2 This file is part of LilyPond, the GNU music typesetter.
4 Copyright (C) 1999--2012 Han-Wen Nienhuys <hanwen@xs4all.nl>
6 LilyPond is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 LilyPond is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with LilyPond. If not, see <http://www.gnu.org/licenses/>.
23 #include "lily-guile.hh"
27 Smobs are GUILEs mechanism of exporting C(++) objects to the Scheme
28 world. They are documented in the GUILE manual.
31 In LilyPond, smobs are created from C++ objects through macros.
32 There are two types of smob objects.
34 1. Simple smobs are intended for simple objects like numbers:
35 immutable objects that can be copied without change of meaning.
37 To obtain an SCM version of a simple smob, use the member function
40 Simple smobs are created by adding the
41 DECLARE_SIMPLE_SMOBS(Classname) to the declaration
43 2. Complex smobs are objects that have an identity. These objects
44 carry this identity in the form of a self_scm () method, which is a
45 SCM pointer to the object itself.
47 The constructor for a complex smob should have 3 steps:
49 * initialize all SCM members to an immediate value (like SCM_EOL)
51 * call smobify_self ()
53 * initialize SCM members
57 Complex_smob::Complex_smob () {
58 scm_member_ = SCM_EOL;
60 scm_member_ = <..what you want to store..>
63 after construction, the self_scm () field of a complex smob is
64 protected from Garbage Collection. This protection should be
65 removed once the object is put into another (reachable) Scheme data
68 Complex_smob *p = new Complex_smob;
69 list = scm_cons (p->self_scm (), list);
72 Since unprotect returns the SCM object itself, this particular case
75 Complex_smob *p = new Complex_smob;
76 list = scm_cons (p->unprotect (), list);
78 Complex smobs are made with DECLARE_SMOBS (Classname) in the class
83 Common public methods to C++ smob objects:
85 unsmob (SCM x) - unpacks X and returns pointer to the C++ object, or 0
86 if it has the wrong type.
88 SCM equal_p (SCM a, SCM b) - compare A and B. Returns a Scheme boolean
93 For implementating a class, the following should be provided
95 - an equal_p () function (a default is in the
96 IMPLEMENT_DEFAULT_EQUAL_P macro in ly-smobs.icc)
98 - mark_smob () function, that calls scm_gc_mark () on all Scheme
101 - a print_smob () function, that displays a representation for
104 - A call to one of the IMPLEMENT_SMOBS or IMPLEMENT_SIMPLE_SMOBS macros
105 from file "ly-smobs.icc"
108 #define DECLARE_SIMPLE_SMOBS(CL) \
110 SCM smobbed_copy () const; \
111 DECLARE_BASE_SMOBS (CL)
113 #define DECLARE_BASE_SMOBS(CL) \
114 friend class Non_existent_class; \
116 static const char* smob_name_; \
117 static scm_t_bits smob_tag_; \
118 static SCM mark_smob (SCM); \
119 static size_t free_smob (SCM s); \
120 static int print_smob (SCM s, SCM p, scm_print_state*); \
122 static SCM equal_p (SCM a, SCM b); \
123 static CL *unsmob (SCM s) __attribute__((pure)) \
125 if (SCM_NIMP (s) && SCM_CELL_TYPE (s) == smob_tag_) \
126 return (CL *) SCM_CELL_WORD_1 (s); \
130 static SCM smob_p (SCM); \
131 static void init_smobs (); \
134 #define DECLARE_SMOBS(CL) \
135 DECLARE_BASE_SMOBS (CL) \
138 SCM unprotected_smobify_self (); \
140 void smobify_self (); \
142 SCM protection_cons_; \
146 SCM self_scm () const { return self_scm_; } \
149 #define DECLARE_UNSMOB(CL, name) \
151 unsmob_ ## name (SCM s) \
153 return CL::unsmob (s); \
156 #define DECLARE_TYPE_P(CL) extern SCM CL ## _type_p_proc
158 void protect_smob (SCM smob, SCM *prot_cons);
159 void unprotect_smob (SCM smob, SCM *prot_cons);
161 extern bool parsed_objects_should_be_dead;
164 static vector<parsed_dead *> elements;
169 data = SCM_UNDEFINED;
173 parsed_dead () : data (SCM_UNDEFINED)
175 elements.push_back (this);
177 void checkin (SCM arg) { data = arg; }
178 static SCM readout ();
182 #define ASSERT_LIVE_IS_ALLOWED(arg) \
184 static parsed_dead pass_here; \
185 if (parsed_objects_should_be_dead) \
186 pass_here.checkin (arg); \
189 #define ASSERT_LIVE_IS_ALLOWED(arg) do { } \
193 #endif /* SMOBS_HH */