/* InstructionBlock Copyright (C) 1998-2002 Jochen Hoenicke.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; see the file COPYING.LESSER.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id: InstructionBlock.java.in,v 4.2.2.2 2002/05/28 17:34:09 hoenicke Exp $
 */

package alterrs.jode.flow;

import java.util.Set;

import alterrs.jode.decompiler.LocalInfo;
import alterrs.jode.decompiler.TabbedPrintWriter;
import alterrs.jode.expr.Expression;
import alterrs.jode.expr.LocalStoreOperator;
import alterrs.jode.expr.StoreInstruction;
import alterrs.jode.type.Type;

/**
 * This is the structured block for atomic instructions.
 */
public class InstructionBlock extends InstructionContainer {
	/**
	 * The loads that are on the stack before cond is executed.
	 */
	VariableStack stack;
	/**
	 * The local to which we push to, if the instruction is non void
	 */
	LocalInfo pushedLocal = null;

	/**
	 * Tells if this expression is a initializing declaration. This can only be
	 * set to true and then never be reset. It is changed by makeDeclaration.
	 */
	boolean isDeclaration = false;

	public InstructionBlock(Expression instr) {
		super(instr);
	}

	public InstructionBlock(Expression instr, Jump jump) {
		super(instr, jump);
	}

	/**
	 * This does take the instr into account and modifies stack accordingly. It
	 * then calls super.mapStackToLocal.
	 * 
	 * @param stack
	 *            the stack before the instruction is called
	 * @return stack the stack afterwards.
	 */
	public VariableStack mapStackToLocal(VariableStack stack) {
		VariableStack newStack;
		int params = instr.getFreeOperandCount();
		if (params > 0)
			this.stack = stack.peek(params);

		if (instr.getType() != Type.tVoid) {
			pushedLocal = new LocalInfo();
			pushedLocal.setType(instr.getType());
			newStack = stack.poppush(params, pushedLocal);
		} else if (params > 0) {
			newStack = stack.pop(params);
		} else
			newStack = stack;
		return super.mapStackToLocal(newStack);
	}

	public void removePush() {
		if (stack != null)
			instr = stack.mergeIntoExpression(instr);
		if (pushedLocal != null) {
			Expression store = new StoreInstruction(new LocalStoreOperator(
					pushedLocal.getType(), pushedLocal)).addOperand(instr);
			instr = store;
		}
		super.removePush();
	}

	/**
	 * Tells if this block needs braces when used in a if or while block.
	 * 
	 * @return true if this block should be sorrounded by braces.
	 */
	public boolean needsBraces() {
		return isDeclaration || (declare != null && !declare.isEmpty());
	}

	/**
	 * Check if this is an local store instruction to a not yet declared
	 * variable. In that case mark this as declaration and return the variable.
	 */
	public void checkDeclaration(Set declareSet) {
		if (instr instanceof StoreInstruction
				&& (((StoreInstruction) instr).getLValue() instanceof LocalStoreOperator)) {
			StoreInstruction storeOp = (StoreInstruction) instr;
			LocalInfo local = ((LocalStoreOperator) storeOp.getLValue())
					.getLocalInfo();
			if (declareSet.contains(local)) {
				/*
				 * Special case: This is a variable assignment, and the variable
				 * has not been declared before. We can change this to a
				 * initializing variable declaration.
				 */
				isDeclaration = true;
				declareSet.remove(local);
			}
		}
	}

	/**
	 * Make the declarations, i.e. initialize the declare variable to correct
	 * values. This will declare every variable that is marked as used, but not
	 * done.
	 * 
	 * @param done
	 *            The set of the already declare variables.
	 */
	public void makeDeclaration(Set done) {
		super.makeDeclaration(done);
		checkDeclaration(declare);
	}

	public void dumpInstruction(TabbedPrintWriter writer)
			throws java.io.IOException {
		if (isDeclaration) {
			StoreInstruction store = (StoreInstruction) instr;
			LocalInfo local = ((LocalStoreOperator) store.getLValue())
					.getLocalInfo();
			writer.startOp(writer.NO_PAREN, 0);
			local.dumpDeclaration(writer);
			writer.breakOp();
			writer.print(" = ");
			store.getSubExpressions()[1].makeInitializer(local.getType());
			store.getSubExpressions()[1].dumpExpression(writer.IMPL_PAREN,
					writer);
			writer.endOp();
		} else {
			try {

				if (instr.getType() != Type.tVoid) {
					writer.print("PUSH ");
					instr.dumpExpression(writer.IMPL_PAREN, writer);
				} else
					instr.dumpExpression(writer.NO_PAREN, writer);
			} catch (RuntimeException ex) {
				writer.print("(RUNTIME ERROR IN EXPRESSION)");
			}
		}
		writer.println(";");
	}
}
