lib/: Pure C machinery for handling `keyword arguments' to functions.

[sod] / lib / keyword.c

diff --git a/lib/keyword.c b/lib/keyword.c
new file mode 100644 (file)
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--- /dev/null
+++ b/lib/keyword.c
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+/* -*-c-*-
+ *
+ * Keyword argument handling
+ *
+ * (c) 2015 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the Sensible Object Design, an object system for C.
+ *
+ * SOD is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * SOD is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with SOD; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include "keyword.h"
+
+/*----- Global variables --------------------------------------------------*/
+
+kw_unkhookfn *kw_unkhook = kw_defunknown;
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @kw_unknown@ --- *
+ *
+ * Arguments:  @const char *set@ = the keyword set name, as a string
+ *             @const char *kw@ = the unknown keyword argument, as a string
+ *
+ * Returns:    Doesn't.
+ *
+ * Use:                Called when an unrecognized keyword argument is encountered
+ *             during parsing.  This calls the @kw_unkhook@ with the same
+ *             arguments. Recovery via @longjmp@ or a similar machanism is
+ *             acceptable.
+ */
+
+void kw_unknown(const char *set, const char *kw)
+  { kw_unkhook(set, kw); kw__hookfailed(); }
+
+/* --- @kw_parseempty@ --- *
+ *
+ * Arguments:  @const char *set@ = the keyword set name, as a string
+ *             @const char *kwfirst@ = the first keyword argument name
+ *             @va_list *ap@ = pointer to argument-tail extraction state
+ *             @const struct kwval *v@ = base address of argument vector
+ *             @size_t n@ = size of argument vector
+ *
+ * Returns:    ---
+ *
+ * Use:                Goes through the motions of parsing keyword arguments, but
+ *             doesn't in fact handle any other than the standard ones
+ *             described above (see @KWSET_PARSEFN@).  This is useful when a
+ *             function doesn't currently define any keyword arguments but
+ *             wants to reserve the right to define some in the future.
+ *             (The usual machinery can't be used in this case, since the
+ *             argument structure would be empty.  Besides, it would be
+ *             pointless to include multiple copies of the same boilerplate
+ *             code in a program.)
+ */
+
+void kw_parseempty(const char *set, const char *kwfirst, va_list *ap,
+                  const struct kwval *v, size_t n)
+{
+  const char *k, *kk;
+  va_list *aap;
+  const struct kwtab *t;
+  const struct kwval *vv;
+  size_t nn;
+
+  for (k = kwfirst; k; k = va_arg(*ap, const char *)) {
+    if (!strcmp(k, "kw.va_list")) {
+      aap = va_arg(*ap, va_list *);
+      kk = va_arg(*aap, const char *);
+      kw_parseempty(set, kk, aap, 0, 0);
+    } else if (!strcmp(k, "kw.tab")) {
+      vv = va_arg(*ap, const struct kwval *);
+      nn = va_arg(*ap, size_t);
+      kw_parseempty(set, 0, 0, vv, nn);
+    } else
+      kw_unknown(set, k);
+  }
+  while (n) {
+    if (!strcmp(v->kw, "kw.va_list")) {
+      aap = *(va_list *const *)v->val;
+      kk = va_arg(*aap, const char *);
+      kw_parseempty(set, kk, aap, 0, 0);
+    } else if (!strcmp(k, "kw.tab")) {
+      t = (const struct kwtab *)v->val;
+      kw_parseempty(set, 0, 0, t->v, t->n);
+    } else
+      kw_unknown(set, k);
+    v++; n--;
+  }
+}
+
+/*----- That's all, folks -------------------------------------------------*/