lily/simple-closure.cc

   1 /*
   2   closure.cc -- chained closures.
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2005--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7
   8 */
   9 #include "simple-closure.hh"
  10
  11 #include "grob.hh"
  12
  13 static scm_t_bits simple_closure_tag;
  14
  15 bool
  16 is_simple_closure (SCM s)
  17 {
  18   return (SCM_NIMP (s) && SCM_CELL_TYPE (s) == simple_closure_tag);
  19 }
  20
  21 SCM
  22 simple_closure_expression (SCM smob)
  23 {
  24   assert (is_simple_closure (smob));
  25   return (SCM) SCM_CELL_WORD_1(smob);
  26 }
  27
  28 SCM
  29 evaluate_args (SCM delayed_argument, SCM args, bool pure, int start, int end)
  30 {
  31   SCM new_args = SCM_EOL;
  32   SCM *tail = &new_args;
  33   for (SCM s = args; scm_is_pair (s); s = scm_cdr (s))
  34     {
  35       *tail = scm_cons (evaluate_with_simple_closure (delayed_argument, scm_car (s),
  36                                                       pure, start, end),
  37                         SCM_EOL);
  38       if (scm_car (*tail) == SCM_UNSPECIFIED)
  39         return SCM_UNSPECIFIED;
  40       tail = SCM_CDRLOC (*tail);
  41     }
  42
  43   return new_args;
  44 }
  45
  46 SCM
  47 evaluate_with_simple_closure (SCM delayed_argument,
  48                               SCM expr,
  49                               bool pure,
  50                               int start,
  51                               int end)
  52 {
  53   if (is_simple_closure (expr))
  54     {
  55       SCM inside = simple_closure_expression (expr);
  56       SCM args = scm_cons (delayed_argument,
  57                            evaluate_args (delayed_argument, scm_cdr (inside),
  58                                           pure, start, end));
  59       if (scm_cdr (args) == SCM_UNSPECIFIED)
  60         return SCM_UNSPECIFIED;
  61       if (pure)
  62         return call_pure_function (scm_car (inside), args, start, end);
  63       return scm_apply_0 (scm_car (inside), args);
  64     }
  65   else if (!scm_is_pair (expr))
  66     return expr;
  67   else if (scm_car (expr) == ly_symbol2scm ("quote"))
  68     return scm_cadr (expr);
  69   else if (ly_is_procedure (scm_car (expr)))
  70     {
  71       SCM args = evaluate_args (delayed_argument, scm_cdr (expr), pure, start, end);
  72       if (args == SCM_UNSPECIFIED)
  73         return SCM_UNSPECIFIED;
  74       if (pure)
  75         return call_pure_function (scm_car (expr), args, start, end);
  76       return scm_apply_0 (scm_car (expr), args);
  77     }
  78   else
  79     // ugh. deviation from standard. Should print error?
  80     return evaluate_args (delayed_argument, scm_cdr (expr), pure, start, end);
  81
  82   assert (false);
  83   return SCM_EOL;
  84 }
  85
  86 LY_DEFINE (ly_simple_closure_p, "ly:simple-closure?",
  87           1,0,0, (SCM clos),
  88           "Type predicate.")
  89 {
  90   return scm_from_bool (is_simple_closure (clos));
  91 }
  92
  93 LY_DEFINE (ly_make_simple_closure, "ly:make-simple-closure",
  94           1, 0, 0, (SCM expr),
  95           "Make a simple closure. @var{expr} should be form of "
  96           "@code{(@var{func} @var{a1} @var{A2} ...)}, and will be invoked "
  97           "as @code{(@var{func} @var{delayed-arg} @var{a1} @var{a2} ... )}.")
  98 {
  99   SCM z;
 100
 101   SCM_NEWSMOB (z, simple_closure_tag, expr);
 102   return z;
 103 }
 104
 105 LY_DEFINE (ly_eval_simple_closure, "ly:eval-simple-closure",
 106           2, 2, 0, (SCM delayed, SCM closure, SCM scm_start, SCM scm_end),
 107           "Evaluate a simple closure with the given delayed argument. "
 108           "If start and end are defined, evaluate it purely with those "
 109           "start- and end-points.")
 110 {
 111   bool pure = (scm_is_number (scm_start) && scm_is_number (scm_end));
 112   int start = robust_scm2int (scm_start, 0);
 113   int end = robust_scm2int (scm_end, 0);
 114   SCM expr = simple_closure_expression (closure);
 115   return evaluate_with_simple_closure (delayed, expr, pure, start, end);
 116 }
 117
 118 int
 119 print_simple_closure (SCM s, SCM port, scm_print_state *)
 120 {
 121   scm_puts ("#<simple-closure ", port);
 122   scm_display (scm_cdr (s), port);
 123   scm_puts (" >", port);
 124   return 1;
 125 }
 126
 127
 128 void init_simple_closure ()
 129 {
 130   simple_closure_tag = scm_make_smob_type ("simple-closure", 0);
 131   scm_set_smob_mark (simple_closure_tag, scm_markcdr);
 132   scm_set_smob_print (simple_closure_tag, print_simple_closure);
 133 };
 134
 135
 136
 137 ADD_SCM_INIT_FUNC (simple_closure, init_simple_closure);