private static async ValueTask <JToken> PerformReadJSONTTokenAsync(
StreamReaderWithResizableBuffer stream,
CharacterReader reader
)
{
stream.EraseReadBytesFromBuffer();
// Read first non-whitespace character
Char charRead;
Int32 prevIdx;
do
{
prevIdx = stream.ReadBytesCount;
charRead = await reader.ReadNextCharacterAsync(stream);
} while (Char.IsWhiteSpace(charRead));
// We know what kind of JToken we will have based on a single character
JToken retVal;
Boolean encounteredContainerEnd;
Int32 startIdx = stream.ReadBytesCount;
Int32 curIdx;
var encoding = reader.Encoding;
switch (charRead)
{
case ARRAY_END:
case OBJ_END:
// This happens only when reading empty array/object, and this is called recursively.
retVal = null;
break;
case ARRAY_START:
var array = new JArray();
encounteredContainerEnd = false;
// Reuse 'retVal' variable since we really need it only at the end of this case block.
while (!encounteredContainerEnd && (retVal = await PerformReadJSONTTokenAsync(stream, reader)) != null)
{
array.Add(retVal);
// Read next non-whitespace character - it will be either array value delimiter (',') or array end (']')
charRead = await reader.ReadNextCharacterAsync(stream, c => !Char.IsWhiteSpace(c));
encounteredContainerEnd = charRead == ARRAY_END;
}
retVal = array;
break;
case OBJ_START:
var obj = new JObject();
encounteredContainerEnd = false;
String keyStr;
// Reuse 'retVal' variable since we really need it only at the end of this case block.
while (!encounteredContainerEnd && (keyStr = await ReadJSONStringAsync(reader, stream, false)) != null)
{
// First JToken should be string being the key
// Skip whitespace and ':'
charRead = await reader.ReadNextCharacterAsync(stream, c => !Char.IsWhiteSpace( c ) && c != OBJ_KEY_VALUE_DELIM);
// Unread previously read character
stream.UnreadBytes(reader.GetByteCount(charRead));
// Read another JToken, this one will be our value
retVal = await PerformReadJSONTTokenAsync(stream, reader);
obj.Add(keyStr, retVal);
// Read next non-whitespace character - it will be either object value delimiter (','), or object end ('}')
charRead = await reader.ReadNextCharacterAsync(stream, c => !Char.IsWhiteSpace(c));
encounteredContainerEnd = charRead == OBJ_END;
}
retVal = obj;
break;
case STR_START:
retVal = new JValue(await ReadJSONStringAsync(reader, stream, true));
break;
case 't':
// Boolean true
// read 'r'
Validate(await reader.ReadNextCharacterAsync(stream), 'r');
// read 'u'
Validate(await reader.ReadNextCharacterAsync(stream), 'u');
// read 'e'
Validate(await reader.ReadNextCharacterAsync(stream), 'e');
retVal = new JValue(true);
break;
case 'f':
//Boolean false
// read 'a'
Validate(await reader.ReadNextCharacterAsync(stream), 'a');
// read 'l'
Validate(await reader.ReadNextCharacterAsync(stream), 'l');
// read 's'
Validate(await reader.ReadNextCharacterAsync(stream), 's');
// read 'e'
Validate(await reader.ReadNextCharacterAsync(stream), 'e');
retVal = new JValue(false);
break;
case 'n':
// null
// read 'u'
Validate(await reader.ReadNextCharacterAsync(stream), 'u');
// read 'l'
Validate(await reader.ReadNextCharacterAsync(stream), 'l');
// read 'l'
Validate(await reader.ReadNextCharacterAsync(stream), 'l');
retVal = JValue.CreateNull();
break;
default:
// The only possibility is number - or malformed JSON string
// Read until first non-number-char
var lastReadChar = await reader.TryReadNextCharacterAsync(stream, c =>
{
// TODO this isn't strictly according to spec... But will do for now.
switch (c)
{
case '-': // Plus is ok after E/e, Minus is ok at beginning of number, and after E/e
case '+':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case (Char)NUMBER_DECIMAL:
case (Char)NUMBER_EXP_LOW:
case (Char)NUMBER_EXP_UPPER:
return(false);
default:
return(true);
}
});
// Unread previously read character, unless we arrived at the end.
if (lastReadChar.HasValue)
{
stream.UnreadBytes(reader.GetByteCount(lastReadChar.Value));
}
// If we have '.' or 'e' or 'E' then it is non-integer
curIdx = prevIdx;
var endIdx = stream.ReadBytesCount;
Byte curASCIIByte;
while (
curIdx < endIdx &&
(curASCIIByte = encoding.ReadASCIIByte(stream.Buffer, ref curIdx)) != NUMBER_DECIMAL &&
curASCIIByte != NUMBER_EXP_LOW &&
curASCIIByte != NUMBER_EXP_UPPER
)
{
;
}
var isInteger = curIdx >= endIdx;
var byteCount = endIdx - prevIdx;
// TODO maybe use Decimal always for non-integers? PgSQL seems to use NUMERIC for non-integers.
retVal = isInteger ?
new JValue(encoding.ParseInt64Textual(stream.Buffer, ref prevIdx, (byteCount / encoding.BytesPerASCIICharacter, true))) :
new JValue(Double.Parse(encoding.Encoding.GetString(stream.Buffer, prevIdx, byteCount), System.Globalization.CultureInfo.InvariantCulture.NumberFormat));
break;
}
return(retVal);
}
