private ReadWithCommentResultType ProcessBuffer(int bufferLen, out int unprocessedCharacters)
{
var buffSpan = Buffer.Buffer.Span;
ReaderStateMachine.AdvanceResult?inBatchableResult = null;
var consistentResultSince = -1;
for (var i = 0; i < bufferLen; i++)
{
var c = buffSpan[i];
var res = StateMachine.Advance(c, false);
var advanceIBy = 0;
// we only see this _if_ there are multiple characters in the separator, which is rare
if (res == ReaderStateMachine.AdvanceResult.LookAhead_MultiCharacterSeparator)
{
var valSepLen = Configuration.ValueSeparatorMemory.Length;
// do we have enough in the buffer to look ahead?
var canCheckForSeparator = bufferLen - i >= valSepLen;
if (canCheckForSeparator)
{
var shouldMatch = buffSpan.Slice(i, valSepLen);
var eq = Utils.AreEqual(shouldMatch, Configuration.ValueSeparatorMemory.Span);
if (eq)
{
// treat it like a value separator
res = StateMachine.AdvanceValueSeparator();
// advance further to the last character in the separator
advanceIBy = valSepLen - 1;
}
else
{
res = StateMachine.Advance(c, true);
}
}
else
{
// we don't have enough in the buffer... so deal with any running batches and ask for more
if (inBatchableResult != null)
{
switch (inBatchableResult.Value)
{
case ReaderStateMachine.AdvanceResult.Skip_Character:
// there's no distinction between skipping several characters and skipping one
// so this doesn't need the length
Partial.SkipCharacter();
break;
case ReaderStateMachine.AdvanceResult.Append_Character:
var length = i - consistentResultSince;
Partial.AppendCharacters(buffSpan, consistentResultSince, length);
break;
default:
unprocessedCharacters = default;
Throw.ImpossibleException($"Unexpected {nameof(ReaderStateMachine.AdvanceResult)}: {inBatchableResult.Value}", Configuration.Options);
return(default);
}
}
// we need to keep everything
unprocessedCharacters = bufferLen - i;
return(ReadWithCommentResultType.NoValue);
}
}
var handledUpTo = i;
// we _might_ need to modify i a bit if we just processed the fallout from a multi-char value separator
i += advanceIBy;
// try and batch skips and appends
// to save time on copying AND on
// basically pointless method calls
if (inBatchableResult != null)
{
if (res == inBatchableResult)
{
continue;
}
else
{
switch (inBatchableResult.Value)
{
case ReaderStateMachine.AdvanceResult.Skip_Character:
// there's no distinction between skipping several characters and skipping one
// so this doesn't need the length
Partial.SkipCharacter();
break;
case ReaderStateMachine.AdvanceResult.Append_Character:
var length = handledUpTo - consistentResultSince;
Partial.AppendCharacters(buffSpan, consistentResultSince, length);
break;
default:
unprocessedCharacters = default;
Throw.ImpossibleException($"Unexpected {nameof(ReaderStateMachine.AdvanceResult)}: {inBatchableResult.Value}", Configuration.Options);
return(default);
}
inBatchableResult = null;
consistentResultSince = -1;
// fall through into the switch to handle the current character
}
}
// inBatchableResult is always null here
// because if it's NOT null we either continue (if res == inBatchableResult),
// thereby not hitting this point, or set it to null (if res != inBatchableResult)
// this means we don't need to handle the inBatchableResult != null cases in
// the following switch
switch (res)
{
case ReaderStateMachine.AdvanceResult.Skip_Character:
inBatchableResult = ReaderStateMachine.AdvanceResult.Skip_Character;
consistentResultSince = i;
continue;
case ReaderStateMachine.AdvanceResult.Append_Character:
inBatchableResult = ReaderStateMachine.AdvanceResult.Append_Character;
consistentResultSince = i;
continue;
case ReaderStateMachine.AdvanceResult.Append_CarriageReturnAndCurrentCharacter:
Partial.AppendCarriageReturn(buffSpan);
Partial.AppendCharacters(buffSpan, i, 1);
break;
case ReaderStateMachine.AdvanceResult.Append_ValueSeparator:
Partial.AppendCharactersFromDifferentBuffer(buffSpan, Configuration.ValueSeparatorMemory.Span);
break;
case ReaderStateMachine.AdvanceResult.Append_CarriageReturnAndValueSeparator:
Partial.AppendCarriageReturn(buffSpan);
Partial.AppendCharactersFromDifferentBuffer(buffSpan, Configuration.ValueSeparatorMemory.Span);
break;
// cannot reach ReaderStateMachine.AdvanceResult.Append_CarriageReturnAndEndComment, because that only happens
// when the data ENDs
case ReaderStateMachine.AdvanceResult.Finished_Unescaped_Value:
PushPendingCharactersToValue(false);
break;
case ReaderStateMachine.AdvanceResult.Finished_Escaped_Value:
PushPendingCharactersToValue(true);
break;
case ReaderStateMachine.AdvanceResult.Finished_LastValueUnescaped_Record:
if (Partial.PendingCharsCount > 0)
{
PushPendingCharactersToValue(false);
}
unprocessedCharacters = bufferLen - i - 1;
return(ReadWithCommentResultType.HasValue);
case ReaderStateMachine.AdvanceResult.Finished_LastValueEscaped_Record:
if (Partial.PendingCharsCount > 0)
{
PushPendingCharactersToValue(true);
}
unprocessedCharacters = bufferLen - i - 1;
return(ReadWithCommentResultType.HasValue);
case ReaderStateMachine.AdvanceResult.Finished_Comment:
unprocessedCharacters = bufferLen - i - 1;
return(ReadWithCommentResultType.HasComment);
