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/*
* Copyright 2000-2009 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.intellij.psi.util;
import com.intellij.psi.*;
import com.intellij.psi.tree.IElementType;
import gnu.trove.THashMap;
import java.util.Map;
public class IsConstantExpressionVisitor extends JavaElementVisitor {
protected boolean myIsConstant;
private final Map<PsiVariable, Boolean> varIsConst = new THashMap<PsiVariable, Boolean>();
public boolean isConstant() {
return myIsConstant;
}
@Override public void visitExpression(PsiExpression expression) {
myIsConstant = false;
}
@Override public void visitLiteralExpression(PsiLiteralExpression expression) {
myIsConstant = !"null".equals(expression.getText());
}
@Override public void visitClassObjectAccessExpression(PsiClassObjectAccessExpression expression) {
myIsConstant = true;
}
@Override public void visitParenthesizedExpression(PsiParenthesizedExpression expression) {
PsiExpression expr = expression.getExpression();
if (expr != null){
expr.accept(this);
}
}
@Override public void visitTypeCastExpression(PsiTypeCastExpression expression) {
PsiExpression operand = expression.getOperand();
if (operand == null){
myIsConstant = false;
return;
}
operand.accept(this);
if (!myIsConstant) return;
PsiTypeElement element = expression.getCastType();
if (element == null){
myIsConstant = false;
return;
}
PsiType type = element.getType();
if (type instanceof PsiPrimitiveType) return;
if (type.equalsToText("java.lang.String")) return;
myIsConstant = false;
}
@Override public void visitPrefixExpression(PsiPrefixExpression expression) {
PsiExpression operand = expression.getOperand();
if (operand == null){
myIsConstant = false;
return;
}
operand.accept(this);
if (!myIsConstant) return;
IElementType opType = expression.getOperationTokenType();
if (opType == JavaTokenType.PLUS || opType == JavaTokenType.MINUS || opType == JavaTokenType.TILDE || opType == JavaTokenType.EXCL) {
return;
}
myIsConstant = false;
}
@Override
public void visitPolyadicExpression(PsiPolyadicExpression expression) {
for (PsiExpression operand : expression.getOperands()) {
operand.accept(this);
if (!myIsConstant) return;
final PsiType type = operand.getType();
if (type != null && !(type instanceof PsiPrimitiveType) && !type.equalsToText(CommonClassNames.JAVA_LANG_STRING)) {
myIsConstant = false;
return;
}
}
}
@Override public void visitConditionalExpression(PsiConditionalExpression expression) {
PsiExpression thenExpr = expression.getThenExpression();
PsiExpression elseExpr = expression.getElseExpression();
if (thenExpr == null || elseExpr == null) {
myIsConstant = false;
return;
}
expression.getCondition().accept(this);
if (!myIsConstant) return;
thenExpr.accept(this);
if (!myIsConstant) return;
elseExpr.accept(this);
}
@Override public void visitReferenceExpression(PsiReferenceExpression expression) {
PsiElement refElement = expression.resolve();
if (!(refElement instanceof PsiVariable)) {
myIsConstant = false;
return;
}
PsiVariable variable = (PsiVariable)refElement;
Boolean isConst = varIsConst.get(variable);
if (isConst != null) {
myIsConstant &= isConst.booleanValue();
return;
}
if (variable instanceof PsiEnumConstant) {
myIsConstant = true;
varIsConst.put(variable, Boolean.TRUE);
return;
}
varIsConst.put(variable, Boolean.FALSE);
if (!variable.hasModifierProperty(PsiModifier.FINAL)){
myIsConstant = false;
return;
}
PsiExpression initializer = variable.getInitializer();
if (initializer == null){
myIsConstant = false;
return;
}
initializer.accept(this);
varIsConst.put(variable, Boolean.valueOf(myIsConstant));
}
}
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