add scnlib (#673)

packages/s/scnlib/xmake.lua

@@ -0,0 +1,39 @@
+package("scnlib")
+
+    set_homepage("https://scnlib.readthedocs.io/")
+    set_description("scnlib is a modern C++ library for replacing scanf and std::istream")
+
+    set_urls("https://github.com/eliaskosunen/scnlib/archive/refs/tags/v$(version).zip")
+    add_versions("0.4", "49a84f1439e52666532fbd5da3fa1d652622fc7ac376070e330e15c528d38190")
+
+    add_configs("header_only", {description = "Use header only version.", default = false, type = "boolean"})
+
+    on_load(function (package)
+        if package:config("header_only") then
+            package:add("defines", "SCN_HEADER_ONLY=1")
+        else
+            package:add("deps", "cmake")
+        end
+    end)
+
+    on_install(function (package)
+        if package:config("header_only") then
+            os.cp("include/scn", package:installdir("include"))
+            return
+        end
+        local configs = {"-DSCN_TESTS=OFF", "-DSCN_DOCS=OFF", "-DSCN_EXAMPLES=OFF", "-DSCN_BENCHMARKS=OFF", "-DSCN_PENDANTIC=OFF", "-DSCN_BUILD_FUZZING=OFF"}
+        import("package.tools.cmake").install(package, configs)
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            #include <scn/scn.h>
+            #include <cstdio>
+
+            static void test() {
+                int i;
+                scn::prompt("What's your favorite number? ", "{}", i);
+                printf("Oh, cool, %d!", i);
+            }
+        ]]}, {configs = {languages = "c++17"}, includes = "scn/scn.h"}))
+    end)