The Ring programming language version 1.10 book - Part 97 of 212
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The document discusses how to use the Ring code generator to wrap C/C++ libraries for use in Ring applications. It describes the configuration file format used as input to the generator, including how to specify function prototypes, constants, structures, and more. Example configuration files are provided, such as for the Allegro game library, to generate wrapper code.
The Ring programming language version 1.10 book - Part 97 of 212
- 1. CHAPTER EIGHTYFOUR CODE GENERATOR FOR WRAPPING C/C++ LIBRARIES In this chapter we will learn how to use the code generator to wrap C/C++ Libraries to use it in our Ring applications. 84.1 Using the tool The code generator program is parsec.ring that can be executed as any ring code using the ring language. URL : https://github.com/ring-lang/ring/tree/master/extensions/codegen for example to read a configuration file called test.cf to generate the source code file test.c run parsec.ring as in the next command ring parsec.ring test.cf test.c 84.2 Configuration file The configuration file (*.cf) is the input file that we pass to the code generator. This file determine the functions prototypes that we need to use from a C/C++ library. Writing configuration files is simple according to the next rules 84.3 Using the function prototype • To generate code that wraps a C function, we just write the C function prototype Example: ALLEGRO_DISPLAY *al_create_display(int w, int h) void al_destroy_display(ALLEGRO_DISPLAY *display) int al_get_new_display_flags(void) void al_set_new_display_flags(int flags) int al_get_new_display_option(int option, int *importance) The previous example will guide the code generator to generate 5 functions that wraps the al_create_display(), al_destroy_display(), al_get_new_display_flags(), al_set_new_diplay_flas() and al_get_new_display_option() func- tions. The generated code will be as in the next example 928
- 2. Ring Documentation, Release 1.10 RING_FUNC(ring_al_create_display) { if ( RING_API_PARACOUNT != 2 ) { RING_API_ERROR(RING_API_MISS2PARA); return ; } if ( ! RING_API_ISNUMBER(1) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } if ( ! RING_API_ISNUMBER(2) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } RING_API_RETCPOINTER(al_create_display( (int ) RING_API_GETNUMBER(1), (int ) RING_API_GETNUMBER(2)),"ALLEGRO_DISPLAY"); } RING_FUNC(ring_al_destroy_display) { if ( RING_API_PARACOUNT != 1 ) { RING_API_ERROR(RING_API_MISS1PARA); return ; } if ( ! RING_API_ISPOINTER(1) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } al_destroy_display((ALLEGRO_DISPLAY *) RING_API_GETCPOINTER(1,"ALLEGRO_DISPLAY")); } RING_FUNC(ring_al_get_new_display_flags) { if ( RING_API_PARACOUNT != 0 ) { RING_API_ERROR(RING_API_BADPARACOUNT); return ; } RING_API_RETNUMBER(al_get_new_display_flags()); } RING_FUNC(ring_al_set_new_display_flags) { if ( RING_API_PARACOUNT != 1 ) { RING_API_ERROR(RING_API_MISS1PARA); return ; } if ( ! RING_API_ISNUMBER(1) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } al_set_new_display_flags( (int ) RING_API_GETNUMBER(1)); } RING_FUNC(ring_al_get_new_display_option) 84.3. Using the function prototype 929
- 3. Ring Documentation, Release 1.10 { if ( RING_API_PARACOUNT != 2 ) { RING_API_ERROR(RING_API_MISS2PARA); return ; } if ( ! RING_API_ISNUMBER(1) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } if ( ! RING_API_ISSTRING(2) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } RING_API_RETNUMBER(al_get_new_display_option( (int ) RING_API_GETNUMBER(1), RING_API_GETINTPOINTER(2))); RING_API_ACCEPTINTVALUE(2) ; } from the previous example we can see how much of time and effort is saved using the Code Generator. 84.4 Adding code to the generated code • To generate code directly type it between <code> and </code> Example : <code> /* some C code will be written here */ </code> We use this feature when we need to do something without the help of the code generator. for example including header files and defining constants using Macro. 84.5 Prefix for Functions Names • To determine a prefix in all of the functions names type it between <funcstart> and </funcstart> for ex- ample when we wrap the Allegro game programming library and we need all of the library functions to start with “al” we type the next code in the configuration file <funcstart> al </funcstart> 84.6 Generate function to wrap structures • To generate functions that wrap structures (create/delete/get structure members) just type the structures names between <struct> and </struct> also after the structure name you can type the structure members between { } separated by comma. Example 84.4. Adding code to the generated code 930
