java/java-impl/src/com/intellij/codeInspection/dataFlow/InstructionVisitor.java

   1 /*
   2  * Copyright 2000-2009 JetBrains s.r.o.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 package com.intellij.codeInspection.dataFlow;
  17
  18 import com.intellij.codeInspection.dataFlow.instructions.*;
  19 import com.intellij.codeInspection.dataFlow.value.DfaUnknownValue;
  20 import com.intellij.codeInspection.dataFlow.value.DfaVariableValue;
  21 import com.intellij.codeInspection.dataFlow.value.DfaValue;
  22 import com.intellij.psi.PsiExpression;
  23
  24 import java.util.ArrayList;
  25
  26 /**
  27  * @author peter
  28  */
  29 public abstract class InstructionVisitor {
  30
  31   public DfaInstructionState[] visitAssign(AssignInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
  32     memState.pop();
  33     memState.push(memState.pop());
  34     return nextInstruction(instruction, runner, memState);
  35   }
  36
  37   protected static DfaInstructionState[] nextInstruction(Instruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
  38     return new DfaInstructionState[]{new DfaInstructionState(runner.getInstruction(instruction.getIndex() + 1), memState)};
  39   }
  40
  41   public DfaInstructionState[] visitInstanceof(InstanceofInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
  42     return visitBinop(instruction, runner, memState);
  43   }
  44
  45   public DfaInstructionState[] visitBinop(BinopInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
  46     memState.pop();
  47     memState.pop();
  48     memState.push(DfaUnknownValue.getInstance());
  49     return nextInstruction(instruction, runner, memState);
  50   }
  51
  52   public DfaInstructionState[] visitCheckReturnValue(CheckReturnValueInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
  53     memState.pop();
  54     return nextInstruction(instruction, runner, memState);
  55   }
  56
  57   public DfaInstructionState[] visitConditionalGoto(ConditionalGotoInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
  58     DfaValue cond = memState.pop();
  59
  60     DfaValue condTrue;
  61     DfaValue condFalse;
  62
  63     if (instruction.isNegated()) {
  64       condFalse = cond;
  65       condTrue = cond.createNegated();
  66     } else {
  67       condTrue = cond;
  68       condFalse = cond.createNegated();
  69     }
  70
  71     if (condTrue == runner.getFactory().getConstFactory().getTrue()) {
  72       markBranchReachable(instruction, true);
  73       return new DfaInstructionState[] {new DfaInstructionState(runner.getInstruction(instruction.getOffset()), memState)};
  74     }
  75
  76     if (condFalse == runner.getFactory().getConstFactory().getTrue()) {
  77       markBranchReachable(instruction, false);
  78       return nextInstruction(instruction, runner, memState);
  79     }
  80
  81     ArrayList<DfaInstructionState> result = new ArrayList<DfaInstructionState>();
  82
  83     DfaMemoryState thenState = memState.createCopy();
  84     DfaMemoryState elseState = memState.createCopy();
  85
  86     if (thenState.applyCondition(condTrue)) {
  87       result.add(new DfaInstructionState(runner.getInstruction(instruction.getOffset()), thenState));
  88       markBranchReachable(instruction, true);
  89     }
  90
  91     if (elseState.applyCondition(condFalse)) {
  92       result.add(new DfaInstructionState(runner.getInstruction(instruction.getIndex() + 1), elseState));
  93       markBranchReachable(instruction, false);
  94     }
  95
  96     return result.toArray(new DfaInstructionState[result.size()]);
  97   }
  98
  99   private static void markBranchReachable(ConditionalGotoInstruction instruction, boolean isTrueBranch) {
 100     if (isTrueBranch ^ instruction.isNegated()) {
 101       instruction.setTrueReachable();
 102     }
 103     else {
 104       instruction.setFalseReachable();
 105     }
 106   }
 107
 108
 109   public DfaInstructionState[] visitEmptyStack(EmptyStackInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 110     memState.emptyStack();
 111     return nextInstruction(instruction, runner, memState);
 112   }
 113
 114   public DfaInstructionState[] visitFieldReference(FieldReferenceInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 115     memState.pop();
 116     return nextInstruction(instruction, runner, memState);
 117   }
 118
 119   public DfaInstructionState[] visitFlushVariable(FlushVariableInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 120     final DfaVariableValue variable = instruction.getVariable();
 121     if (variable != null) {
 122       memState.flushVariable(variable);
 123     } else {
 124       memState.flushFields(runner);
 125     }
 126     return nextInstruction(instruction, runner, memState);
 127   }
 128
 129   public DfaInstructionState[] visitMethodCall(MethodCallInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 130     //noinspection UnusedDeclaration
 131     for (PsiExpression arg : instruction.getArgs()) {
 132       memState.pop();
 133     }
 134
 135     memState.pop(); //qualifier
 136     memState.push(DfaUnknownValue.getInstance());
 137     return nextInstruction(instruction, runner, memState);
 138   }
 139
 140   public DfaInstructionState[] visitCast(MethodCallInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 141     return visitMethodCall(instruction, runner, memState);
 142   }
 143
 144   public DfaInstructionState[] visitNot(NotInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 145     DfaValue dfaValue = memState.pop();
 146
 147     dfaValue = dfaValue.createNegated();
 148     memState.push(dfaValue);
 149     return nextInstruction(instruction, runner, memState);
 150   }
 151
 152   public DfaInstructionState[] visitPush(PushInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 153     memState.push(instruction.getValue());
 154     return nextInstruction(instruction, runner, memState);
 155   }
 156
 157   public DfaInstructionState[] visitTypeCast(TypeCastInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
 158     return nextInstruction(instruction, runner, memState);
 159   }
 160
 161 }