/*******************************************************************************
* Copyright (c) 2000, 2011 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Stephan Herrmann - Contribution for bug 319201 - [null] no warning when unboxing SingleNameReference causes NPE
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import java.util.Arrays;
import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
import org.eclipse.jdt.internal.compiler.codegen.*;
import org.eclipse.jdt.internal.compiler.flow.*;
import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
import org.eclipse.jdt.internal.compiler.impl.Constant;
import org.eclipse.jdt.internal.compiler.lookup.*;
import org.eclipse.jdt.internal.compiler.problem.ProblemSeverities;
public class SwitchStatement extends Statement {
public Expression expression;
public Statement[] statements;
public BlockScope scope;
public int explicitDeclarations;
public BranchLabel breakLabel;
public CaseStatement[] cases;
public CaseStatement defaultCase;
public int blockStart;
public int caseCount;
int[] constants;
String[] stringConstants;
// fallthrough
public final static int CASE = 0;
public final static int FALLTHROUGH = 1;
public final static int ESCAPING = 2;
// for switch on strings
private static final char[] SecretStringVariableName = " switchDispatchString".toCharArray(); //$NON-NLS-1$
public SyntheticMethodBinding synthetic; // use for switch on enums types
// for local variables table attributes
int preSwitchInitStateIndex = -1;
int mergedInitStateIndex = -1;
CaseStatement[] duplicateCaseStatements = null;
int duplicateCaseStatementsCounter = 0;
private LocalVariableBinding dispatchStringCopy = null;
public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) {
try {
flowInfo = this.expression.analyseCode(currentScope, flowContext, flowInfo);
if ((this.expression.implicitConversion & TypeIds.UNBOXING) != 0
|| (this.expression.resolvedType != null && this.expression.resolvedType.id == T_JavaLangString)) {
this.expression.checkNPE(currentScope, flowContext, flowInfo);
}
SwitchFlowContext switchContext =
new SwitchFlowContext(flowContext, this, (this.breakLabel = new BranchLabel()));
// analyse the block by considering specially the case/default statements (need to bind them
// to the entry point)
FlowInfo caseInits = FlowInfo.DEAD_END;
// in case of statements before the first case
this.preSwitchInitStateIndex = currentScope.methodScope().recordInitializationStates(flowInfo);
int caseIndex = 0;
if (this.statements != null) {
int initialComplaintLevel = (flowInfo.reachMode() & FlowInfo.UNREACHABLE) != 0 ? Statement.COMPLAINED_FAKE_REACHABLE : Statement.NOT_COMPLAINED;
int complaintLevel = initialComplaintLevel;
int fallThroughState = CASE;
for (int i = 0, max = this.statements.length; i < max; i++) {
Statement statement = this.statements[i];
if ((caseIndex < this.caseCount) && (statement == this.cases[caseIndex])) { // statement is a case
this.scope.enclosingCase = this.cases[caseIndex]; // record entering in a switch case block
caseIndex++;
if (fallThroughState == FALLTHROUGH
&& (statement.bits & ASTNode.DocumentedFallthrough) == 0) { // the case is not fall-through protected by a line comment
this.scope.problemReporter().possibleFallThroughCase(this.scope.enclosingCase);
}
caseInits = caseInits.mergedWith(flowInfo.unconditionalInits());
complaintLevel = initialComplaintLevel; // reset complaint
fallThroughState = CASE;
} else if (statement == this.defaultCase) { // statement is the default case
this.scope.enclosingCase = this.defaultCase; // record entering in a switch case block
if (fallThroughState == FALLTHROUGH
&& (statement.bits & ASTNode.DocumentedFallthrough) == 0) {
this.scope.problemReporter().possibleFallThroughCase(this.scope.enclosingCase);
}
