public async Task <(string?errorMessage, JsonValue?value)> TryParseAsync(TextReader stream, CancellationToken token)
{
var buffer = SmallBufferCache.Acquire(4);
var count = await stream.ReadBlockAsync(buffer, 0, 4);
if (count < 4)
{
SmallBufferCache.Release(buffer);
return("Unexpected end of input.", null);
}
JsonValue?value = null;
string? errorMessage = null;
if ((buffer[0] == 'n' || buffer[0] == 'N') &&
(buffer[1] == 'u' || buffer[1] == 'U') &&
(buffer[2] == 'l' || buffer[2] == 'L') &&
(buffer[3] == 'l' || buffer[3] == 'L'))
{
value = JsonValue.Null;
}
else
{
errorMessage = $"Value not recognized: '{new string(buffer).Trim('\0')}'.";
}
SmallBufferCache.Release(buffer);
return(errorMessage, value);
}
public string TryParse(TextReader stream, out JsonValue value)
{
value = null;
int count;
var current = (char)stream.Peek();
if (current == 't' || current == 'T')
{
count = 4;
}
else
{
count = 5;
}
var buffer = SmallBufferCache.Acquire(count);
var charsRead = stream.ReadBlock(buffer, 0, count);
if (charsRead != count)
{
SmallBufferCache.Release(buffer);
return(_unexpectedEndOfInput);
}
string errorMessage = null;
if (count == 4)
{
if ((buffer[0] == 't' || buffer[0] == 'T') &&
(buffer[1] == 'r' || buffer[1] == 'R') &&
(buffer[2] == 'u' || buffer[2] == 'U') &&
(buffer[3] == 'e' || buffer[3] == 'E'))
{
value = true;
}
else
{
errorMessage = $"Value not recognized: '{new string(buffer, 0, count)}'.";
}
}
else
{
if ((buffer[0] == 'f' || buffer[0] == 'F') &&
(buffer[1] == 'a' || buffer[1] == 'A') &&
(buffer[2] == 'l' || buffer[2] == 'L') &&
(buffer[3] == 's' || buffer[3] == 'S') &&
(buffer[4] == 'e' || buffer[4] == 'E'))
{
value = false;
}
else
{
errorMessage = $"Value not recognized: '{new string(buffer, 0, count)}'.";
}
}
SmallBufferCache.Release(buffer);
return(errorMessage);
}
public bool TryParse(TextReader stream, [NotNullWhen(true)] out JsonValue?value, [NotNullWhen(false)] out string?errorMessage)
{
value = null;
var buffer = SmallBufferCache.Acquire(4);
var charsRead = stream.ReadBlock(buffer, 0, 4);
if (charsRead != 4)
{
SmallBufferCache.Release(buffer);
errorMessage = _unexpectedEndOfInput;
return(false);
}
if ((buffer[0] == 'n' || buffer[0] == 'N') &&
(buffer[1] == 'u' || buffer[1] == 'U') &&
(buffer[2] == 'l' || buffer[2] == 'L') &&
(buffer[3] == 'l' || buffer[3] == 'L'))
{
value = JsonValue.Null;
}
else
{
errorMessage = $"Value not recognized: '{new string(buffer).Trim('\0')}'.";
return(false);
}
SmallBufferCache.Release(buffer);
errorMessage = null;
return(true);
}
public string TryParse(TextReader stream, out JsonValue value)
{
value = null;
var buffer = SmallBufferCache.Acquire(4);
var charsRead = stream.ReadBlock(buffer, 0, 4);
if (charsRead != 4)
{
SmallBufferCache.Release(buffer);
return(_unexpectedEndOfInput);
}
string errorMessage = null;
if ((buffer[0] == 'n' || buffer[0] == 'N') &&
(buffer[1] == 'u' || buffer[1] == 'U') &&
(buffer[2] == 'l' || buffer[2] == 'L') &&
(buffer[3] == 'l' || buffer[3] == 'L'))
{
value = JsonValue.Null;
}
else
{
errorMessage = $"Value not recognized: '{new string(buffer).Trim('\0')}'.";
}
SmallBufferCache.Release(buffer);
return(errorMessage);
}
public async Task <(string errorMessage, JsonValue value)> TryParseAsync(TextReader stream, CancellationToken token)
{
var scratch = SmallBufferCache.Acquire(4);
await stream.TryRead(scratch, 0, 1, token); // waste the '"'
System.Diagnostics.Debug.Assert(scratch[0] == '"');
var builder = StringBuilderCache.Acquire();
var complete = false;
bool mustInterpret = false;
char c;
while (stream.Peek() != -1)
{
c = (char)stream.Peek();
if (c == '\\')
{
mustInterpret = true;
break;
}
await stream.TryRead(scratch, 0, 1, token); // eat the character
if (c == '"')
{
complete = true;
break;
}
builder.Append(c);
}
// if there are not any escape sequences--most of a JSON's strings--just
// return the string as-is.
