plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/codeInspection/validity/GroovyDuplicateSwitchBranchInspection.java

/*
 * Copyright 2007-2008 Dave Griffith
 *
 * 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.codeInspection.validity;

import com.intellij.psi.PsiElement;
import org.jetbrains.annotations.Nls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.jetbrains.plugins.groovy.codeInspection.BaseInspection;
import org.jetbrains.plugins.groovy.codeInspection.BaseInspectionVisitor;
import org.jetbrains.plugins.groovy.codeInspection.utils.EquivalenceChecker;
import org.jetbrains.plugins.groovy.lang.psi.GroovyRecursiveElementVisitor;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrSwitchStatement;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.clauses.GrCaseLabel;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrExpression;

import java.util.HashSet;
import java.util.Set;

public class GroovyDuplicateSwitchBranchInspection extends BaseInspection {
  @Override
  public boolean isEnabledByDefault() {
    return true;
  }

  @Override
  @Nls
  @NotNull
  public String getGroupDisplayName() {
    return VALIDITY_ISSUES;
  }

  @Override
  @Nls
  @NotNull
  public String getDisplayName() {
    return "Duplicate switch case";
  }

  @Override
  @Nullable
  protected String buildErrorString(Object... args) {
    return "Duplicate switch case '#ref' #loc";
  }

  @NotNull
  @Override
  public BaseInspectionVisitor buildVisitor() {
    return new Visitor();
  }

  private static class Visitor extends BaseInspectionVisitor {
    @Override
    public void visitSwitchStatement(GrSwitchStatement grSwitchStatement) {
      super.visitSwitchStatement(grSwitchStatement);
      final Set<GrExpression> duplicateExpressions = new HashSet<GrExpression>();
      final GrCaseLabel[] labels = collectCaseLabels(grSwitchStatement);
      for (int i = 0; i < labels.length; i++) {
        final GrCaseLabel label1 = labels[i];
        final GrExpression expression1 = getExpressionForCaseLabel(label1);
        for (int j = i + 1; j < labels.length; j++) {
          final GrCaseLabel label2 = labels[j];
          final GrExpression expression2 = getExpressionForCaseLabel(label2);
          if (EquivalenceChecker.expressionsAreEquivalent(expression1, expression2)) {
            duplicateExpressions.add(expression1);
            duplicateExpressions.add(expression2);
          }
        }
      }
      for (GrExpression duplicateExpression : duplicateExpressions) {
        registerError(duplicateExpression);
      }
    }
  }

  private static GrCaseLabel[] collectCaseLabels(final GrSwitchStatement containingStatelent) {
    final Set<GrCaseLabel> labels = new HashSet<GrCaseLabel>();
    final GroovyRecursiveElementVisitor visitor = new GroovyRecursiveElementVisitor() {
      @Override
      public void visitCaseLabel(GrCaseLabel grCaseLabel) {
        super.visitCaseLabel(grCaseLabel);
        labels.add(grCaseLabel);
      }

      @Override
      public void visitSwitchStatement(GrSwitchStatement grSwitchStatement) {
        if (containingStatelent.equals(grSwitchStatement)) {
          super.visitSwitchStatement(grSwitchStatement);
        }
      }
    };
    containingStatelent.accept(visitor);
    return labels.toArray(new GrCaseLabel[labels.size()]);
  }

  @Nullable
  private static GrExpression getExpressionForCaseLabel(GrCaseLabel label) {
    for (PsiElement child : label.getChildren()) {
      if (child instanceof GrExpression) {
        return (GrExpression) child;
      }
    }
    return null;
  }
}