caseInits = caseInits.mergedWith(flowInfo.unconditionalInits());
complaintLevel = initialComplaintLevel; // reset complaint
fallThroughState = CASE;
} else {
fallThroughState = FALLTHROUGH; // reset below if needed
}
if ((complaintLevel = statement.complainIfUnreachable(caseInits, this.scope, complaintLevel)) < Statement.COMPLAINED_UNREACHABLE) {
caseInits = statement.analyseCode(this.scope, switchContext, caseInits);
if (caseInits == FlowInfo.DEAD_END) {
fallThroughState = ESCAPING;
}
}
}
}
final TypeBinding resolvedTypeBinding = this.expression.resolvedType;
if (resolvedTypeBinding.isEnum()) {
final SourceTypeBinding sourceTypeBinding = currentScope.classScope().referenceContext.binding;
this.synthetic = sourceTypeBinding.addSyntheticMethodForSwitchEnum(resolvedTypeBinding);
}
// if no default case, then record it may jump over the block directly to the end
if (this.defaultCase == null) {
// only retain the potential initializations
flowInfo.addPotentialInitializationsFrom(caseInits.mergedWith(switchContext.initsOnBreak));
this.mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(flowInfo);
return flowInfo;
}
// merge all branches inits
FlowInfo mergedInfo = caseInits.mergedWith(switchContext.initsOnBreak);
this.mergedInitStateIndex =
currentScope.methodScope().recordInitializationStates(mergedInfo);
return mergedInfo;
} finally {
if (this.scope != null) this.scope.enclosingCase = null; // no longer inside switch case block
}
}
/**
* Switch on String code generation
* This assumes that hashCode() specification for java.lang.String is API
* and is stable.
* @see "http://java.sun.com/j2se/1.4.2/docs/api/java/lang/String.html"
* @see "http://download.oracle.com/docs/cd/E17409_01/javase/6/docs/api/java/lang/String.html"
*
* @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
* @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
*/
public void generateCodeForStringSwitch(BlockScope currentScope, CodeStream codeStream) {
try {
if ((this.bits & IsReachable) == 0) {
return;
}
int pc = codeStream.position;
class StringSwitchCase implements Comparable {
int hashCode;
String string;
BranchLabel label;
public StringSwitchCase(int hashCode, String string, BranchLabel label) {
this.hashCode = hashCode;
this.string = string;
this.label = label;
}
public int compareTo(Object o) {
StringSwitchCase that = (StringSwitchCase) o;
if (this.hashCode == that.hashCode) {
return 0;
}
if (this.hashCode > that.hashCode) {
return 1;
}
return -1;
}
public String toString() {
return "StringSwitchCase :\n" + //$NON-NLS-1$
"case " + this.hashCode + ":(" + this.string + ")\n"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
}
}
final boolean hasCases = this.caseCount != 0;
StringSwitchCase [] stringCases = new StringSwitchCase[this.caseCount]; // may have to shrink later if multiple strings hash to same code.
BranchLabel[] sourceCaseLabels = new BranchLabel[this.caseCount];
CaseLabel [] hashCodeCaseLabels = new CaseLabel[this.caseCount];
this.constants = new int[this.caseCount]; // hashCode() values.
for (int i = 0, max = this.caseCount; i < max; i++) {
this.cases[i].targetLabel = (sourceCaseLabels[i] = new BranchLabel(codeStream)); // A branch label, not a case label.
sourceCaseLabels[i].tagBits |= BranchLabel.USED;
stringCases[i] = new StringSwitchCase(this.stringConstants[i].hashCode(), this.stringConstants[i], sourceCaseLabels[i]);
hashCodeCaseLabels[i] = new CaseLabel(codeStream);
hashCodeCaseLabels[i].tagBits |= BranchLabel.USED;
}
Arrays.sort(stringCases);
int uniqHashCount = 0;
int lastHashCode = 0;
for (int i = 0, length = this.caseCount; i < length; ++i) {
int hashCode = stringCases[i].hashCode;
if (i == 0 || hashCode != lastHashCode) {
lastHashCode = this.constants[uniqHashCount++] = hashCode;
}
}
if (uniqHashCount != this.caseCount) { // multiple keys hashed to the same value.
