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   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v0.5
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v05.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  ******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.ast;
  12
  13 import net.sourceforge.phpdt.internal.compiler.IAbstractSyntaxTreeVisitor;
  14 import net.sourceforge.phpdt.internal.compiler.codegen.CodeStream;
  15 import net.sourceforge.phpdt.internal.compiler.codegen.ExceptionLabel;
  16 import net.sourceforge.phpdt.internal.compiler.codegen.Label;
  17 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  18 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  19 import net.sourceforge.phpdt.internal.compiler.flow.InsideSubRoutineFlowContext;
  20 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  21 import net.sourceforge.phpdt.internal.compiler.lookup.LocalVariableBinding;
  22 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  23
  24 public class SynchronizedStatement extends Statement {
  25
  26         public Expression expression;
  27         public Block block;
  28         public BlockScope scope;
  29
  30         boolean blockExit;
  31         public LocalVariableBinding synchroVariable;
  32         static final char[] SecretLocalDeclarationName = " syncValue".toCharArray(); //$NON-NLS-1$
  33
  34         public SynchronizedStatement(
  35                 Expression expression,
  36                 Block statement,
  37                 int s,
  38                 int e) {
  39
  40                 this.expression = expression;
  41                 this.block = statement;
  42                 sourceEnd = e;
  43                 sourceStart = s;
  44         }
  45
  46         public FlowInfo analyseCode(
  47                 BlockScope currentScope,
  48                 FlowContext flowContext,
  49                 FlowInfo flowInfo) {
  50
  51                 // mark the synthetic variable as being used
  52                 synchroVariable.used = true;
  53
  54                 // simple propagation to subnodes
  55                 flowInfo =
  56                         block.analyseCode(
  57                                 scope,
  58                                 new InsideSubRoutineFlowContext(flowContext, this),
  59                                 expression.analyseCode(scope, flowContext, flowInfo));
  60
  61                 // optimizing code gen
  62                 if ((flowInfo == FlowInfo.DeadEnd) || flowInfo.isFakeReachable()) {
  63                         blockExit = true;
  64                 }
  65                 return flowInfo;
  66         }
  67
  68         /**
  69          * Synchronized statement code generation
  70          *
  71          * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
  72          * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
  73          */
  74         public void generateCode(BlockScope currentScope, CodeStream codeStream) {
  75
  76                 if ((bits & IsReachableMASK) == 0) {
  77                         return;
  78                 }
  79                 int pc = codeStream.position;
  80
  81                 // generate the synchronization expression
  82                 expression.generateCode(scope, codeStream, true);
  83                 if (block.isEmptyBlock()) {
  84                         if ((synchroVariable.type == LongBinding)
  85                                 || (synchroVariable.type == DoubleBinding)) {
  86                                 codeStream.dup2();
  87                         } else {
  88                                 codeStream.dup();
  89                         }
  90                         // only take the lock
  91                         codeStream.monitorenter();
  92                         codeStream.monitorexit();
  93                 } else {
  94                         // enter the monitor
  95                         codeStream.store(synchroVariable, true);
  96                         codeStream.monitorenter();
  97
  98                         // generate  the body of the synchronized block
  99                         ExceptionLabel anyExceptionHandler = new ExceptionLabel(codeStream, null);
 100                         //'null' denotes any kind of exception
 101                         block.generateCode(scope, codeStream);
 102                         Label endLabel = new Label(codeStream);
 103                         if (!blockExit) {
 104                                 codeStream.load(synchroVariable);
 105                                 codeStream.monitorexit();
 106                                 codeStream.goto_(endLabel);
 107                         }
 108                         // generate the body of the exception handler
 109                         anyExceptionHandler.placeEnd();
 110                         anyExceptionHandler.place();
 111                         codeStream.incrStackSize(1);
 112                         codeStream.load(synchroVariable);
 113                         codeStream.monitorexit();
 114                         codeStream.athrow();
 115                         if (!blockExit) {
 116                                 endLabel.place();
 117                         }
 118                 }
 119                 if (scope != currentScope) {
 120                         codeStream.exitUserScope(scope);
 121                 }
 122                 codeStream.recordPositionsFrom(pc, this.sourceStart);
 123         }
 124
 125         public void resolve(BlockScope upperScope) {
 126
 127                 // special scope for secret locals optimization.
 128                 scope = new BlockScope(upperScope);
 129                 TypeBinding type = expression.resolveType(scope);
 130                 if (type == null)
 131                         return;
 132                 switch (type.id) {
 133                         case (T_boolean) :
 134                         case (T_char) :
 135                         case (T_float) :
 136                         case (T_double) :
 137                         case (T_byte) :
 138                         case (T_short) :
 139                         case (T_int) :
 140                         case (T_long) :
 141                                 scope.problemReporter().invalidTypeToSynchronize(expression, type);
 142                                 break;
 143                         case (T_void) :
 144                                 scope.problemReporter().illegalVoidExpression(expression);
 145                                 break;
 146                         case (T_null) :
 147                                 scope.problemReporter().invalidNullToSynchronize(expression);
 148                                 break;
 149                 }
 150                 //continue even on errors in order to have the TC done into the statements
 151                 synchroVariable = new LocalVariableBinding(SecretLocalDeclarationName, type, AccDefault, false);
 152                 scope.addLocalVariable(synchroVariable);
 153                 synchroVariable.constant = NotAConstant; // not inlinable
 154                 expression.implicitWidening(type, type);
 155                 block.resolveUsing(scope);
 156         }
 157
 158         public String toString(int tab) {
 159
 160                 String s = tabString(tab);
 161                 s = s + "synchronized (" + expression.toStringExpression() + ")";  //$NON-NLS-1$ //$NON-NLS-2$
 162                 s = s + "\n" + block.toString(tab + 1); //$NON-NLS-1$
 163                 return s;
 164         }
 165
 166         public void traverse(
 167                 IAbstractSyntaxTreeVisitor visitor,
 168                 BlockScope blockScope) {
 169
 170                 if (visitor.visit(this, blockScope)) {
 171                         expression.traverse(visitor, scope);
 172                         block.traverse(visitor, scope);
 173                 }
 174                 visitor.endVisit(this, blockScope);
 175         }
 176 }