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 org.jetbrains.annotations.NotNull;
020    import org.jetbrains.kotlin.cfg.pseudocode.instructions.Instruction;
021    import org.jetbrains.kotlin.cfg.pseudocode.instructions.InstructionVisitorWithResult;
022    import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.MagicInstruction;
023    import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.MergeInstruction;
024    import org.jetbrains.kotlin.cfg.pseudocode.instructions.jumps.AbstractJumpInstruction;
025    import org.jetbrains.kotlin.cfg.pseudocode.instructions.jumps.ThrowExceptionInstruction;
026    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.MarkInstruction;
027    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.SubroutineExitInstruction;
028    import org.jetbrains.kotlin.cfg.pseudocode.instructions.special.SubroutineSinkInstruction;
029    import org.jetbrains.kotlin.psi.KtElement;
030    
031    /**
032     * Returns true when visited instruction may lie on a path from a tail-call-like operation to the sink of the subroutine
033     */
034    public class TailInstructionDetector extends InstructionVisitorWithResult<Boolean>  {
035        private final KtElement subroutine;
036    
037        public TailInstructionDetector(@NotNull KtElement subroutine) {
038            this.subroutine = subroutine;
039        }
040    
041        @Override
042        public Boolean visitInstruction(@NotNull Instruction instruction) {
043            return false;
044        }
045    
046        @Override
047        public Boolean visitSubroutineExit(@NotNull SubroutineExitInstruction instruction) {
048            return !instruction.isError() && instruction.getSubroutine() == subroutine;
049        }
050    
051        @Override
052        public Boolean visitSubroutineSink(@NotNull SubroutineSinkInstruction instruction) {
053            return instruction.getSubroutine() == subroutine;
054        }
055    
056        @Override
057        public Boolean visitJump(@NotNull AbstractJumpInstruction instruction) {
058            return true;
059        }
060    
061        @Override
062        public Boolean visitThrowExceptionInstruction(@NotNull ThrowExceptionInstruction instruction) {
063            return false;
064        }
065    
066        @Override
067        public Boolean visitMarkInstruction(@NotNull MarkInstruction instruction) {
068            return true;
069        }
070    
071        @Override
072        public Boolean visitMagic(@NotNull MagicInstruction instruction) {
073            return instruction.getSynthetic();
074        }
075    
076        @Override
077        public Boolean visitMerge(@NotNull MergeInstruction instruction) {
078            return true;
079        }
080    }