public static JsonToken GetNextToken(
BsonJsonBuffer buffer
)
{
// skip leading whitespace
var c = buffer.Read();
while (c != -1 && char.IsWhiteSpace((char) c)) {
c = buffer.Read();
}
if (c == -1) {
return new JsonToken(JsonTokenType.EndOfFile, "<eof>");
}
// leading character determines token type
switch (c) {
case '{': return new JsonToken(JsonTokenType.BeginObject, "{");
case '}': return new JsonToken(JsonTokenType.EndObject, "}");
case '[': return new JsonToken(JsonTokenType.BeginArray, "[");
case ']': return new JsonToken(JsonTokenType.EndArray, "]");
case ':': return new JsonToken(JsonTokenType.Colon, ":");
case ',': return new JsonToken(JsonTokenType.Comma, ",");
case '"': return GetStringToken(buffer);
case '/': return GetRegularExpressionToken(buffer);
default:
if (c == '-' || char.IsDigit((char) c)) {
return GetNumberToken(buffer, c);
} else if (c == '$' || char.IsLetter((char) c)) {
return GetUnquotedStringToken(buffer);
} else {
buffer.UnRead(c);
throw new FileFormatException(FormatMessage("Invalid JSON input", buffer, buffer.Position));
}
}
}
private static JsonToken GetRegularExpressionToken(
BsonJsonBuffer buffer
)
{
// opening slash has already been read
var start = buffer.Position - 1;
var state = RegularExpressionState.InPattern;
while (true) {
var c = buffer.Read();
switch (state) {
case RegularExpressionState.InPattern:
switch (c) {
case '/': state = RegularExpressionState.InOptions; break;
case '\\': state = RegularExpressionState.InEscapeSequence; break;
default: state = RegularExpressionState.InPattern; break;
}
break;
case RegularExpressionState.InEscapeSequence:
state = RegularExpressionState.InPattern;
break;
case RegularExpressionState.InOptions:
switch (c) {
case 'g':
case 'i':
case 'm':
state = RegularExpressionState.InOptions;
break;
case ',':
case '}':
case ']':
case -1:
state = RegularExpressionState.Done;
break;
default:
if (char.IsWhiteSpace((char) c)) {
state = RegularExpressionState.Done;
} else {
state = RegularExpressionState.Invalid;
}
break;
}
break;
}
switch (state) {
case RegularExpressionState.Done:
buffer.UnRead(c);
var count = buffer.Position - start;
return new JsonToken(JsonTokenType.RegularExpression, buffer.Substring(start, count));
case RegularExpressionState.Invalid:
throw new FileFormatException(FormatMessage("Invalid JSON regular expression", buffer, start));
}
}
}
private static JsonToken GetUnquotedStringToken(
BsonJsonBuffer buffer
)
{
// opening letter or $ has already been read
var start = buffer.Position - 1;
while (true) {
var c = buffer.Read();
switch (c) {
case ':':
case ',':
case '}':
case ']':
case -1:
buffer.UnRead(c);
return new JsonToken(JsonTokenType.UnquotedString, buffer.Substring(start, buffer.Position - start));
default:
if (c == '$' || char.IsLetterOrDigit((char) c)) {
// continue
} else if (char.IsWhiteSpace((char) c)) {
buffer.UnRead(c);
return new JsonToken(JsonTokenType.UnquotedString, buffer.Substring(start, buffer.Position - start));
} else {
throw new FileFormatException(FormatMessage("Invalid JSON unquoted string", buffer, start));
}
break;
}
}
}
private static JsonToken GetNumberToken(
BsonJsonBuffer buffer,
int c // first character
)
{
// leading digit or '-' has already been read
var start = buffer.Position - 1;
NumberState state;
switch (c) {
case '-': state = NumberState.SawLeadingMinus; break;
case '0': state = NumberState.SawLeadingZero; break;
default: state = NumberState.SawIntegerDigits; break;
}
var type = JsonTokenType.Integer; // assume integer until proved otherwise
while (true) {
c = buffer.Read();
switch (state) {
case NumberState.SawLeadingMinus:
switch (c) {
case '0':
state = NumberState.SawLeadingZero;
break;
default:
if (char.IsDigit((char) c)) {
state = NumberState.SawIntegerDigits;
} else {
state = NumberState.Invalid;
}
break;
}
break;
case NumberState.SawLeadingZero:
switch (c) {
case '.':
state = NumberState.SawDecimalPoint;
break;
case 'e':
case 'E':
state = NumberState.SawExponentLetter;
break;
case ',':
case '}':
case ']':
case -1:
state = NumberState.Done;
break;
default:
if (char.IsWhiteSpace((char) c)) {
state = NumberState.Done;
} else {
state = NumberState.Invalid;
}
break;
}
break;
case NumberState.SawIntegerDigits:
switch (c) {
case '.':
state = NumberState.SawDecimalPoint;
break;
case 'e':
case 'E':
state = NumberState.SawExponentLetter;
break;
case ',':
case '}':
case ']':
case -1:
state = NumberState.Done;
break;
default:
if (char.IsDigit((char) c)) {
state = NumberState.SawIntegerDigits;
} else if (char.IsWhiteSpace((char) c)) {
state = NumberState.Done;
} else {
state = NumberState.Invalid;
}
break;
}
break;
case NumberState.SawDecimalPoint:
type = JsonTokenType.FloatingPoint;
if (char.IsDigit((char) c)) {
state = NumberState.SawFractionDigits;
} else {
state = NumberState.Invalid;
}
break;
case NumberState.SawFractionDigits:
switch (c) {
case 'e':
case 'E':
state = NumberState.SawExponentLetter;
break;
case ',':
case '}':
case ']':
case -1:
state = NumberState.Done;
break;
default:
if (char.IsDigit((char) c)) {
state = NumberState.SawFractionDigits;
} else if (char.IsWhiteSpace((char) c)) {
state = NumberState.Done;
} else {
state = NumberState.Invalid;
}
break;
}
break;
case NumberState.SawExponentLetter:
type = JsonTokenType.FloatingPoint;
switch (c) {
case '+':
case '-':
state = NumberState.SawExponentSign;
break;
default:
if (char.IsDigit((char) c)) {
state = NumberState.SawExponentDigits;
} else {
state = NumberState.Invalid;
}
break;
}
break;
case NumberState.SawExponentSign:
if (char.IsDigit((char) c)) {
state = NumberState.SawExponentDigits;
} else {
state = NumberState.Invalid;
}
break;
case NumberState.SawExponentDigits:
switch (c) {
case ',':
case '}':
case ']':
case -1:
state = NumberState.Done;
break;
default:
if (char.IsDigit((char) c)) {
state = NumberState.SawExponentDigits;
} else if (char.IsWhiteSpace((char) c)) {
state = NumberState.Done;
} else {
state = NumberState.Invalid;
}
break;
}
break;
}
switch (state) {
case NumberState.Done:
buffer.UnRead(c);
return new JsonToken(type, buffer.Substring(start, buffer.Position - start));
case NumberState.Invalid:
throw new FileFormatException(FormatMessage("Invalid JSON number", buffer, start));
}
}
}