X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Finclude%2Fsmobs.hh;h=00217866dc07dc92eff400e23050d50b46f67a3b;hb=5d84bfad4626892bcffd05adcced53c8a2329047;hp=cd28a29c3f0af531de7cb954f65e538fb1c80b02;hpb=2da5c55cf0a968982223682227a0cf3b019d03a8;p=lilypond.git diff --git a/lily/include/smobs.hh b/lily/include/smobs.hh index cd28a29c3f..00217866dc 100644 --- a/lily/include/smobs.hh +++ b/lily/include/smobs.hh @@ -1,7 +1,7 @@ /* This file is part of LilyPond, the GNU music typesetter. - Copyright (C) 1999--2012 Han-Wen Nienhuys + Copyright (C) 1999--2015 Han-Wen Nienhuys LilyPond is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -21,14 +21,19 @@ #define SMOBS_HH #include "lily-guile.hh" +#include "lily-proto.hh" #include "warn.hh" +#include /* Smobs are GUILEs mechanism of exporting C(++) objects to the Scheme world. They are documented in the GUILE manual. - In LilyPond, smobs are created from C++ objects through macros. + In LilyPond, C++ objects can be placed under the control of GUILE's + type system and garbage collection mechanism by inheriting from one + of several Smob base classes. + There are two types of smob objects. 1. Simple smobs are intended for simple objects like numbers: @@ -37,16 +42,29 @@ To obtain an SCM version of a simple smob, use the member function SCM smobbed_copy (). - Simple smobs are created by adding the - DECLARE_SIMPLE_SMOBS(Classname) to the declaration + Simple smobs are created by deriving from Simple_smob. + + A simple smob is only optionally under the reign of the GUILE + garbage collector: its usual life time is that of a normal C++ + object. While a smobbed_copy () is fully under control of the + garbage collector and will have its mark_smob function called during + garbage collection, an automatic variable of this type will not have + mark_smob called, but rather have its memory image in the call stack + scanned for contained non-immediate SCM values. Anything requiring + more complex mark_smob behavior is not suitable for a simple smob. + + When you create a smobbed_copy, the _copy_ is fully managed by the + GUILE memory system. As a corollary, multiple smobbed_copy calls + yield multiple GUILE objects generally not eq? to each other. 2. Complex smobs are objects that have an identity. These objects carry this identity in the form of a self_scm () method, which is a - SCM pointer to the object itself. + SCM pointer to the object itself. Complex smobs are always under + control of the GUILE memory system. The constructor for a complex smob should have 3 steps: - * initialize all SCM members to a non-immediate value (like SCM_EOL) + * initialize all SCM members to an immediate value (like SCM_EOL) * call smobify_self () @@ -54,7 +72,7 @@ For example, - Complex_smob::Complex_smob () { + Complex_smob::Complex_smob : public Smob () { scm_member_ = SCM_EOL; smobify_self (); scm_member_ = <..what you want to store..> @@ -67,91 +85,265 @@ Complex_smob *p = new Complex_smob; list = scm_cons (p->self_scm (), list); - scm_gc_unprotect_object (p->self_scm ()); + p->unprotect (); - Complex smobs are made with DECLARE_SMOBS (Classname) in the class - declaration. + Since unprotect returns the SCM object itself, this particular case + can be written as - CALLING INTERFACE + Complex_smob *p = new Complex_smob; + list = scm_cons (p->unprotect (), list); + + Complex smobs are created by deriving from Smob. + + However, this is not sufficient when classes with their own + protectable elements are derived from the Complex base class. This + is because initialization order is a tricky thing: once a base class + calls smobify_self () in its constructor, further allocations during + construction of base class and derived classes might lead to + mark_smob calls on the object under construction. When those call a + virtual function like derived_mark, the virtual function + corresponding to the incompletely initialized object of derived + class type is likely to be called. + + The order of initialization of an object consists in calling the + constructors of virtual base classes, then of non-virtual base + classes, then initializing all data members. - Common public methods to C++ smob objects: + As a result, the constructor of a derived class comes too late for + initialization of data members that may be accessed in the + derived_mark kind of functions. - unsmob (SCM x) - unpacks X and returns pointer to the C++ object, or 0 - if it has the wrong type. + Such data members are consequently moved into Preinit_* classes + which come before the smobifying base class in derivation order and + construct the contained data members in a state suitable for + derived_mark