Revamped line match finder

// Copyright (C) 2014 Josh Ventura
// Code is part of LateralGM <lateralgm.org> and is released under the terms of
// the GNU General Public License as published by the Free Software Foundation;
// version 3 of the license, or any later version.

private static final Pattern newline = Pattern.compile("\r\n|\r|\n");
public static LineMatch[] getMatchingLines(String code, Pattern content) {
  List<LineMatch> res = new ArrayList<>();
  Matcher m = content.matcher(code), nl = newline.matcher(code);
  int lineNum = 1, lineAt = 0, lastEnd = -1;
  LineMatch lastMatch = null;
  while (m.find()) {
    nl.region(lineAt, m.start());
    int firstSkippedLineAt = lineAt;
    if (nl.find()) {
      firstSkippedLineAt = nl.start();
      lineAt = nl.end();
      ++lineNum;
      while (nl.find()) {
        ++lineNum;
        lineAt = nl.end();
      }
    }
    if (lastMatch != null) {
      // We have to add the rest of the line to the old match, either way.
      // And if we're matching on the same line, we add that match, too.
      if (lineNum == lastMatch.lineNum) {
        lastMatch.matchedText.add(new MatchBlock(code.substring(lastEnd, m.start()), false));
        lastMatch.matchedText.add(new MatchBlock(code.substring(m.start(), m.end()), true));
      } else {
        lastMatch.matchedText.add(
            new MatchBlock(code.substring(lastEnd, firstSkippedLineAt), false));
      }
    }
    if (lastMatch == null || lineNum != lastMatch.lineNum) {
      lastMatch = new LineMatch();
      lastMatch.lineNum = lineNum;
      if (m.start() > lineAt) {
        lastMatch.matchedText.add(new MatchBlock(code.substring(lineAt, m.start()), false));
      }
      lastMatch.matchedText.add(new MatchBlock(code.substring(m.start(), m.end()), false));
      res.add(lastMatch);
    }
    lastEnd = m.end();
  }
  if (lastMatch != null) {
    nl.region(lastEnd, code.length());
    int indTo = (nl.find())? nl.start() : code.length();
    lastMatch.matchedText.add(new MatchBlock(code.substring(lastEnd, indTo), false));
  }
  return res.toArray(new LineMatch[] {});
}