degenerate let forms

[bpt/guile.git] / libguile / keywords.c

diff --git a/libguile/keywords.c b/libguile/keywords.c
index e4a79ac..f630259 100644 (file)
--- a/libguile/keywords.c
+++ b/libguile/keywords.c
@@ -1,5 +1,6 @@
-/* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2003, 2004, 2006, 2008, 2009, 2011 Free Software Foundation, Inc.
- * 
+/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004,
+ *   2006, 2008, 2009, 2011, 2013 Free Software Foundation, Inc.
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
  * as published by the Free Software Foundation; either version 3 of
@@ -23,6 +24,7 @@
 #endif
 
 #include <string.h>
+#include <stdarg.h>
 
 #include "libguile/_scm.h"
 #include "libguile/async.h"
@@ -124,6 +126,75 @@ scm_from_utf8_keyword (const char *name)
   return scm_symbol_to_keyword (scm_from_utf8_symbol (name));
 }
 
+SCM_SYMBOL (scm_keyword_argument_error, "keyword-argument-error");
+
+void
+scm_c_bind_keyword_arguments (const char *subr, SCM rest,
+                              scm_t_keyword_arguments_flags flags, ...)
+{
+  va_list va;
+
+  if (SCM_UNLIKELY (!(flags & SCM_ALLOW_NON_KEYWORD_ARGUMENTS)
+                    && scm_ilength (rest) % 2 != 0))
+    scm_error (scm_keyword_argument_error,
+               subr, "Odd length of keyword argument list",
+               SCM_EOL, SCM_BOOL_F);
+
+  while (scm_is_pair (rest))
+    {
+      SCM kw_or_arg = SCM_CAR (rest);
+      SCM tail = SCM_CDR (rest);
+
+      if (scm_is_keyword (kw_or_arg) && scm_is_pair (tail))
+        {
+          SCM kw;
+          SCM *arg_p;
+
+          va_start (va, flags);
+          for (;;)
+            {
+              kw = va_arg (va, SCM);
+              if (SCM_UNBNDP (kw))
+                {
+                  /* KW_OR_ARG is not in the list of expected keywords.  */
+                  if (!(flags & SCM_ALLOW_OTHER_KEYS))
+                    scm_error_scm (scm_keyword_argument_error,
+                                  scm_from_locale_string (subr),
+                                  scm_from_latin1_string
+                                  ("Unrecognized keyword"),
+                                  SCM_EOL, scm_list_1 (kw_or_arg));
+                  break;
+                }
+              arg_p = va_arg (va, SCM *);
+              if (scm_is_eq (kw_or_arg, kw))
+                {
+                  /* We found the matching keyword.  Store the
+                     associated value and break out of the loop.  */
+                  *arg_p = SCM_CAR (tail);
+                  break;
+                }
+            }
+          va_end (va);
+
+          /* Advance REST.  */
+          rest = SCM_CDR (tail);
+        }
+      else
+        {
+          /* The next argument is not a keyword, or is a singleton
+             keyword at the end of REST.  */
+          if (!(flags & SCM_ALLOW_NON_KEYWORD_ARGUMENTS))
+            scm_error_scm (scm_keyword_argument_error,
+                          scm_from_locale_string (subr),
+                          scm_from_latin1_string ("Invalid keyword"),
+                          SCM_EOL, scm_list_1 (kw_or_arg));
+
+           /* Advance REST.  */
+           rest = tail;
+        }
+    }
+}
+
 /* njrev: critical sections reviewed so far up to here */
 void
 scm_init_keywords ()