if (!mustInterpret)
{
SmallBufferCache.Release(scratch);
string errorMessage = null;
JsonValue value = null;
if (!complete)
{
errorMessage = "Could not find end of string value.";
}
else
{
value = StringBuilderCache.GetStringAndRelease(builder);
}
return(errorMessage, value);
}
// NOTE: TryParseInterpretedString is responsible for releasing builder
// NOTE: TryParseInterpretedString assumes stream is sitting at the '\\'
// NOTE: TryParseInterpretedString assumes scratch can hold at least 4 chars
return(await _TryParseInterpretedStringAsync(builder, stream, scratch));
}
public async Task <(string errorMessage, JsonValue value)> TryParseAsync(TextReader stream, CancellationToken token)
{
var buffer = SmallBufferCache.Acquire(5);
var count = await stream.ReadAsync(buffer, 0, 4);
if (count < 4)
{
SmallBufferCache.Release(buffer);
return(_unexpectedEndOfInput, null);
}
if (token.IsCancellationRequested)
{
SmallBufferCache.Release(buffer);
return("Parsing incomplete. The task was cancelled.", null);
}
JsonValue value = null;
string errorMessage = null;
if ((buffer[0] == 't' || buffer[0] == 'T') &&
(buffer[1] == 'r' || buffer[1] == 'R') &&
(buffer[2] == 'u' || buffer[2] == 'U') &&
(buffer[3] == 'e' || buffer[3] == 'E'))
{
value = true;
}
else if ((buffer[0] == 'f' || buffer[0] == 'F') &&
(buffer[1] == 'a' || buffer[1] == 'A') &&
(buffer[2] == 'l' || buffer[2] == 'L') &&
(buffer[3] == 's' || buffer[3] == 'S'))
{
if (await stream.TryRead(buffer, 4, 1, token))
{
if (buffer[4] == 'e' || buffer[4] == 'E')
{
value = false;
}
else
{
errorMessage = $"Value not recognized: 'fals{buffer[4]}'.";
}
}
else
{
errorMessage = "Unexpected end of input.";
}
}
else
{
errorMessage = $"Value not recognized: '{new string(buffer, 0, count)}'.";
}
SmallBufferCache.Release(buffer);
return(errorMessage, value);
}
public async Task <(string?errorMessage, JsonValue?value)> TryParseAsync(TextReader stream, CancellationToken token)
{
var buffer = StringBuilderCache.Acquire();
var scratch = SmallBufferCache.Acquire(1);
string?errorMessage = null;
while (stream.Peek() != -1)
{
if (token.IsCancellationRequested)
{
errorMessage = "Parsing incomplete. The task was cancelled.";
break;
}
var c = (char)stream.Peek();
if (char.IsWhiteSpace(c) || c == ',' || c == ']' || c == '}')
{
break;
}
await stream.TryRead(scratch, 0, 1, token); // eat the character
if (!_IsNumberChar(c))
{
errorMessage = "Expected ',', ']', or '}'.";
break;
}
buffer.Append(c);
}
SmallBufferCache.Release(scratch);
if (errorMessage != null)
{
StringBuilderCache.Release(buffer);
return(errorMessage, null);
}
var result = StringBuilderCache.GetStringAndRelease(buffer);
if (!double.TryParse(result, NumberStyles.Any, CultureInfo.InvariantCulture, out double dbl))
{
return($"Value not recognized: '{result}'", null);
}
return(null, dbl);
}
public async Task <(string errorMessage, JsonValue value)> TryParseAsync(TextReader stream, CancellationToken token)
{
System.Diagnostics.Debug.Assert(stream.Peek() == '[');
var scratch = SmallBufferCache.Acquire(1);
var array = new JsonArray();
bool complete = false;
char c;
string errorMessage = null;
while (stream.Peek() != -1)
{
if (token.IsCancellationRequested)
{
errorMessage = "Parsing incomplete. The task was cancelled.";
