javaparser-symbol-solver-model/src/main/java/com/github/javaparser/symbolsolver/model/typesystem/NullType.java

/*
 * Copyright 2016 Federico Tomassetti
 *
 * 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.github.javaparser.symbolsolver.model.typesystem;

import com.github.javaparser.resolution.types.ResolvedType;

/**
 * This is a virtual type used to represent null values.
 *
 * @author Federico Tomassetti
 */
public class NullType implements ResolvedType {

    public static final NullType INSTANCE = new NullType();

    private NullType() {
        // prevent instantiation
    }

    @Override
    public boolean isArray() {
        return false;
    }

    @Override
    public boolean isPrimitive() {
        return false;
    }

    public boolean isNull() {
        return true;
    }

    @Override
    public boolean isReferenceType() {
        return false;
    }

    @Override
    public String describe() {
        return "null";
    }

    @Override
    public boolean isTypeVariable() {
        return false;
    }

    @Override
    public boolean isAssignableBy(ResolvedType other) {
        throw new UnsupportedOperationException("It does not make sense to assign a value to null, it can only be assigned");
    }

}