System.arraycopy(this.constants, 0, this.constants = new int[uniqHashCount], 0, uniqHashCount);
System.arraycopy(hashCodeCaseLabels, 0, hashCodeCaseLabels = new CaseLabel[uniqHashCount], 0, uniqHashCount);
}
int[] sortedIndexes = new int[uniqHashCount]; // hash code are sorted already anyways.
for (int i = 0; i < uniqHashCount; i++) {
sortedIndexes[i] = i;
}
CaseLabel defaultCaseLabel = new CaseLabel(codeStream);
defaultCaseLabel.tagBits |= BranchLabel.USED;
// prepare the labels and constants
this.breakLabel.initialize(codeStream);
BranchLabel defaultBranchLabel = new BranchLabel(codeStream);
if (hasCases) defaultBranchLabel.tagBits |= BranchLabel.USED;
if (this.defaultCase != null) {
this.defaultCase.targetLabel = defaultBranchLabel;
}
// generate expression
this.expression.generateCode(currentScope, codeStream, true);
codeStream.store(this.dispatchStringCopy, true); // leaves string on operand stack
codeStream.addVariable(this.dispatchStringCopy);
codeStream.invokeStringHashCode();
if (hasCases) {
codeStream.lookupswitch(defaultCaseLabel, this.constants, sortedIndexes, hashCodeCaseLabels);
for (int i = 0, j = 0, max = this.caseCount; i < max; i++) {
int hashCode = stringCases[i].hashCode;
if (i == 0 || hashCode != lastHashCode) {
lastHashCode = hashCode;
if (i != 0) {
codeStream.goto_(defaultBranchLabel);
}
hashCodeCaseLabels[j++].place();
}
codeStream.load(this.dispatchStringCopy);
codeStream.ldc(stringCases[i].string);
codeStream.invokeStringEquals();
codeStream.ifne(stringCases[i].label);
}
codeStream.goto_(defaultBranchLabel);
} else {
codeStream.pop();
}
// generate the switch block statements
int caseIndex = 0;
if (this.statements != null) {
for (int i = 0, maxCases = this.statements.length; i < maxCases; i++) {
Statement statement = this.statements[i];
if ((caseIndex < this.caseCount) && (statement == this.cases[caseIndex])) { // statements[i] is a case
this.scope.enclosingCase = this.cases[caseIndex]; // record entering in a switch case block
if (this.preSwitchInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.preSwitchInitStateIndex);
}
caseIndex++;
} else {
if (statement == this.defaultCase) { // statements[i] is a case or a default case
defaultCaseLabel.place(); // branch label gets placed by generateCode below.
