com.google.errorprone.bugpatterns.overloading.ParameterTree Maven / Gradle / Ivy
/*
* Copyright 2017 The Error Prone Authors.
*
* 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.bugpatterns.overloading;
import com.google.auto.value.AutoValue;
import com.google.common.base.Preconditions;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.Tree;
import com.sun.source.tree.VariableTree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import java.util.Set;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.Name;
/**
* A simpler version of standard {@link VariableTree} used to distinguish between real variable
* declarations and method parameters.
*
* {@link VariableTree} is in a sense "too rich" to represent method parameters. For example, it
* is allowed to have an initializer or arbitrary modifiers. This class is a much simpler version of
* variable tree used to distinguish actual real {@link VariableTree} (variable declarations) from
* simple method parameters. During construction it is validated that the underlying {@link
* VariableTree} can really be used as method parameter.
*
*
It also provides slightly more sensible (for our purposes) {@link Object#toString()}
* implementation.
*
* @author [email protected] (Łukasz Hanuszczak)
*/
@AutoValue
abstract class ParameterTree {
public abstract Name getName();
public abstract Tree getType();
public abstract boolean isVarArgs();
public static ParameterTree create(VariableTree variableTree) {
Preconditions.checkArgument(isValidParameterTree(variableTree));
Name name = variableTree.getName();
Tree type = variableTree.getType();
boolean isVarargs = isVariableTreeVarArgs(variableTree);
return new AutoValue_ParameterTree(name, type, isVarargs);
}
private static boolean isValidParameterTree(VariableTree variableTree) {
// A valid parameter has no initializer.
if (variableTree.getInitializer() != null) {
return false;
}
// A valid parameter either has no modifiers or has only `final` keyword.
Set flags = variableTree.getModifiers().getFlags();
return flags.isEmpty() || (flags.size() == 1 && flags.contains(Modifier.FINAL));
}
@Override
public final String toString() {
String type = getType().toString();
String name = getName().toString();
// Hacky fix to improve pretty-printing of varargs (otherwise they are printed as Type[]).
if (isVarArgs()) {
type = type.substring(0, type.length() - 2) + "...";
}
return type + " " + name;
}
// TODO(hanuszczak): This should probably be moved to ASTHelpers.
private static boolean isVariableTreeVarArgs(VariableTree variableTree) {
Symbol sym = ASTHelpers.getSymbol(variableTree);
Preconditions.checkArgument(
sym.owner instanceof MethodSymbol, "sym must be a parameter to a method");
MethodSymbol method = (MethodSymbol) sym.owner;
return method.isVarArgs() && method.getParameters().last() == sym;
}
}