static (string, object) ReadObjectEntry(StringView input)
{
#if SHARE_INTERNAL_METHODS
input.TrimStart();
#endif
if (input.Length < 1 || input[0] != '"')
{
throw new Exception($"Unexpected value at offset {input.offset}. Expected object-key string at {input.offset}");
}
string key = ReadString(input);
input.TrimStart();
if (input.Length == 0 || input[0] != ':')
{
throw new Exception($"Unexpected value at offset {input.offset}. Expected object key-value separator ':'");
}
input.Move(1);
object value = ReadElement(input);
return(key, value);
}
static IEnumerable <object> ReadArray(StringView input)
{
#if SHARE_INTERNAL_METHODS
input.TrimStart();
if (input.Length < 1 || input[0] != '[')
{
throw new Exception($"No Array at offset {input.offset}");
}
#endif
input.Move(1);
input.TrimStart();
List <object> objects = new List <object>();
int startOffset = input.offset;
if (input.Length != 0 && input[0] == ']')
{
input.Move(1);
return(objects);
}
while (true)
{
input.TrimStart();
#if ALLOW_TRAILING_ARRAY_COMMAS
if (input.Length == 0 || input[0] == ']')
{
break;
}
#endif
object child = ReadElement(input);
objects.Add(child);
input.TrimStart();
if (input.Length == 0 || input[0] == ']')
{
break;
}
if (input[0] != ',')
{
throw new Exception($"Unexpected char at offset {input.offset}. Expected array separator ','");
}
input.Move(1);
}
if (input.Length == 0)
{
throw new Exception($"Array at offset {startOffset} isn't closed");
}
input.Move(1);
return(objects);
}
static object ReadNumber(StringView input)
{
#if SHARE_INTERNAL_METHODS
input.TrimStart();
#endif
int offset = -1;
while (++offset < input.Length)
{
char c = input[offset];
if (c == '.' || c == 'e')
{
return(ReadDouble(input));
}
if (c == '-' && offset == 0)
{
continue;
}
//ASCII 0 - 9
if (c >= 0x30 && c <= 0x39)
{
continue;
}
break;
}
return(ReadInt(input));
}
static object ReadJSON(StringView input)
{
object result = ReadElement(input);
input.TrimStart();
if (input.Length != 0)
{
throw new Exception($"Forbidden second root element at offset {input.offset}");
}
return(result);
}
static object ReadElement(StringView input)
{
input.TrimStart();
if (input.Length == 0)
{
throw new Exception("Unexpected EOF");
}
char indicator = input[0];
//ASCII 0 - 9
if (indicator >= 0x30 && indicator <= 0x39)
{
return(ReadNumber(input));
}
switch (input[0])
{
case '{':
return(ReadObject(input));
case '[':
return(ReadArray(input));
case '"':
return(ReadString(input));
case '-':
return(ReadNumber(input));
case 't':
case 'f':
return(ReadBool(input));
case 'n':
return(ReadNull(input));
}
throw new Exception("Unknown value at pos " + input.offset);
}
static string ReadString(StringView input)
{
#if SHARE_INTERNAL_METHODS
input.TrimStart();
if (input.Length < 1 || input[0] != '"')
{
throw new Exception($"No string at offset {input.offset}");
}
#endif
if (input.Length < 2)
{
throw new Exception($"Invalid string at offset {input.offset}");
}
input.Move(1);
var builder = new StringBuilder();
bool escape = false;
bool stringClosed = false;
while (input.Length != 0)
{
char c = input[0];
input.Move(1);
if (escape)
{
switch (c)
{
case '\\':
builder.Append('\\');
break;
case 'b':
builder.Append('\b');
break;
case 'f':
builder.Append('\f');
break;
case 'r':
builder.Append('\r');
break;
case 'n':
builder.Append('\n');
break;
case 't':
builder.Append('\t');
break;
case '"':
builder.Append('"');
break;
case 'u':
builder.Append(ReadEscapedUnicodeChar());
break;
default:
throw new Exception($"Invalid string escape sequence at offset {input.offset - 2}");
}
escape = false;
continue;
}
if (c == '\\')
{
escape = true;
continue;
}
if (c == '"')
{
stringClosed = true;
break;
}
builder.Append(c);
}
if (!stringClosed)
{
throw new Exception($"String not closed at offset {input.offset}");
}
return(builder.ToString());
char ReadEscapedUnicodeChar()
{
if (input.Length < 4)
{
throw new Exception($"Invalid Unicode escape sequence at offset {input.offset}");
}
string hexChars = input.SubString(0, 4);
foreach (var c in hexChars)
{
if ((c >= 0x30 && c <= 0x39) || (c >= 0x41 && c <= 0x46) || (c >= 0x61 && c <= 0x66))
{
continue;
}
throw new Exception($"Invalid Unicode escape sequence at offset {input.offset}");
}
input.Move(4);
int unicodePos = int.Parse(hexChars, NumberStyles.HexNumber);
return((char)unicodePos);
}
}
static Dictionary <string, object> ReadObject(StringView input)
{
#if SHARE_INTERNAL_METHODS
input.TrimStart();
if (input.Length < 1 || input[0] != '{')
{
throw new Exception($"No Object at offset {input.offset}");
}
#endif
input.Move(1);
input.TrimStart();
Dictionary <string, object> childs = new Dictionary <string, object>();
int startOffset = input.offset;
if (input.Length != 0 && input[0] == '}')
{
input.Move(1);
return(childs);
}
while (true)
{
input.TrimStart();
#if ALLOW_TRAILING_OBJECT_COMMAS
if (input.Length == 0 || input[0] == '}')
{
break;
}
#endif
var(key, value) = ReadObjectEntry(input);
if (childs.ContainsKey(key))
{
throw new Exception($"Key '{key}' already exists in object at offset {startOffset}");
}
childs[key] = value;
input.TrimStart();
if (input.Length == 0 || input[0] == '}')
{
break;
}
if (input[0] != ',')
{
throw new Exception($"Unexpected char at offset {input.offset}. Expected object separator ','");
}
input.Move(1);
}
input.TrimStart();
if (input.Length == 0)
{
throw new Exception($"Object at offset {startOffset} isn't closed");
}
input.Move(1);
return(childs);
}