com.google.copybara.util.DiffUtil.java Source code

Introduction

Here is the source code for com.google.copybara.util.DiffUtil.java

Source

/*
 * Copyright (C) 2016 Google 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.google.copybara.util;

import com.google.common.base.Preconditions;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.copybara.util.console.AnsiColor;
import com.google.copybara.util.console.Console;
import com.google.devtools.build.lib.shell.Command;
import com.google.devtools.build.lib.shell.CommandException;
import java.io.IOException;
import java.nio.file.Path;

/**
 * Diff utilities that are repository-agnostic.
 */
public class DiffUtil {

    private static final byte[] EMPTY_DIFF = new byte[] {};

    /**
     * Calculates the diff between two sibling directory trees.
     *
     * <p>Returns the diff as an encoding-independent {@code byte[]} that can be write to a file or
     * fed directly into {@link DiffUtil#patch}.
     */
    public static byte[] diff(Path one, Path other, boolean verbose) throws IOException {
        Preconditions.checkArgument(one.getParent().equals(other.getParent()),
                "Paths 'one' and 'other' must be sibling directories.");
        Path root = one.getParent();
        String[] params = new String[] { "git", "diff", "--no-color", root.relativize(one).toString(),
                root.relativize(other).toString() };
        Command cmd = new Command(params, /*envVars*/ null, root.toFile());
        try {
            CommandUtil.executeCommand(cmd, verbose);
            return EMPTY_DIFF;
        } catch (BadExitStatusWithOutputException e) {
            CommandOutput output = e.getOutput();
            // git diff returns exit status 0 when contents are identical, or 1 when they are different
            if (!Strings.isNullOrEmpty(output.getStderr())) {
                throw new IOException(
                        "Error executing 'git diff': " + e.getMessage() + ". Stderr: \n" + output.getStderr(), e);
            }
            return output.getStdoutBytes();
        } catch (CommandException e) {
            throw new IOException("Error executing 'patch'", e);
        }
    }

    /**
     * Applies the diff into a directory tree.
     *
     * <p>{@code diffContents} is the result of invoking {@link DiffUtil#diff}.
     */
    public static void patch(Path rootDir, byte[] diffContents, boolean verbose) throws IOException {
        // TODO(copybara-team): Think if it makes sense to throw EmptyChangeException here
        if (diffContents.length == 0) {
            return;
        }
        String[] params = new String[] { "git", "apply", "-p2", "-" };
        Command cmd = new Command(params, /*envVars*/ null, rootDir.toFile());
        try {
            CommandUtil.executeCommand(cmd, diffContents, verbose);
        } catch (BadExitStatusWithOutputException e) {
            throw new IOException(
                    "Error executing 'patch': " + e.getMessage() + ". Stderr: \n" + e.getOutput().getStderr(), e);
        } catch (CommandException e) {
            throw new IOException("Error executing 'patch'", e);
        }
    }

    /**
     * Given a git compatible diff, returns the diff colorized if the console allows it.
     */
    public static String colorize(Console console, String diffText) {
        StringBuilder sb = new StringBuilder();
        for (String line : Splitter.on("\n").split(diffText)) {
            sb.append("\n");
            if (line.startsWith("+")) {
                sb.append(console.colorize(AnsiColor.GREEN, line));
            } else if (line.startsWith("-")) {
                sb.append(console.colorize(AnsiColor.RED, line));
            } else {
                sb.append(line);
            }
        }
        return sb.toString();
    }
}