plugins/cvs/cvs-plugin/src/com/intellij/cvsSupport2/actions/merge/CvsConflictsParser.java

/*
 * Copyright 2000-2012 JetBrains s.r.o.
 *
 * 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.intellij.cvsSupport2.actions.merge;

import com.intellij.util.containers.Stack;

import java.io.*;

/**
 * @author lesya
 */
public class CvsConflictsParser {

  private static final String LEFT = "<<<<<<< ";
  private static final String RIGHT = "=======";
  private static final String END = ">>>>>>> ";
  private static final int LENGTH = RIGHT.length();

  private enum State {
    RIGHT, LEFT
  }

  private final StringBuilder myLeftBuffer = new StringBuilder();
  private final StringBuilder myCenterBuffer = new StringBuilder();
  private final StringBuilder myRightBuffer = new StringBuilder();
  private final Stack<State> myStateStack = new Stack<State>();

  public String getLeftVersion() {
    return myLeftBuffer.toString();
  }

  public String getCenterVersion() {
    return myCenterBuffer.toString();
  }

  public String getRightVersion() {
    return myRightBuffer.toString();
  }

  private CvsConflictsParser() {}

  public static CvsConflictsParser createOn(InputStream merged) throws IOException {
    final CvsConflictsParser result = new CvsConflictsParser();
    result.parseFile(merged);
    return result;
  }

  private void parseFile(final InputStream merged) throws IOException {
    final BufferedReader br = new BufferedReader(new InputStreamReader(merged));
    try {
      for (String line; (line = br.readLine()) != null; ) {
        if (!processLeftMarker(line) && !processRightMarker(line) && !processEndMarker(line)) {
          appendToMainOrCurrent(line);
        }
      }
    }
    finally {
      br.close();
    }
  }

  private boolean processLeftMarker(String line) {
    final int idx = line.lastIndexOf(LEFT);
    if (idx < 0) {
      return false;
    }
    if (myStateStack.isEmpty()) {
      final String fragment = line.substring(0, idx);
      if (!fragment.isEmpty()) {
        appendToMainOrCurrent(fragment);
      }
    }
    else {
      appendToMainOrCurrent(line);
    }
    myStateStack.push(State.LEFT);
    return true;
  }

  private boolean processRightMarker(String line) {
    if (!line.endsWith(RIGHT)) {
      return false;
    }
    if (!myStateStack.isEmpty() && myStateStack.peek() == State.LEFT) {
      if (myStateStack.size() > 1) {
        appendToMainOrCurrent(line);
      }
      else {
        final String fragment = line.substring(0, line.length() - LENGTH);
        if (!fragment.isEmpty()) {
          appendToMainOrCurrent(fragment);
        }
      }
      myStateStack.pop();
      myStateStack.push(State.RIGHT);
    }
    else {
      appendToMainOrCurrent(line);
    }
    return true;
  }

  private boolean processEndMarker(String line) {
    final int idx = line.lastIndexOf(END);
    if (idx < 0) {
      return false;
    }
    if (!myStateStack.isEmpty()) {
      if (myStateStack.size() > 1) {
        appendToMainOrCurrent(line);
      }
      else {
        final String fragment = line.substring(0, idx);
        if (!fragment.isEmpty()) {
          appendToMainOrCurrent(fragment);
        }
      }
      myStateStack.pop();
    }
    else {
      appendToMainOrCurrent(line);
    }
    return true;
  }

  private void appendToMainOrCurrent(String line) {
    if (myStateStack.isEmpty()) {
      append(line, myLeftBuffer);
      append(line, myCenterBuffer);
      append(line, myRightBuffer);
    } else {
      if (myStateStack.get(0) == State.RIGHT) {
        append(line, myRightBuffer);
      } else {
        append(line, myLeftBuffer);
      }
    }
  }

  private static void append(String line, StringBuilder out) {
    if (out.length() > 0) {
      out.append("\n");
    }
    out.append(line);
  }
}