encodeCharset method

int encodeCharset(String contents, Charset charset, int position)

Encode the string starting at position position starting with the character set charset

Implementation

int encodeCharset(String contents, Charset charset, int position) {
  assert(position < contents.length);
  final mCost = memoizedCost![charset.index][position];
  if (mCost > 0) {
    return mCost;
  }

  int minCost = MathUtils.maxValue;
  Latch minLatch = Latch.none;
  final atEnd = position + 1 >= contents.length;

  final sets = [Charset.A, Charset.B];
  for (int i = 0; i <= 1; i++) {
    if (canEncode(contents, sets[i], position)) {
      int cost = 1;
      Latch latch = Latch.none;
      if (charset != sets[i]) {
        cost++;
        latch = Latch.values[sets[i].index];
      }
      if (!atEnd) {
        cost += encodeCharset(contents, sets[i], position + 1);
      }
      if (cost < minCost) {
        minCost = cost;
        minLatch = latch;
      }
      cost = 1;
      if (charset == sets[(i + 1) % 2]) {
        cost++;
        latch = Latch.shift;
        if (!atEnd) {
          cost += encodeCharset(contents, charset, position + 1);
        }
        if (cost < minCost) {
          minCost = cost;
          minLatch = latch;
        }
      }
    }
  }
  if (canEncode(contents, Charset.C, position)) {
    int cost = 1;
    Latch latch = Latch.none;
    if (charset != Charset.C) {
      cost++;
      latch = Latch.C;
    }
    final advance =
        contents.codeUnitAt(position) == Code128Writer._escapeFnc1 ? 1 : 2;
    if (position + advance < contents.length) {
      cost += encodeCharset(contents, Charset.C, position + advance);
    }
    if (cost < minCost) {
      minCost = cost;
      minLatch = latch;
    }
  }
  if (minCost == MathUtils.maxValue) {
    throw ArgumentError('Bad character in input: '
        'ASCII value=${contents.codeUnitAt(position)}');
  }
  memoizedCost![charset.index][position] = minCost;
  minPath![charset.index][position] = minLatch;
  return minCost;
}