public JsonToken ReadToken()
{
if (BackToken.Count > 0)
return BackToken.Pop();
TokenType tokenType = TokenType.Unidentified;
string token = string.Empty;
bool endToken = false;
while(!endToken)
{
int read = _textReader.Read();
if (read == -1)
break;
switch ((char)read)
{
case '\t':
case '\r':
case '\n':
case ' ':
if (token != string.Empty)
endToken = true;
break;
case ',':
case ':':
case '{':
case '}':
case '[':
case ']':
var nextToken = new JsonToken(TokenType.SpecialChar, ((char)read).ToString());
if (token != string.Empty)
{
endToken = true;
BackToken.Push(nextToken);
break;
}
return nextToken;
case '\"':
if (token != string.Empty)
throw new LexicalException("Unexpected char '\"' while reading \"" + token + "\"");
while(true)
{
int tokenChar = _textReader.Read();
if (tokenChar == -1)
break;
if (tokenChar != '\"')
{
if (tokenChar != '\\')
token += (char)tokenChar;
else
{
tokenChar = _textReader.Read();
if (tokenChar == -1)
break;
switch (tokenChar)
{
case 'b': token += "\b"; break;
case 'f': token += "\f"; break;
case 'n': token += "\n"; break;
case 'r': token += "\r"; break;
case 't': token += "\t"; break;
case 'v': token += "\v"; break;
case '\"': token += "\""; break;
case '\\': token += "\\"; break;
case '/': token += "/"; break;
case 'u':
var code = new StringBuilder();
for(int i = 0; i < 4; i++) {
tokenChar = _textReader.Read();
if (tokenChar == -1)
break;
code.Append((char)tokenChar);
}
if(code.Length < 4)
break;
token += (char)int.Parse(code.ToString(), NumberStyles.HexNumber);
break;
default:
throw new LexicalException("Bad escape sequence: \'\\" + tokenChar + "\'");
}
}
}
else
{
return new JsonToken(TokenType.String, token);
}
}
throw new LexicalException("End quote not found");
default:
if (token == string.Empty)
{
if (char.IsNumber((char)read) || read == '+' || read == '-')
tokenType = TokenType.Number;
}
else if (tokenType == TokenType.Number && !char.IsNumber((char)read) && (read != '.' || token.Contains(".")))
tokenType = TokenType.String;
token += (char)read;
break;
}
}
if (tokenType == TokenType.Unidentified)
{
switch (token)
{
case "true":
case "false":
case "null":
tokenType = TokenType.KeyWord;
break;
default:
tokenType = TokenType.String;
break;
}
}
return new JsonToken(tokenType, token);
}
public void PutBack(JsonToken token)
{
BackToken.Push(token);
}
