add cpp-peglib (#2059)

* add cpp-peglib

* use is_plat

* remove flag

* add flag

* improve is_plat

packages/c/cpp-peglib/xmake.lua

@@ -0,0 +1,39 @@
+package("cpp-peglib")
+
+    set_kind("library", {headeronly = true})
+    set_homepage("https://yhirose.github.io/cpp-peglib")
+    set_description("A single file C++ header-only PEG (Parsing Expression Grammars) library")
+    set_license("MIT")
+
+    set_urls("https://github.com/yhirose/cpp-peglib/archive/refs/tags/v$(version).tar.gz",
+             "https://github.com/yhirose/cpp-peglib.git")
+
+    add_versions("1.8.3", "3de8aeb44a262f9c2478e2a7e7bc2bb9426a2bdd176cf0654ff5a3d291c77b73")
+
+    on_install(function (package)
+        if package:is_plat("windows") then
+            package:add("cxxflags", "/Zc:__cplusplus")
+        end
+        os.cp("peglib.h", package:installdir("include"))
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            #include <peglib.h>
+            #include <assert.h>
+            using namespace peg;
+
+            void test() {
+                parser parser(R"(
+                    # Grammar for Calculator...
+                    Additive    <- Multitive '+' Additive / Multitive
+                    Multitive   <- Primary '*' Multitive / Primary
+                    Primary     <- '(' Additive ')' / Number
+                    Number      <- < [0-9]+ >
+                    %whitespace <- [ \t]*
+                  )");
+                
+                assert(static_cast<bool>(parser) == true);
+            }
+        ]]}, {configs = {languages = "c++17"}}))
+    end)