src/main/java/com/android/tools/build/apkzlib/zip/AlignmentRules.java

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * 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.android.tools.build.apkzlib.zip;

import com.google.common.base.Preconditions;
import javax.annotation.Nonnull;

/**
 * Factory for instances of {@link AlignmentRule}.
 */
public final class AlignmentRules {

    private AlignmentRules() {}

    /**
     * A rule that defines a constant alignment for all files.
     *
     * @param alignment the alignment
     * @return the rule
     */
    public static AlignmentRule constant(int alignment) {
        Preconditions.checkArgument(alignment > 0, "alignment <= 0");

        return (String path) -> alignment;
    }

    /**
     * A rule that defines constant alignment for all files with a certain suffix, placing no
     * restrictions on other files.
     *
     * @param suffix the suffix
     * @param alignment the alignment for paths that match the provided suffix
     * @return the rule
     */
    public static AlignmentRule constantForSuffix(@Nonnull String suffix, int alignment) {
        Preconditions.checkArgument(!suffix.isEmpty(), "suffix.isEmpty()");
        Preconditions.checkArgument(alignment > 0, "alignment <= 0");

        return (String path) -> path.endsWith(suffix) ? alignment : AlignmentRule.NO_ALIGNMENT;
    }

    /**
     * A rule that applies other rules in order.
     *
     * @param rules all rules to be tried; the first rule that does not return
     * {@link AlignmentRule#NO_ALIGNMENT} will define the alignment for a path; if there are no
     * rules that return a value different from {@link AlignmentRule#NO_ALIGNMENT}, then
     * {@link AlignmentRule#NO_ALIGNMENT} is returned
     * @return the composition rule
     */
    public static AlignmentRule compose(@Nonnull AlignmentRule... rules) {
        return (String path) -> {
            for (AlignmentRule r : rules) {
                int align = r.alignment(path);
                if (align != AlignmentRule.NO_ALIGNMENT) {
                    return align;
                }
            }

            return AlignmentRule.NO_ALIGNMENT;
        };
    }
}