ReplaceIfWithTernaryIntention.java

/*
 * Copyright 2000-2017 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jetbrains.plugins.groovy.intentions.control;

import com.intellij.openapi.editor.Editor;
import com.intellij.openapi.project.Project;
import com.intellij.psi.PsiElement;
import com.intellij.util.IncorrectOperationException;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.plugins.groovy.codeInspection.utils.EquivalenceChecker;
import org.jetbrains.plugins.groovy.intentions.base.Intention;
import org.jetbrains.plugins.groovy.intentions.base.PsiElementPredicate;
import org.jetbrains.plugins.groovy.lang.lexer.GroovyTokenTypes;
import org.jetbrains.plugins.groovy.lang.psi.GroovyPsiElementFactory;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrBlockStatement;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrIfStatement;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.branch.GrReturnStatement;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrAssignmentExpression;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrConditionalExpression;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrExpression;

/**
 * @author Max Medvedev
 */
public class ReplaceIfWithTernaryIntention extends Intention {
  @Override
  protected void processIntention(@NotNull PsiElement element, @NotNull Project project, Editor editor) throws IncorrectOperationException {
    final GrIfStatement ifStatement = (GrIfStatement)element.getParent();

    final PsiElement thenBranch = skipBlock(ifStatement.getThenBranch());
    final PsiElement elseBranch = skipBlock(ifStatement.getElseBranch());

    if (thenBranch instanceof GrAssignmentExpression && elseBranch instanceof GrAssignmentExpression) {
      final GrAssignmentExpression assignment = (GrAssignmentExpression)GroovyPsiElementFactory.getInstance(project).createStatementFromText("a = b ? c : d");

      assignment.getLValue().replaceWithExpression(((GrAssignmentExpression)thenBranch).getLValue(), true);

      final GrConditionalExpression conditional = (GrConditionalExpression)assignment.getRValue();
      replaceConditional(conditional, ifStatement.getCondition(), ((GrAssignmentExpression)thenBranch).getRValue(), ((GrAssignmentExpression)elseBranch).getRValue());
      ifStatement.replaceWithStatement(assignment);
    }


    if (thenBranch instanceof GrReturnStatement && elseBranch instanceof GrReturnStatement) {
      final GrReturnStatement returnSt = (GrReturnStatement)GroovyPsiElementFactory.getInstance(project).createStatementFromText("return a ? b : c");
      final GrConditionalExpression conditional = (GrConditionalExpression)returnSt.getReturnValue();
      replaceConditional(conditional, ifStatement.getCondition(), ((GrReturnStatement)thenBranch).getReturnValue(), ((GrReturnStatement)elseBranch).getReturnValue());

      ifStatement.replaceWithStatement(returnSt);
    }
  }

  @SuppressWarnings("ConstantConditions")
  private static void replaceConditional(GrConditionalExpression conditional,
                                         GrExpression condition,
                                         GrExpression then,
                                         GrExpression elze) {
    conditional.getCondition().replaceWithExpression(condition, true);
    conditional.getThenBranch().replaceWithExpression(then, true);
    conditional.getElseBranch().replaceWithExpression(elze, true);
  }

  @NotNull
  @Override
  protected PsiElementPredicate getElementPredicate() {
    return new PsiElementPredicate() {
      @Override
      public boolean satisfiedBy(@NotNull PsiElement e) {
        if (!e.getNode().getElementType().equals(GroovyTokenTypes.kIF)) return false;
        if (!(e.getParent() instanceof GrIfStatement)) return false;

        final GrIfStatement ifStatement = (GrIfStatement)e.getParent();
        final PsiElement thenBranch = skipBlock(ifStatement.getThenBranch());
        final PsiElement elseBranch = skipBlock(ifStatement.getElseBranch());

        if (thenBranch instanceof GrAssignmentExpression &&
            elseBranch instanceof GrAssignmentExpression &&
            ((GrAssignmentExpression)thenBranch).getRValue() != null &&
            ((GrAssignmentExpression)elseBranch).getRValue() != null) {
          final GrExpression lvalue1 = ((GrAssignmentExpression)thenBranch).getLValue();
          final GrExpression lvalue2 = ((GrAssignmentExpression)elseBranch).getLValue();
          return EquivalenceChecker.expressionsAreEquivalent(lvalue1, lvalue2);
        }

        if (thenBranch instanceof GrReturnStatement &&
            elseBranch instanceof GrReturnStatement &&
            ((GrReturnStatement)thenBranch).getReturnValue() != null &&
            ((GrReturnStatement)elseBranch).getReturnValue() != null) {
          return true;
        }

        return false;
      }
    };
  }

  private static PsiElement skipBlock(PsiElement e) {
    if (e instanceof GrBlockStatement && ((GrBlockStatement)e).getBlock().getStatements().length == 1) {
      return ((GrBlockStatement)e).getBlock().getStatements()[0];
    }
    else {
      return e;
    }
  }
}