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{ "id": 26392, "url": "https://patchwork.libcamera.org/api/patches/26392/?format=api", "web_url": "https://patchwork.libcamera.org/patch/26392/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260331-mali-cru-v7-2-4caedc898a0e@ideasonboard.com>", "date": "2026-03-31T16:36:30", "name": "[v7,2/8] libcamera: utils: Add overloaded visitor helpers", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": false, "hash": "65803e23419407a73577be2c0eafbe91a0cc49fd", "submitter": { "id": 143, "url": "https://patchwork.libcamera.org/api/people/143/?format=api", "name": "Jacopo Mondi", "email": "jacopo.mondi@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/26392/mbox/", "series": [ { "id": 5860, "url": "https://patchwork.libcamera.org/api/series/5860/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=5860", "date": "2026-03-31T16:36:28", "name": "libcamera: mali-c55: Add support for memory-to-memory", "version": 7, "mbox": "https://patchwork.libcamera.org/series/5860/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/26392/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/26392/checks/", "tags": {}, "headers": { "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>", "X-Original-To": "parsemail@patchwork.libcamera.org", "Delivered-To": "parsemail@patchwork.libcamera.org", "Received": [ "from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 15961BDCBD\n\tfor <parsemail@patchwork.libcamera.org>;\n\tTue, 31 Mar 2026 16:36:57 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id C684262D18;\n\tTue, 31 Mar 2026 18:36:53 +0200 (CEST)", "from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 7E2B062D13\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tTue, 31 Mar 2026 18:36:50 +0200 (CEST)", "from [100.93.44.16] (net-93-65-100-155.cust.vodafonedsl.it\n\t[93.65.100.155])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id F11E625B5;\n\tTue, 31 Mar 2026 18:35:27 +0200 (CEST)" ], "Authentication-Results": "lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"A6uvPMF2\"; dkim-atps=neutral", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1774974928;\n\tbh=FegylNAS/ZE8S1oZUyAdmGxPOxc4ElLR/QAsnKcxhNE=;\n\th=From:Date:Subject:References:In-Reply-To:To:Cc:From;\n\tb=A6uvPMF2ndYHCNaiMbSV3nN8kVYk2tILt+nU5/5Z7FVyPL2stpiCfaQKcoF3jl3La\n\tKGqKNZmGzKiBsFaEeOAElXTQ/C5bh8LHmoBHkQ/9kkxvbRclNFtBL8ZkWhcViSFJ9Z\n\tKiiVHRaDi2pt21XP9iAg/aDTvBVBk9Zntao59sXE=", "From": "Jacopo Mondi <jacopo.mondi@ideasonboard.com>", "Date": "Tue, 31 Mar 2026 18:36:30 +0200", "Subject": "[PATCH v7 2/8] libcamera: utils: Add overloaded visitor helpers", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "8bit", "Message-Id": "<20260331-mali-cru-v7-2-4caedc898a0e@ideasonboard.com>", "References": "<20260331-mali-cru-v7-0-4caedc898a0e@ideasonboard.com>", "In-Reply-To": "<20260331-mali-cru-v7-0-4caedc898a0e@ideasonboard.com>", "To": "Daniel Scally <dan.scally@ideasonboard.com>, \n\tlibcamera-devel@lists.libcamera.org", "Cc": "=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= <barnabas.pocze@ideasonboard.com>,\n\tJacopo Mondi <jacopo.mondi@ideasonboard.com>", "X-Mailer": "b4 0.14.3", "X-Developer-Signature": "v=1; a=openpgp-sha256; l=4147;\n\ti=jacopo.mondi@ideasonboard.com; h=from:subject:message-id;\n\tbh=FegylNAS/ZE8S1oZUyAdmGxPOxc4ElLR/QAsnKcxhNE=;\n\tb=owEBbQKS/ZANAwAKAXI0Bo8WoVY8AcsmYgBpy/gggN1+I9Fr8/70j8mu3wnLf+8qfdNBQgP4a\n\twoRfATOSmyJAjMEAAEKAB0WIQS1xD1IgJogio9YOMByNAaPFqFWPAUCacv4IAAKCRByNAaPFqFW\n\tPGIJD/4rhei/fdDAGoOqorP4Xw9R9cT2r/bcXQ4Akere6M4GaX3hYZ8g7QB4F4sMgKAD9OhZTPr\n\tDuSQ7Jo7vbyyiT6XQQX2JqcmvYfS8uxUwsIr0VexU0u1QNP/yTjoz8sahNURRIsRwrwQfhCJzTd\n\tbfiaGhy/sLpZEdOiu20GrPTEMf+lcx1gZvJRWEIUwlRKfEJO8SkiK51xiWI9bp5YRleW/rs/z/Z\n\tKzcKWqWX1+Nto5WU03mH5ItDwRvdu8xBtNLdd10tzO0xlebMI4s4TO0raJm+vZZJmEniogKOfS8\n\tKDSKOD5BeMPMEsjThCm50Ubc//CrjCAdJtZnAnJ6NBDynT1LTyCVdkVJZkMsFYviE5dSGPfD8p+\n\t97FJQtw79s3xjedKECkoUsAUnv3RUK3b2/MjGQcpaDG10qxbQnKSjZiwmUsp3641l/y4aOqDe6g\n\tfx90CkAR/az8QdbmG3+mfk4hwjQriNd4y+MSizAE8KutOvC+s14IaYzT2UV3fAH/GtbtlZ0cGwn\n\tX76L4JfQ9uhrhhzvb1+qZwK3ynfzn/uTsMu0gHAMvz8ys1aBe2okREqvvUAILUpbkuC+sfQgJv4\n\t090oLkbo0rAtLg4XCvJVQXngubhA9vnDUGt1eeyTLLnFRFjso5vxQJ3E/cxTCo6yeszdGm+6cJq\n\tsuj3CG/JAJzEDng==", "X-Developer-Key": "i=jacopo.mondi@ideasonboard.com; a=openpgp;\n\tfpr=72392EDC88144A65C701EA9BA5826A2587AD026B", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "content": "std::visit() allows quite elegant type-matching implementation of the\nvisitor pattern.