| /* |
| * Copyright 2003-2010 Dave Griffith, Bas Leijdekkers |
| * |
| * 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.ig.psiutils; |
| |
| import com.intellij.psi.*; |
| import com.intellij.psi.search.searches.MethodReferencesSearch; |
| import com.intellij.util.Processor; |
| import com.intellij.util.Query; |
| import org.jetbrains.annotations.NotNull; |
| |
| public class SingletonUtil { |
| |
| private SingletonUtil() { |
| } |
| |
| public static boolean isSingleton(@NotNull PsiClass aClass) { |
| if (aClass.isInterface() || aClass.isEnum() || |
| aClass.isAnnotationType()) { |
| return false; |
| } |
| if (aClass instanceof PsiTypeParameter || |
| aClass instanceof PsiAnonymousClass) { |
| return false; |
| } |
| final PsiMethod[] constructors = getIfOnlyInvisibleConstructors(aClass); |
| if (constructors.length == 0) { |
| return false; |
| } |
| final PsiField selfInstance = getIfOneStaticSelfInstance(aClass); |
| if (selfInstance == null) { |
| return false; |
| } |
| return newOnlyAssignsToStaticSelfInstance(constructors[0], selfInstance); |
| } |
| |
| private static PsiField getIfOneStaticSelfInstance(PsiClass aClass) { |
| final PsiField[] fields = aClass.getFields(); |
| PsiField result = null; |
| for (final PsiField field : fields) { |
| final String className = aClass.getQualifiedName(); |
| if (!field.hasModifierProperty(PsiModifier.STATIC)) { |
| continue; |
| } |
| final PsiType type = field.getType(); |
| final String fieldTypeName = type.getCanonicalText(); |
| if (!fieldTypeName.equals(className)) { |
| continue; |
| } |
| if (result != null) { |
| return null; |
| } |
| result = field; |
| } |
| return result; |
| } |
| |
| private static PsiMethod[] getIfOnlyInvisibleConstructors(PsiClass aClass) { |
| final PsiMethod[] constructors = aClass.getConstructors(); |
| if (constructors.length == 0) { |
| return PsiMethod.EMPTY_ARRAY; |
| } |
| for (final PsiMethod constructor : constructors) { |
| if (constructor.hasModifierProperty(PsiModifier.PUBLIC)) { |
| return PsiMethod.EMPTY_ARRAY; |
| } |
| if (!constructor.hasModifierProperty(PsiModifier.PRIVATE) && |
| !constructor.hasModifierProperty(PsiModifier.PROTECTED)) { |
| return PsiMethod.EMPTY_ARRAY; |
| } |
| } |
| return constructors; |
| } |
| |
| private static boolean newOnlyAssignsToStaticSelfInstance( |
| PsiMethod method, final PsiField field) { |
| final Query<PsiReference> search = |
| MethodReferencesSearch.search(method, field.getUseScope(), |
| false); |
| final NewOnlyAssignedToFieldProcessor processor = |
| new NewOnlyAssignedToFieldProcessor(field); |
| search.forEach(processor); |
| return processor.isNewOnlyAssignedToField(); |
| } |
| |
| private static class NewOnlyAssignedToFieldProcessor |
| implements Processor<PsiReference> { |
| |
| private boolean newOnlyAssignedToField = true; |
| private final PsiField field; |
| |
| public NewOnlyAssignedToFieldProcessor(PsiField field) { |
| this.field = field; |
| } |
| |
| @Override |
| public boolean process(PsiReference reference) { |
| final PsiElement element = reference.getElement(); |
| final PsiElement parent = element.getParent(); |
| if (!(parent instanceof PsiNewExpression)) { |
| newOnlyAssignedToField = false; |
| return false; |
| } |
| final PsiElement grandParent = parent.getParent(); |
| if (field.equals(grandParent)) { |
| return true; |
| } |
| if (!(grandParent instanceof PsiAssignmentExpression)) { |
| newOnlyAssignedToField = false; |
| return false; |
| } |
| final PsiAssignmentExpression assignmentExpression = |
| (PsiAssignmentExpression)grandParent; |
| final PsiExpression lhs = assignmentExpression.getLExpression(); |
| if (!(lhs instanceof PsiReferenceExpression)) { |
| newOnlyAssignedToField = false; |
| return false; |
| } |
| final PsiReferenceExpression referenceExpression = |
| (PsiReferenceExpression)lhs; |
| final PsiElement target = referenceExpression.resolve(); |
| if (!field.equals(target)) { |
| newOnlyAssignedToField = false; |
| return false; |
| } |
| return true; |
| } |
| |
| public boolean isNewOnlyAssignedToField() { |
| return newOnlyAssignedToField; |
| } |
| } |
| } |