private static Syntax ParseVector(Token thisToken, Tokenizer moreTokens)
{
var listContents = new ListSyntax( );
Token dotToken = null;
var nextToken = moreTokens.ReadToken();
while (nextToken != null && nextToken.type != TokenType.CloseBracket)
{
// Parse this token
listContents.Add(ParseToken(nextToken, moreTokens));
// Fetch the next token
nextToken = moreTokens.ReadToken();
if (nextToken == null)
{
throw ParserError.SyntaxError("parser", "Improperly formed list.", dotToken);
}
//if (!improper && nextToken.Type == TokenType.Symbol && dotSymbol.Equals(nextToken.Value) && thisToken.Type == TokenType.OpenBracket)
if (nextToken.type == TokenType.Dot)
{
throw ParserError.SyntaxError("parser", "Improperly formed dotted list", nextToken);
}
}
if (nextToken == null) // Missing ')'
{
throw ParserError.SyntaxError("parser", "Missing close parenthesis", thisToken);
}
return(Syntax.Create(listContents, thisToken.location));
}
/// <summary>
/// Turns thisToken into an object, using moreTokens to get further tokens if required
/// </summary>
/// <returns></returns>
private static Syntax ParseToken(Token thisToken, Tokenizer moreTokens)
{
if (thisToken == null)
{
throw ParserError.SyntaxError("parser", "unexpectedly reached the end of the input", moreTokens.LastToken);
}
switch (thisToken.type)
{
//case TokenType.Dot:
// return thisToken; //TODO maybe exception or symbol .
case TokenType.Character:
return(Syntax.Create(thisToken.GetCharacter(), thisToken.location));
case TokenType.Boolean:
return(Syntax.Create(thisToken.GetBool(), thisToken.location));
case TokenType.String:
return(Syntax.Create(thisToken.GetString(), thisToken.location));
case TokenType.Symbol:
return(Syntax.Create(thisToken.GetName(), thisToken.location));
case TokenType.Heximal:
case TokenType.Integer:
return(Syntax.Create(thisToken.GetInteger(), thisToken.location));
case TokenType.Floating:
return(Syntax.Create(thisToken.GetFloat(), thisToken.location));
case TokenType.OpenBracket:
return(ParseList(thisToken, moreTokens));
case TokenType.OpenVector:
return(ParseVector(thisToken, moreTokens));
case TokenType.Quote:
case TokenType.Unquote:
case TokenType.UnquoteSplicing:
case TokenType.QuasiQuote:
return(ParseQuoted(thisToken, moreTokens));
case TokenType.BadNumber:
throw ParserError.SyntaxError("parser", "looks like it should be a number, but it contains a syntax error", thisToken);
default:
// Unknown token type
throw ParserError.SyntaxError("parser", "the element is being used in a context where it is not understood", thisToken);
}
}
/// <summary>
/// Parses a scheme expression in the default manner
/// </summary>
/// <returns>A scheme object</returns>
/// <remarks>It is an error to pass scheme to this method with 'extraneous' tokens, such as trailing closing brackets</remarks>
public static Syntax Parse(string scheme, string filepath)
{
var reader = new Tokenizer(new System.IO.StringReader(scheme), filepath);
var res = Parse(reader);
var token = reader.ReadToken();
if (token != null)
{
throw ParserError.SyntaxError("parser", "found extra tokens after the end of a scheme expression", token);
}
return(res);
}
private static Syntax ParseList(Token thisToken, Tokenizer moreTokens)
{
// Is a list/vector
var listContents = new LinkedList <Syntax> ( );
Token dotToken = null;
var nextToken = moreTokens.ReadToken();
while (nextToken != null && nextToken.type != TokenType.CloseBracket)
{
// Parse this token
listContents.AddLast(ParseToken(nextToken, moreTokens));
// Fetch the next token
nextToken = moreTokens.ReadToken();
if (nextToken == null)
{
throw ParserError.SyntaxError("parser", "Improperly formed list.", dotToken);
}
if (nextToken.type == TokenType.Dot)
{
if (dotToken != null || thisToken.type != TokenType.OpenBracket)
{
throw ParserError.SyntaxError("parser", "Improperly formed dotted list", nextToken);
}
dotToken = nextToken;
nextToken = moreTokens.ReadToken();
if (nextToken == null)
{
throw ParserError.SyntaxError("parser", "Improperly formed dotted list", dotToken);
}
if (nextToken.type == TokenType.CloseBracket)
{
throw ParserError.SyntaxError("parser", "Improperly formed dotted list", dotToken);
}
listContents.AddLast(ParseToken(nextToken, moreTokens));
nextToken = moreTokens.ReadToken();
if (nextToken.type != TokenType.CloseBracket)
{
throw ParserError.SyntaxError("parser", "Improperly formed dotted list", dotToken);
}
break;
}
}
if (nextToken == null)
{
// Missing ')'
throw ParserError.SyntaxError("parser", "missing close parenthesis", thisToken);
}
if (dotToken != null)
{
if (listContents.Count == 2)
{
return(Syntax.Create(new Pair(listContents[0], listContents[1]), thisToken.location));
}
else
{
throw ParserError.SyntaxError("parser", "improper dot syntax", thisToken);
}
}
else
{
return(Syntax.Create(listContents, thisToken.location));
}
}
