getColumn method

int getColumn (int offset, { int line })

Gets the 0-based column corresponding to offset.

If line is passed, it's assumed to be the line containing offset and is used to more efficiently compute the column.

Implementation 

int getColumn(int offset, {int line}) {
  if (offset < 0) {
    throw new RangeError("Offset may not be negative, was $offset.");
  } else if (offset > length) {
    throw new RangeError("Offset $offset must be not be greater than the "
        "number of characters in the file, $length.");
  }

  if (line == null) {
    line = getLine(offset);
  } else if (line < 0) {
    throw new RangeError("Line may not be negative, was $line.");
  } else if (line >= lines) {
    throw new RangeError("Line $line must be less than the number of "
        "lines in the file, $lines.");
  }

  var lineStart = _lineStarts[line];
  if (lineStart > offset) {
    throw new RangeError("Line $line comes after offset $offset.");
  }

  return offset - lineStart;
}