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