break;
}
await stream.TryRead(scratch, 0, 1, token); // waste the '[' or ','
(errorMessage, c) = await stream.SkipWhiteSpaceAsync(scratch);
if (errorMessage != null)
{
break;
}
// check for empty array
if (c == ']')
{
if (array.Count == 0)
{
complete = true;
await stream.TryRead(scratch, 0, 1, token); // waste the ']'
break;
}
else
{
errorMessage = "Expected value.";
break;
}
}
// get value
JsonValue item;
(errorMessage, item) = await JsonParser.TryParseAsync(stream, token);
array.Add(item);
if (errorMessage != null)
{
break;
}
(errorMessage, c) = await stream.SkipWhiteSpaceAsync(scratch);
if (errorMessage != null)
{
break;
}
// check for end or separator
if (c == ']')
{
complete = true;
await stream.TryRead(scratch, 0, 1, token); // waste the ']'
break;
}
if (c != ',')
{
errorMessage = "Expected ','.";
break;
}
}
if (!complete)
{
errorMessage = "Unterminated array (missing ']')";
}
SmallBufferCache.Release(scratch);
return(errorMessage, array);
}
public async Task <(string?errorMessage, JsonValue?value)> TryParseAsync(TextReader stream, CancellationToken token)
{
bool complete = false;
var obj = new JsonObject();
var scratch = SmallBufferCache.Acquire(1);
string?errorMessage = null;
while (stream.Peek() != -1)
{
if (token.IsCancellationRequested)
{
errorMessage = "Parsing incomplete. The task was cancelled.";
break;
}
await stream.TryRead(scratch, 0, 1, token); // waste the '{' or ','
char c;
(errorMessage, c) = await stream.SkipWhiteSpaceAsync(scratch);
if (errorMessage != null)
{
break;
}
// check for empty object
if (c == '}')
{
if (obj.Count == 0)
{
complete = true;
await stream.TryRead(scratch, 0, 1, token); // waste the '}'
break;
}
else
{
errorMessage = "Expected key.";
break;
}
}
// get key
(errorMessage, c) = await stream.SkipWhiteSpaceAsync(scratch);
if (errorMessage != null)
{
break;
}
if (c != '\"')
{
errorMessage = "Expected key.";
break;
}
JsonValue?item;
(errorMessage, item) = await JsonParser.TryParseAsync(stream, token);
if (errorMessage != null)
{
break;
}
var key = item !.String;
// check for colon
(errorMessage, c) = await stream.SkipWhiteSpaceAsync(scratch);
if (errorMessage != null)
{
break;
}
if (c != ':')
{
obj.Add(key, null !);
errorMessage = "Expected ':'.";
break;
}
await stream.TryRead(scratch, 0, 1, token); // waste the ':'
// get value (whitespace is removed in Parse)
(errorMessage, item) = await JsonParser.TryParseAsync(stream, token);
obj.Add(key, item !);
if (errorMessage != null)
{
break;
}
(errorMessage, c) = await stream.SkipWhiteSpaceAsync(scratch);
if (errorMessage != null)
{
break;
}
// check for end or separator
if (c == '}')
{
complete = true;
await stream.TryRead(scratch, 0, 1, token); // waste the '}'
break;
}
if (c != ',')
{
errorMessage = "Expected ','.";
break;
}
}
if (!complete && errorMessage == null)
{
errorMessage = "Unterminated object (missing '}').";
}
SmallBufferCache.Release(scratch);
return(errorMessage, obj);
}
private static async Task <(string errorMessage, JsonValue value)> _TryParseInterpretedStringAsync(StringBuilder builder, TextReader stream, char[] scratch)
{
// NOTE: `builder` contains the portion of the string found in `stream`, up to the first
// (possible) escape sequence.
