com.facebook.buck.rules.ExportFileRule.java Source code

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Here is the source code for com.facebook.buck.rules.ExportFileRule.java

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/*
 * Copyright 2012-present Facebook, Inc.
 *
 * 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.facebook.buck.rules;

import com.facebook.buck.step.fs.MkdirAndSymlinkFileStep;
import com.facebook.buck.step.Step;
import com.facebook.buck.util.BuckConstant;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;

import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.Map;

import javax.annotation.Nullable;

/**
 * Export a file so that it can be easily referenced by other {@link BuildRule}s. There are several
 * valid ways of using export_file (all examples in a build file located at "path/to/buck/BUCK").
 * The most common usage of export_file is:
 * <pre>
 *   export_file(name = 'some-file.html')
 * </pre>
 * This is equivalent to:
 * <pre>
 *   export_file(name = 'some-file.html',
 *     src = 'some-file.html',
 *     out = 'some-file.html')
 * </pre>
 * This results in "//path/to/buck:some-file.html" as the rule, and will export the file
 * "some-file.html" as "some-file.html".
 * <pre>
 *   export_file(
 *     name = 'foobar.html',
 *     src = 'some-file.html',
 *   )
 * </pre>
 * Is equivalent to:
 * <pre>
 *    export_file(name = 'foobar.html', src = 'some-file.html', out = 'foobar.html')
 * </pre>
 * Finally, it's possible to refer to the exported file with a logical name, while controlling the
 * actual file name. For example:
 * <pre>
 *   export_file(name = 'ie-exports',
 *     src = 'some-file.js',
 *     out = 'some-file-ie.js',
 *   )
 * </pre>
 * As a rule of thumb, if the "out" parameter is missing, the "name" parameter is used as the name
 * of the file to be saved.
 */
// TODO(simons): Extend to also allow exporting a rule.
public class ExportFileRule extends AbstractCachingBuildRule {

    private final String src;
    private final Supplier<File> out;

    @VisibleForTesting
    ExportFileRule(BuildRuleParams params, Optional<String> src, Optional<String> out) {
        super(params);

        String shortName = params.getBuildTarget().getShortName();

        this.src = src.or(shortName);

        final String outName = out.or(shortName);

        this.out = Suppliers.memoize(new Supplier<File>() {
            @Override
            public File get() {
                String name = new File(outName).getName();
                String outputPath = String.format("%s/%s%s", BuckConstant.GEN_DIR,
                        getBuildTarget().getBasePathWithSlash(), name);

                return new File(outputPath);
            }
        });
    }

    @Override
    public BuildRuleType getType() {
        return BuildRuleType.EXPORT_FILE;
    }

    @Override
    protected Iterable<String> getInputsToCompareToOutput(BuildContext context) {
        return ImmutableSet.of(src);
    }

    @Override
    protected List<Step> buildInternal(BuildContext context) throws IOException {
        File inputFile = context.getProjectFilesystem().getFileForRelativePath(src);
        File outputFile = out.get();

        ImmutableList.Builder<Step> builder = ImmutableList.<Step>builder()
                .add(new MkdirAndSymlinkFileStep(inputFile, outputFile));

        return builder.build();
    }

    @Nullable
    @Override
    public File getOutput() {
        return out.get();
    }

    public static Builder newExportFileBuilder() {
        return new Builder();
    }

    public static class Builder extends AbstractBuildRuleBuilder {
        private Optional<String> src;
        private Optional<String> out;

        public Builder setSrc(Optional<String> src) {
            this.src = src;
            return this;
        }

        public Builder setOut(Optional<String> out) {
            this.out = out;
            return this;
        }

        @Override
        public ExportFileRule build(Map<String, BuildRule> buildRuleIndex) {
            BuildRuleParams params = createBuildRuleParams(buildRuleIndex);

            return new ExportFileRule(params, src, out);
        }
    }
}