- 4. Ring Documentation, Release 1.10 <struct> ALLEGRO_COLOR ALLEGRO_EVENT { type , keyboard.keycode , mouse.x , mouse.y } </struct> from the previous example we will generate two function to create/delete the structure ALLEGRO_COLOR Also we will generate two functions to create/delete the structure ALLEGRO_EVENT and four functions to get the structure ALLEGRO_EVENT members (type, keyboard.keycode, mouse.x, mouse.y). 84.7 Determine Structure Members Types You can determine the pointer name before the strucuture member name. Example: SDL_Surface {flags,SDL_PixelFormat *format,w,h,pitch,void *pixels} 84.8 Defining Constants You can define constants using <constant> and </constant> The generator will generate the required functions to get the constant values And will define the constants to be used with the same name in Ring code using *.rh file that will be generated too. rh = Ring Header Example: <constant> MIX_DEFAULT_FORMAT SDL_QUIT SDL_BUTTON_LEFT SDL_BUTTON_MIDDLE SDL_BUTTON_RIGHT </constant> Note: You will need to pass the *.rh file name to parsec.ring after the generated source file name. Example: ring ..codegenparsec.ring libsdl.cf ring_libsdl.c ring_libsdl.rh 84.9 Register New Functions We can register functions by typing the function prototype between <register> and </register> We need this feature only when we don’t provide the function prototype as input directly where we need to write the code of this function. Example: <register> void al_exit(void) </register> 84.7. Determine Structure Members Types 931
- 5. Ring Documentation, Release 1.10 <code> RING_FUNC(ring_al_exit) { if ( RING_API_PARACOUNT != 0 ) { RING_API_ERROR(RING_API_BADPARACOUNT); return ; } exit(0); } </code> In the previous example we register the al_exit() function. This function is not part of the Allegro Library, it’s just an extra function that we need to add. Then the code if this function is written inside <code> and </code>. This function call the exit() function from the C language library. 84.10 Writing comments in the configuration file • To type comments just type it between <comment> and </comment> Example: <comment> configuration files </comment> 84.11 Executing code during code generation • To ask from the code generator to execute Ring code during reading the configuration file, just write the code between <runcode> and </runcode> Example: <runcode> aNumberTypes + "al_fixed" </runcode> The previoud line of code add the string “al_fixed” to the list aNumberTypes, This list contains types that can be considered as numbers when the code generator find it in the function prototype. 84.12 Enum and Numbers We have the list aEnumTypes to use for adding each Enumeration we uses in the functions prototype. Example: <runcode> aNumberTypes + "qreal" aNumberTypes + "qint64" aEnumTypes + "Qt::GestureType" aEnumTypes + "Qt::GestureFlag" </runcode> 84.10. Writing comments in the configuration file 932
- 6. Ring Documentation, Release 1.10 84.13 Filtering using Expressions using <filter> and </filter> we can include/exclude parts of the configuration file based on a condition, for example <filter> iswindows() ... functions related to windows </filter> 84.14 Constants Type The default type for constant is Number But Some constants may be another type, for example (pointer : void *) before using <constant> and </constant> we can use <runcode> and </runcode> to determine the constant type using two global variables used by the code generator. The first variable is $nDefaultConstantType which can be * C_CONSTANT_TYPE_NUMBER * C_CONSTANT_TYPE_STRING * C_CONSTANT_TYPE_POINTER if we are using C_CONSTANT_TYPE_POINTER then we will need the second