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240 lines
6.9 KiB
240 lines
6.9 KiB
/* IfThenElseBlock Copyright (C) 1998-2002 Jochen Hoenicke.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; see the file COPYING.LESSER. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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*/
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package net.sf.jode.flow;
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import net.sf.jode.decompiler.TabbedPrintWriter;
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import net.sf.jode.expr.Expression;
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import net.sf.jode.util.SimpleSet;
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///#def COLLECTIONS java.util
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import java.util.Set;
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///#enddef
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/**
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* An IfThenElseBlock is the structured block representing an if
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* instruction. The else part may be null.
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*/
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public class IfThenElseBlock extends StructuredBlock {
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/**
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* The condition. Must be of boolean type.
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*/
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Expression cond;
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/**
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* The loads that are on the stack before cond is executed.
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*/
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VariableStack condStack;
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/**
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* The then part. This is always a valid block and not null
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*/
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StructuredBlock thenBlock;
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/**
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* The else part, may be null, and mustn't be the then part.
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*/
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StructuredBlock elseBlock;
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/**
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* Creates a new if then else block. The method setThenBlock must
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* be called shortly after the creation.
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*/
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public IfThenElseBlock(Expression cond) {
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this.cond = cond;
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}
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/**
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* Gets the condition. The expression returned has boolean type.
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*/
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public Expression getCondition() {
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return cond;
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}
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/**
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* Sets the then block.
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* @param thenBlock the then block, must be non null.
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*/
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public void setThenBlock(StructuredBlock thenBlock) {
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this.thenBlock = thenBlock;
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thenBlock.outer = this;
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thenBlock.setFlowBlock(flowBlock);
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}
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/**
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* Sets the else block.
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* @param elseBlock the else block
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*/
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public void setElseBlock(StructuredBlock elseBlock) {
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this.elseBlock = elseBlock;
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elseBlock.outer = this;
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elseBlock.setFlowBlock(flowBlock);
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}
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/* The implementation of getNext[Flow]Block is the standard
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* implementation */
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/**
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* Replaces the given sub block with a new block.
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* @param oldBlock the old sub block.
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* @param newBlock the new sub block.
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* @return false, if oldBlock wasn't a direct sub block.
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*/
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public boolean replaceSubBlock(StructuredBlock oldBlock,
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StructuredBlock newBlock) {
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if (thenBlock == oldBlock)
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thenBlock = newBlock;
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else if (elseBlock == oldBlock)
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elseBlock = newBlock;
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else
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return false;
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return true;
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}
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/**
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* This does take the instr into account and modifies stack
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* accordingly. It then calls super.mapStackToLocal.
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* @param stack the stack before the instruction is called
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* @return stack the stack afterwards.
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*/
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public VariableStack mapStackToLocal(VariableStack stack) {
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VariableStack newStack;
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int params = cond.getFreeOperandCount();
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if (params > 0) {
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condStack = stack.peek(params);
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newStack = stack.pop(params);
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} else
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newStack = stack;
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VariableStack after
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= VariableStack.merge(thenBlock.mapStackToLocal(newStack),
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elseBlock == null ? newStack
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: elseBlock.mapStackToLocal(newStack));
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if (jump != null) {
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jump.stackMap = after;
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return null;
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}
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return after;
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}
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public void removePush() {
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if (condStack != null)
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cond = condStack.mergeIntoExpression(cond);
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thenBlock.removePush();
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if (elseBlock != null)
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elseBlock.removePush();
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}
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public Set getDeclarables() {
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Set used = new SimpleSet();
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cond.fillDeclarables(used);
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return used;
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}
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/**
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* Make the declarations, i.e. initialize the declare variable
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* to correct values. This will declare every variable that
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* is marked as used, but not done.<br>
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*
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* This will now also combine locals, that use the same slot, have
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* compatible types and are declared in the same block. <br>
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*
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* @param done The set of the already declare variables.
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*/
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public void makeDeclaration(Set done) {
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cond.makeDeclaration(done);
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super.makeDeclaration(done);
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}
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/**
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* Print the source code for this structured block. This may be
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* called only once, because it remembers which local variables
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* were declared.
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*/
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public void dumpInstruction(TabbedPrintWriter writer)
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throws java.io.IOException
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{
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boolean needBrace = thenBlock.needsBraces();
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writer.print("if (");
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cond.dumpExpression(TabbedPrintWriter.EXPL_PAREN, writer);
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writer.print(")");
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if (needBrace)
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writer.openBrace();
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else
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writer.println();
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writer.tab();
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thenBlock.dumpSource(writer);
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writer.untab();
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if (elseBlock != null) {
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if (needBrace)
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writer.closeBraceContinue();
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if (elseBlock instanceof IfThenElseBlock
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&& (elseBlock.declare == null
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|| elseBlock.declare.isEmpty())) {
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needBrace = false;
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writer.print("else ");
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elseBlock.dumpSource(writer);
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} else {
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needBrace = elseBlock.needsBraces();
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writer.print("else");
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if (needBrace)
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writer.openBrace();
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else
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writer.println();
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writer.tab();
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elseBlock.dumpSource(writer);
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writer.untab();
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}
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}
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if (needBrace)
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writer.closeBrace();
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}
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/**
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* Returns all sub block of this structured block.
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*/
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public StructuredBlock[] getSubBlocks() {
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return (elseBlock == null)
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? new StructuredBlock[] { thenBlock }
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: new StructuredBlock[] { thenBlock, elseBlock };
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}
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/**
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* Determines if there is a sub block, that flows through to the end
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* of this block. If this returns true, you know that jump is null.
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* @return true, if the jump may be safely changed.
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*/
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public boolean jumpMayBeChanged() {
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return (thenBlock.jump != null || thenBlock.jumpMayBeChanged())
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&& elseBlock != null
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&& (elseBlock.jump != null || elseBlock.jumpMayBeChanged());
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}
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public void simplify() {
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cond = cond.simplify();
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super.simplify();
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}
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public boolean doTransformations() {
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StructuredBlock last = flowBlock.lastModified;
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return CreateCheckNull.transformJikes(this, last)
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|| CreateClassField.transform(this,last);
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}
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}
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