/// <summary>
/// Returns a <see cref="SyntaxError"/> for an unexpected token.
/// </summary>
/// <param name="token">The unexpected token.</param>
/// <returns>A <see cref="SyntaxError"/> for <paramref name="token"/>.</returns>
Exception UnexpectedToken(Json5Token token)
{
if (token.Type == Json5TokenType.Eof)
{
return(new Json5UnexpectedEndOfInputException(token.Line, token.Column));
}
return(new Json5UnexpectedInputException(token.Input, token.Line, token.Column));
}
/// <summary>
/// Parses and returns a <see cref="Json5Value"/>.
/// </summary>
/// <returns>A <see cref="Json5Value"/>.</returns>
public Json5Value Parse()
{
if (this.parsed)
{
throw new InvalidOperationException("A Json5Parser may only be used once.");
}
this.state = State.Value;
this.root = null;
this.stack = new Stack <Json5Container>();
this.currentContainer = null;
this.parsed = true;
string key = null;
start:
Json5Token token = this.lexer.Read();
switch (this.state)
{
case State.Value:
switch (token.Type)
{
case Json5TokenType.String:
this.Add(new Json5String(token.String), key);
goto start;
case Json5TokenType.Number:
this.Add(new Json5Number(token.Number), key);
goto start;
case Json5TokenType.Punctuator:
switch (token.Character)
{
case '[':
this.Add(new Json5Array(), key);
goto start;
case '{':
this.Add(new Json5Object(), key);
goto start;
}
throw UnexpectedToken(token);
case Json5TokenType.Identifier:
// Since these are literal tokens, check token.Input
// instead of token.String. Whereas `true` and `\x74rue`
// are both valid identifiers that represent the same
// thing, only `true` is a boolean literal.
switch (token.Input)
{
case "true":
this.Add(new Json5Boolean(true), key);
goto start;
case "false":
this.Add(new Json5Boolean(false), key);
goto start;
case "null":
this.Add(Json5Value.Null, key);
goto start;
case "Infinity":
this.Add(new Json5Number(double.PositiveInfinity), key);
goto start;
case "NaN":
this.Add(new Json5Number(double.NaN), key);
goto start;
}
break;
}
break;
case State.BeforeArrayElement:
if (token.Type == Json5TokenType.Punctuator && token.Character == ']')
{
this.Pop();
goto start;
}
this.state = State.Value;
goto case State.Value;
case State.AfterArrayElement:
if (token.Type == Json5TokenType.Punctuator)
{
switch (token.Character)
{
case ',':
this.state = State.BeforeArrayElement;
goto start;
case ']':
this.Pop();
goto start;
}
}
break;
case State.BeforeObjectKey:
switch (token.Type)
{
case Json5TokenType.Punctuator:
if (token.Character == '}')
{
this.Pop();
goto start;
}
break;
case Json5TokenType.Identifier:
case Json5TokenType.String:
// All identifiers are valid as keys
// even if they are literals like
// `true`, `null`, or `Infinity`.
key = token.String;
this.state = State.AfterObjectKey;
goto start;
}
break;
case State.AfterObjectKey:
if (token.Type != Json5TokenType.Punctuator || token.Character != ':')
{
break;
}
this.state = State.Value;
goto start;
case State.AfterObjectValue:
if (token.Type == Json5TokenType.Punctuator)
{
switch (token.Character)
{
case ',':
this.state = State.BeforeObjectKey;
goto start;
case '}':
this.Pop();
goto start;
}
}
break;
case State.End:
if (token.Type == Json5TokenType.Eof)
{
return(this.root);
}
break;
}
throw UnexpectedToken(token);
//throw new Exception("Invalid tree state.");
}