calls. - SCM equal_p (SCM a, SCM b) - compare A and B. Returns a Scheme boolean + CALLING INTERFACE + + Common global functions for accessing C++ smob objects: + + - unsmob (SCM x) - unpack X and return a pointer to the C++ object, + or 0 if it has the wrong type. IMPLEMENTATION - For implementating a class, the following should be provided + For implementating a class, the following public members can be + provided in the top class itself: - - an equal_p () function (a default is in the - IMPLEMENT_DEFAULT_EQUAL_P macro in ly-smobs.icc) + - SCM equal_p (SCM a, SCM b) - compare A and B. Returns a Scheme + boolean. If the class does not define this function, equal? will + be equivalent to eq?. The function will only be called when both + objects are of the respective type and not eq? to each other. - mark_smob () function, that calls scm_gc_mark () on all Scheme - objects in the class + objects in the class. If the class does not define this function, + it must not contain non-immediate Scheme values. - a print_smob () function, that displays a representation for - debugging purposes + debugging purposes. If the class does not define this function, + the output will be # when printing. + + - a static const * const type_p_name_ string set to something like + "ly:grob?". When provided, an accordingly named function for + checking for the given smob type will be available in Scheme. - - A call to one of the IMPLEMENT_SMOBS or IMPLEMENT_SIMPLE_SMOBS macros - from file "ly-smobs.icc" */ -#define DECLARE_SIMPLE_SMOBS(CL) \ - public: \ - SCM smobbed_copy () const; \ - DECLARE_BASE_SMOBS (CL) - -#define DECLARE_BASE_SMOBS(CL) \ - friend class Non_existent_class; \ - private: \ - static const char* smob_name_; \ - static scm_t_bits smob_tag_; \ - static SCM mark_smob (SCM); \ - static size_t free_smob (SCM s); \ - static int print_smob (SCM s, SCM p, scm_print_state*); \ - public: \ - static SCM equal_p (SCM a, SCM b); \ - static CL *unsmob (SCM s) __attribute__((pure)) \ - { \ - if (SCM_NIMP (s) && SCM_CELL_TYPE (s) == smob_tag_) \ - return (CL *) SCM_CELL_WORD_1 (s); \ - else \ - return 0; \ - } \ - static SCM smob_p (SCM); \ - static void init_smobs (); \ - private: - -#define DECLARE_SMOBS(CL) \ - DECLARE_BASE_SMOBS (CL) \ - protected: \ - virtual ~CL (); \ - SCM unprotected_smobify_self (); \ - private: \ - void smobify_self (); \ - SCM self_scm_; \ - SCM protection_cons_; \ - public: \ - SCM unprotect (); \ - void protect (); \ - SCM self_scm () const { return self_scm_; } \ - private: - -#define DECLARE_UNSMOB(CL, name) \ - inline CL * \ - unsmob_ ## name (SCM s) \ - { \ - return CL::unsmob (s); \ - } - -#define DECLARE_TYPE_P(CL) extern SCM CL ## _type_p_proc +// Initialization class. Create a variable or static data member of +// this type at global scope (or creation will happen too late for +// Scheme initialization), initialising with a function to be called. +// Reference somewhere (like in the constructor of the containing +// class) to make sure the variable is actually instantiated. + +class Scm_init { + static const Scm_init * list_; + void (*const fun_)(void); + Scm_init const * const next_; + Scm_init (); // don't use default constructor, don't define + Scm_init (const Scm_init &); // don't define copy constructor +public: + Scm_init (void (*fun) (void)) : fun_ (fun), next_ (list_) + { list_ = this; } + static void init (); +}; + +template +class Smob_base +{ + static scm_t_bits smob_tag_; + static Scm_init scm_init_; + static void init (void); + static string smob_name_; +protected: + static Super *unchecked_unsmob (SCM s) + { + return reinterpret_cast (SCM_SMOB_DATA (s)); + } + // reference scm_init_ in smob_tag which is sure to be called. The + // constructor, in contrast, may not be called at all in classes + // like Smob1. + static scm_t_bits smob_tag () { (void) scm_init_; return smob_tag_; } + Smob_base () { } + static SCM register_ptr (Super *p); + static Super *unregister_ptr (SCM obj); +private: + // Those fallbacks are _only_ for internal use by Smob_base. They + // are characterized by no knowledge about the implemented type + // apart from the type's name. Overriding them as a template + // specialization is _not_ intended since a type-dependent + // implementation will in general need access to possibly private + // parts of the Super class. So any class-dependent override should + // be done by redefining the respective function in the Super class + // (where it will mask the private template member) rather than + // specializing a different template function/pointer. + // + // Most default functions are do-nothings. void init() will + // recognize their address