2 context-property.cc -- implement manipulation of immutable Grob
5 source file of the GNU LilyPond music typesetter
7 (c) 2004--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
11 #include "engraver.hh"
12 #include "international.hh"
15 #include "simple-closure.hh"
21 general_pushpop_property (Context *context,
23 SCM grob_property_path,
27 if (!scm_is_symbol (context_property)
28 || !scm_is_symbol (scm_car (grob_property_path)))
30 warning (_ ("need symbol arguments for \\override and \\revert"));
31 if (do_internal_type_checking_global)
35 execute_general_pushpop_property (context, context_property,
36 grob_property_path, new_value);
42 Grob descriptions (ie. alists with layout properties) are
43 represented as a (ALIST . BASED-ON) pair, where BASED-ON is the
44 alist defined in a parent context. BASED-ON should always be a tail
47 Push or pop (depending on value of VAL) a single entry entry from a
48 translator property list by name of PROP. GROB_PROPERTY_PATH
49 indicates nested alists, eg. '(beamed-stem-lengths details)
55 execute_override_property (Context *context,
57 SCM grob_property_path,
60 SCM current_context_val = SCM_EOL;
62 Context *where = context->where_defined (context_property,
63 ¤t_context_val);
73 SCM base = updated_grob_properties (context, context_property);
74 current_context_val = scm_cons (base, base);
75 context->set_property (context_property, current_context_val);
78 if (!scm_is_pair (current_context_val))
80 programming_error ("Grob definition should be cons");
84 SCM target_alist = scm_car (current_context_val);
86 SCM symbol = scm_car (grob_property_path);
87 if (scm_is_pair (scm_cdr (grob_property_path)))
89 new_value = nested_property_alist (ly_assoc_get (symbol, target_alist,
91 scm_cdr (grob_property_path),
95 // it's tempting to replace the head of the list if it's the same
96 // property. However, we have to keep this info around, in case we have to
97 // \revert back to it.
99 target_alist = scm_acons (symbol, new_value, target_alist);
102 if (!ly_is_procedure (new_value)
103 && !is_simple_closure (new_value))
104 ok = type_check_assignment (symbol, new_value,
105 ly_symbol2scm ("backend-type?"));
108 tack onto alist. We can use set_car, since
109 updated_grob_properties () in child contexts will check
110 for changes in the car.
114 scm_set_car_x (current_context_val, target_alist);
119 execute_revert_property (Context *context,
120 SCM context_property,
121 SCM grob_property_path);
124 execute_general_pushpop_property (Context *context,
125 SCM context_property,
126 SCM grob_property_path,
130 if (new_value != SCM_UNDEFINED)
131 execute_override_property (context, context_property,
135 execute_revert_property (context, context_property,
140 execute_revert_property (Context *context,
141 SCM context_property,
142 SCM grob_property_path)
147 SCM current_context_val = SCM_EOL;
148 if (context->where_defined (context_property, ¤t_context_val) == context)
150 SCM current_alist = scm_car (current_context_val);
151 SCM daddy = scm_cdr (current_context_val);
153 if (!scm_is_pair (grob_property_path)
154 || !scm_is_symbol (scm_car (grob_property_path)))
156 programming_error ("Grob property path should be list of symbols.");
160 SCM symbol = scm_car (grob_property_path);
162 if (scm_is_pair (scm_cdr (grob_property_path)))
164 SCM current_sub_alist = ly_assoc_get (symbol, current_alist, SCM_EOL);
165 SCM new_val = nested_property_revert_alist (current_sub_alist, scm_cdr (grob_property_path));
167 if (scm_is_pair (current_alist)
168 && scm_caar (current_alist) == symbol
169 && current_alist != daddy)
170 current_alist = scm_cdr (current_alist);
172 current_alist = scm_acons (symbol, new_val, current_alist);
173 scm_set_car_x (current_context_val, current_alist);
177 SCM new_alist = evict_from_alist (symbol, current_alist, daddy);
179 if (new_alist == daddy)
180 context->unset_property (context_property);
182 context->set_property (context_property, scm_cons (new_alist, daddy));
188 execute_pushpop_property (Context *context,
189 SCM context_property,
194 general_pushpop_property (context, context_property,
195 scm_list_1 (grob_property),
200 PRE_INIT_OPS is in the order specified, and hence must be reversed.
203 apply_property_operations (Context *tg, SCM pre_init_ops)
205 SCM correct_order = scm_reverse (pre_init_ops);
206 for (SCM s = correct_order; scm_is_pair (s); s = scm_cdr (s))
208 SCM entry = scm_car (s);
209 SCM type = scm_car (entry);
210 entry = scm_cdr (entry);
212 if (type == ly_symbol2scm ("push"))
214 SCM context_prop = scm_car (entry);
215 SCM val = scm_cadr (entry);
216 SCM grob_prop_path = scm_cddr (entry);
217 execute_general_pushpop_property (tg, context_prop, grob_prop_path, val);
219 else if (type == ly_symbol2scm ("pop"))
221 SCM context_prop = scm_car (entry);
222 SCM val = SCM_UNDEFINED;
223 SCM grob_prop_path = scm_cdr (entry);
224 execute_general_pushpop_property (tg, context_prop, grob_prop_path, val);
226 else if (type == ly_symbol2scm ("assign"))
227 tg->set_property (scm_car (entry), scm_cadr (entry));
232 Return the object alist for SYM, checking if its base in enclosing
233 contexts has changed. The alist is updated if necessary.
236 updated_grob_properties (Context *tg, SCM sym)
238 assert (scm_is_symbol (sym));
241 tg = tg->where_defined (sym, &props);
246 = (tg->get_parent_context ())
247 ? updated_grob_properties (tg->get_parent_context (), sym)
250 if (!scm_is_pair (props))
252 programming_error ("grob props not a pair?");
256 SCM based_on = scm_cdr (props);
257 if (based_on == daddy_props)
258 return scm_car (props);
261 SCM copy = daddy_props;
263 SCM p = scm_car (props);
264 while (p != based_on)
266 *tail = scm_cons (scm_car (p), daddy_props);
267 tail = SCM_CDRLOC (*tail);
271 scm_set_car_x (props, copy);
272 scm_set_cdr_x (props, daddy_props);