/// <summary>
/// Store the given tokenized line buffer.
/// </summary>
private void StoreLine(Stream stream)
{
if (_protected)
{
throw new ReplRuntimeException(ReplExceptionCode.IllegalFunctionCall);
}
stream.Seek(1, SeekOrigin.Begin);
var scanLine = stream.ReadLineNumber();
// check if stream is an empty line after the line number
var nextNonWhitespace = stream.SkipWhitespace();
var empty = nextNonWhitespace == -1 || nextNonWhitespace == '\0';
var codePosition = FindCodePosition(scanLine, scanLine);
if (empty && codePosition.Deleteable.Length == 0)
{
throw new ReplRuntimeException(ReplExceptionCode.UndefinedLineNumber);
}
// read the remainder of the program into a buffer to be pasted back after the write
Bytecode.Seek(codePosition.AfterPosition, SeekOrigin.Begin);
var rest = Bytecode.ReadToEnd();
Bytecode.Seek(codePosition.StartPosition, SeekOrigin.Begin);
var length = 0;
// write the line buffer to the program buffer
if (!empty)
{
// set offsets
length = stream.ReadToEnd().Length;
stream.Seek(0, SeekOrigin.Begin); // pass \x00\xC0\xDE
Bytecode.WriteByte(0);
Bytecode.Write(((int)(Position + 1 + codePosition.StartPosition + length)).ToBasicUnsignedInteger());
Bytecode.WriteByte((byte)stream.ReadByte());
}
// write back the remainder of the program
Truncate(rest);
// update all next offsets by shifting them by the length of the added line
UpdateLineMap(codePosition, length);
if (!empty)
{
_lineNumberMap[scanLine] = codePosition.StartPosition;
}
_lastStored = scanLine;
}
/// <summary>
/// Deletes the stored program within specified range
/// </summary>
/// <param name="startLine">Starting line</param>
/// <param name="lastLine">Ending line</param>
public void Delete(int startLine, int lastLine)
{
var codePosition = FindCodePosition(startLine, lastLine);
if (codePosition.Deleteable.Length == 0) // no lines selected
{
throw new ReplRuntimeException(ReplExceptionCode.IllegalFunctionCall);
}
Bytecode.Seek(codePosition.AfterPosition, SeekOrigin.Begin);
var rest = Bytecode.ReadToEnd();
Bytecode.Seek(codePosition.StartPosition, SeekOrigin.Begin);
Truncate(rest);
UpdateLineMap(codePosition, 0);
}