{"id":22322,"url":"https://patchwork.libcamera.org/api/patches/22322/?format=json","web_url":"https://patchwork.libcamera.org/patch/22322/","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":"<20241215230206.11002-3-laurent.pinchart@ideasonboard.com>","date":"2024-12-15T23:02:00","name":"[RFC,2/8] libcamera: base: utils: Add string_view concatenation operators","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"7f56f267ac15b034b7d06d21c46a47c10d3a14cf","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/22322/mbox/","series":[{"id":4889,"url":"https://patchwork.libcamera.org/api/series/4889/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=4889","date":"2024-12-15T23:01:58","name":"libcamera: Use std::string_view","version":1,"mbox":"https://patchwork.libcamera.org/series/4889/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/22322/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/22322/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 12977C32F6\n\tfor ;\n\tSun, 15 Dec 2024 23:02:32 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id BB31067F32;\n\tMon, 16 Dec 2024 00:02:28 +0100 (CET)","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 DBFF067F1D\n\tfor ;\n\tMon, 16 Dec 2024 00:02:25 +0100 (CET)","from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi\n\t[81.175.209.231])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 499B92C6;\n\tMon, 16 Dec 2024 00:01:49 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"LCpaqpXv\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1734303709;\n\tbh=uauMBSHP1hmbgl27o/OtM059YBY7Ft15XGKnQd3nRuw=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=LCpaqpXvmJInQ8Jdbpa/AKzyrJ1nbjwoiZyMOugtBeID6UCAdfkJgF0qb+UnB6Ray\n\tL/2ZSeKBvysgDam19XtC/5yzPlhtIbMFwtQnf+w3oVsp2e1EP/ddQqLYiOEI2HHd8M\n\taa+TldSlwc4Kc7/aavkvLumNqDhS7buXYLcS7lSA=","From":"Laurent Pinchart ","To":"libcamera-devel@lists.libcamera.org","Cc":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Subject":"[RFC PATCH 2/8] libcamera: base: utils: Add string_view\n\tconcatenation operators","Date":"Mon, 16 Dec 2024 01:02:00 +0200","Message-ID":"<20241215230206.11002-3-laurent.pinchart@ideasonboard.com>","X-Mailer":"git-send-email 2.45.2","In-Reply-To":"<20241215230206.11002-1-laurent.pinchart@ideasonboard.com>","References":"<20241215230206.11002-1-laurent.pinchart@ideasonboard.com>","MIME-Version":"1.0","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":"The operator+() overloads to concatenate std::string and\nstd::string_view instances have been introduced in C++26 only. Add a\nlocal implementation in utils.cpp, conditioned by a meson check for\navailability in the standard C++ library.\n\nSigned-off-by: Laurent Pinchart \n---\n include/libcamera/base/utils.h | 47 ++++++++++++++++++++++++++++++++++\n src/libcamera/base/meson.build | 12 +++++++++\n test/utils.cpp | 34 ++++++++++++++++++++++++\n 3 files changed, 93 insertions(+)","diff":"diff --git a/include/libcamera/base/utils.h b/include/libcamera/base/utils.h\nindex 780aeda6a0ce732a..dd012fd58501cd8d 100644\n--- a/include/libcamera/base/utils.h\n+++ b/include/libcamera/base/utils.h\n@@ -433,6 +433,53 @@ private:\n template\n std::basic_ostream &operator<<(std::basic_ostream &os,\n \t\t\t\t\t const utils::Duration &d);\n+\n+#if not HAVE_STD_STRING_VIEW_OPERATOR_PLUS\n+template\n+std::basic_string\n+operator+(const std::basic_string &lhs,\n+\t std::basic_string_view rhs)\n+{\n+\tstd::basic_string str;\n+\n+\tstr.reserve(lhs.size() + rhs.size());\n+\tstr.append(lhs);\n+\tstr.append(rhs);\n+\n+\treturn str;\n+}\n+\n+template\n+std::basic_string\n+operator+(std::basic_string_view lhs,\n+\t const std::basic_string &rhs)\n+{\n+\tstd::basic_string str;\n+\n+\tstr.reserve(lhs.size() + rhs.size());\n+\tstr.append(lhs);\n+\tstr.append(rhs);\n+\n+\treturn str;\n+}\n+\n+template\n+std::basic_string\n+operator+(std::basic_string &&lhs,\n+\t std::basic_string_view rhs)\n+{\n+\treturn std::move(lhs.append(rhs));\n+}\n+\n+template\n+std::basic_string\n+operator+(std::basic_string_view lhs,\n+\t std::basic_string &&rhs)\n+{\n+\treturn std::move(rhs.insert(0, lhs));\n+}\n+#endif /* HAVE_STD_STRING_VIEW_OPERATOR_PLUS */\n+\n #endif\n \n } /* namespace libcamera */\ndiff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build\nindex a742dfdfeb24f9a9..1643d6034921a0cb 100644\n--- a/src/libcamera/base/meson.build\n+++ b/src/libcamera/base/meson.build\n@@ -41,6 +41,18 @@ if libunwind.found()\n config_h.set('HAVE_UNWIND', 1)\n endif\n \n+if cxx.compiles('''\n+#include \n+#include \n+\n+int main()\n+{\n+ std::string s = std::string() + std::string_view();\n+ return s.size();\n+}''', name : 'concatenation of std::string and std::string_view')\n+ config_h.set('HAVE_STD_STRING_VIEW_OPERATOR_PLUS', 1)\n+endif\n+\n libcamera_base_deps = [\n libatomic,\n libdw,\ndiff --git a/test/utils.cpp b/test/utils.cpp\nindex d25475cb93b96a0a..29e3c26406b4f72e 100644\n--- a/test/utils.cpp\n+++ b/test/utils.cpp\n@@ -170,6 +170,36 @@ protected:\n \t\treturn TestPass;\n \t}\n \n+\tint testStringView()\n+\t{\n+\t\tstd::string s{ \"Hello\" };\n+\t\tstd::string_view sv{ \"World!\" };\n+\n+\t\tif (s + sv != \"HelloWorld!\") {\n+\t\t\tcerr << \"operator+(const std::string &, std::string_view) test failed\";\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\tif (sv + s != \"World!Hello\") {\n+\t\t\tcerr << \"operator+(std::string_view, const std::string &) test failed\";\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\tif (std::move(s) + sv != \"HelloWorld!\") {\n+\t\t\tcerr << \"operator+(std::string &&, std::string_view) test failed\";\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\ts = \"Hello\";\n+\n+\t\tif (sv + std::move(s) != \"World!Hello\") {\n+\t\t\tcerr << \"operator+(std::string_view, std::string &&) test failed\";\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\treturn TestPass;\n+\t}\n+\n \tint run()\n \t{\n \t\t/* utils::hex() test. */\n@@ -307,6 +337,10 @@ protected:\n \t\tif (testDuration() != TestPass)\n \t\t\treturn TestFail;\n \n+\t\t/* std::string_view operator+() test. */\n+\t\tif (testStringView() != TestPass)\n+\t\t\treturn TestFail;\n+\n \t\treturn TestPass;\n \t}\n };\n","prefixes":["RFC","2/8"]}