global variable which is $cDefault- ConstantPointerType to determine the pointer type. Example : The next example uses this feature to define constants in the FreeGLUT library <runcode> $nDefaultConstantType = C_CONSTANT_TYPE_POINTER $cDefaultConstantPointerType = "void" </runcode> <constant> GLUT_STROKE_ROMAN GLUT_STROKE_MONO_ROMAN GLUT_BITMAP_9_BY_15 GLUT_BITMAP_8_BY_13 GLUT_BITMAP_TIMES_ROMAN_10 GLUT_BITMAP_TIMES_ROMAN_24 GLUT_BITMAP_HELVETICA_10 GLUT_BITMAP_HELVETICA_12 GLUT_BITMAP_HELVETICA_18 </constant> 84.15 Configuration file for the Allegro Library The next configuration file enable us to use the Allegro library functions. The configuration file size is less than 1000 lines. when the code generator take this file as input the generated source code file in the C language will be 12000 lines of code! We can see this configuration file as a complete example about using the code generator Also we can use it to know the functions that can be used from RingAllegro when you use it to create 2D games! <code> #define ALLEGRO_NO_MAGIC_MAIN #include <allegro5/allegro.h> #include "allegro5/allegro_image.h" 84.13. Filtering using Expressions 933
- 7. Ring Documentation, Release 1.10 #include <allegro5/allegro_font.h> #include <allegro5/allegro_ttf.h> #include <allegro5/allegro_audio.h> #include <allegro5/allegro_acodec.h> #include <allegro5/allegro_opengl.h> #include <allegro5/allegro_direct3d.h> #include <allegro5/allegro_color.h> #include <allegro5/allegro_memfile.h> #include "allegro5/allegro_native_dialog.h" #include <allegro5/allegro_physfs.h> #include <allegro5/allegro_primitives.h> </code> <funcstart> al </funcstart> <struct> ALLEGRO_EVENT { type , keyboard.keycode , mouse.x , mouse.y } ALLEGRO_TIMEOUT ALLEGRO_SAMPLE_ID ALLEGRO_COLOR </struct> <register> void al_exit(void) </register> <code> RING_FUNC(ring_al_exit) { if ( RING_API_PARACOUNT != 0 ) { RING_API_ERROR(RING_API_BADPARACOUNT); return ; } exit(0); } </code> int al_init(void) <comment> configuration files </comment> <runcode> aNumberTypes + "al_fixed" </runcode> ALLEGRO_CONFIG *al_create_config(void) void al_destroy_config(ALLEGRO_CONFIG *config) ALLEGRO_CONFIG *al_load_config_file(const char *filename) ALLEGRO_CONFIG *al_load_config_file_f(ALLEGRO_FILE *file) bool al_save_config_file(const char *filename, const ALLEGRO_CONFIG *config) bool al_save_config_file_f(ALLEGRO_FILE *file, const ALLEGRO_CONFIG *config) void al_add_config_section(ALLEGRO_CONFIG *config, const char *name) Note: we just provided part of the configuration file, for complete copy check the Ring source code distribution. 84.15. Configuration file for the Allegro Library 934
- 8. Ring Documentation, Release 1.10 84.16 Threads Support Next, another part of the configutaiton file, it’s important because we can learn from it how to add threads to our Ring applications by using a threads library. The idea is using ring_vm_mutexfunctions() and ring_vm_runcodefromthread() to execute Ring code. <comment> Threads </comment> <code> void *al_func_thread(ALLEGRO_THREAD *thread, void *pPointer) { List *pList; VM *pVM; const char *cStr; pList = (List *) pPointer ; pVM = (VM *) ring_list_getpointer(pList,2); cStr = ring_list_getstring(pList,1); ring_vm_runcodefromthread(pVM,cStr); ring_list_delete(pList); return NULL; } RING_FUNC(ring_al_create_thread) { ALLEGRO_THREAD *pThread; List *pList; if ( RING_API_PARACOUNT != 1 ) { RING_API_ERROR(RING_API_MISS1PARA); return ; } if ( ! RING_API_ISSTRING(1) ) { RING_API_ERROR(RING_API_BADPARATYPE); return ; } pList = ring_list_new(0); ring_list_addstring(pList,RING_API_GETSTRING(1)); ring_list_addpointer(pList,pPointer); ring_vm_mutexfunctions((VM *) pPointer,al_create_mutex, al_lock_mutex,al_unlock_mutex,al_destroy_mutex); pThread = al_create_thread(al_func_thread, pList); al_start_thread(pThread); RING_API_RETCPOINTER(pThread,"ALLEGRO_THREAD"); } RING_FUNC(ring_al_run_detached_thread) { List *pList; if ( RING_API_PARACOUNT != 1 ) { RING_API_ERROR(RING_API_MISS1PARA); return ; } if ( ! RING_API_ISSTRING(1) ) { 84.16. Threads Support 935
