From 6f3243db55e61847784178ea812f28ddf003544a Mon Sep 17 00:00:00 2001
From: Paul Pogonyshev
Date: Sat, 26 Mar 2016 11:19:43 +0300
Subject: Implement 'func-arity'

* src/eval.c (Ffunc_arity, lambda_arity): New functions.
* src/bytecode.c (get_byte_code_arity): New function.
* src/lisp.h (get_byte_code_arity): Add prototype.

* doc/lispref/functions.texi (What Is a Function): Document
'func-arity'.

* etc/NEWS: Mention 'func-arity'.

* test/src/fns-tests.el (fns-tests-func-arity): New test set.
---
 src/bytecode.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

(limited to 'src/bytecode.c')

diff --git a/src/bytecode.c b/src/bytecode.c
index 9ae2e820d51..4ff15d2912a 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -1987,6 +1987,24 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
   return result;
 }
 
+/* `args_template' has the same meaning as in exec_byte_code() above.  */
+Lisp_Object
+get_byte_code_arity (Lisp_Object args_template)
+{
+  if (INTEGERP (args_template))
+    {
+      ptrdiff_t at = XINT (args_template);
+      bool rest = (at & 128) != 0;
+      int mandatory = at & 127;
+      ptrdiff_t nonrest = at >> 8;
+
+      return Fcons (make_number (mandatory),
+		    rest ? Qmany : make_number (nonrest));
+    }
+  else
+    error ("Unknown args template!");
+}
+
 void
 syms_of_bytecode (void)
 {
-- 
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