when not overriden and will then refrain + // altogether from passing the the respective callbacks to GUILE. + + SCM mark_smob (void) const; + static SCM mark_trampoline (SCM); // Used for calling mark_smob + static size_t free_smob (SCM obj); + static SCM equal_p (SCM, SCM); + int print_smob (SCM, scm_print_state *) const; + static int print_trampoline (SCM, SCM, scm_print_state *); + static void smob_proc_init (scm_t_bits) { }; + + // Define type_p_name_ in the Super class as a const char * const. + // Without such definition it defaults to 0, producing no predicate. + + static const char * const type_p_name_; // = 0 + + // LY_DECLARE_SMOB_PROC is used in the Super class definition for + // making a smob callable like a function. Its first argument is a + // function member pointer constant, to a function taking the + // correct number of SCM arguments and returning SCM. The function + // itself has to be defined separately. + +#define LY_DECLARE_SMOB_PROC(PMF, REQ, OPT, VAR) \ + static void smob_proc_init (scm_t_bits smob_tag) \ + { \ + scm_set_smob_apply (smob_tag, \ + (scm_t_subr)smob_trampoline, \ + REQ, OPT, VAR); \ + } + + // Well, function template argument packs are a C++11 feature. So + // we just define a bunch of trampolines manually. It turns out + // that GUILE 1.8.8 cannot actually make callable structures with + // more than 3 arguments anyway. That's surprising, to say the + // least, but in emergency situations one can always use a "rest" + // argument and take it apart manually. + + template + static SCM smob_trampoline (SCM self) + { + return (Super::unchecked_unsmob (self)->*pmf)(); + } + template + static SCM smob_trampoline (SCM self, SCM arg1) + { + return (Super::unchecked_unsmob (self)->*pmf)(arg1); + } + template + static SCM smob_trampoline (SCM self, SCM arg1, SCM arg2) + { + return (Super::unchecked_unsmob (self)->*pmf)(arg1, arg2); + } + template + static SCM smob_trampoline (SCM self, SCM arg1, SCM arg2, SCM arg3) + { + return (Super::unchecked_unsmob (self)->*pmf)(arg1, arg2, arg3); + } + + static bool is_smob (SCM s) + { + return SCM_SMOB_PREDICATE (smob_tag (), s); + } + static SCM smob_p (SCM s) + { + return is_smob (s) ? SCM_BOOL_T : SCM_BOOL_F; + } + + template + friend T *unsmob (SCM s); + + template + friend T *ly_assert_smob (SCM s, int number, const char *fun); +}; + +template +inline T *unsmob (SCM s) +{ + return T::is_smob (s) ? dynamic_cast (T::unchecked_unsmob (s)) : 0; +} + +// Simple smobs +template +class Simple_smob : public Smob_base { +public: + static size_t free_smob (SCM obj) + { + delete Smob_base::unregister_ptr (obj); + return 0; + } + SCM smobbed_copy () const + { + Super *p = new Super(*static_cast (this)); + return Smob_base::register_ptr (p); + } +}; void protect_smob (SCM smob, SCM *prot_cons); void unprotect_smob (SCM smob, SCM *prot_cons); +// The Smob_core class is not templated and contains material not +// depending on the Super class. + +class Smob_core { +protected: + SCM self_scm_; + Smob_core () : self_scm_ (SCM_UNDEFINED) { }; +public: + SCM self_scm () const { return self_scm_; } + Listener get_listener (SCM callback); +}; + +template +class Smob : public Smob_core, public Smob_base { +private: + SCM protection_cons_; + Smob (const Smob &); // Do not define! Not copyable! +protected: + Smob () : protection_cons_ (SCM_EOL) { }; +public: + static size_t free_smob (SCM obj) + { + delete Smob_base::unregister_ptr (obj); + return 0; + } + SCM unprotected_smobify_self () + { + SCM s = Smob_base::register_ptr (static_cast (this)); + self_scm_ = s; + return s; + } + void protect () + { + protect_smob (self_scm_, &protection_cons_); + } + void smobify_self () { + protect_smob (unprotected_smobify_self (), &protection_cons_); + } + SCM unprotect () + { + SCM s = self_scm_; + unprotect_smob (s, &protection_cons_); + return s; + } +}; + extern bool parsed_objects_should_be_dead; class parsed_dead { @@ -172,7 +364,12 @@ public: static SCM readout (); }; -#ifndef NDEBUG +// This does not appear to work with GUILEv2's garbage collector: +// Objects are found in the GC phase but printing them will crash at +// least some, so they are apparently not protected in spite of being +// included in the GC scans. So it would appear that scanning smobs +// is not equivalent to marking them. Ugh. +#if defined(DEBUG) && !GUILEV2 #define ASSERT_LIVE_IS_ALLOWED(arg) \ do { \ static parsed_dead pass_here; \ @@ -180,9 +377,9 @@ public: pass_here.checkin (arg); \ } while (0) #else -#define ASSERT_LIVE_IS_ALLOWED(arg) do { } \ +#define ASSERT_LIVE_IS_ALLOWED(arg) do { (void)(arg); } \ while (0) #endif +#include "smobs.tcc" #endif /* SMOBS_HH */ -