaScope(staticnames, this).initialize(body.block, 0);
	}
	
	public JavaScope popJavaScope() {
		return (JavaScope) outerScope;
	}
	
	final String getJavaName(Variable nv) {
		for ( JavaScope s = this; s != null; s = (JavaScope) s.outerScope )
			if ( s.astele2javaname.containsKey(nv) )
				return (String) s.astele2javaname.get(nv);
		return allocateJavaName( nv, nv.name );
	}

	final private String allocateJavaName(Object astele, String proposal) {
		for ( int i=0; true; i++ ) {
			String jname = proposal+(i==0? "": "$"+i);
			if ( ! isJavanameInScope(jname) && ! SPECIALS.contains(jname) && !staticnames.contains(jname)  ) {
				javanames.add(jname);
				astele2javaname.put(astele,jname);
				return jname;
			}
		}
	}

	public void setJavaName(Variable astele, String javaname) {
		javanames.add(javaname);
		astele2javaname.put(astele,javaname);
	}	

	private boolean isJavanameInScope(String javaname) {
		for ( JavaScope s = this; s != null; s = (JavaScope) s.outerScope )
			if ( s.javanames.contains(javaname) )
				return true;
		return false;
	}
	
	public String createConstantName(String proposal) {
		proposal = toLegalJavaName(proposal);
		for ( int i=0; true; i++ ) {
			String jname = proposal+(i==0? "": "$"+i);
			if ( ! isJavanameInScope(jname) && ! SPECIALS.contains(jname) && !staticnames.contains(jname) ) {
				javanames.add(jname);
				staticnames.add(jname);
				return jname;
			}
		}
	}

	public static String toLegalJavaName(String string) {
		String better = string.replaceAll("[^\\w]", "_");
		if ( better.length() > MAX_CONSTNAME_LEN )
			better = better.substring(0,MAX_CONSTNAME_LEN);
		if ( better.length() == 0 || !Character.isJavaIdentifierStart( better.charAt(0) ) )
			better = "_"+better;
		return better;
	}
	
	private JavaScope initialize(Block block, int nreturns) {
		NewScopeVisitor v = new NewScopeVisitor(nreturns);
		block.accept( v );
		this.nreturns = v.nreturns;
		this.needsbinoptmp = v.needsbinoptmp;
		this.usesvarargs = v.usesvarargs;
		return this;
	}

	class NewScopeVisitor extends Visitor {
		int nreturns = 0;
		boolean needsbinoptmp = false;
		boolean usesvarargs = false;
		NewScopeVisitor(int nreturns) {
			this.nreturns = nreturns;
		}
		public void visit(FuncBody body) {}
		public void visit(Return s) {
			int n = s.nreturns();
			nreturns = (nreturns<0||n<0? -1: Math.max(n,nreturns));
			super.visit(s);
		}
		public void visit(BinopExp exp) {
			switch ( exp.op ) {
			case Lua.OP_AND: case Lua.OP_OR:
				needsbinoptmp = true;
				break;
			}
			super.visit(exp);
		}
		public void visit(VarargsExp exp) {
			usesvarargs = true;
		}
		
	}

}