/* CatchBlock 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: CatchBlock.java.in,v 4.2.2.3 2002/05/28 17:34:08 hoenicke Exp $
 */

package alterrs.jode.flow;

import java.util.Collections;
import java.util.Iterator;
import java.util.Set;

import alterrs.jode.decompiler.Declarable;
import alterrs.jode.decompiler.LocalInfo;
import alterrs.jode.expr.Expression;
import alterrs.jode.expr.LocalLoadOperator;
import alterrs.jode.expr.LocalStoreOperator;
import alterrs.jode.expr.NopOperator;
import alterrs.jode.expr.StoreInstruction;
import alterrs.jode.type.Type;

/**
 * @author Jochen Hoenicke
 */
public class CatchBlock extends StructuredBlock {

	/**
	 * The catch block.
	 */
	StructuredBlock catchBlock;

	/**
	 * The type of the exception.
	 */
	Type exceptionType;

	/**
	 * The local containing the exception. May be null.
	 */
	LocalInfo exceptionLocal;

	public CatchBlock(Type type) {
		exceptionType = type;
	}

	public Type getExceptionType() {
		return exceptionType;
	}

	public LocalInfo getLocal() {
		return exceptionLocal;
	}

	/**
	 * Sets the catch block.
	 * 
	 * @param catchBlock
	 *            the catch block.
	 */
	public void setCatchBlock(StructuredBlock catchBlock) {
		this.catchBlock = catchBlock;
		catchBlock.outer = this;
		catchBlock.setFlowBlock(flowBlock);
		if (exceptionLocal == null)
			combineLocal();
	}

	/*
	 * The implementation of getNext[Flow]Block is the standard implementation
	 */

	/**
	 * Replaces the given sub block with a new block.
	 * 
	 * @param oldBlock
	 *            the old sub block.
	 * @param newBlock
	 *            the new sub block.
	 * @return false, if oldBlock wasn't a direct sub block.
	 */
	public boolean replaceSubBlock(StructuredBlock oldBlock,
			StructuredBlock newBlock) {
		if (catchBlock == oldBlock)
			catchBlock = newBlock;
		else
			return false;
		return true;
	}

	/**
	 * Returns all sub block of this structured block.
	 */
	public StructuredBlock[] getSubBlocks() {
		return new StructuredBlock[] { catchBlock };
	}

	LocalInfo pushedLocal;

	/**
	 * A catch block pushes the exception on the stack, iff a local doesn't
	 * exists.
	 * 
	 * @param stack
	 *            the stack before the instruction is called
	 * @return stack the stack afterwards.
	 */
	public VariableStack mapStackToLocal(VariableStack stack) {
		VariableStack newStack;
		if (exceptionLocal == null) {
			pushedLocal = new LocalInfo();
			pushedLocal.setType(exceptionType);
			newStack = stack.push(pushedLocal);
		} else
			newStack = stack;
		return super.mapStackToLocal(newStack);
	}

	public void removePush() {
		if (pushedLocal != null)
			exceptionLocal = pushedLocal;
		super.removePush();
	}

	public Set getDeclarables() {
		if (exceptionLocal != null)
			return Collections.singleton(exceptionLocal);
		return Collections.EMPTY_SET;
	}

	/**
	 * 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);
		/*
		 * Normally we have to declare our exceptionLocal. This is automatically
		 * done in dumpSource.
		 * 
		 * If we are unlucky the exceptionLocal is used outside of this block.
		 * In that case we do a transformation.
		 */
		if (exceptionLocal != null) {
			if (declare.contains(exceptionLocal))
				declare.remove(exceptionLocal);
			else {
				LocalInfo dummyLocal = new LocalInfo();
				Expression store = new StoreInstruction(new LocalStoreOperator(
						exceptionLocal.getType(), exceptionLocal))
						.addOperand(new LocalLoadOperator(dummyLocal.getType(),
								null, dummyLocal));
				InstructionBlock ib = new InstructionBlock(store);
				ib.setFlowBlock(flowBlock);
				ib.appendBlock(catchBlock);
				catchBlock = ib;
				exceptionLocal = dummyLocal;
				String localName = dummyLocal.guessName();
				Iterator doneIter = done.iterator();
				while (doneIter.hasNext()) {
					Declarable previous = (Declarable) doneIter.next();
					if (localName.equals(previous.getName())) {
						/* A name conflict happened. */
						dummyLocal.makeNameUnique();
						break;
					}
				}
			}
		}
	}

	public void dumpInstruction(alterrs.jode.decompiler.TabbedPrintWriter writer)
			throws java.io.IOException {
		writer.closeBraceContinue();
		writer.print("catch (");
		writer.printType(exceptionType);
		writer.print(" "
				+ (exceptionLocal != null ? exceptionLocal.getName() : "PUSH")
				+ ")");
		writer.openBrace();
		writer.tab();
		catchBlock.dumpSource(writer);
		writer.untab();
	}

	/**
	 * Determines if there is a sub block, that flows through to the end of this
	 * block. If this returns true, you know that jump is null.
	 * 
	 * @return true, if the jump may be safely changed.
	 */
	public boolean jumpMayBeChanged() {
		return (catchBlock.jump != null || catchBlock.jumpMayBeChanged());
	}

	/**
	 * 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 boolean combineLocal() {
		StructuredBlock firstInstr = (catchBlock instanceof SequentialBlock) ? catchBlock
				.getSubBlocks()[0] : catchBlock;

		if (firstInstr instanceof SpecialBlock
				&& ((SpecialBlock) firstInstr).type == SpecialBlock.POP
				&& ((SpecialBlock) firstInstr).count == 1) {
			/* The exception is ignored. Create a dummy local for it */
			exceptionLocal = new LocalInfo();
			exceptionLocal.setType(exceptionType);
			firstInstr.removeBlock();
			return true;
		} else if (firstInstr instanceof InstructionBlock) {
			Expression instr = ((InstructionBlock) firstInstr).getInstruction();
			if (instr instanceof StoreInstruction) {
				StoreInstruction store = (StoreInstruction) instr;
				if (store.getOperatorIndex() == store.OPASSIGN_OP
						&& store.getSubExpressions()[1] instanceof NopOperator
						&& store.getLValue() instanceof LocalStoreOperator) {
					/* The exception is stored in a local variable */
					exceptionLocal = ((LocalStoreOperator) store.getLValue())
							.getLocalInfo();
					exceptionLocal.setType(exceptionType);
					firstInstr.removeBlock();
					return true;
				}
			}
		}
		return false;
	}
}
