Method to_svg

imperative/src/impl/profiler/memory_chunk.cpp:121–234

    }

    XMLWriter to_svg() const {
        using namespace std::chrono_literals;
        XMLWriter writer;
        auto&& [addr_begin, addr_end] = address_range();
        auto&& [time_begin, time_end] = time_range();
        writer.doctype(
                "svg", "PUBLIC",
                {"\"-//W3C//DTD SVG 1.1//EN\"",
                 "\"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\""});
        auto svg = writer.element("svg");
        svg.attr("xmlns", std::string{"http://www.w3.org/2000/svg"});
        svg.attr("xmlns:tag", std::string{"https://megengine.org.cn"});
        auto time_scale = 100us;
        double addr_scale = 1e6;
        svg.attr("width", (time_end - time_begin) / time_scale);
        svg.attr("height", (addr_end - addr_begin) / addr_scale);
        {
            auto rect = writer.element("rect");
            rect.attr("x", 0);
            rect.attr("y", 0);
            rect.attr("width", (time_end - time_begin) / time_scale);
            rect.attr("height", (addr_end - addr_begin) / addr_scale);
            rect.attr("fill", std::string{"blue"});
        }
        double us = 1e3, ms = 1e6;
        std::map<double, std::string> time2color = {
                {0 * us, "#DDDDDD"},
                {100 * us, "#CCCCCC"},
                {1 * ms, "#BBBBBB"},
                {10 * ms, "#AAAAAA"},
                {100 * ms, "#999999"},
                {1000 * ms, "#888888"},
                {std::numeric_limits<double>::infinity(), "#555555"},
        };
        auto time2str = [](profiler::Duration ns) {
            using pair_t = std::pair<uint64_t, const char*>;
            static pair_t units[] = {
                    {1, "ns "},
                    {1e3, "us "},
                    {1e6, "ms "},
                    {1e9, "s "},
            };
            std::string builder;
            auto comparator = [](const pair_t& lhs, const pair_t& rhs) {
                return lhs.first < rhs.first;
            };
            while (ns.count() > 0) {
                auto iter = std::upper_bound(
                                    std::begin(units), std::end(units),
                                    std::make_pair(ns.count(), ""), comparator) -
                            1;
                builder += std::to_string(ns.count() / iter->first) + iter->second;
                ns = ns % iter->first;
            }
            return builder;
        };
        auto size2str = [](size_t sz) {
            using pair_t = std::pair<size_t, const char*>;