/*
* Copyright 2014 Google Inc. All Rights Reserved.
*
* 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.google.errorprone.dataflow;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.util.Context;
import org.checkerframework.dataflow.constantpropagation.Constant;
import org.checkerframework.dataflow.constantpropagation.ConstantPropagationTransfer;
/**
* An interface to the constant propagation analysis.
*/
public final class ConstantPropagationAnalysis {
private static final ConstantPropagationTransfer CONSTANT_PROPAGATION =
new ConstantPropagationTransfer();
/**
* Returns the value of the leaf of {@code exprPath}, if it is determined to be a constant
* (always evaluates to the same numeric value), and null otherwise.
* Note that returning null does not necessarily mean the expression is *not* a constant.
*/
public static Number numberValue(TreePath exprPath, Context context) {
Constant val = DataFlow.expressionDataflow(exprPath, context, CONSTANT_PROPAGATION);
if (val == null || !val.isConstant()) {
return null;
}
return val.getValue();
}
}