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/*
 * Copyright 2010-2015 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 kotlin.reflect.jvm.internal.pcollections;

/**
 * An efficient persistent map from integer keys to non-null values.
 */
final class IntTreePMap {
    private static final IntTreePMap EMPTY = new IntTreePMap(IntTree.EMPTYNODE);

    @SuppressWarnings("unchecked")
    public static  IntTreePMap empty() {
        return (IntTreePMap) EMPTY;
    }

    private final IntTree root;

    private IntTreePMap(IntTree root) {
        this.root = root;
    }

    private IntTreePMap withRoot(IntTree root) {
        if (root == this.root) return this;
        return new IntTreePMap(root);
    }

    public V get(int key) {
        return root.get(key);
    }

    public IntTreePMap plus(int key, V value) {
        return withRoot(root.plus(key, value));
    }

    public IntTreePMap minus(int key) {
        return withRoot(root.minus(key));
    }
}