#pragma region _Generic Macros // ____ _ ______ _ _ ____ _ __ _ // / ___} (_) | ____} | | (_) / __ \ | | | |(_) // | | ___ ___ _ __ ___ _ __ _ ___ | |__ _ _ _ __ ___| |_ _ ___ _ __ | | | |_ _____ _ __ | | ___ __ _ __| | _ _ __ __ _ // | |{__ |/ _ \ '_ \ / _ \ '__} |/ __| | __} | | | '_ \ / __} __} |/ _ \| '_ \ | | | \ \ / / _ \ '_ \| |/ _ \ / _` |/ _` || | '_ \ / _` | // | |__j | __/ | | | __/ | | | (__ | | | |_| | | | | (__| l_| | (_) | | | | | l__| |\ V / __/ | | | | (_) | (_| | (_| || | | | | (_| | // \____/ \___}_l l_l\___}_l l_l\___| l_l \__,_l_l l_l\___}\__}_l\___/l_l l_l \____/ \_/ \___}_l l_l_l\___/ \__,_l\__,_l|_|_| |_|\__, | // This implemnents macros for utilizing "The Naive Extendible _Generic Macro" explained in: __| | // https://github.com/JacksonAllan/CC/blob/main/articles/Better_C_Generics_Part_1_The_Extendible_Generic.md {___/ // Since gencpp is used to generate the c-library, it was choosen over the more novel implementations to keep the macros as easy to understand and unobfuscated as possible. #define GEN_COMMA_OPERATOR , // The comma operator is used by preprocessor macros to delimit arguments, so we have to represent it via a macro to prevent parsing incorrectly. // Helper macros for argument selection #define GEN_SELECT_ARG_1( _1, ... ) _1 // <-- Of all th args passed pick _1. #define GEN_SELECT_ARG_2( _1, _2, ... ) _2 // <-- Of all the args passed pick _2. #define GEN_SELECT_ARG_3( _1, _2, _3, ... ) _3 // etc.. #define GEN_GENERIC_SEL_ENTRY_TYPE GEN_SELECT_ARG_1 // Use the arg expansion macro to select arg 1 which should have the type. #define GEN_GENERIC_SEL_ENTRY_FUNCTION GEN_SELECT_ARG_2 // Use the arg expansion macro to select arg 2 which should have the function. #define GEN_GENERIC_SEL_ENTRY_COMMA_DELIMITER GEN_SELECT_ARG_3 // Use the arg expansion macro to select arg 3 which should have the comma delimiter ','. #define GEN_RESOLVED_FUNCTION_CALL // Just used to indicate where the call "occurs" // ---------------------------------------------------------------------------------------------------------------------------------- // GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( macro ) includes a _Generic slot only if the specified macro is defined (as type, function_name). // It takes advantage of the fact that if the macro is defined, then the expanded text will contain a comma. // Expands to ',' if it can find (type): (function) // Where GEN_GENERIC_SEL_ENTRY_COMMA_DELIMITER is specifically looking for that , #define GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( slot_exp ) GEN_GENERIC_SEL_ENTRY_COMMA_DELIMITER( slot_exp, GEN_GENERIC_SEL_ENTRY_TYPE( slot_exp, ): GEN_GENERIC_SEL_ENTRY_FUNCTION( slot_exp, ) GEN_COMMA_OPERATOR, , ) // ^ Selects the comma ^ is the type ^ is the function ^ Insert a comma // The slot won't exist if that comma is not found. | // For the occastion where an expression didn't resolve to a selection option the "default: " will be set to: typedef struct GENCPP_NO_RESOLVED_GENERIC_SELECTION GENCPP_NO_RESOLVED_GENERIC_SELECTION; struct GENCPP_NO_RESOLVED_GENERIC_SELECTION { void* _THE_VOID_SLOT_; }; GENCPP_NO_RESOLVED_GENERIC_SELECTION const gen_generic_selection_fail = {0}; // Which will provide the message: error: called object type 'struct NO_RESOLVED_GENERIC_SELECTION' is not a function or function pointer // ---------------------------------------------------------------------------------------------------------------------------------- // Below are generated on demand for an overlaod depdendent on a type: // ---------------------------------------------------------------------------------------------------------------------------------- #define GEN_FUNCTION_GENERIC_EXAMPLE( selector_arg ) _Generic( \ (selector_arg), /* Select Via Expression*/ \ /* Extendibility slots: */ \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( FunctionID__ARGS_SIG_1 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( FunctionID__ARGS_SIG_1 ) \ default: gen_generic_selection_fail \ ) GEN_RESOLVED_FUNCTION_CALL( selector_arg ) // ---------------------------------------------------------------------------------------------------------------------------------- // Then each definiton of a function has an associated define: #// #define GENERIC_SLOT_<#>_ , // Then somehwere later on // ( ) { } // Concrete example: // To add support for long: #define GENERIC_SLOT_1_gen_example_hash long, gen_example_hash__P_long size_t gen_example_hash__P_long( long val ) { return val * 2654435761ull; } // To add support for long long: #define GENERIC_SLOT_2_gen_example_hash long long, gen_example_hash__P_long_long size_t gen_example_hash__P_long_long( long long val ) { return val * 2654435761ull; } // If using an Editor with support for syntax hightlighting macros: HASH__ARGS_SIG_1 and HASH_ARGS_SIG_2 should show color highlighting indicating the slot is enabled, // or, "defined" for usage during the compilation pass that handles the _Generic instrinsic. #define gen_hash_example( function_arguments ) _Generic( \ (function_arguments), /* Select Via Expression*/ \ /* Extendibility slots: */ \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_1 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_2 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_3 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_4 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_5 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_6 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_7 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( HASH__ARGS_SIG_8 ) \ default: gen_generic_selection_fail \ ) GEN_RESOLVED_FUNCTION_CALL( function_arguments ) // Additional Variations: // If the function takes more than one argument the following is used: #define GEN_FUNCTION_GENERIC_EXAMPLE_VARADIC( selector_arg, ... ) _Generic( \ (selector_arg), \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( FunctionID__ARGS_SIG_1 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( FunctionID__ARGS_SIG_2 ) \ /* ... */ \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT(FunctionID__ARGS_SIG_N ) \ default: gen_generic_selection_fail \ ) GEN_RESOLVED_FUNCTION_CALL( selector_arg, __VA_ARG__ ) // If the function does not take the arugment as a parameter: #define GEN_FUNCTION_GENERIC_EXAMPLE_DIRECT_TYPE( selector_arg ) _Generic( \ ( GEN_TYPE_TO_EXP(selector_arg) ), \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( FunctionID__ARGS_SIG_1 ) \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT( FunctionID__ARGS_SIG_2 ) \ /* ... */ \ GEN_IF_MACRO_DEFINED_INCLUDE_THIS_SLOT(FunctionID__ARGS_SIG_N ) \ default: gen_generic_selection_fail \ ) GEN_RESOLVED_FUNCTION_CALL() // Used to keep the _Generic keyword happy as bare types are not considered "expressions" #define GEN_TYPE_TO_EXP(type) (* (type*)NULL) // Instead of using this macro, you'll see it directly expanded by the code generation. // typedef void* GEN_GenericExampleType; // GEN_FUNCTION_GENERIC_EXAMPLE_DIRECT_TYPE( GEN_GenericExampleType ); #pragma endregion _Generic Macros