From ae7038c520882d1a90cec63bc33e90a91ab60bd6 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 13 Feb 2022 12:38:33 -0800
Subject: New function: cat-files.

* lisplib.c (copy_file_instantiate): Trigger autoload on
cat-files.

* stdlib/copy-file.tl (cat-files): New function.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.
---
 lisplib.c           |  2 +-
 stdlib/copy-file.tl | 13 +++++++++++++
 stdlib/doc-syms.tl  |  1 +
 txr.1               | 20 ++++++++++++++++++++
 4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/lisplib.c b/lisplib.c
index 0f48b82e..2edee144 100644
--- a/lisplib.c
+++ b/lisplib.c
@@ -830,7 +830,7 @@ static val copy_file_instantiate(val set_fun)
 static val copy_file_set_entries(val dlt, val fun)
 {
   val name[] = {
-    lit("copy-path-opts"), lit("copy-file"), lit("copy-files"),
+    lit("copy-path-opts"), lit("copy-file"), lit("copy-files"), lit("cat-files"),
     lit("copy-path-rec"), lit("remove-path-rec"),
     lit("chown-rec"), lit("chmod-rec"), lit("touch"), lit("rel-path"),
     lit("path-equal"),
diff --git a/stdlib/copy-file.tl b/stdlib/copy-file.tl
index 50408aca..beab2fbc 100644
--- a/stdlib/copy-file.tl
+++ b/stdlib/copy-file.tl
@@ -87,6 +87,19 @@
         (skip `skip copying @path` (exc . args) (return))
         (retry `retry copying @path` (exc . args))))))
 
+(defun cat-files (to-path . from-paths)
+  (let ((buf (make-buf copy-size)))
+    (with-stream (ost (open-file to-path "wb"))
+      (each ((from-path from-paths))
+        (with-stream (ist (open-file from-path "b"))
+          (while (eql (len buf) copy-size)
+            (fill-buf-adjust buf 0 ist)
+            (put-buf buf 0 ost)))
+        (buf-set-length buf copy-size)))
+    (buf-set-length buf 0)
+    (buf-trim buf)
+    nil))
+
 (defun do-tweak-obj (to-path st opts link-p)
   (when (and opts.perms (not link-p))
     (chmod to-path st.mode))
diff --git a/stdlib/doc-syms.tl b/stdlib/doc-syms.tl
index 754a0ae6..8a472752 100644
--- a/stdlib/doc-syms.tl
+++ b/stdlib/doc-syms.tl
@@ -269,6 +269,7 @@
       ("casequal*" "N-02FB71A2")
       ("cases" "N-039458F2")
       ("cat" "N-03336E1B")
+      ("cat-files" "N-01249D65")
       ("cat-str" "N-00B6ACE3")
       ("cat-streams" "N-020BF082")
       ("cat-vec" "N-01AEB28B")
diff --git a/txr.1 b/txr.1
index cfb28100..4d5090ef 100644
--- a/txr.1
+++ b/txr.1
@@ -70055,6 +70055,26 @@ exception.
     (file-error (throw 'skip)))
 .brev
 
+.coNP Function @ cat-files
+.synb
+.mets (cat-files < to-path << from-path *)
+.syne
+.desc
+The
+.code cat-files
+function catenates the contents of zero or more files into one file.
+The destination path is specified by
+.metn to-path .
+Regardless of whether there are any
+.meta from-path
+arguments, the file named by
+.meta to-path
+is created, if necessary or else truncated to zero length.
+Then, the files named by each
+.meta from-path
+are traversed in left-to-right order; the contents of each file
+is appended to the destination file.
+
 .coNP Function @ copy-path-rec
 .synb
 .mets (copy-path-rec < from-path < to-path << option *)
-- 
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