private IExpression ParseHashLiteral()
{
var hash = new HashLiteral {
Token = _curToken, Pairs = new Dictionary <IExpression, IExpression>()
};
while (!PeekTokenIs(TokenType.RBrace))
{
NextToken();
var key = ParseExpression(PrecedenceLevel.Lowest);
if (!ExpectPeek(TokenType.Colon))
{
return(null);
}
NextToken();
var value = ParseExpression(PrecedenceLevel.Lowest);
hash.Pairs.Add(key, value);
if (!PeekTokenIs(TokenType.RBrace) && !ExpectPeek(TokenType.Comma))
{
return(null);
}
}
if (!ExpectPeek(TokenType.RBrace))
{
return(null);
}
return(hash);
}
private static IMonkeyObject EvalHashLiteral(HashLiteral node, MonkeyEnvironment env)
{
var pairs = new Dictionary <HashKey, HashPair>();
foreach (var kv in node.Pairs)
{
var key = Eval(kv.Key, env);
if (IsError(key))
{
return(key);
}
if (key is IHashable k)
{
var value = Eval(kv.Value, env);
if (IsError(value))
{
return(value);
}
var hashKey = k.HashKey();
var hashPair = new HashPair {
Key = key, Value = value
};
pairs.Add(hashKey, hashPair);
}
else
{
return(NewError($"Unusable as hash key: {key.GetType()}"));
}
}
return(new MonkeyHash {
Pairs = pairs
});
}