UnifiedPatchParser.java

/*
 * SPDX-License-Identifier: Apache-1.1
 *
 * ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.
 * Copyright (c) 2010 Dmitry Naumenko (dm.naumenko@gmail.com)
 * Copyright (c) 2015-2016 Brenden Kromhout and contributors to java-diff-utils
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    any, must include the following acknowledgement:
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 *        Apache Software Foundation (http://www.apache.org/)."
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package difflib.event;

import difflib.DiffUtils;
import difflib.Patch;
import difflib.Utils;

import javax.annotation.Nonnull;
import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class UnifiedPatchParser {

    public void parse(File unifiedPatch, @Nonnull PatchHandler<String> handler) throws IOException {
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(new FileInputStream(unifiedPatch), Utils.UTF_8))) {
            String line = reader.readLine();
            do {
                List<String> patch = new ArrayList<>();
                while (!line.startsWith("---")) {
                    // in prelude: skip all lines
                    line = reader.readLine();
                }
                assert line.startsWith("---");
                patch.add(line);
                final String originalFileName = line.substring(4);

                line = reader.readLine();
                assert line.startsWith("+++");
                patch.add(line);
                final String revisedFileName = line.substring(4);

                line = reader.readLine();
                do {
                    patch.add(line);
                    line = reader.readLine();
                } while (
                    // TODO this implementation expects that we have comment between 2 diffs.
                        line != null && (line.startsWith("@@ ") || line.startsWith(" ") || line.startsWith("+")
                                || line.startsWith("-")));

                Patch<String> parsed = DiffUtils.parseUnifiedDiff(patch);
                handler.handle(originalFileName, revisedFileName, parsed);
            } while (line != null);
        }
    }
}