this.scope.enclosingCase = this.defaultCase; // record entering in a switch case block
if (this.preSwitchInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.preSwitchInitStateIndex);
}
}
}
statement.generateCode(this.scope, codeStream);
}
}
// May loose some local variable initializations : affecting the local variable attributes
if (this.mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
codeStream.addDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
}
codeStream.removeVariable(this.dispatchStringCopy);
if (this.scope != currentScope) {
codeStream.exitUserScope(this.scope);
}
// place the trailing labels (for break and default case)
this.breakLabel.place();
if (this.defaultCase == null) {
// we want to force an line number entry to get an end position after the switch statement
codeStream.recordPositionsFrom(codeStream.position, this.sourceEnd, true);
defaultCaseLabel.place();
defaultBranchLabel.place();
}
codeStream.recordPositionsFrom(pc, this.sourceStart);
} catch (Throwable e) {
e.printStackTrace();
}
finally {
if (this.scope != null) this.scope.enclosingCase = null; // no longer inside switch case block
}
}
/**
* Switch 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.expression.resolvedType.id == TypeIds.T_JavaLangString) {
generateCodeForStringSwitch(currentScope, codeStream);
return;
}
try {
if ((this.bits & IsReachable) == 0) {
return;
}
int pc = codeStream.position;
// prepare the labels and constants
this.breakLabel.initialize(codeStream);
CaseLabel[] caseLabels = new CaseLabel[this.caseCount];
for (int i = 0, max = this.caseCount; i < max; i++) {
this.cases[i].targetLabel = (caseLabels[i] = new CaseLabel(codeStream));
caseLabels[i].tagBits |= BranchLabel.USED;
}
CaseLabel defaultLabel = new CaseLabel(codeStream);
final boolean hasCases = this.caseCount != 0;
if (hasCases) defaultLabel.tagBits |= BranchLabel.USED;
if (this.defaultCase != null) {
this.defaultCase.targetLabel = defaultLabel;
}
final TypeBinding resolvedType = this.expression.resolvedType;
boolean valueRequired = false;
if (resolvedType.isEnum()) {
// go through the translation table
codeStream.invoke(Opcodes.OPC_invokestatic, this.synthetic, null /* default declaringClass */);
this.expression.generateCode(currentScope, codeStream, true);
// get enum constant ordinal()
codeStream.invokeEnumOrdinal(resolvedType.constantPoolName());
codeStream.iaload();
if (!hasCases) {
// we can get rid of the generated ordinal value
codeStream.pop();
}
} else {
valueRequired = this.expression.constant == Constant.NotAConstant || hasCases;
// generate expression
this.expression.generateCode(currentScope, codeStream, valueRequired);
}
// generate the appropriate switch table/lookup bytecode
if (hasCases) {
int[] sortedIndexes = new int[this.caseCount];
// we sort the keys to be able to generate the code for tableswitch or lookupswitch
for (int i = 0; i < this.caseCount; i++) {
sortedIndexes[i] = i;
}
int[] localKeysCopy;
System.arraycopy(this.constants, 0, (localKeysCopy = new int[this.caseCount]), 0, this.caseCount);
CodeStream.sort(localKeysCopy, 0, this.caseCount - 1, sortedIndexes);
int max = localKeysCopy[this.caseCount - 1];
int min = localKeysCopy[0];
if ((long) (this.caseCount * 2.5) > ((long) max - (long) min)) {
// work-around 1.3 VM bug, if max>0x7FFF0000, must use lookup bytecode
// see http://dev.eclipse.org/bugs/show_bug.cgi?id=21557
if (max > 0x7FFF0000 && currentScope.compilerOptions().complianceLevel < ClassFileConstants.JDK1_4) {
codeStream.lookupswitch(defaultLabel, this.constants, sortedIndexes, caseLabels);
} else {
codeStream.tableswitch(
defaultLabel,
min,
max,
this.constants,
sortedIndexes,
caseLabels);
}
} else {
codeStream.lookupswitch(defaultLabel, this.constants, sortedIndexes, caseLabels);
}
codeStream.updateLastRecordedEndPC(this.scope, codeStream.position);
} else if (valueRequired) {
codeStream.pop();
}
// generate the switch block statements
int caseIndex = 0;
if (this.statements != null) {
for (int i = 0, maxCases = this.statements.length; i < maxCases; i++) {
Statement statement = this.statements[i];
