public AST Parse(IEnumerable <string> tokens)
{
_lexer = new Lexer(tokens);
if (_lexer.CurrentToken.Type == TokenType.EOF)
{
return(null);
}
var tree = _lexer.CurrentToken.Value.ToLower() == "fn" ? ParseFnDef() : ParseExpr();
_lexer.AcceptToken(TokenType.EOF);
return(tree);
}
private AST ParseFnDef()
{
_lexer.AcceptToken(TokenType.Identifier);
var fName = _lexer.CurrentToken.Value;
_lexer.AcceptToken(TokenType.Identifier);
var formalParams = new List <string>();
while (_lexer.CurrentToken.Type == TokenType.Identifier)
{
formalParams.Add(_lexer.CurrentToken.Value);
_lexer.AcceptToken(TokenType.Identifier);
}
_lexer.AcceptToken(TokenType.FnBodyDef);
var body = ParseExpr(formalParams);
var fnDef = new FnDefAST(fName, formalParams, body);
Context.AddDef(fName, fnDef);
return(fnDef);
}