--- /dev/null
+/*******************************************************************************
+ * Copyright (c) 2000, 2004 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Common Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Contributors:
+ * IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.jdt.internal.compiler.ast;
+
+import org.eclipse.jdt.internal.compiler.ASTVisitor;
+import org.eclipse.jdt.internal.compiler.impl.*;
+import org.eclipse.jdt.internal.compiler.codegen.*;
+import org.eclipse.jdt.internal.compiler.flow.*;
+import org.eclipse.jdt.internal.compiler.lookup.*;
+
+public class IfStatement extends Statement {
+
+ //this class represents the case of only one statement in
+ //either else and/or then branches.
+
+ public Expression condition;
+ public Statement thenStatement;
+ public Statement elseStatement;
+
+ boolean thenExit;
+
+ // for local variables table attributes
+ int thenInitStateIndex = -1;
+ int elseInitStateIndex = -1;
+ int mergedInitStateIndex = -1;
+
+ public IfStatement(Expression condition, Statement thenStatement, int sourceStart, int sourceEnd) {
+
+ this.condition = condition;
+ this.thenStatement = thenStatement;
+ // remember useful empty statement
+ if (thenStatement instanceof EmptyStatement) thenStatement.bits |= IsUsefulEmptyStatementMASK;
+ this.sourceStart = sourceStart;
+ this.sourceEnd = sourceEnd;
+ }
+
+ public IfStatement(Expression condition, Statement thenStatement, Statement elseStatement, int sourceStart, int sourceEnd) {
+
+ this.condition = condition;
+ this.thenStatement = thenStatement;
+ // remember useful empty statement
+ if (thenStatement instanceof EmptyStatement) thenStatement.bits |= IsUsefulEmptyStatementMASK;
+ this.elseStatement = elseStatement;
+ if (elseStatement instanceof IfStatement) elseStatement.bits |= IsElseIfStatement;
+ this.sourceStart = sourceStart;
+ this.sourceEnd = sourceEnd;
+ }
+
+ public FlowInfo analyseCode(
+ BlockScope currentScope,
+ FlowContext flowContext,
+ FlowInfo flowInfo) {
+
+ // process the condition
+ flowInfo = condition.analyseCode(currentScope, flowContext, flowInfo);
+
+ Constant cst = this.condition.optimizedBooleanConstant();
+ boolean isConditionOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true;
+ boolean isConditionOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false;
+
+ // process the THEN part
+ FlowInfo thenFlowInfo = flowInfo.initsWhenTrue().copy();
+ if (isConditionOptimizedFalse) {
+ thenFlowInfo.setReachMode(FlowInfo.UNREACHABLE);
+ }
+ if (this.thenStatement != null) {
+ // Save info for code gen
+ thenInitStateIndex =
+ currentScope.methodScope().recordInitializationStates(thenFlowInfo);
+ if (!thenStatement.complainIfUnreachable(thenFlowInfo, currentScope, false)) {
+ thenFlowInfo =
+ thenStatement.analyseCode(currentScope, flowContext, thenFlowInfo);
+ }
+ }
+ // code gen: optimizing the jump around the ELSE part
+ this.thenExit = !thenFlowInfo.isReachable();
+
+ // process the ELSE part
+ FlowInfo elseFlowInfo = flowInfo.initsWhenFalse().copy();
+ if (isConditionOptimizedTrue) {
+ elseFlowInfo.setReachMode(FlowInfo.UNREACHABLE);
+ }
+ if (this.elseStatement != null) {
+ // signal else clause unnecessarily nested, tolerate else-if code pattern
+ if (thenFlowInfo == FlowInfo.DEAD_END
+ && (this.bits & IsElseIfStatement) == 0 // else of an else-if
+ && !(this.elseStatement instanceof IfStatement)) {
+ currentScope.problemReporter().unnecessaryElse(this.elseStatement);
+ }
+ // Save info for code gen
+ elseInitStateIndex =
+ currentScope.methodScope().recordInitializationStates(elseFlowInfo);
+ if (!elseStatement.complainIfUnreachable(elseFlowInfo, currentScope, false)) {
+ elseFlowInfo =
+ elseStatement.analyseCode(currentScope, flowContext, elseFlowInfo);
+ }
+ }
+
+ // merge THEN & ELSE initializations
+ FlowInfo mergedInfo = FlowInfo.mergedOptimizedBranches(
+ thenFlowInfo,
+ isConditionOptimizedTrue,
+ elseFlowInfo,
+ isConditionOptimizedFalse,