if ((caseIndex < this.caseCount) && (statement == this.cases[caseIndex])) { // statements[i] is a case
this.scope.enclosingCase = this.cases[caseIndex]; // record entering in a switch case block
if (this.preSwitchInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.preSwitchInitStateIndex);
}
caseIndex++;
} else {
if (statement == this.defaultCase) { // statements[i] is a case or a default case
this.scope.enclosingCase = this.defaultCase; // record entering in a switch case block
if (this.preSwitchInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.preSwitchInitStateIndex);
}
}
}
statement.generateCode(this.scope, codeStream);
}
}
// May loose some local variable initializations : affecting the local variable attributes
if (this.mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
codeStream.addDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
}
if (this.scope != currentScope) {
codeStream.exitUserScope(this.scope);
}
// place the trailing labels (for break and default case)
this.breakLabel.place();
if (this.defaultCase == null) {
// we want to force an line number entry to get an end position after the switch statement
codeStream.recordPositionsFrom(codeStream.position, this.sourceEnd, true);
defaultLabel.place();
}
codeStream.recordPositionsFrom(pc, this.sourceStart);
} finally {
if (this.scope != null) this.scope.enclosingCase = null; // no longer inside switch case block
}
}
public StringBuffer printStatement(int indent, StringBuffer output) {
printIndent(indent, output).append("switch ("); //$NON-NLS-1$
this.expression.printExpression(0, output).append(") {"); //$NON-NLS-1$
if (this.statements != null) {
for (int i = 0; i < this.statements.length; i++) {
output.append('\n');
if (this.statements[i] instanceof CaseStatement) {
this.statements[i].printStatement(indent, output);
} else {
this.statements[i].printStatement(indent+2, output);
}
}
}
output.append("\n"); //$NON-NLS-1$
return printIndent(indent, output).append('}');
}
public void resolve(BlockScope upperScope) {
try {
boolean isEnumSwitch = false;
boolean isStringSwitch = false;
TypeBinding expressionType = this.expression.resolveType(upperScope);
if (expressionType != null) {
this.expression.computeConversion(upperScope, expressionType, expressionType);
checkType: {
if (!expressionType.isValidBinding()) {
expressionType = null; // fault-tolerance: ignore type mismatch from constants from hereon
break checkType;
} else if (expressionType.isBaseType()) {
if (this.expression.isConstantValueOfTypeAssignableToType(expressionType, TypeBinding.INT))
break checkType;
if (expressionType.isCompatibleWith(TypeBinding.INT))
break checkType;
} else if (expressionType.isEnum()) {
isEnumSwitch = true;
break checkType;
} else if (upperScope.isBoxingCompatibleWith(expressionType, TypeBinding.INT)) {
this.expression.computeConversion(upperScope, TypeBinding.INT, expressionType);
break checkType;
} else if (upperScope.compilerOptions().complianceLevel >= ClassFileConstants.JDK1_7 && expressionType.id == TypeIds.T_JavaLangString) {
isStringSwitch = true;
break checkType;
}
upperScope.problemReporter().incorrectSwitchType(this.expression, expressionType);
expressionType = null; // fault-tolerance: ignore type mismatch from constants from hereon
}
}
if (isStringSwitch) {
// the secret variable should be created before iterating over the switch's statements that could
// create more locals. This must be done to prevent overlapping of locals
// See https://bugs.eclipse.org/bugs/show_bug.cgi?id=356002
this.dispatchStringCopy = new LocalVariableBinding(SecretStringVariableName, upperScope.getJavaLangString(), ClassFileConstants.AccDefault, false);
upperScope.addLocalVariable(this.dispatchStringCopy);
this.dispatchStringCopy.setConstant(Constant.NotAConstant);
this.dispatchStringCopy.useFlag = LocalVariableBinding.USED;
}
if (this.statements != null) {
this.scope = new BlockScope(upperScope);
int length;
// collection of cases is too big but we will only iterate until caseCount
this.cases = new CaseStatement[length = this.statements.length];
if (!isStringSwitch) {
this.constants = new int[length];
} else {