\n\nThe 'overloaded' type helpers allow to define a hierarchy of overloaded\noperator() implementations which can be used by std::visit().\n\nCurrently only the Virtual pipeline handler uses this type-matching\nimplementation of std::visit. To prepare to add another user in the Mali\nC55 pipeline handler move the 'overloaded' helper type to\nlibcamera::utils for easier re-use.\n\nReviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>\nSigned-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>\n---\n include/libcamera/base/utils.h | 7 ++++++\n src/libcamera/base/utils.cpp | 35 ++++++++++++++++++++++++++++++\n src/libcamera/pipeline/virtual/virtual.cpp | 10 ++-------\n 3 files changed, 44 insertions(+), 8 deletions(-)", "diff": "diff --git a/include/libcamera/base/utils.h b/include/libcamera/base/utils.h\nindex 7083b7ce9ce9..62c7f89c25a1 100644\n--- a/include/libcamera/base/utils.h\n+++ b/include/libcamera/base/utils.h\n@@ -37,6 +37,13 @@ namespace libcamera {\n \n namespace utils {\n \n+template<class... Ts>\n+struct overloaded : Ts... {\n+\tusing Ts::operator()...;\n+};\n+template<class... Ts>\n+overloaded(Ts...) -> overloaded<Ts...>;\n+\n const char *basename(const char *path);\n \n char *secure_getenv(const char *name);\ndiff --git a/src/libcamera/base/utils.cpp b/src/libcamera/base/utils.cpp\nindex 42a516097be2..836aec87c539 100644\n--- a/src/libcamera/base/utils.cpp\n+++ b/src/libcamera/base/utils.cpp\n@@ -23,6 +23,41 @@ namespace libcamera {\n \n namespace utils {\n \n+/**\n+ * \\struct overloaded\n+ * \\brief Helper type for type-matching std::visit implementations\n+ * \\tparam Ts... Template arguments pack of visitors\n+ *\n+ * Expand the template argument pack \\a Ts... to provide overloaded \\a\n+ * operator() to support type-matching implementations of the visitor design\n+ * pattern using std::visit.\n+ *\n+ * An example is provided by the STL documentation in the form of:\n+ *\n+ * \\code{.cpp}\n+ * template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };\n+ * template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;\n+ *\n+ * using var_t = std::variant<int, long, double, std::string>;\n+ * std::vector<var_t> vec = {10, 15l, 1.5, \"hello\"};\n+ *\n+ * for (auto& v: vec) {\n+ * \tstd::visit(overloaded {\n+ * \t\t[](auto arg) { std::cout << arg << ' '; },\n+ * \t\t[](double arg) { std::cout << std::fixed << arg << ' '; },\n+ * \t\t[](const std::string& arg) { std::cout << std::quoted(arg) << ' '; },\n+ * \t}, v);\n+ * \\endcode\n+ *\n+ * Use this helper to implement type-matching visitors using std::visit().\n+ */\n+\n+/**\n+ * \\var <class... Ts> overloaded(Ts...) -> overloaded<Ts...>\n+ * \\brief Deduction guide necessary for C++17 compatibility\n+ * \\tparam Ts... Template arguments pack of visitor functions\n+ */\n+\n /**\n * \\brief Strip the directory prefix from the path\n * \\param[in] path The path to process\ndiff --git a/src/libcamera/pipeline/virtual/virtual.cpp b/src/libcamera/pipeline/virtual/virtual.cpp\nindex efd800ebe3d6..e8ef7e524ccf 100644\n--- a/src/libcamera/pipeline/virtual/virtual.cpp\n+++ b/src/libcamera/pipeline/virtual/virtual.cpp\n@@ -23,6 +23,7 @@\n \n #include <libcamera/base/flags.h>\n #include <libcamera/base/log.h>\n+#include <libcamera/base/utils.h>\n \n #include <libcamera/control_ids.h>\n #include <libcamera/controls.h>\n@@ -57,13 +58,6 @@ uint64_t currentTimestamp()\n \n } /* namespace */\n \n-template<class... Ts>\n-struct overloaded : Ts... {\n-\tusing Ts::operator()...;\n-};\n-template<class... Ts>\n-overloaded(Ts...) -> overloaded<Ts...>;\n-\n class VirtualCameraConfiguration : public CameraConfiguration\n {\n public:\n@@ -428,7 +422,7 @@ bool PipelineHandlerVirtual::initFrameGenerator(Camera *camera)\n {\n \tauto data = cameraData(camera);\n \tauto &frame = data->config_.frame;\n-\tstd::visit(overloaded{\n+\tstd::visit(utils::overloaded{\n \t\t\t [&](TestPattern &testPattern) {\n \t\t\t\t for (auto &streamConfig : data->streamConfigs_) {\n \t\t\t\t\t if (testPattern == TestPattern::DiagonalLines)\n", "prefixes": [ "v7", "2/8" ] }