public async Task StartPositionPointsToNonExistingCharachter_Backward()
{
StreamTextAccess buf = new StreamTextAccess(
S().Add('a', 10).ToStream(Encoding.UTF8),
Encoding.UTF8
);
await buf.BeginReading(11, TextAccessDirection.Backward);
Assert.AreEqual(S().Add('a', 10).ToString(), buf.BufferString);
int idx = buf.PositionToCharIndex(new TextStreamPosition(11));
}
public void StreamPositionToCharIndexTest_IdxFromPrevBlock()
{
StreamTextAccess buf = new StreamTextAccess(
S().Add('a', blockSz * 3).ToStream(Encoding.UTF8),
Encoding.UTF8
);
buf.BeginReading(0, TextAccessDirection.Forward);
buf.Advance(100);
Assert.Throws <ArgumentOutOfRangeException>(() => buf.PositionToCharIndex(new TextStreamPosition(50)));
}
public async Task StartPositionPointsToNonExistingCharachter_Backward_SecondBlock()
{
StreamTextAccess buf = new StreamTextAccess(
S().Add('a', blockSz).Add('b', blockSz).ToStream(Encoding.UTF8),
Encoding.UTF8
);
await buf.BeginReading(blockSz *2, TextAccessDirection.Backward);
Assert.AreEqual("", buf.BufferString);
int idx = buf.PositionToCharIndex(new TextStreamPosition(blockSz * 2));
Assert.AreEqual(0, idx);
}
public async Task StreamPositionToCharIndexTest_InvalidBigTextStreamPositionIsMappedToPastTheEndCharIndex()
{
StreamTextAccess buf = new StreamTextAccess(
S().Add('a', blockSz * 3).ToStream(Encoding.Unicode),
Encoding.Unicode
);
await buf.BeginReading(0, TextAccessDirection.Forward);
// valid Unicode text stream positions are from 0 to blockSz/2. below is invalid position.
var invalidTextStreamPosition = new TextStreamPosition(blockSz - 10);
Assert.AreEqual(blockSz / 2, buf.PositionToCharIndex(invalidTextStreamPosition));
}
static void TestCharPosMapping(StreamTextAccess sut, TextStreamPosition pos, int charIdx)
{
Assert.AreEqual(pos.Value, sut.CharIndexToPosition(charIdx).Value);
Assert.AreEqual(charIdx, sut.PositionToCharIndex(pos));
}