001    /*
002     * Copyright 2010-2013 JetBrains s.r.o.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package org.jetbrains.jet.lang.cfg;
018    
019    import org.jetbrains.annotations.NotNull;
020    import org.jetbrains.jet.lang.cfg.pseudocode.*;
021    import org.jetbrains.jet.lang.psi.JetElement;
022    
023    public class TailRecursionDetector extends InstructionVisitorWithResult<Boolean> implements PseudocodeTraverser.InstructionHandler {
024        private final JetElement subroutine;
025        private final Instruction start;
026    
027        public TailRecursionDetector(@NotNull JetElement subroutine, @NotNull Instruction start) {
028            this.subroutine = subroutine;
029            this.start = start;
030        }
031    
032        @Override
033        public boolean handle(@NotNull Instruction instruction) {
034            return instruction == start || instruction.accept(this);
035        }
036    
037        @Override
038        public Boolean visitInstruction(Instruction instruction) {
039            return false;
040        }
041    
042        @Override
043        public Boolean visitSubroutineExit(SubroutineExitInstruction instruction) {
044            return !instruction.isError() && instruction.getSubroutine() == subroutine;
045        }
046    
047        @Override
048        public Boolean visitSubroutineSink(SubroutineSinkInstruction instruction) {
049            return instruction.getSubroutine() == subroutine;
050        }
051    
052        @Override
053        public Boolean visitJump(AbstractJumpInstruction instruction) {
054            return true;
055        }
056    
057        @Override
058        public Boolean visitThrowExceptionInstruction(ThrowExceptionInstruction instruction) {
059            return false;
060        }
061    
062        @Override
063        public Boolean visitMarkInstruction(MarkInstruction instruction) {
064            return true;
065        }
066    }