From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 912923858C33 for ; Tue, 13 Sep 2022 11:10:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 912923858C33 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663067455; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TRRjiukqVY6gu1AHiZKLO3DmnrceGgM4u1CYxjts/gI=; b=d0krHcBA698lipFEMFZWOwPJa27QUk1D5dN/08uCtSQsAaZm27d/mtJyPZ5rjTRH2wlafH w8fgaAAGUIdyI70DazO2qUhUH8GJXisU2upnm2q1L2hCU60TkbY+/QXDME3T0Sof+PzQP8 TfiAygV8Z5dsv4jrgywC8O73/7J0Azs= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-134-LyDGSK5jNU64ubhqefMTig-1; 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Tue, 13 Sep 2022 04:10:53 -0700 (PDT) X-Google-Smtp-Source: AA6agR7f/OXfaMUyAvJ7YvANwqDRh6O4Ek3mQ734T0eQ+WWwSd30x96aM6bszN1N7mDNHcDWMymZgM356thpW2M6ndw= X-Received: by 2002:a05:622a:11c2:b0:343:69d:65b2 with SMTP id n2-20020a05622a11c200b00343069d65b2mr28085628qtk.491.1663067453291; Tue, 13 Sep 2022 04:10:53 -0700 (PDT) MIME-Version: 1.0 References: <20220912164531.1742034-1-ppalka@redhat.com> <20220912164531.1742034-3-ppalka@redhat.com> In-Reply-To: <20220912164531.1742034-3-ppalka@redhat.com> From: Jonathan Wakely Date: Tue, 13 Sep 2022 12:10:42 +0100 Message-ID: Subject: Re: [PATCH 3/4] libstdc++: Implement ranges::chunk_view from P2442R1 To: Patrick Palka Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,KAM_NUMSUBJECT,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Mon, 12 Sept 2022 at 17:48, Patrick Palka via Libstdc++ wrote: > > This also implements the LWG 3707, 3710 and 3712 changes to chunk_view. > + > + template > + requires input_range<_Vp> > + class chunk_view<_Vp>::_OuterIter > + { > + chunk_view* _M_parent; > + > + constexpr explicit > + _OuterIter(chunk_view& __parent) This can be noexcept. > + : _M_parent(std::__addressof(__parent)) > + { } > + > + friend chunk_view; > + > + public: > + using iterator_concept = input_iterator_tag; > + using difference_type = range_difference_t<_Vp>; > + > + struct value_type; > + > + _OuterIter(_OuterIter&&) = default; > + _OuterIter& operator=(_OuterIter&&) = default; > + > + constexpr value_type > + operator*() const > + { > + __glibcxx_assert(*this != default_sentinel); > + return value_type(*_M_parent); > + } > + > + constexpr _OuterIter& > + operator++() > + { > + __glibcxx_assert(*this != default_sentinel); > + ranges::advance(*_M_parent->_M_current, _M_parent->_M_remainder, > + ranges::end(_M_parent->_M_base)); > + _M_parent->_M_remainder = _M_parent->_M_n; > + return *this; > + } > + > + constexpr void > + operator++(int) > + { ++*this; } > + > + friend constexpr bool > + operator==(const _OuterIter& __x, default_sentinel_t) > + { > + return *__x._M_parent->_M_current == ranges::end(__x._M_parent->_M_base) > + && __x._M_parent->_M_remainder != 0; > + } > + > + friend constexpr difference_type > + operator-(default_sentinel_t, const _OuterIter& __x) > + requires sized_sentinel_for, iterator_t<_Vp>> > + { > + const auto __dist = ranges::end(__x._M_parent->_M_base) - *__x._M_parent->_M_current; > + > + if (__dist < __x._M_parent->_M_remainder) > + return __dist == 0 ? 0 : 1; > + > + return 1 + __detail::__div_ceil(__dist - __x._M_parent->_M_remainder, > + __x._M_parent->_M_n); > + } > + > + friend constexpr difference_type > + operator-(const _OuterIter& __x, default_sentinel_t __y) > + requires sized_sentinel_for, iterator_t<_Vp>> > + { return -(__y - __x); } > + }; > + > + template > + requires input_range<_Vp> > + struct chunk_view<_Vp>::_OuterIter::value_type : view_interface > + { > + private: > + chunk_view* _M_parent; > + > + constexpr explicit > + value_type(chunk_view& __parent) And this. > + : _M_parent(std::__addressof(__parent)) > + { } > + > + friend _OuterIter; > + > + template > + requires input_range<_Vp> > + class chunk_view<_Vp>::_InnerIter > + { > + chunk_view* _M_parent; > + > + constexpr explicit > + _InnerIter(chunk_view& __parent) noexcept And this already is, so that's nice. > + : _M_parent(std::__addressof(__parent)) > + { } > + > + friend _OuterIter::value_type; > + > + public: > + using iterator_concept = input_iterator_tag; > + using difference_type = range_difference_t<_Vp>; > + using value_type = range_value_t<_Vp>; > + > + _InnerIter(_InnerIter&&) = default; > + _InnerIter& operator=(_InnerIter&&) = default; > + > + constexpr const iterator_t<_Vp>& > + base() const & > + { return *_M_parent->_M_current; } > + > + constexpr range_reference_t<_Vp> > + operator*() const > + { > + __glibcxx_assert(*this != default_sentinel); > + return **_M_parent->_M_current; > + } > + > + constexpr _InnerIter& > + operator++() > + { > + __glibcxx_assert(*this != default_sentinel); > + ++*_M_parent->_M_current; > + if (*_M_parent->_M_current == ranges::end(_M_parent->_M_base)) > + _M_parent->_M_remainder = 0; > + else > + --_M_parent->_M_remainder; > + return *this; > + } > + > + constexpr void > + operator++(int) > + { ++*this; } > + > + friend constexpr bool > + operator==(const _InnerIter& __x, default_sentinel_t) noexcept OK with those tweaks.