python/src/com/jetbrains/python/inspections/PyReturnFromInitInspection.java

/*
 * Copyright 2000-2013 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 com.jetbrains.python.inspections;

import com.intellij.codeInspection.LocalInspectionToolSession;
import com.intellij.codeInspection.ProblemsHolder;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiElementVisitor;
import com.jetbrains.python.PyBundle;
import com.jetbrains.python.PyNames;
import com.jetbrains.python.inspections.quickfix.PyRemoveStatementQuickFix;
import com.jetbrains.python.psi.PyClass;
import com.jetbrains.python.psi.PyFunction;
import com.jetbrains.python.psi.PyReturnStatement;
import org.jetbrains.annotations.Nls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.ArrayList;
import java.util.Collection;

/**
 * Checks that no value is returned from __init__().
 * User: dcheryasov
 * Date: Nov 12, 2009 10:20:49 PM
 */
public class PyReturnFromInitInspection extends PyInspection {
  @Nls
  @NotNull
  public String getDisplayName() {
    return PyBundle.message("INSP.NAME.init.return");
  }

  @NotNull
  @Override
  public PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder,
                                        boolean isOnTheFly,
                                        @NotNull LocalInspectionToolSession session) {
    return new Visitor(holder, session);
  }

  public static class Visitor extends PyInspectionVisitor {
    public Visitor(@Nullable ProblemsHolder holder, @NotNull LocalInspectionToolSession session) {
      super(holder, session);
    }

    public void visitPyFunction(PyFunction function) {
      if (function.getContainingClass() != null && PyNames.INIT.equals(function.getName())) {
        Collection<PsiElement> offenders = new ArrayList<PsiElement>();
        findReturnValueInside(function, offenders);
        for (PsiElement offender : offenders) {
          registerProblem(offender, PyBundle.message("INSP.cant.return.value.from.init"), new PyRemoveStatementQuickFix());
        }
      }
    }

    private static void findReturnValueInside(@NotNull PsiElement node, Collection<PsiElement> offenders) {
      for (PsiElement child = node.getFirstChild(); child != null; child = child.getNextSibling()) {
        if (child instanceof PyFunction || child instanceof PyClass) continue; // ignore possible inner functions and classes
        if (child instanceof PyReturnStatement) {
          if (((PyReturnStatement)child).getExpression() != null) offenders.add(child);
        }
        findReturnValueInside(child, offenders);
      }
    }
  }
}