gradle-master/subprojects/ide-native/src/main/java/org/gradle/ide/xcode/internal/xcodeproj/GidGenerator.java
/*
 * Copyright 2017 the original author or 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 org.gradle.ide.xcode.internal.xcodeproj;

import com.google.common.collect.Sets;

import java.util.Set;

/**
 * Generator for Global ID (GID) which are present on every xcode project object.
 *
 * The GID is a 96 bit identifier that's unique on a per-project basis.
 */
public class GidGenerator {
    private final Set<String> generatedAndReservedIds;

    public GidGenerator(Set<String> reservedIds) {
        generatedAndReservedIds = Sets.newHashSet(reservedIds);
    }

    /**
     * Generate a stable GID based on the class name and hash of some object info.
     *
     * GIDs generated this way will be in the form of
     * {@code <class-name-hash-32> <obj-hash-32> <counter-32>}
     */
    public String generateGid(String pbxClassName, int hash) {
        int counter = 0;
        String gid;
        do {
            gid = String.format("%08X%08X%08X", pbxClassName.hashCode(), hash, counter++);
        } while (generatedAndReservedIds.contains(gid));
        generatedAndReservedIds.add(gid);
        return gid;
    }
}
