{"id":26523,"url":"https://patchwork.libcamera.org/api/patches/26523/?format=json","web_url":"https://patchwork.libcamera.org/patch/26523/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260423230059.3180987-2-laurent.pinchart@ideasonboard.com>","date":"2026-04-23T23:00:23","name":"[v3,01/37] libcamera: utils: Add overloaded visitor helpers","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"9acd6cabe59adea62c118575940a8321940365c2","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/?format=json","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/26523/mbox/","series":[{"id":5883,"url":"https://patchwork.libcamera.org/api/series/5883/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5883","date":"2026-04-23T23:00:22","name":"libcamera: Global configuration file improvements","version":3,"mbox":"https://patchwork.libcamera.org/series/5883/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/26523/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/26523/checks/","tags":{},"headers":{"Return-Path":"","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 6E6C1BDCB5\n\tfor ;\n\tThu, 23 Apr 2026 23:01:05 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 02DF262F5E;\n\tFri, 24 Apr 2026 01:01:05 +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 AEF5C62EAA\n\tfor ;\n\tFri, 24 Apr 2026 01:01:02 +0200 (CEST)","from killaraus.ideasonboard.com\n\t(2001-14ba-703d-e500--2a1.rev.dnainternet.fi\n\t[IPv6:2001:14ba:703d:e500::2a1])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id B8D7134;\n\tFri, 24 Apr 2026 00:59:22 +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=\"bdTGOPZy\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1776985162;\n\tbh=sKNd9y42pqTvjlTDTe3/j20UzQr4dKfSyUqd6SGOC4g=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=bdTGOPZyqfQmBxxBjvbDPl/Wi7lRrCLC5asUFH+2uKFD1xca2SLZNWyGb85xq4o3o\n\tEMep/xrf607KBIrNMtX3c2FTK8EJ14Uu1Z02cbZkXdgl2Ao7/NpxxTjgtgmK2qTloM\n\tTzejCWDa1sOWfdeTUkY0uWZGBaxBO/NVr9M6yju0=","From":"Laurent Pinchart ","To":"libcamera-devel@lists.libcamera.org","Cc":"Jacopo Mondi ","Subject":"[PATCH v3 01/37] libcamera: utils: Add overloaded visitor helpers","Date":"Fri, 24 Apr 2026 02:00:23 +0300","Message-ID":"<20260423230059.3180987-2-laurent.pinchart@ideasonboard.com>","X-Mailer":"git-send-email 2.53.0","In-Reply-To":"<20260423230059.3180987-1-laurent.pinchart@ideasonboard.com>","References":"<20260423230059.3180987-1-laurent.pinchart@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"From: Jacopo Mondi \n\nstd::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\nMali C55 pipeline handler move the 'overloaded' helper type to\nlibcamera::utils for easier re-use.\n\nSigned-off-by: Jacopo Mondi \nReviewed-by: Barnabás Pőcze \nReviewed-by: Laurent Pinchart \nSigned-off-by: Laurent Pinchart \n---\nChanges since v8 of \"[PATCH v8 0/8] libcamera: mali-c55: Add support for memory-to-memory\":\n\n- Small improvements to documentation\n- Drop documentation of deduction guide\n---\n include/libcamera/base/utils.h | 9 +++++++\n src/libcamera/base/utils.cpp | 30 ++++++++++++++++++++++\n src/libcamera/pipeline/virtual/virtual.cpp | 10 ++------\n 3 files changed, 41 insertions(+), 8 deletions(-)","diff":"diff --git a/include/libcamera/base/utils.h b/include/libcamera/base/utils.h\nindex 7083b7ce9ce9..b33a4c644a87 100644\n--- a/include/libcamera/base/utils.h\n+++ b/include/libcamera/base/utils.h\n@@ -37,6 +37,15 @@ namespace libcamera {\n \n namespace utils {\n \n+template\n+struct overloaded : Ts... {\n+\tusing Ts::operator()...;\n+};\n+#ifndef __DOXYGEN__\n+template\n+overloaded(Ts...) -> overloaded;\n+#endif\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..4ab2bd863e11 100644\n--- a/src/libcamera/base/utils.cpp\n+++ b/src/libcamera/base/utils.cpp\n@@ -23,6 +23,36 @@ 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 C++ standard library documentation in the form\n+ * of:\n+ *\n+ * \\code{.cpp}\n+ * template struct overloaded : Ts... { using Ts::operator()...; };\n+ * template overloaded(Ts...) -> overloaded;\n+ *\n+ * using var_t = std::variant;\n+ * std::vector 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 * \\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 \n #include \n+#include \n \n #include \n #include \n@@ -57,13 +58,6 @@ uint64_t currentTimestamp()\n \n } /* namespace */\n \n-template\n-struct overloaded : Ts... {\n-\tusing Ts::operator()...;\n-};\n-template\n-overloaded(Ts...) -> overloaded;\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":["v3","01/37"]}