this.stringConstants = new String[length];
}
int counter = 0;
for (int i = 0; i < length; i++) {
Constant constant;
final Statement statement = this.statements[i];
if ((constant = statement.resolveCase(this.scope, expressionType, this)) != Constant.NotAConstant) {
if (!isStringSwitch) {
int key = constant.intValue();
//----check for duplicate case statement------------
for (int j = 0; j < counter; j++) {
if (this.constants[j] == key) {
reportDuplicateCase((CaseStatement) statement, this.cases[j], length);
}
}
this.constants[counter++] = key;
} else {
String key = constant.stringValue();
//----check for duplicate case statement------------
for (int j = 0; j < counter; j++) {
if (this.stringConstants[j].equals(key)) {
reportDuplicateCase((CaseStatement) statement, this.cases[j], length);
}
}
this.stringConstants[counter++] = key;
}
}
}
if (length != counter) { // resize constants array
if (!isStringSwitch) {
System.arraycopy(this.constants, 0, this.constants = new int[counter], 0, counter);
} else {
System.arraycopy(this.stringConstants, 0, this.stringConstants = new String[counter], 0, counter);
}
}
} else {
if ((this.bits & UndocumentedEmptyBlock) != 0) {
upperScope.problemReporter().undocumentedEmptyBlock(this.blockStart, this.sourceEnd);
}
}
// for enum switch, check if all constants are accounted for (if no default)
if (isEnumSwitch && this.defaultCase == null
&& upperScope.compilerOptions().getSeverity(CompilerOptions.IncompleteEnumSwitch) != ProblemSeverities.Ignore) {
int constantCount = this.constants == null ? 0 : this.constants.length; // could be null if no case statement
if (constantCount == this.caseCount
&& this.caseCount != ((ReferenceBinding)expressionType).enumConstantCount()) {
FieldBinding[] enumFields = ((ReferenceBinding)expressionType.erasure()).fields();
for (int i = 0, max = enumFields.length; i <max; i++) {
FieldBinding enumConstant = enumFields[i];
if ((enumConstant.modifiers & ClassFileConstants.AccEnum) == 0) continue;
findConstant : {
for (int j = 0; j < this.caseCount; j++) {
if ((enumConstant.id + 1) == this.constants[j]) // zero should not be returned see bug 141810
break findConstant;
}
// enum constant did not get referenced from switch
upperScope.problemReporter().missingEnumConstantCase(this, enumConstant);
}
}
}
}
} finally {
if (this.scope != null) this.scope.enclosingCase = null; // no longer inside switch case block
}
}
private void reportDuplicateCase(final CaseStatement duplicate, final CaseStatement original, int length) {
if (this.duplicateCaseStatements == null) {
this.scope.problemReporter().duplicateCase(original);
this.scope.problemReporter().duplicateCase(duplicate);
this.duplicateCaseStatements = new CaseStatement[length];
this.duplicateCaseStatements[this.duplicateCaseStatementsCounter++] = original;
this.duplicateCaseStatements[this.duplicateCaseStatementsCounter++] = duplicate;
} else {
boolean found = false;
searchReportedDuplicate: for (int k = 2; k < this.duplicateCaseStatementsCounter; k++) {
if (this.duplicateCaseStatements[k] == duplicate) {
found = true;
break searchReportedDuplicate;
}
}
if (!found) {
this.scope.problemReporter().duplicateCase(duplicate);
this.duplicateCaseStatements[this.duplicateCaseStatementsCounter++] = duplicate;
}
}
}
public void traverse(
ASTVisitor visitor,
BlockScope blockScope) {
if (visitor.visit(this, blockScope)) {
this.expression.traverse(visitor, blockScope);
if (this.statements != null) {
int statementsLength = this.statements.length;
for (int i = 0; i < statementsLength; i++)
this.statements[i].traverse(visitor, this.scope);
}
}
visitor.endVisit(this, blockScope);
}
/**
* Dispatch the call on its last statement.
*/
public void branchChainTo(BranchLabel label) {
// in order to improve debug attributes for stepping (11431)
// we want to inline the jumps to #breakLabel which already got
// generated (if any), and have them directly branch to a better
// location (the argument label).
// we know at this point that the breakLabel already got placed
if (this.breakLabel.forwardReferenceCount() > 0) {
label.becomeDelegateFor(this.breakLabel);
}
}
}