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{
    "id": 21877,
    "url": "https://patchwork.libcamera.org/api/1.1/patches/21877/?format=api",
    "web_url": "https://patchwork.libcamera.org/patch/21877/",
    "project": {
        "id": 1,
        "url": "https://patchwork.libcamera.org/api/1.1/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": "<20241112185637.10232-1-laurent.pinchart@ideasonboard.com>",
    "date": "2024-11-12T18:56:37",
    "name": "libcamera: yaml_parser: Use std::from_chars()",
    "commit_ref": "5c71df927ddaaa01204bff1e647c9d2bf653d95f",
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "ae2411303e6b782a55bf375e4fd98a4867107028",
    "submitter": {
        "id": 2,
        "url": "https://patchwork.libcamera.org/api/1.1/people/2/?format=api",
        "name": "Laurent Pinchart",
        "email": "laurent.pinchart@ideasonboard.com"
    },
    "delegate": null,
    "mbox": "https://patchwork.libcamera.org/patch/21877/mbox/",
    "series": [
        {
            "id": 4786,
            "url": "https://patchwork.libcamera.org/api/1.1/series/4786/?format=api",
            "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=4786",
            "date": "2024-11-12T18:56:37",
            "name": "libcamera: yaml_parser: Use std::from_chars()",
            "version": 1,
            "mbox": "https://patchwork.libcamera.org/series/4786/mbox/"
        }
    ],
    "comments": "https://patchwork.libcamera.org/api/patches/21877/comments/",
    "check": "pending",
    "checks": "https://patchwork.libcamera.org/api/patches/21877/checks/",
    "tags": {},
    "headers": {
        "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>",
        "X-Original-To": "parsemail@patchwork.libcamera.org",
        "Delivered-To": "parsemail@patchwork.libcamera.org",
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            "from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 5D8B7C324C\n\tfor <parsemail@patchwork.libcamera.org>;\n\tTue, 12 Nov 2024 18:56:47 +0000 (UTC)",
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        ],
        "Authentication-Results": "lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"rRYiNxgs\"; dkim-atps=neutral",
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        "From": "Laurent Pinchart <laurent.pinchart@ideasonboard.com>",
        "To": "libcamera-devel@lists.libcamera.org",
        "Subject": "[PATCH] libcamera: yaml_parser: Use std::from_chars()",
        "Date": "Tue, 12 Nov 2024 20:56:37 +0200",
        "Message-ID": "<20241112185637.10232-1-laurent.pinchart@ideasonboard.com>",
        "X-Mailer": "git-send-email 2.45.2",
        "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": "<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::from_chars(), introduced in C++17, is a fast, locale-independent\nstring-to-arithmetic conversion function. The C++ standard library\nprovides overloads for all integer types, making it a prime candidate to\nreplace the manual handling of integer sizes in the YamlParser string to\ninteger conversion.\n\nCompared to std::strtol(), std::from_chars() doesn't recognize the '0x'\nprefix or '+' prefix, and doesn't ignore leading white space. As the\nYamlParser doesn't require those features, std::from_chars() can be used\nsafely, reducing the amount of code.\n\nC++17 also requires the standard C++ library to provide overloads for\nfloating-point types, but libc++ does not implement those. The float and\nbool implementations of YamlParser::Getter::get() are therefore kept\nas-is.\n\nSigned-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>\n---\n include/libcamera/internal/yaml_parser.h |   2 +-\n src/libcamera/yaml_parser.cpp            | 168 ++++-------------------\n 2 files changed, 29 insertions(+), 141 deletions(-)\n\n\nbase-commit: dcb90f13cf79d909d04dacf2cfbd256a4744347f",
    "diff": "diff --git a/include/libcamera/internal/yaml_parser.h b/include/libcamera/internal/yaml_parser.h\nindex de452844fe0a..8c7916565946 100644\n--- a/include/libcamera/internal/yaml_parser.h\n+++ b/include/libcamera/internal/yaml_parser.h\n@@ -224,7 +224,7 @@ private:\n \t\tEmpty,\n \t};\n \n-\ttemplate<typename T>\n+\ttemplate<typename T, typename Enable = void>\n \tstruct Getter {\n \t\tstd::optional<T> get(const YamlObject &obj) const;\n \t};\ndiff --git a/src/libcamera/yaml_parser.cpp b/src/libcamera/yaml_parser.cpp\nindex 7c0b341a32e7..db256ec5b04d 100644\n--- a/src/libcamera/yaml_parser.cpp\n+++ b/src/libcamera/yaml_parser.cpp\n@@ -7,6 +7,7 @@\n \n #include \"libcamera/internal/yaml_parser.h\"\n \n+#include <charconv>\n #include <cstdlib>\n #include <errno.h>\n #include <functional>\n@@ -146,151 +147,38 @@ YamlObject::Getter<bool>::get(const YamlObject &obj) const\n \treturn std::nullopt;\n }\n \n-namespace {\n-\n-bool parseSignedInteger(const std::string &str, long min, long max,\n-\t\t\tlong *result)\n+template<typename T>\n+struct YamlObject::Getter<T, std::enable_if_t<\n+\tstd::is_same_v<int8_t, T> ||\n+\tstd::is_same_v<uint8_t, T> ||\n+\tstd::is_same_v<int16_t, T> ||\n+\tstd::is_same_v<uint16_t, T> ||\n+\tstd::is_same_v<int32_t, T> ||\n+\tstd::is_same_v<uint32_t, T>>>\n {\n-\tif (str == \"\")\n-\t\treturn false;\n+\tstd::optional<T> get(const YamlObject &obj) const\n+\t{\n+\t\tif (obj.type_ != Type::Value)\n+\t\t\treturn std::nullopt;\n \n-\tchar *end;\n+\t\tconst std::string &str = obj.value_;\n+\t\tT value;\n \n-\terrno = 0;\n-\tlong value = std::strtol(str.c_str(), &end, 10);\n+\t\tauto [ptr, ec] = std::from_chars(str.data(), str.data() + str.size(),\n+\t\t\t\t\t\t value);\n+\t\tif (ptr != str.data() + str.size() || ec != std::errc())\n+\t\t\treturn std::nullopt;\n \n-\tif ('\\0' != *end || errno == ERANGE || value < min || value > max)\n-\t\treturn false;\n+\t\treturn value;\n+\t}\n+};\n \n-\t*result = value;\n-\treturn true;\n-}\n-\n-bool parseUnsignedInteger(const std::string &str, unsigned long max,\n-\t\t\t  unsigned long *result)\n-{\n-\tif (str == \"\")\n-\t\treturn false;\n-\n-\t/*\n-\t * strtoul() accepts strings representing a negative number, in which\n-\t * case it negates the converted value. We don't want to silently accept\n-\t * negative values and return a large positive number, so check for a\n-\t * minus sign (after optional whitespace) and return an error.\n-\t */\n-\tstd::size_t found = str.find_first_not_of(\" \\t\");\n-\tif (found != std::string::npos && str[found] == '-')\n-\t\treturn false;\n-\n-\tchar *end;\n-\n-\terrno = 0;\n-\tunsigned long value = std::strtoul(str.c_str(), &end, 10);\n-\n-\tif ('\\0' != *end || errno == ERANGE || value > max)\n-\t\treturn false;\n-\n-\t*result = value;\n-\treturn true;\n-}\n-\n-} /* namespace */\n-\n-template<>\n-std::optional<int8_t>\n-YamlObject::Getter<int8_t>::get(const YamlObject &obj) const\n-{\n-\tif (obj.type_ != Type::Value)\n-\t\treturn std::nullopt;\n-\n-\tlong value;\n-\n-\tif (!parseSignedInteger(obj.value_, std::numeric_limits<int8_t>::min(),\n-\t\t\t\tstd::numeric_limits<int8_t>::max(), &value))\n-\t\treturn std::nullopt;\n-\n-\treturn value;\n-}\n-\n-template<>\n-std::optional<uint8_t>\n-YamlObject::Getter<uint8_t>::get(const YamlObject &obj) const\n-{\n-\tif (obj.type_ != Type::Value)\n-\t\treturn std::nullopt;\n-\n-\tunsigned long value;\n-\n-\tif (!parseUnsignedInteger(obj.value_, std::numeric_limits<uint8_t>::max(),\n-\t\t\t\t  &value))\n-\t\treturn std::nullopt;\n-\n-\treturn value;\n-}\n-\n-template<>\n-std::optional<int16_t>\n-YamlObject::Getter<int16_t>::get(const YamlObject &obj) const\n-{\n-\tif (obj.type_ != Type::Value)\n-\t\treturn std::nullopt;\n-\n-\tlong value;\n-\n-\tif (!parseSignedInteger(obj.value_, std::numeric_limits<int16_t>::min(),\n-\t\t\t\tstd::numeric_limits<int16_t>::max(), &value))\n-\t\treturn std::nullopt;\n-\n-\treturn value;\n-}\n-\n-template<>\n-std::optional<uint16_t>\n-YamlObject::Getter<uint16_t>::get(const YamlObject &obj) const\n-{\n-\tif (obj.type_ != Type::Value)\n-\t\treturn std::nullopt;\n-\n-\tunsigned long value;\n-\n-\tif (!parseUnsignedInteger(obj.value_, std::numeric_limits<uint16_t>::max(),\n-\t\t\t\t  &value))\n-\t\treturn std::nullopt;\n-\n-\treturn value;\n-}\n-\n-template<>\n-std::optional<int32_t>\n-YamlObject::Getter<int32_t>::get(const YamlObject &obj) const\n-{\n-\tif (obj.type_ != Type::Value)\n-\t\treturn std::nullopt;\n-\n-\tlong value;\n-\n-\tif (!parseSignedInteger(obj.value_, std::numeric_limits<int32_t>::min(),\n-\t\t\t\tstd::numeric_limits<int32_t>::max(), &value))\n-\t\treturn std::nullopt;\n-\n-\treturn value;\n-}\n-\n-template<>\n-std::optional<uint32_t>\n-YamlObject::Getter<uint32_t>::get(const YamlObject &obj) const\n-{\n-\tif (obj.type_ != Type::Value)\n-\t\treturn std::nullopt;\n-\n-\tunsigned long value;\n-\n-\tif (!parseUnsignedInteger(obj.value_, std::numeric_limits<uint32_t>::max(),\n-\t\t\t\t  &value))\n-\t\treturn std::nullopt;\n-\n-\treturn value;\n-}\n+template struct YamlObject::Getter<int8_t>;\n+template struct YamlObject::Getter<uint8_t>;\n+template struct YamlObject::Getter<int16_t>;\n+template struct YamlObject::Getter<uint16_t>;\n+template struct YamlObject::Getter<int32_t>;\n+template struct YamlObject::Getter<uint32_t>;\n \n template<>\n std::optional<float>\n",
    "prefixes": []
}