From 51cdc93b40dbebd65b14e931385cb3bd354a8082 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 22 Apr 2016 06:50:55 -0700
Subject: Support list of paths in ftw.

* ftw.c (ftw_wrap): Handle case when dirpath is a list,
by recursion.

* txr.1: Documented.
---
 ftw.c | 12 ++++++++++++
 txr.1 | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/ftw.c b/ftw.c
index 6128a652..c906d6a3 100644
--- a/ftw.c
+++ b/ftw.c
@@ -91,6 +91,18 @@ val ftw_wrap(val dirpath, val fn, val flags_in, val nopenfd_in)
   if (s_callback) {
     uw_throwf(error_s, lit("ftw: cannot be re-entered from "
                            "ftw callback"), nao);
+  } else if (dirpath == nil) {
+    return t;
+  } else if (consp(dirpath)) {
+    uses_or2;
+    val ret = nil;
+    for (; dirpath; dirpath = cdr(dirpath)) {
+      val res = ftw_wrap(car(dirpath), fn, flags_in, nopenfd_in);
+      if (res != t && res != nil)
+        return res;
+      ret = or2(ret, res);
+    }
+    return ret;
   } else {
     int nopenfd = c_num(default_arg(nopenfd_in, num_fast(20)));
     int flags = c_num(default_arg(flags_in, zero));
diff --git a/txr.1 b/txr.1
index 5c68b8f6..0384aa82 100644
--- a/txr.1
+++ b/txr.1
@@ -38020,6 +38020,12 @@ defaults to zero, and
 .meta nopenfd
 defaults to 20.
 
+Also note that, unlike in the C function, multiple
+paths may be processed by passing a list
+for the
+.meta path
+argument.
+
 The
 .code nftw
 function walks the filesystem, as directed by the
@@ -38102,6 +38108,47 @@ is terminated by a return value from
 .metn callback-func ,
 then that value is returned. Such a value is always a nonzero integer.
 
+If the
+.meta path
+passed to
+.code ftw
+is a list, then all of the paths contained in that
+list are walked, as if by recursive application of
+.code ftw
+to each element of the list taken as the
+.meta path
+argument, the other argument values being the same.
+The traversal stops when any recursive
+invocation of
+.code ftw
+returns a value other than
+.codn t
+or
+.codn nil ,
+and that value is returned. If
+.code t
+or
+.code nil
+is returned, the traversal continues with the
+application of
+.code ftw
+to the next list element, if any.
+If the list is completely traversed, and some recursive
+invocations of
+.code ftw
+return
+.codn t ,
+then the return value is
+.codn t .
+If all recursive invocations return
+.code nil
+then
+.code nil
+is returned.
+If the list is empty,
+.code t
+is returned.
+
 The
 .meta callback-func
 may terminate the traversal by a nonlocal exit, such as by throwing
-- 
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