private (Ast.Identifier, Ast.IExpression) ParseDeclaration()
{
if (!ExpectPeek(TokenType.Ident))
{
return(null, null);
}
var name = new Ast.Identifier {
Token = _curToken, Value = _curToken.Literal
};
if (!ExpectPeek(TokenType.Assign))
{
return(null, null);
}
NextToken();
var value = ParseExpression(Precedence.Lowest);
if (PeekTokenIs(TokenType.Semicolon))
{
NextToken();
}
return(name, value);
}
private static IObject EvalIdentifier(Ast.Identifier node, Environment env)
{
var val = env.Get(node.Value);
if (val != null)
{
return(val);
}
if (Builtins.BuiltinFunctions.ContainsKey(node.Value))
{
return(Builtins.BuiltinFunctions[node.Value]);
}
return(new Error {
Message = $"identifier not found: {node.Value}"
});
}
private List <Ast.Identifier> ParseFunctionParameters()
{
var identifiers = new List <Ast.Identifier>();
if (PeekTokenIs(TokenType.Rparen))
{
NextToken();
return(identifiers);
}
NextToken();
var ident = new Ast.Identifier
{
Token = _curToken,
Value = _curToken.Literal
};
identifiers.Add(ident);
while (PeekTokenIs(TokenType.Comma))
{
NextToken();
NextToken();
ident = new Ast.Identifier
{
Token = _curToken,
Value = _curToken.Literal
};
identifiers.Add(ident);
}
if (!ExpectPeek(TokenType.Rparen))
{
return(null);
}
return(identifiers);
}