protected int LookAhead(char[] json, int index)
{
var ias = new IndexAndSuccess();
ias.index = index;
return(this.NextToken(json, ias));
}
protected object ParseValue(char[] json, IndexAndSuccess ias)
{
switch (this.LookAhead(json, ias.index))
{
case TOKEN_STRING:
return(this.ParseString(json, ias));
case TOKEN_NUMBER:
return(this.ParseNumber(json, ias));
case TOKEN_CURLY_OPEN:
return(this.ParseObject(json, ias));
case TOKEN_SQUARED_OPEN:
return(this.ParseArray(json, ias));
case TOKEN_TRUE:
this.NextToken(json, ias);
return(true);
case TOKEN_FALSE:
this.NextToken(json, ias);
return(false);
case TOKEN_NULL:
this.NextToken(json, ias);
return(null);
case TOKEN_NONE:
break;
}
ias.success = false;
return(null);
}
protected Hashtable ParseObject(char[] json, IndexAndSuccess ias)
{
var table = new Hashtable();
int token;
// {
this.NextToken(json, ias);
var done = false;
while (!done)
{
token = this.LookAhead(json, ias.index);
if (token == TOKEN_NONE)
{
ias.success = false;
return(null);
}
if (token == TOKEN_COMMA)
{
this.NextToken(json, ias);
}
else if (token == TOKEN_CURLY_CLOSE)
{
this.NextToken(json, ias);
return(table);
}
else
{
// name
var name = this.ParseString(json, ias);
if (!ias.success)
{
ias.success = false;
return(null);
}
// :
token = this.NextToken(json, ias);
if (token != TOKEN_COLON)
{
ias.success = false;
return(null);
}
// value
var value = this.ParseValue(json, ias);
if (!ias.success)
{
ias.success = false;
return(null);
}
table[name] = value;
}
}
return(table);
}
/// <summary>
/// Parses the string json into a value
/// </summary>
/// <param name="json">A JSON string.</param>
/// <returns>An ArrayList, a Hashtable, a double, a string, null, true, or false</returns>
public object JsonDecode(string json)
{
var ias = new IndexAndSuccess();
ias.success = true;
return(this.JsonDecode(json, ias));
}
protected void EatWhitespace(char[] json, IndexAndSuccess ias)
{
for (; ias.index < json.Length; ias.index++)
{
if (" \t\n\r".IndexOf(json[ias.index]) == -1)
{
break;
}
}
}
/// <summary>
/// Parses the string json into a value; and fills 'success' with the successfullness of the parse.
/// </summary>
/// <param name="json">A JSON string.</param>
/// <param name="success">Successful parse?</param>
/// <returns>An ArrayList, a Hashtable, a double, a string, null, true, or false</returns>
public object JsonDecode(string json, IndexAndSuccess ias)
{
ias.success = true;
if (json != null)
{
var charArray = json.ToCharArray();
ias.index = 0;
var value = this.ParseValue(charArray, ias);
return(value);
}
return(null);
}
protected double ParseNumber(char[] json, IndexAndSuccess ias)
{
this.EatWhitespace(json, ias);
var lastIndex = this.GetLastIndexOfNumber(json, ias.index);
var charLength = (lastIndex - ias.index) + 1;
double number;
ias.success = Double.TryParse(new string(json, ias.index, charLength), NumberStyles.Any,
CultureInfo.InvariantCulture, out number);
ias.index = lastIndex + 1;
return(number);
}
protected ArrayList ParseArray(char[] json, IndexAndSuccess ias)
{
var array = new ArrayList();
// [
this.NextToken(json, ias);
var done = false;
while (!done)
{
var token = this.LookAhead(json, ias.index);
if (token == TOKEN_NONE)
{
ias.success = false;
return(null);
}
if (token == TOKEN_COMMA)
{
this.NextToken(json, ias);
}
else if (token == TOKEN_SQUARED_CLOSE)
{
this.NextToken(json, ias);
break;
}
else
{
var value = this.ParseValue(json, ias);
if (!ias.success)
{
return(null);
}
array.Add(value);
}
}
return(array);
}
protected int NextToken(char[] json, IndexAndSuccess ias)
{
this.EatWhitespace(json, ias);
if (ias.index == json.Length)
{
return(TOKEN_NONE);
}
var c = json[ias.index];
ias.index++;
switch (c)
{
case '{':
return(TOKEN_CURLY_OPEN);
case '}':
return(TOKEN_CURLY_CLOSE);
case '[':
return(TOKEN_SQUARED_OPEN);
case ']':
return(TOKEN_SQUARED_CLOSE);
case ',':
return(TOKEN_COMMA);
case '"':
return(TOKEN_STRING);
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case '-':
return(TOKEN_NUMBER);
case ':':
return(TOKEN_COLON);
}
ias.index--;
var remainingLength = json.Length - ias.index;
// false
if (remainingLength >= 5)
{
if (json[ias.index] == 'f' &&
json[ias.index + 1] == 'a' &&
json[ias.index + 2] == 'l' &&
json[ias.index + 3] == 's' &&
json[ias.index + 4] == 'e')
{
ias.index += 5;
return(TOKEN_FALSE);
}
}
// true
if (remainingLength >= 4)
{
if (json[ias.index] == 't' &&
json[ias.index + 1] == 'r' &&
json[ias.index + 2] == 'u' &&
json[ias.index + 3] == 'e')
{
ias.index += 4;
return(TOKEN_TRUE);
}
}
// null
if (remainingLength >= 4)
{
if (json[ias.index] == 'n' &&
json[ias.index + 1] == 'u' &&
json[ias.index + 2] == 'l' &&
json[ias.index + 3] == 'l')
{
ias.index += 4;
return(TOKEN_NULL);
}
}
return(TOKEN_NONE);
}
protected string ParseString(char[] json, IndexAndSuccess ias)
{
var s = new StringBuilder(BUILDER_CAPACITY);
char c;
this.EatWhitespace(json, ias);
// "
c = json[ias.index++];
var complete = false;
while (!complete)
{
if (ias.index == json.Length)
{
break;
}
c = json[ias.index++];
if (c == '"')
{
complete = true;
break;
}
if (c == '\\')
{
if (ias.index == json.Length)
{
break;
}
c = json[ias.index++];
if (c == '"')
{
s.Append('"');
}
else if (c == '\\')
{
s.Append('\\');
}
else if (c == '/')
{
s.Append('/');
}
else if (c == 'b')
{
s.Append('\b');
}
else if (c == 'f')
{
s.Append('\f');
}
else if (c == 'n')
{
s.Append('\n');
}
else if (c == 'r')
{
s.Append('\r');
}
else if (c == 't')
{
s.Append('\t');
}
else if (c == 'u')
{
var remainingLength = json.Length - ias.index;
if (remainingLength >= 4)
{
// parse the 32 bit hex into an integer codepoint
uint codePoint;
if (
!(ias.success =
UInt32.TryParse(new string(json, ias.index, 4), NumberStyles.HexNumber,
CultureInfo.InvariantCulture, out codePoint)))
{
return("");
}
// convert the integer codepoint to a unicode char and add to string
s.Append(Char.ConvertFromUtf32((int)codePoint));
// skip 4 chars
ias.index += 4;
}
else
{
break;
}
}
}
else
{
s.Append(c);
}
}
if (!complete)
{
ias.success = false;
return(null);
}
return(s.ToString());
}