- 9. Ring Documentation, Release 1.10 RING_API_ERROR(RING_API_BADPARATYPE); return ; } pList = ring_list_new(0); ring_list_addstring(pList,RING_API_GETSTRING(1)); ring_list_addpointer(pList,pPointer); ring_vm_mutexfunctions((VM *) pPointer,al_create_mutex, al_lock_mutex,al_unlock_mutex,al_destroy_mutex); al_run_detached_thread(al_func_thread, pList); } </code> <register> ALLEGRO_THREAD *al_create_thread(void) void al_run_detached_thread(void) </register> void al_start_thread(ALLEGRO_THREAD *thread) void al_join_thread(ALLEGRO_THREAD *thread, void **ret_value) void al_set_thread_should_stop(ALLEGRO_THREAD *thread) bool al_get_thread_should_stop(ALLEGRO_THREAD *thread) void al_destroy_thread(ALLEGRO_THREAD *thread) ALLEGRO_MUTEX *al_create_mutex(void) ALLEGRO_MUTEX *al_create_mutex_recursive(void) void al_lock_mutex(ALLEGRO_MUTEX *mutex) void al_unlock_mutex(ALLEGRO_MUTEX *mutex) void al_destroy_mutex(ALLEGRO_MUTEX *mutex) ALLEGRO_COND *al_create_cond(void) void al_destroy_cond(ALLEGRO_COND *cond) void al_wait_cond(ALLEGRO_COND *cond, ALLEGRO_MUTEX *mutex) 84.17 Code Generator Rules for Wrapping C++ Classes • We can define classes between <class> and </class> • Between <class> and <class> we set attributes like “name, nonew, para, parent, codename, passvmpointer, abstract and staticmethods” • we set the attributes using the style attributename:value or attributename only if no values are required • The “name” attribute determine the class name in C++ code and this name will be the default name in the Ring code • The nonew instruction means that we don’t need new/delete methods • The parent attribute determine the parent class name • The codename attribute determine another class name in C++ code • The passvmpoint instruction means passing the Ring VM pointer to the class constructor when we create new objects, this happens when we set the codename attribute to a class that we will define and this class need the Virtual Machine pointer (for example to use it to execute Ring code from C++ code). • The abstract instruction means that no new method is required for this class “no objects will be created”. • The staticmethods instruction means that method doesn’t need an object to be called. • Using <nodllstartup> we can avoid #include “ring.h”, We need this to write our startup code. • Using <libinitfunc> we can change the function name that register the library functions 84.17. Code Generator Rules for Wrapping C++ Classes 936
- 10. Ring Documentation, Release 1.10 • Using <ignorecpointertype> we can ignore pointer type check • Using the aStringTypes list when can defined new types that treated like const char * • Using the aBeforeReturn list when can define code that is inserted after the variable name when we return that variable from a function • Using the aNewMethodName list we can define another method name to be used in Ring code when we call the C++ method. this feature is required because some C++ method may be identical to Ring Keywords like “load”,”next”,”end” and “done”. • in method prototype - when we use @ in the method name, we mean that we have the same method with different parameters (As in C++) 84.18 Using configuration file that wrap C++ Library To run the code generator to generate code for using C++ library in the Ring application, we can do that as we did with using C libraries but here we will generate .cpp file instead of *.c file. Also we will determine another file to be generated (.ring). This file will contains classes in Ring code that wraps C++ functions for using C++ classes and objects. ring parsec.ring generatorqt.cf ring_qt.cpp ring_qt.ring 84.19 Configuration file for the Qt Framework The next configuration file is used to wrap many Qt classes The configuration file is around 3500 lines and generate C++ code around 56000 lines and generate also Ring code around 9000 lines. <nodllstartup> <libinitfunc> ring_qt_start <ignorecpointertype> <code> extern "C" { #include "ring.h" } #include "ring_qt.h" #include "gpushbutton.h" #include "gaction.h" #include "glineedit.h" #include "gtextedit.h" #include "glistwidget.h" #include "gtreeview.h" #include "gtreewidget.h" #include "gcombobox.h" #include "gtabwidget.h" #include "gtablewidget.h" #include "gprogressbar.h" #include "gspinbox.h" #include "gslider.h" #include "gdial.h" 84.18. Using configuration file that wrap C++ Library 937