each

/*
 *  call-seq:
 *     WIN32OLE#each {|i|...}
 * 
 *  Iterates over each item of OLE collection which has IEnumVARIANT interface.
 *
 *     excel = WIN32OLE.new('Excel.Application')
 *     book = excel.workbooks.add
 *     sheets = book.worksheets(1)
 *     cells = sheets.cells("A1:A5")
 *     cells.each do |cell|
 *       cell.value = 10
 *     end
 */
static VALUE
fole_each(self)
    VALUE self;
{
    LCID    lcid = LOCALE_SYSTEM_DEFAULT;

    struct oledata *pole;

    unsigned int argErr;
    EXCEPINFO excepinfo;
    DISPPARAMS dispParams;
    VARIANT result;
    HRESULT hr;
    IEnumVARIANT *pEnum = NULL;

    VariantInit(&result);
    dispParams.rgvarg = NULL;
    dispParams.rgdispidNamedArgs = NULL;
    dispParams.cNamedArgs = 0;
    dispParams.cArgs = 0;
    memset(&excepinfo, 0, sizeof(excepinfo));
    
    OLEData_Get_Struct(self, pole);
    hr = pole->pDispatch->lpVtbl->Invoke(pole->pDispatch, DISPID_NEWENUM,
                                         &IID_NULL, lcid,
                                         DISPATCH_METHOD | DISPATCH_PROPERTYGET,
                                         &dispParams, &result,
                                         &excepinfo, &argErr);

    if (FAILED(hr)) {
        VariantClear(&result);
        ole_raise(hr, eWIN32OLE_RUNTIME_ERROR, "failed to get IEnum Interface");
    }

    if (V_VT(&result) == VT_UNKNOWN)
        hr = V_UNKNOWN(&result)->lpVtbl->QueryInterface(V_UNKNOWN(&result),
                                                        &IID_IEnumVARIANT,
                                                        (void**)&pEnum);
    else if (V_VT(&result) == VT_DISPATCH)
        hr = V_DISPATCH(&result)->lpVtbl->QueryInterface(V_DISPATCH(&result),
                                                         &IID_IEnumVARIANT,
                                                         (void**)&pEnum);
    if (FAILED(hr) || !pEnum) {
        VariantClear(&result);
        ole_raise(hr, rb_eRuntimeError, "failed to get IEnum Interface");
    }

    VariantClear(&result);
    rb_ensure(ole_each_sub, (VALUE)pEnum, ole_ienum_free, (VALUE)pEnum);
    return Qnil;
}