/// <summary>
/// Update line number dictionary after deleting lines.
/// </summary>
private void UpdateLineMap(CodePosition position, int length)
{
// subtract length of line we replaced
length -= (int)(position.AfterPosition - position.StartPosition);
var address = Position + 1 + position.AfterPosition;
Bytecode.Seek(position.AfterPosition + length + 1, SeekOrigin.Begin); // pass \x00
while (true)
{
var nextAddressStr = Bytecode.Read(2);
if (nextAddressStr.Length < 2 || nextAddressStr == "\0\0")
{
break;
}
var nextAddress = nextAddressStr.ToUnsignedInteger();
Bytecode.Seek(-2, SeekOrigin.Current);
Bytecode.Write((nextAddress + length).ToBasicUnsignedInteger());
Bytecode.Seek(nextAddress - address - 2, SeekOrigin.Current);
address = nextAddress;
}
// update line number dict
foreach (var line in position.Deleteable)
{
_lineNumberMap.Remove(line);
}
foreach (var line in position.Beyond)
{
_lineNumberMap[line] += length;
}
}
/// <summary>
/// Preparse to build line number dictionary.
/// </summary>
private void RebuildLineNumbers()
{
_lineNumberMap.Clear();
var offsets = new List <long>();
Bytecode.Seek(0, SeekOrigin.Begin);
var scanPosition = 0L;
while (true)
{
Bytecode.ReadByte(); // pass \x00
var scanline = Bytecode.ReadLineNumber();
if (scanline == -1)
{
// if parse_line_number returns -1, it leaves the stream pointer here: 00 _00_ 00 1A
break;
}
_lineNumberMap[scanline] = scanPosition;
Bytecode.SkipUntilLineEnd();
scanPosition = Bytecode.Position;
offsets.Add(scanPosition);
}
_lineNumberMap[BasicLastLineNumber] = scanPosition;
// rebuild offsets
Bytecode.Seek(0, SeekOrigin.Begin);
var lastPosition = 0L;
foreach (var postion in offsets)
{
Bytecode.ReadByte();
Bytecode.Write(((int)(Position + 1 + postion)).ToBasicUnsignedInteger());
Bytecode.Read((int)(postion - lastPosition - 3));
lastPosition = postion;
}
// ensure program is properly sealed - last offset must be 00 00. keep, but ignore, anything after.
Bytecode.Write("\0\0\0");
}