plugins/IntentionPowerPak/src/com/siyeh/ipp/decls/MoveDeclarationPredicate.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.decls;

import com.intellij.psi.*;
import com.intellij.psi.search.searches.ReferencesSearch;
import com.intellij.psi.util.PsiTreeUtil;
import com.siyeh.ipp.base.PsiElementPredicate;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

class MoveDeclarationPredicate implements PsiElementPredicate {

  public boolean satisfiedBy(@NotNull PsiElement element) {
    if (!(element instanceof PsiLocalVariable)) {
      return false;
    }
    final PsiLocalVariable variable = (PsiLocalVariable)element;
    final PsiExpression initializer = variable.getInitializer();
    if (initializer != null) {
      return false;
    }
    final PsiCodeBlock variableBlock =
      PsiTreeUtil.getParentOfType(variable, PsiCodeBlock.class);
    if (variableBlock == null) {
      return false;
    }
    final PsiManager manager = variable.getManager();
    final PsiReference[] references = ReferencesSearch.search(variable, variable.getUseScope(), false).toArray(PsiReference.EMPTY_ARRAY);
    if (references.length == 0) {
      return false;
    }
    final PsiElement tightestBlock = getTightestBlock(references);
    if (tightestBlock == null) {
      return false;
    }
    if (!variableBlock.equals(tightestBlock)) {
      return true;
    }

    final PsiReference firstReference = references[0];
    final PsiElement referenceElement = firstReference.getElement();
    if (referenceElement == null) {
      return false;
    }
    final PsiElement child = getChildWhichContainsElement(variableBlock,
                                                          referenceElement);
    if (child == null) {
      return false;
    }
    PsiElement prevSibling = child.getPrevSibling();
    if (prevSibling instanceof PsiWhiteSpace) {
      prevSibling = prevSibling.getPrevSibling();
    }
    if (prevSibling == null) {
      return false;
    }
    return !prevSibling.equals(variable.getParent());
  }

  @Nullable
  public static PsiElement getChildWhichContainsElement(
    @NotNull PsiCodeBlock ancestor, @NotNull PsiElement descendant) {
    PsiElement element = descendant;
    while (!element.equals(ancestor)) {
      descendant = element;
      element = descendant.getParent();
      if (element == null) {
        return null;
      }
    }
    return descendant;
  }

  @Nullable
  public static PsiCodeBlock getTightestBlock(
    @NotNull PsiReference[] references) {
    PsiCodeBlock commonParentBlock = null;
    for (PsiReference reference : references) {
      final PsiElement referenceElement = reference.getElement();
      final PsiCodeBlock block =
        PsiTreeUtil.getParentOfType(referenceElement,
                                    PsiCodeBlock.class);
      if (block == null) {
        return commonParentBlock;
      }
      if (commonParentBlock != null && !commonParentBlock.equals(block)) {
        final PsiElement commonParent =
          PsiTreeUtil.findCommonParent(commonParentBlock, block);
        if (commonParent instanceof PsiCodeBlock) {
          commonParentBlock = (PsiCodeBlock)commonParent;
        }
        else {
          commonParentBlock =
            PsiTreeUtil.getParentOfType(commonParent,
                                        PsiCodeBlock.class);
        }
      }
      else {
        commonParentBlock = block;
      }
    }
    return commonParentBlock;
  }
}