public static SSObject Swap(SSExpression[] exps, SSScope scope)
{
var na = exps[0].Token.Value;
var va = exps[0].Evaluate(scope);
var nb = exps[1].Token.Value;
var vb = exps[1].Evaluate(scope);
scope.Undefine(nb);
scope.Undefine(na);
scope.Define(nb, va);
scope.Define(na, vb);
return(true);
}
/// <summary>
/// (rename old-name new-name)
/// </summary>
public static SSObject Rename(SSExpression[] exps, SSScope scope)
{
string oname = exps[0].Token.Value;
string nname = exps[1].Token.Value;
(!oname.Equals(nname)).OrThrows("same name {0}".Fmt(oname));
try
{
var obj = scope.Find(oname);
scope.Define(nname, obj);
scope.Undefine(oname);
return(nname + " " + obj.ToString());
}
catch (Exception)
{
Func <SSExpression[], SSScope, SSObject> obj = null;
if (SSScope.BuiltinFunctions.TryGetValue(oname, out obj))
{
SSScope.BuiltinFunctions[nname] = obj;
SSScope.BuiltinFunctions.Remove(oname);
return(nname + " " + obj.ToString());
}
throw new Exception("cannot find {0} in scope, and it is not a builtin".Fmt(nname));
}
}
/// <summary>
/// set name value
/// </summary>
public static SSObject Set(SSExpression[] exps, SSScope scope)
{
(exps.Length == 2).OrThrows("expect two parameters");
var b0 = exps[0];
var b1 = exps[1].Evaluate(scope);
if (!b0.Evaluate(scope).Replace(b1))
{
scope.Undefine(b0.Token.Value);
scope.Define(b0.Token.Value, b1);
}
return(b1);
}
