lily/simple-closure.cc

   1 /*
   2   This file is part of LilyPond, the GNU music typesetter.
   3
   4   Copyright (C) 2005--2011 Han-Wen Nienhuys <hanwen@xs4all.nl>
   5
   6
   7   LilyPond is free software: you can redistribute it and/or modify
   8   it under the terms of the GNU General Public License as published by
   9   the Free Software Foundation, either version 3 of the License, or
  10   (at your option) any later version.
  11
  12   LilyPond is distributed in the hope that it will be useful,
  13   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15   GNU General Public License for more details.
  16
  17   You should have received a copy of the GNU General Public License
  18   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20 #include "simple-closure.hh"
  21
  22 #include "grob.hh"
  23
  24 static scm_t_bits simple_closure_tag;
  25
  26 bool
  27 is_simple_closure (SCM s)
  28 {
  29   return (SCM_NIMP (s) && SCM_CELL_TYPE (s) == simple_closure_tag);
  30 }
  31
  32 SCM
  33 simple_closure_expression (SCM smob)
  34 {
  35   assert (is_simple_closure (smob));
  36   return (SCM) SCM_CELL_WORD_1(smob);
  37 }
  38
  39 SCM
  40 evaluate_args (SCM delayed_argument, SCM args, bool pure, int start, int end)
  41 {
  42   SCM new_args = SCM_EOL;
  43   SCM *tail = &new_args;
  44   for (SCM s = args; scm_is_pair (s); s = scm_cdr (s))
  45     {
  46       *tail = scm_cons (evaluate_with_simple_closure (delayed_argument, scm_car (s),
  47                                                       pure, start, end),
  48                         SCM_EOL);
  49       if (scm_car (*tail) == SCM_UNSPECIFIED)
  50         return SCM_UNSPECIFIED;
  51       tail = SCM_CDRLOC (*tail);
  52     }
  53
  54   return new_args;
  55 }
  56
  57 SCM
  58 evaluate_with_simple_closure (SCM delayed_argument,
  59                               SCM expr,
  60                               bool pure,
  61                               int start,
  62                               int end)
  63 {
  64   if (is_simple_closure (expr))
  65     {
  66       SCM inside = simple_closure_expression (expr);
  67       SCM args = scm_cons (delayed_argument,
  68                            evaluate_args (delayed_argument, scm_cdr (inside),
  69                                           pure, start, end));
  70       if (scm_cdr (args) == SCM_UNSPECIFIED)
  71         return SCM_UNSPECIFIED;
  72       if (pure)
  73         return call_pure_function (scm_car (inside), args, start, end);
  74       return scm_apply_0 (scm_car (inside), args);
  75     }
  76   else if (!scm_is_pair (expr))
  77     return expr;
  78   else if (scm_car (expr) == ly_symbol2scm ("quote"))
  79     return scm_cadr (expr);
  80   else if (ly_is_procedure (scm_car (expr)))
  81     {
  82       SCM args = evaluate_args (delayed_argument, scm_cdr (expr), pure, start, end);
  83       if (args == SCM_UNSPECIFIED)
  84         return SCM_UNSPECIFIED;
  85       if (pure)
  86         return call_pure_function (scm_car (expr), args, start, end);
  87       return scm_apply_0 (scm_car (expr), args);
  88     }
  89   else
  90     // ugh. deviation from standard. Should print error?
  91     return evaluate_args (delayed_argument, scm_cdr (expr), pure, start, end);
  92
  93   assert (false);
  94   return SCM_EOL;
  95 }
  96
  97 LY_DEFINE (ly_simple_closure_p, "ly:simple-closure?",
  98           1, 0, 0, (SCM clos),
  99           "Is @var{clos} a simple closure?")
 100 {
 101   return scm_from_bool (is_simple_closure (clos));
 102 }
 103
 104 LY_DEFINE (ly_make_simple_closure, "ly:make-simple-closure",
 105           1, 0, 0, (SCM expr),
 106           "Make a simple closure.  @var{expr} should be form of"
 107           " @code{(@var{func} @var{a1} @var{a2} @dots{})}, and will be"
 108           " invoked as @code{(@var{func} @var{delayed-arg} @var{a1}"
 109           " @var{a2} @dots{})}.")
 110 {
 111   SCM z;
 112
 113   SCM_NEWSMOB (z, simple_closure_tag, expr);
 114   return z;
 115 }
 116
 117 LY_DEFINE (ly_eval_simple_closure, "ly:eval-simple-closure",
 118           2, 2, 0, (SCM delayed, SCM closure, SCM scm_start, SCM scm_end),
 119           "Evaluate a simple @var{closure} with the given @var{delayed}"
 120           " argument.  If @var{scm-start} and @var{scm-end} are defined,"
 121           " evaluate it purely with those start and end points.")
 122 {
 123   bool pure = (scm_is_number (scm_start) && scm_is_number (scm_end));
 124   int start = robust_scm2int (scm_start, 0);
 125   int end = robust_scm2int (scm_end, 0);
 126   SCM expr = simple_closure_expression (closure);
 127   return evaluate_with_simple_closure (delayed, expr, pure, start, end);
 128 }
 129
 130 int
 131 print_simple_closure (SCM s, SCM port, scm_print_state *)
 132 {
 133   scm_puts ("#<simple-closure ", port);
 134   scm_display (scm_cdr (s), port);
 135   scm_puts (" >", port);
 136   return 1;
 137 }
 138
 139
 140 void init_simple_closure ()
 141 {
 142   simple_closure_tag = scm_make_smob_type ("simple-closure", 0);
 143   scm_set_smob_mark (simple_closure_tag, scm_markcdr);
 144   scm_set_smob_print (simple_closure_tag, print_simple_closure);
 145 };
 146
 147
 148
 149 ADD_SCM_INIT_FUNC (simple_closure, init_simple_closure);