default:
HandleUncommonAdvanceResults(res, c);
break;
}
}
// handle any batch that was still pending
if (inBatchableResult != null)
{
switch (inBatchableResult.Value)
{
case ReaderStateMachine.AdvanceResult.Skip_Character:
// there's no distinction between skipping several characters and skipping one
// so this doesn't need the length
Partial.SkipCharacter();
break;
case ReaderStateMachine.AdvanceResult.Append_Character:
// we read all the up to the end, so length needs to include the last character
var length = bufferLen - consistentResultSince;
Partial.AppendCharacters(buffSpan, consistentResultSince, length);
break;
default:
unprocessedCharacters = default;
Throw.ImpossibleException($"Unexpected {nameof(ReaderStateMachine.AdvanceResult)}: {inBatchableResult.Value}", Configuration.Options);
return(default);
}
}
unprocessedCharacters = 0;
return(ReadWithCommentResultType.NoValue);
}
private readonly unsafe bool TryLookupAdaptiveRadixTrie(string key, out int value)
{
AssertNotDisposedInternal(this);
fixed(char *keyPtrConst = key)
{
// as the search continues, keyPtr will have the remaining
// parts of the key
char *keyPtr = keyPtrConst;
int keyLen = key.Length;
var trieSpan = Memory.Span;
fixed(char *triePtrConst = trieSpan)
{
// likewise, triePtr will always be pointing at the _start_
// of the prefix group
char *triePtr = triePtrConst;
// starting point for processing a single prefix group
// as we descend the trie we'll come back here
processPrefixGroup:
// this can read 1 past the end of keyPtr (if keyPtr == "")
// but this is fine because key is always a string AND
// .NET strings are always null terminated (with a zero
// char not just a zero byte)
var firstKeyChar = *keyPtr;
var numPrefixes = FromPrefixCount(*triePtr);
// advance past the prefix count
triePtr++;
for (var i = 0; i < numPrefixes; i++)
{
var prefixLen = FromPrefixLength(*triePtr);
// move past the len, we're either pointing at the first
// letter of the prefix OR the value/offset slot (if
// prefixLen == 0)
triePtr++;
// the key being empty will only ever happen when i == 0
// and indicates that we need to either accept the current
// value (if prefixLen == 0, that is the prefix is "")
// or bail
if (keyLen == 0)
{
if (prefixLen == 0)
{
// offset is already point at value, since prefixLen == 0
value = FromValue(*triePtr);
return(true);
}
value = -1;
return(false);
}
// terminal empty node, and keySpan is not empty
if (prefixLen == 0)
{
// did not find key, skip the value and continue;
triePtr++;
continue;
}
var firstPrefixChar = *triePtr;
// we've gone far enough that we're not going to find a prefix
// that matches key (since this prefix occurs after key
// lexicographically), bail
if (firstKeyChar < firstPrefixChar)
{
value = -1;
return(false);
}
else if (firstKeyChar > firstPrefixChar)
{
// key may be found after the current prefix (which occurs
// before key lexiocographically), skip it
triePtr += prefixLen;
triePtr++; // skip the offset or value slot
continue;
}
else
{
// key needs to match prefix, at least up to prefix length
if (keyLen < prefixLen)
{
// key overlaps prefix, but the actual key value isn't in the trie, bail
//
// if key were in the trie, then the prefix would either match or
// overlap the key (that is, there'd be 0 or more key chars
// to process).
// taking this branch means that some value that is key + "<some other chars>"
// IS in the trie.
value = -1;
return(false);
}
// we've already checked the first char, but need to check the rest of the prefix
if (!Utils.AreEqual(prefixLen - 1, keyPtr + 1, triePtr + 1))
{
// key starts with the same char as prefix, but isn't actually equal to the prefix
// which can only happen if key doesn't appear in the trie (if it did, the prefix
// would be split after the last common character).
value = -1;
return(false);
}
// we're now pointing at the value / offset slot
triePtr += prefixLen;
// we've handled prefixLen number of chars in the key now
var remainingKeyPtr = keyPtr + prefixLen;
var remainingKeyLen = keyLen - prefixLen;
// figure out if the current prefix is the terminal
// part of a key, or if there's more work to be done.
//
// if there is more work to do, then we'll find an offset
// to the next prefix group to process.
var valueOrOffset = *triePtr;
var isOffset = IsOffset(valueOrOffset);
if (isOffset)
{
// jump to the group pointed to by offset
var toNextGroupOffset = FromOffset(valueOrOffset);
var nextGroupPtr = triePtr + toNextGroupOffset;
// trim the parts of the key we've dealt with off
keyPtr = remainingKeyPtr;
keyLen = remainingKeyLen;
// move the whole triePtr forward to the next group
triePtr = nextGroupPtr;
// start over at the new prefix group
goto processPrefixGroup;
}
else
{
// if we've found a value in the trie, we can take it
// only if key is fully consumed
// otherwise, we know the key is not in the trie
if (remainingKeyLen == 0)
{
value = FromValue(valueOrOffset);
return(true);
}
value = -1;
return(false);
}
}
}
}
}
// enumerated all the prefixes in this group, and key is still after them
// lexicographically so we're never going to find it
value = -1;
return(false);
}
