/// <summary>
/// Creates new instance of SymbolicExpression.
/// </summary>
/// <param name="engine">The engine.</param>
/// <param name="pointer">The pointer.</param>
protected internal SymbolicExpression(REngine engine, IntPtr pointer)
: base(IntPtr.Zero, true)
{
this.engine = engine;
this.sexp = (SEXPREC)Marshal.PtrToStructure(pointer, typeof(SEXPREC));
SetHandle(pointer);
Preserve();
}
/// <summary>
/// Gets an enumerator over this pairlist
/// </summary>
/// <returns>The enumerator</returns>
public IEnumerator <Symbol> GetEnumerator()
{
if (Count != 0)
{
for (SEXPREC sexp = GetInternalStructure(); sexp.sxpinfo.type != SymbolicExpressionType.Null; sexp = (SEXPREC)Marshal.PtrToStructure(sexp.listsxp.cdrval, typeof(SEXPREC)))
{
yield return(new Symbol(Engine, sexp.listsxp.tagval));
}
}
}