Add luaL_checkboolean and luaL_optboolean (#221)

Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>

VM/include/lualib.h

@@ -25,6 +25,9 @@ LUALIB_API const char* luaL_optlstring(lua_State* L, int numArg, const char* def
 LUALIB_API double luaL_checknumber(lua_State* L, int numArg);
 LUALIB_API double luaL_optnumber(lua_State* L, int nArg, double def);
 
+LUALIB_API int luaL_checkboolean(lua_State* L, int narg);
+LUALIB_API int luaL_optboolean(lua_State* L, int narg, int def);
+
 LUALIB_API int luaL_checkinteger(lua_State* L, int numArg);
 LUALIB_API int luaL_optinteger(lua_State* L, int nArg, int def);
 LUALIB_API unsigned luaL_checkunsigned(lua_State* L, int numArg);

VM/src/laux.cpp

@@ -183,6 +183,22 @@ LUALIB_API double luaL_optnumber(lua_State* L, int narg, double def)
     return luaL_opt(L, luaL_checknumber, narg, def);
 }
 
+LUALIB_API int luaL_checkboolean(lua_State* L, int narg)
+{
+    // This checks specifically for boolean values, ignoring
+    // all other truthy/falsy values. If the desired result
+    // is true if value is present then lua_toboolean should
+    // directly be used instead.
+    if (!lua_isboolean(L, narg))
+        tag_error(L, narg, LUA_TBOOLEAN);
+    return lua_toboolean(L, narg);
+}
+
+LUALIB_API int luaL_optboolean(lua_State* L, int narg, int def)
+{
+    return luaL_opt(L, luaL_checkboolean, narg, def);
+}
+
 LUALIB_API int luaL_checkinteger(lua_State* L, int narg)
 {
     int isnum;

tests/Conformance.test.cpp

@@ -524,7 +524,7 @@ TEST_CASE("Debugger")
                 L,
                 [](lua_State* L) -> int {
                     int line = luaL_checkinteger(L, 1);
-                    bool enabled = lua_isboolean(L, 2) ? lua_toboolean(L, 2) : true;
+                    bool enabled = luaL_optboolean(L, 2, true);
 
                     lua_Debug ar = {};
                     lua_getinfo(L, 1, "f", &ar);