internal static void SkipWhitespace(CharReader reader)
{
// Purpose: Skip over any whitespace characters or any recognized comments
// Author : Scott Bakker
// Created: 09/23/2019
// LastMod: 08/11/2020
// Notes : Comments consist of "/*...*/" or "//" to eol (aka line comment).
// : "//" comments don't need an eol if at the end, but "/*" does need "*/".
if (reader == null)
{
return;
}
bool inComment = false;
bool inLineComment = false;
while (reader.Peek() != -1)
{
if (inComment)
{
if (reader.Peek() == '*' && reader.PeekNext() == '/') // found ending "*/"
{
inComment = false;
reader.Read();
}
reader.Read();
continue;
}
if (inLineComment)
{
if (reader.Peek() == '\r' || reader.Peek() == '\n') // found end of line
{
inLineComment = false;
}
reader.Read();
continue;
}
if (reader.Peek() == '/' && reader.PeekNext() == '*')
{
inComment = true;
reader.Read();
reader.Read();
continue;
}
if (reader.Peek() == '/' && reader.PeekNext() == '/')
{
inLineComment = true;
reader.Read();
reader.Read();
continue;
}
if (IsWhitespace((char)reader.Peek()))
{
reader.Read();
continue;
}
break;
}
if (inComment)
{
throw new SystemException("JSON Error: Comment starting with /* is not terminated by */");
}
}
internal static JObject Parse(CharReader reader)
{
// Purpose: Convert a partial string into a JObject
// Author : Scott Bakker
// Created: 09/13/2019
// LastMod: 08/11/2020
if (reader == null || reader.Peek() == -1)
{
return(null);
}
JObject result = new JObject();
JsonRoutines.SkipBOM(reader);
JsonRoutines.SkipWhitespace(reader);
if (reader.Peek() != '{')
{
throw new SystemException(
$"JSON Error: Unexpected token to start JObject: {reader.Peek()}");
}
reader.Read();
do
{
JsonRoutines.SkipWhitespace(reader);
// check for symbols
if (reader.Peek() == '}')
{
reader.Read();
break; // done building JObject
}
if (reader.Peek() == ',')
{
// this logic ignores extra commas, but is ok
reader.Read();
continue; // Next key/value
}
string tempKey = JsonRoutines.GetToken(reader);
if (JsonRoutines.IsWhitespaceString(tempKey))
{
throw new SystemException(JsonKeyError);
}
if (tempKey.Length <= 2 || !tempKey.StartsWith("\"") || !tempKey.EndsWith("\""))
{
throw new SystemException($"JSON Error: Invalid key format: {tempKey}");
}
// Convert to usable key
tempKey = JsonRoutines.JsonValueToObject(tempKey).ToString();
if (JsonRoutines.IsWhitespaceString(tempKey.Substring(1, tempKey.Length - 2)))
{
throw new SystemException(JsonKeyError);
}
// Check for ":" between key and value
JsonRoutines.SkipWhitespace(reader);
if (JsonRoutines.GetToken(reader) != ":")
{
throw new SystemException($"JSON Error: Missing colon: {tempKey}");
}
// Get value
JsonRoutines.SkipWhitespace(reader);
if (reader.Peek() == '{') // JObject
{
JObject jo = JObject.Parse(reader);
result[tempKey] = jo;
continue;
}
if (reader.Peek() == '[') // JArray
{
JArray ja = JArray.Parse(reader);
result[tempKey] = ja;
continue;
}
// Get value as a string, convert to object
string tempValue = JsonRoutines.GetToken(reader);
result[tempKey] = JsonRoutines.JsonValueToObject(tempValue);
} while (true);
return(result);
}
internal static string GetToken(CharReader reader)
{
// Purpose: Get a single token from string value for parsing
// Author : Scott Bakker
// Created: 09/13/2019
// LastMod: 03/09/2021
// Notes : Does not do escaped character expansion here, just passes exact value.
// : Properly handles \" within strings this way, but nothing else.
if (reader == null || reader.Peek() == -1)
{
return(null);
}
char c;
// Ignore whitespace before token
SkipWhitespace(reader);
// Stop if one-character JSON symbol found
if (IsJsonSymbol((char)reader.Peek()))
{
return(((char)reader.Read()).ToString());
}
// Have to build token char by char
StringBuilder result = new();
bool inQuote = false;
bool lastBackslash = false;
do
{
// Peek char for this loop
c = (char)reader.Peek();
// Check for whitespace or symbols to end token
if (!inQuote)
{
if (IsWhitespace(c))
{
reader.Read(); // gobble char
break; // end token
}
if (IsJsonSymbol(c))
{
// don't gobble char
break; // end token
}
// Any comments end the token
if (c == '/')
{
if (reader.PeekNext() == '*' || reader.PeekNext() == '/')
{
// don't gobble char
break; // end token
}
}
if (c != '\"' && !IsJsonValueChar(c))
{
throw new SystemException($"JSON Error: Unexpected character: {c}");
}
}
// Check for escaped chars
if (inQuote && lastBackslash)
{
// Add backslash and character, no expansion here
result.Append('\\');
result.Append((char)reader.Read());
lastBackslash = false;
}
else if (inQuote && c == '\\')
{
// Remember backslash for next loop, but don't add it to result
lastBackslash = true;
}
else if (c == '\"')
{
// Check for quotes around a string
if (inQuote)
{
result.Append((char)reader.Read()); // add ending quote
inQuote = false;
break; // Token is done
}
if (result.Length > 0)
{
// Quote in the middle of a token?
throw new SystemException("JSON Error: Unexpected quote char");
}
result.Append((char)reader.Read()); // add beginning quote
inQuote = true;
}
else
{
// Add this char
result.Append((char)reader.Read());
}
}while (reader.Peek() != -1);
return(result.ToString());
}
