[{"id":3563,"web_url":"https://patchwork.libcamera.org/comment/3563/","msgid":"<20200122150208.GK1124294@oden.dyn.berto.se>","date":"2020-01-22T15:02:08","subject":"Re: [libcamera-devel] [PATCH 1/3] libcamera: utils: Add a new\n\tmake_array() function","submitter":{"id":5,"url":"https://patchwork.libcamera.org/api/people/5/","name":"Niklas Söderlund","email":"niklas.soderlund@ragnatech.se"},"content":"Hi Laurent,\n\nThanks for your work.\n\nOn 2020-01-20 19:38:14 +0200, Laurent Pinchart wrote:\n> Add a custom implementation of std::make_array() as defined by the\n> library fundamentals TS v2 ([1]). The function is useful to initialize\n> static arrays without requiring manually specifying the number of\n> elements, which could lead to bugs when the specified size is larger\n> than the number of initializers.\n> \n> This is an experimental feature in the C++ standard, and while available\n> in in stdlibc++ from g++-6 onwards, it is not\n> provided by libc++.\n> \n> [1] https://en.cppreference.com/w/cpp/experimental/make_array\n> \n> Signed-off-by: Laurent Pinchart \n\nReviewed-by: Niklas Söderlund \n\n> ---\n> Documentation/Doxyfile.in | 1 +\n> src/libcamera/include/utils.h | 42 +++++++++++++++++++++++++++++++++++\n> src/libcamera/utils.cpp | 14 ++++++++++++\n> 3 files changed, 57 insertions(+)\n> \n> diff --git a/Documentation/Doxyfile.in b/Documentation/Doxyfile.in\n> index 8e6fbdbb92b6..6de59d407e7b 100644\n> --- a/Documentation/Doxyfile.in\n> +++ b/Documentation/Doxyfile.in\n> @@ -877,6 +877,7 @@ EXCLUDE_SYMBOLS = libcamera::BoundMethodArgs \\\n> libcamera::BoundMethodPackBase \\\n> libcamera::BoundMethodStatic \\\n> libcamera::SignalBase \\\n> + *::details::* \\\n> std::*\n> \n> # The EXAMPLE_PATH tag can be used to specify one or more files or directories\n> diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h\n> index e467eb21c518..6e9b9259456a 100644\n> --- a/src/libcamera/include/utils.h\n> +++ b/src/libcamera/include/utils.h\n> @@ -8,12 +8,15 @@\n> #define __LIBCAMERA_UTILS_H__\n> \n> #include \n> +#include \n> #include \n> +#include \n> #include \n> #include \n> #include \n> #include \n> #include \n> +#include \n> \n> #define ARRAY_SIZE(a)\t(sizeof(a) / sizeof(a[0]))\n> \n> @@ -108,6 +111,45 @@ inline _hex hex(uint64_t value, unsigned int width)\n> \n> size_t strlcpy(char *dst, const char *src, size_t size);\n> \n> +namespace details {\n> +\n> +namespace make_array {\n> +\n> +\ttemplate\n> +\tstruct negation : std::integral_constant {};\n> +\n> +\ttemplate struct conjunction : std::true_type {};\n> +\ttemplate struct conjunction : B1 {};\n> +\ttemplate\n> +\tstruct conjunction\n> +\t\t: std::conditional_t, B1> {};\n> +\n> +\ttemplate struct is_ref_wrapper : std::false_type {};\n> +\ttemplate struct is_ref_wrapper> : std::true_type {};\n> +\n> +\ttemplate\n> +\tstruct return_type_helper {\n> +\t\tusing type = D;\n> +\t};\n> +\ttemplate \n> +\tstruct return_type_helper : std::common_type {\n> +\t\tstatic_assert(conjunction>>...>::value,\n> +\t\t\t \"Types cannot contain reference_wrappers when D is void\");\n> +\t};\n> +\n> +\ttemplate\n> +\tusing return_type = std::array::type,\n> +\t\t\t\t sizeof...(Types)>;\n> +} /* namespace make_array */\n> +\n> +} /* namespace details */\n> +\n> +template\n> +constexpr details::make_array::return_type make_array(Types&&... t)\n> +{\n> +\treturn {std::forward(t)... };\n> +}\n> +\n> } /* namespace utils */\n> \n> } /* namespace libcamera */\n> diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp\n> index 4beffdab5eb6..b639cfa83d0c 100644\n> --- a/src/libcamera/utils.cpp\n> +++ b/src/libcamera/utils.cpp\n> @@ -199,6 +199,20 @@ size_t strlcpy(char *dst, const char *src, size_t size)\n> \treturn strlen(src);\n> }\n> \n> +/**\n> + * \\fn template libcamera::utils::make_array(Types&&... t)\n> + * \\brief Create a std::array with automatic deduction of element type and count\n> + * \\param[in] t The initialization values for the array elements\n> + *\n> + * This function creates and returns an instance of std::array whose size is\n> + * equal to the number of arguments. If the template argument \\a D is void, the\n> + * array element type is deduced from the elements through\n> + * std::common_types_t. Otherwise it is set to D. The elements are\n> + * initialized from the corresponding arguments.\n> + *\n> + * \\return A std::array initialized from the arguments\n> + */\n> +\n> } /* namespace utils */\n> \n> } /* namespace libcamera */\n> -- \n> Regards,\n> \n> Laurent Pinchart\n> \n> _______________________________________________\n> libcamera-devel mailing list\n> libcamera-devel@lists.libcamera.org\n> https://lists.libcamera.org/listinfo/libcamera-devel","headers":{"Return-Path":"","Received":["from mail-lf1-x141.google.com (mail-lf1-x141.google.com\n\t[IPv6:2a00:1450:4864:20::141])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id CDE71607F3\n\tfor ;\n\tWed, 22 Jan 2020 16:02:09 +0100 (CET)","by mail-lf1-x141.google.com with SMTP id b15so5571093lfc.4\n\tfor ;\n\tWed, 22 Jan 2020 07:02:09 -0800 (PST)","from localhost (h-93-159.A463.priv.bahnhof.se. 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