/*
- smobs.hh -- declare smob related stuff.
+ This file is part of LilyPond, the GNU music typesetter.
- source file of the GNU LilyPond music typesetter
+ Copyright (C) 1999--2015 Han-Wen Nienhuys <hanwen@xs4all.nl>
- (c) 1999--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
+ LilyPond is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ LilyPond is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with LilyPond. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SMOBS_HH
#include "lily-guile.hh"
#include "warn.hh"
+#include <string>
/*
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:
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<Classname>.
+
+ 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 ()
For example,
- Complex_smob::Complex_smob () {
+ Complex_smob::Complex_smob : public Smob<Complex_smob> () {
scm_member_ = SCM_EOL;
smobify_self ();
scm_member_ = <..what you want to store..>
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);
- Common public methods to C++ smob objects:
+ Complex smobs are created by deriving from Smob<Classname>.
- unsmob (SCM x) - unpacks X and returns pointer to the C++ object, or 0
- if it has the wrong type.
+ CALLING INTERFACE
- SCM equal_p (SCM a, SCM b) - compare A and B. Returns a Scheme boolean
+ Common public methods to C++ smob objects:
+ - unsmob (SCM x) - unpacks X and returns pointer to the C++ object,
+ or 0 if it has the wrong type. This can be used as a boolean
+ condition at C++ level.
+ - smob_p (SCM x) returns #t or #f at Scheme level.
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 #<Classname> when printing.
+
+ - a static 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 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) \
- { \
- 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); \
+// 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 {
+public:
+ Scm_init () { }
+ Scm_init (void (*fun) (void))
+ {
+ add_scm_init_func (fun);
}
-
-#define DECLARE_TYPE_P(CL) extern SCM CL ## _type_p_proc
+};
+
+template <class Super>
+class Smob_base
+{
+ static scm_t_bits smob_tag_;
+ static Scm_init scm_init_;
+ static void init (void);
+ static string smob_name_;
+ static Super *unchecked_unsmob (SCM s)
+ {
+ return reinterpret_cast<Super *> (SCM_SMOB_DATA (s));
+ }
+protected:
+ // 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);
+ 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 *);
+ static int print_trampoline (SCM, SCM, scm_print_state *);
+
+ // type_p_name_ can be overriden in the Super class with a static
+ // const char [] string. This requires both a declaration in the
+ // class as well as a single instantiation outside. Using a
+ // template specialization for supplying a different string name
+ // right in Smob_base<Super> itself seems tempting, but the C++
+ // rules would then require a specialization declaration at the
+ // class definition site as well as a specialization instantiation
+ // in a single compilation unit. That requires just as much source
+ // code maintenance while being harder to understand and quite
+ // trickier in its failure symptoms when things go wrong. So we
+ // just use a static zero as "not here" indication.
+ static const int type_p_name_ = 0;
+
+ // LY_DECLARE_SMOB_PROC is used in the Super class definition for
+ // making a smob callable like a function. Declaration has to be
+ // public. It may be either be completed with a semicolon in which
+ // case a definition of the member function smob_proc has to be done
+ // outside of the class body, or the semicolon is left off and an
+ // inline function body is added immediately below. It would be
+ // nice if this were a non-static member function but it would seem
+ // tricky to do the required trampolining for unsmobbing the first
+ // argument of the callback and using it as a this pointer.
+#define LY_DECLARE_SMOB_PROC(REQ, OPT, VAR, ARGLIST) \
+ static const int smob_proc_signature_ = ((REQ)<<8)|((OPT)<<4)|(VAR); \
+ static SCM smob_proc ARGLIST
+
+ // a separate LY_DEFINE_SMOB_PROC seems sort of pointless as it
+ // would just result in SCM CLASS::smob_proc ARGLIST
+ //
+ // The default case without function functionality is recognized by
+ // smob_proc_signature being -1.
+ static const int smob_proc = 0;
+ static const int smob_proc_signature_ = -1;
+
+public:
+ 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;
+ }
+ static Super *unsmob (SCM s)
+ {
+ return is_smob (s) ? Super::unchecked_unsmob (s) : 0;
+ }
+};
+
+// Simple smobs
+template <class Super>
+class Simple_smob : public Smob_base<Super> {
+public:
+ static size_t free_smob (SCM obj)
+ {
+ delete Smob_base<Super>::unregister_ptr (obj);
+ return 0;
+ }
+ SCM smobbed_copy () const
+ {
+ Super *p = new Super(*static_cast<const Super *> (this));
+ return Smob_base<Super>::register_ptr (p);
+ }
+};
void protect_smob (SCM smob, SCM *prot_cons);
void unprotect_smob (SCM smob, SCM *prot_cons);
-extern bool parsed_objects_should_be_dead;
-
-#define ASSERT_LIVE_IS_ALLOWED() \
- static bool passed_here_once;\
- if (parsed_objects_should_be_dead && !passed_here_once) { \
- programming_error (string ("Parsed object should be dead: ") + __PRETTY_FUNCTION__ ); \
- passed_here_once = true;\
- }
+template <class Super>
+class Smob : public Smob_base<Super> {
+private:
+ SCM self_scm_;
+ SCM protection_cons_;
+ Smob (const Smob<Super> &); // Do not define! Not copyable!
+protected:
+ Smob () : self_scm_ (SCM_UNDEFINED), protection_cons_ (SCM_EOL) { };
+public:
+ static size_t free_smob (SCM obj)
+ {
+ delete Smob_base<Super>::unregister_ptr (obj);
+ return 0;
+ }
+ SCM unprotected_smobify_self ()
+ {
+ self_scm_ = Smob_base<Super>::register_ptr (static_cast<Super *> (this));
+ return self_scm_;
+ }
+ void protect ()
+ {
+ protect_smob (self_scm_, &protection_cons_);
+ }
+ SCM unprotect ()
+ {
+ unprotect_smob (self_scm_, &protection_cons_);
+ return self_scm_;
+ }
+ void smobify_self () {
+ self_scm_ = unprotected_smobify_self ();
+ protect ();
+ }
+ SCM self_scm () const { return self_scm_; }
+};
+extern bool parsed_objects_should_be_dead;
+class parsed_dead
+{
+ static vector<parsed_dead *> elements;
+ SCM data;
+ SCM readout_one ()
+ {
+ SCM res = data;
+ data = SCM_UNDEFINED;
+ return res;
+ }
+public:
+ parsed_dead () : data (SCM_UNDEFINED)
+ {
+ elements.push_back (this);
+ }
+ void checkin (SCM arg) { data = arg; }
+ static SCM readout ();
+};
+
+// 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(NDEBUG) && !GUILEV2
+#define ASSERT_LIVE_IS_ALLOWED(arg) \
+ do { \
+ static parsed_dead pass_here; \
+ if (parsed_objects_should_be_dead) \
+ pass_here.checkin (arg); \
+ } while (0)
+#else
+#define ASSERT_LIVE_IS_ALLOWED(arg) do { (void)(arg); } \
+ while (0)
+#endif
+
+#include "smobs.tcc"
#endif /* SMOBS_HH */
-
projects / lilypond.git / blobdiff