plugins/IntentionPowerPak/src/com/siyeh/ipp/commutative/FlipCommutativeMethodCallPredicate.java

/*
 * Copyright 2003-2005 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 com.siyeh.ipp.commutative;

import com.intellij.psi.*;
import com.intellij.psi.util.TypeConversionUtil;
import com.siyeh.ipp.base.PsiElementPredicate;
import com.siyeh.ipp.psiutils.ErrorUtil;

class FlipCommutativeMethodCallPredicate implements PsiElementPredicate {

  public boolean satisfiedBy(PsiElement element) {
    if (!(element instanceof PsiMethodCallExpression)) {
      return false;
    }
    if (ErrorUtil.containsError(element)) {
      return false;
    }
    final PsiMethodCallExpression expression =
      (PsiMethodCallExpression)element;
    // do it only when there is just one argument.
    final PsiExpressionList argumentList = expression.getArgumentList();
    final PsiExpression[] args = argumentList.getExpressions();
    if (args.length != 1) {
      return false;
    }
    final PsiReferenceExpression methodExpression =
      expression.getMethodExpression();
    final PsiExpression qualifier =
      methodExpression.getQualifierExpression();
    // make sure that there is a caller and a caller
    if (qualifier == null) {
      return false;
    }
    final String methodName = methodExpression.getReferenceName();
    // the logic is...
    // if the argument takes a method of the same name with the caller
    // as parameter then we can switch the argument and the caller.
    final PsiType callerType = qualifier.getType();
    final PsiType argumentType = args[0].getType();
    if (argumentType == null || !(argumentType instanceof PsiClassType)) {
      return false;
    }
    if (callerType == null || !(callerType instanceof PsiClassType)) {
      return false;
    }
    final PsiClassType.ClassResolveResult resolveResult = ((PsiClassType)argumentType).resolveGenerics();
    final PsiClass argumentClass = resolveResult.getElement();
    if (argumentClass == null) {
      return false;
    }
    final PsiMethod[] methods =
      argumentClass.findMethodsByName(methodName, true);
    for (final PsiMethod testMethod : methods) {
      final String testMethodName = testMethod.getName();
      if (testMethodName.equals(methodName)) {
        final PsiParameterList parameterList =
          testMethod.getParameterList();
        final PsiParameter[] parameters = parameterList.getParameters();
        if (parameters.length == 1) {
          final PsiParameter parameter = parameters[0];
          final PsiClass containingClass = testMethod.getContainingClass();
          if (containingClass != null) {
            final PsiSubstitutor substitutor =
              TypeConversionUtil.getClassSubstitutor(containingClass, argumentClass, resolveResult.getSubstitutor());
            if (substitutor != null) {
              final PsiType type = substitutor.substitute(parameter.getType());
              if (type != null && type.isAssignableFrom(callerType)) {
                return true;
              }
            }
          }
        }
      }
    }
    return false;
  }
}