System.Diagnostics.Debug.Assert('\\' == (char)stream.Peek());
System.Diagnostics.Debug.Assert(scratch.Length >= 4);
bool complete = false;
int?previousHex = null;
char c;
while (stream.Peek() != -1)
{
await stream.TryRead(scratch, 0, 1); // eat this character
c = scratch[0];
if (c == '\\')
{
if (stream.Peek() == -1)
{
StringBuilderCache.Release(builder);
SmallBufferCache.Release(scratch);
return("Could not find end of string value.", null);
}
// escape sequence
var lookAhead = (char)stream.Peek();
if (!_MustInterpretComplex(lookAhead))
{
await stream.TryRead(scratch, 0, 1); // eat the simple escape
c = _InterpretSimpleEscapeSequence(lookAhead);
}
else
{
// NOTE: Currently we only handle 'u' here
if (lookAhead != 'u')
{
StringBuilderCache.Release(builder);
SmallBufferCache.Release(scratch);
return($"Invalid escape sequence: '\\{lookAhead}'.", null);
}
await stream.TryRead(scratch, 0, 1); // eat the 'u'
var charsRead = await stream.ReadAsync(scratch, 0, 4);
if (charsRead < 4)
{
StringBuilderCache.Release(builder);
SmallBufferCache.Release(scratch);
return("Could not find end of string value.", null);
}
var hexString = new string(scratch, 0, 4);
var currentHex = int.Parse(hexString, NumberStyles.HexNumber);
if (previousHex != null)
{
// Our last character was \u, so combine and emit the UTF32 codepoint
currentHex = StringExtensions.CalculateUtf32(previousHex.Value, currentHex);
if (currentHex.IsValidUtf32CodePoint())
{
builder.Append(char.ConvertFromUtf32(currentHex));
}
else
{
return("Invalid UTF-32 code point.", null);
}
previousHex = null;
}
else
{
previousHex = currentHex;
}
continue;
}
}
else if (c == '"')
{
complete = true;
break;
}
// Check if last character was \u, and if so emit it as-is, because
// this character is not a continuation of a UTF-32 escape sequence
if (previousHex != null)
{
builder.Append(char.ConvertFromUtf32(previousHex.Value));
previousHex = null;
}
// non-escape sequence
builder.Append(c);
}
SmallBufferCache.Release(scratch);
// if we had a hanging UTF32 escape sequence, apply it now
if (previousHex != null)
{
builder.Append(char.ConvertFromUtf32(previousHex.Value));
}
if (!complete)
{
StringBuilderCache.Release(builder);
return("Could not find end of string value.", null);
}
JsonValue value = StringBuilderCache.GetStringAndRelease(builder);
return(null, value);
}
private static string _TryParseInterpretedString(StringBuilder builder, TextReader stream, out JsonValue value)
{
// NOTE: `builder` contains the portion of the string found in `stream`, up to the first
// (possible) escape sequence.
System.Diagnostics.Debug.Assert('\\' == (char)stream.Peek());
value = null;
string errorMessage = null;
bool complete = false;
int?previousHex = null;
char c;
while (stream.Peek() != -1)
{
c = (char)stream.Read(); // eat this character
if (c == '\\')
{
if (stream.Peek() == -1)
{
StringBuilderCache.Release(builder);
return("Could not find end of string value.");
}
// escape sequence
var lookAhead = (char)stream.Peek();
if (!_MustInterpretComplex(lookAhead))
{
stream.Read(); // eat the simple escape
c = _InterpretSimpleEscapeSequence(lookAhead);
}
else
{
// NOTE: Currently we only handle 'u' here
if (lookAhead != 'u')
{
StringBuilderCache.Release(builder);
return($"Invalid escape sequence: '\\{lookAhead}'.");
}
var buffer = SmallBufferCache.Acquire(4);
stream.Read(); // eat the 'u'
if (4 != stream.Read(buffer, 0, 4))
{
StringBuilderCache.Release(builder);
return("Could not find end of string value.");
}
var hexString = new string(buffer, 0, 4);
if (!_IsValidHex(hexString, 0, 4) ||
!int.TryParse(hexString, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var currentHex))
{
StringBuilderCache.Release(builder);
return($"Invalid escape sequence: '\\{lookAhead}{hexString}'.");
}
if (previousHex != null)
{
// Our last character was \u, so combine and emit the UTF32 codepoint
currentHex = StringExtensions.CalculateUtf32(previousHex.Value, currentHex);
if (currentHex.IsValidUtf32CodePoint())
{
builder.Append(char.ConvertFromUtf32(currentHex));
}
else
{
value = null;
return("Invalid UTF-32 code point.");
}
previousHex = null;
}
else
{
previousHex = currentHex;
}
SmallBufferCache.Release(buffer);
continue;
}
}
else if (c == '"')
{
complete = true;
break;
}
// Check if last character was \u, and if so emit it as-is, because
// this character is not a continuation of a UTF-32 escape sequence
if (previousHex != null)
{
builder.Append(char.ConvertFromUtf32(previousHex.Value));
previousHex = null;
}
// non-escape sequence
builder.Append(c);
}
// if we had a hanging UTF32 escape sequence, apply it now
if (previousHex != null)
{
builder.Append(char.ConvertFromUtf32(previousHex.Value));
}
if (!complete)
{
value = null;
StringBuilderCache.Release(builder);
return("Could not find end of string value.");
}
value = StringBuilderCache.GetStringAndRelease(builder);
return(errorMessage);
}