+ true /*if(true){ return; } fake-reachable(); */);
+ mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo);
+ return mergedInfo;
+ }
+
+ /**
+ * If code generation
+ *
+ * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
+ * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
+ */
+ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
+
+ if ((this.bits & IsReachableMASK) == 0) {
+ return;
+ }
+ int pc = codeStream.position;
+ Label endifLabel = new Label(codeStream);
+
+ // optimizing the then/else part code gen
+ Constant cst;
+ boolean hasThenPart =
+ !(((cst = this.condition.optimizedBooleanConstant()) != NotAConstant
+ && cst.booleanValue() == false)
+ || this.thenStatement == null
+ || this.thenStatement.isEmptyBlock());
+ boolean hasElsePart =
+ !((cst != NotAConstant && cst.booleanValue() == true)
+ || this.elseStatement == null
+ || this.elseStatement.isEmptyBlock());
+
+ if (hasThenPart) {
+ Label falseLabel;
+ // generate boolean condition
+ this.condition.generateOptimizedBoolean(
+ currentScope,
+ codeStream,
+ null,
+ (falseLabel = new Label(codeStream)),
+ true);
+ // May loose some local variable initializations : affecting the local variable attributes
+ if (thenInitStateIndex != -1) {
+ codeStream.removeNotDefinitelyAssignedVariables(
+ currentScope,
+ thenInitStateIndex);
+ codeStream.addDefinitelyAssignedVariables(currentScope, thenInitStateIndex);
+ }
+ // generate then statement
+ this.thenStatement.generateCode(currentScope, codeStream);
+ // jump around the else statement
+ if (hasElsePart && !thenExit) {
+ this.thenStatement.branchChainTo(endifLabel);
+ int position = codeStream.position;
+ codeStream.goto_(endifLabel);
+ codeStream.updateLastRecordedEndPC(position);
+ //goto is tagged as part of the thenAction block
+ }
+ falseLabel.place();
+ } else {
+ if (hasElsePart) {
+ // generate boolean condition
+ this.condition.generateOptimizedBoolean(
+ currentScope,
+ codeStream,
+ endifLabel,
+ null,
+ true);
+ } else {
+ // generate condition side-effects
+ this.condition.generateCode(currentScope, codeStream, false);
+ codeStream.recordPositionsFrom(pc, this.sourceStart);
+ }
+ }
+ // generate else statement
+ if (hasElsePart) {
+ // May loose some local variable initializations : affecting the local variable attributes
+ if (elseInitStateIndex != -1) {
+ codeStream.removeNotDefinitelyAssignedVariables(
+ currentScope,
+ elseInitStateIndex);
+ codeStream.addDefinitelyAssignedVariables(currentScope, elseInitStateIndex);
+ }
+ this.elseStatement.generateCode(currentScope, codeStream);
+ }
+ endifLabel.place();
+ // May loose some local variable initializations : affecting the local variable attributes
+ if (mergedInitStateIndex != -1) {
+ codeStream.removeNotDefinitelyAssignedVariables(
+ currentScope,
+ mergedInitStateIndex);
+ }
+ codeStream.recordPositionsFrom(pc, this.sourceStart);
+ }
+
+ public StringBuffer printStatement(int indent, StringBuffer output) {
+
+ printIndent(indent, output).append("if ("); //$NON-NLS-1$
+ condition.printExpression(0, output).append(")\n"); //$NON-NLS-1$
+ thenStatement.printStatement(indent + 2, output);
+ if (elseStatement != null) {
+ output.append('\n');
+ printIndent(indent, output);
+ output.append("else\n"); //$NON-NLS-1$
+ elseStatement.printStatement(indent + 2, output);
+ }
+ return output;
+ }
+
+ public void resolve(BlockScope scope) {
+
+ TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding);
+ condition.implicitWidening(type, type);
+ if (thenStatement != null)
+ thenStatement.resolve(scope);
+ if (elseStatement != null)
+ elseStatement.resolve(scope);
+ }
+
+ public void traverse(
+ ASTVisitor visitor,
+ BlockScope blockScope) {
+
+ if (visitor.visit(this, blockScope)) {
+ condition.traverse(visitor, blockScope);
+ if (thenStatement != null)
+ thenStatement.traverse(visitor, blockScope);
+ if (elseStatement != null)
+ elseStatement.traverse(visitor, blockScope);
+ }
+ visitor.endVisit(this, blockScope);
+ }
+}
projects / org.ibex.tool.git / blobdiff