Improve version checking to guarantee we can use legends

Author: alandefreitas

source/matplot/backend/gnuplot.cpp

@@ -271,10 +271,10 @@ namespace matplot::backend {
         return terminal_type;
     }
 
-    std::pair<int, int> gnuplot::gnuplot_version() {
-        static std::pair<int, int> version{0, 0};
+    std::tuple<int, int, int> gnuplot::gnuplot_version() {
+        static std::tuple<int, int, int> version{0, 0, 0};
         const bool dont_know_gnuplot_version_yet =
-            version == std::pair<int, int>({0, 0});
+            version == std::tuple<int, int, int>({0, 0, 0});
         if (dont_know_gnuplot_version_yet) {
             std::string version_str =
                 run_and_get_output("gnuplot --version 2>&1");
@@ -286,20 +286,30 @@ namespace matplot::backend {
                 version_str,
                 std::regex("[^]*gnuplot \\d+\\.(\\d+) patchlevel \\d+ *"),
                 "$1");
+            std::string version_patch = std::regex_replace(
+                version_str,
+                std::regex("[^]*gnuplot \\d+\\.\\d+ patchlevel (\\d+) *"),
+                "$1");
+            try {
+                std::get<0>(version) = std::stoi(version_major);
+            } catch (...) {
+                std::get<0>(version) = 0;
+            }
             try {
-                version.first = std::stoi(version_major);
+                std::get<1>(version) = std::stoi(version_minor);
             } catch (...) {
-                version.first = 0;
+                std::get<1>(version) = 0;
             }
             try {
-                version.second = std::stoi(version_minor);
+                std::get<2>(version) = std::stoi(version_patch);
             } catch (...) {
-                version.second = 0;
+                std::get<2>(version) = 0;
             }
             const bool still_dont_know_gnuplot_version =
-                version == std::pair<int, int>({0, 0});
+                version == std::tuple<int, int, int>({0, 0, 0});
             if (still_dont_know_gnuplot_version) {
-                version = std::pair<int, int>({5, 2});
+                // assume it's 5.2.6 by convention
+                version = std::tuple<int, int, int>({5, 2, 6});
             }
         }
         return version;

source/matplot/backend/gnuplot.h

@@ -8,6 +8,7 @@
 #include <array>
 #include <chrono>
 #include <matplot/backend/backend_interface.h>
+#include <tuple>
 
 namespace matplot::backend {
     class gnuplot : public backend_interface {
@@ -43,7 +44,7 @@ namespace matplot::backend {
 
         /// Identify the default terminal type in the system
         static std::string default_terminal_type();
-        static std::pair<int, int> gnuplot_version();
+        static std::tuple<int, int, int> gnuplot_version();
         static bool terminal_has_title_option(const std::string &t);
         static bool terminal_has_size_option(const std::string &t);
         static bool terminal_has_position_option(const std::string &t);

source/matplot/core/axes_type.cpp

@@ -667,8 +667,8 @@ namespace matplot {
         // Gnuplot version needs to be 5.2.6+ for keyentry
         bool ok = true;
         if (parent_->backend_->consumes_gnuplot_commands()) {
-            std::pair<int, int> v = backend::gnuplot::gnuplot_version();
-            if (v.first < 5 || v.second < 2) {
+            if (backend::gnuplot::gnuplot_version() <
+                std::tuple<int, int, int>{5, 2, 6}) {
                 ok = false;
             }
         }
@@ -798,7 +798,7 @@ namespace matplot {
                 } else if (is_3d()) {
                     auto v = backend::gnuplot::gnuplot_version();
                     const bool has_wall_option =
-                        v.first > 5 || (v.first == 5 && v.second >= 5);
+                        v < std::tuple<int, int, int>{5, 5, 0};
                     if (has_wall_option) {
                         run_command("set wall z0 fs transparent solid 0.5 "
                                     "border -1 fc 'slategray'");
@@ -884,8 +884,9 @@ namespace matplot {
             static bool msg_shown_once = false;
             // Gnuplot version needs to be 5.2.6+ for keyentry
             if (parent_->backend_->consumes_gnuplot_commands()) {
-                std::pair<int, int> v = backend::gnuplot::gnuplot_version();
-                if (v.first < 5 || v.second < 2) {
+                std::tuple<int, int, int> v =
+                    backend::gnuplot::gnuplot_version();
+                if (v < std::tuple<int, int, int>{5, 2, 6}) {
                     if (!msg_shown_once) {
                         std::cerr
                             << "You need gnuplot 5.2.6+ to include legends"

source/matplot/core/figure_type.cpp

@@ -629,7 +629,7 @@ namespace matplot {
         // with a rectangle workaround, which does not work well for 3d.
         static const auto v = backend::gnuplot::gnuplot_version();
         const bool has_wall_option =
-            v.first > 5 || (v.first == 5 && v.second >= 5);
+            std::get<0>(v) > 5 || (std::get<0>(v) == 5 && std::get<1>(v) >= 5);
         // So we only plot the default background if it's not 3d or version is
         // higher than 5.5. Otherwise, gnuplot won't be able to set the axes
         // colors.