001    /*
002     * Copyright 2010-2015 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.kotlin.cfg;
018    
019    import kotlin.jvm.functions.Function1;
020    import org.jetbrains.annotations.NotNull;
021    import org.jetbrains.kotlin.cfg.pseudocode.instructions.Instruction;
022    import org.jetbrains.kotlin.cfg.pseudocode.instructions.InstructionVisitorWithResult;
023    import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.MagicInstruction;
024    import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.MergeInstruction;
025    import org.jetbrains.kotlin.cfg.pseudocode.instructions.jumps.AbstractJumpInstruction;
026    import org.jetbrains.kotlin.cfg.pseudocode.instructions.jumps.ThrowExceptionInstruction;
027    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.MarkInstruction;
028    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.SubroutineExitInstruction;
029    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.SubroutineSinkInstruction;
030    import org.jetbrains.kotlin.cfg.pseudocodeTraverser.TraverseInstructionResult;
031    import org.jetbrains.kotlin.psi.KtElement;
032    
033    public class TailRecursionDetector extends InstructionVisitorWithResult<Boolean> implements Function1<Instruction, TraverseInstructionResult> {
034        private final KtElement subroutine;
035        private final Instruction start;
036    
037        public TailRecursionDetector(@NotNull KtElement subroutine, @NotNull Instruction start) {
038            this.subroutine = subroutine;
039            this.start = start;
040        }
041    
042        @Override
043        public TraverseInstructionResult invoke(@NotNull Instruction instruction) {
044            return instruction == start || instruction.accept(this) ? TraverseInstructionResult.CONTINUE : TraverseInstructionResult.HALT;
045        }
046    
047        @Override
048        public Boolean visitInstruction(@NotNull Instruction instruction) {
049            return false;
050        }
051    
052        @Override
053        public Boolean visitSubroutineExit(@NotNull SubroutineExitInstruction instruction) {
054            return !instruction.isError() && instruction.getSubroutine() == subroutine;
055        }
056    
057        @Override
058        public Boolean visitSubroutineSink(@NotNull SubroutineSinkInstruction instruction) {
059            return instruction.getSubroutine() == subroutine;
060        }
061    
062        @Override
063        public Boolean visitJump(@NotNull AbstractJumpInstruction instruction) {
064            return true;
065        }
066    
067        @Override
068        public Boolean visitThrowExceptionInstruction(@NotNull ThrowExceptionInstruction instruction) {
069            return false;
070        }
071    
072        @Override
073        public Boolean visitMarkInstruction(@NotNull MarkInstruction instruction) {
074            return true;
075        }
076    
077        @Override
078        public Boolean visitMagic(@NotNull MagicInstruction instruction) {
079            return instruction.getSynthetic();
080        }
081    
082        @Override
083        public Boolean visitMerge(@NotNull MergeInstruction instruction) {
084            return true;
085        }
086    }