From 61ec270c837bdcef179d99f6515ee68fe617ff73 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 4 Nov 2018 22:10:15 -0800
Subject: buffers: implement copy-buf.

* buf.c (copy_buf): New function.
(buf_init): Register copy-buf intrinsic.

* buf.h (copy_buf): Declared.

* lib.c (copy): Handle BUF via copy_buf.

* txr.1: Documented.
---
 buf.c |  9 +++++++++
 buf.h |  1 +
 lib.c |  2 ++
 txr.1 | 22 ++++++++++++++++++++++
 4 files changed, 34 insertions(+)

diff --git a/buf.c b/buf.c
index 40e81607..959b7880 100644
--- a/buf.c
+++ b/buf.c
@@ -137,6 +137,14 @@ static struct buf *buf_handle(val buf, val ctx)
             ctx, buf, nao);
 }
 
+val copy_buf(val buf)
+{
+  struct buf *b = buf_handle(buf, lit("copy-buf"));
+  return if3(b->size,
+             make_duplicate_buf(b->len, b->data),
+             make_borrowed_buf(b->len, b->data));
+}
+
 static void buf_grow(struct buf *b, val init_val, val self)
 {
   cnum len = c_num(b->len);
@@ -935,6 +943,7 @@ void buf_init(void)
   reg_fun(intern(lit("buf-trim"), user_package), func_n1(buf_trim));
   reg_fun(intern(lit("buf-set-length"), user_package), func_n3o(buf_set_length, 2));
   reg_fun(intern(lit("length-buf"), user_package), func_n1(length_buf));
+  reg_fun(intern(lit("copy-buf"), user_package), func_n1(copy_buf));
 
 #if HAVE_I8
   reg_fun(intern(lit("buf-put-i8"), user_package), func_n3(buf_put_i8));
diff --git a/buf.h b/buf.h
index cf394ff0..0086f6f0 100644
--- a/buf.h
+++ b/buf.h
@@ -30,6 +30,7 @@ val bufp(val object);
 val make_borrowed_buf(val len, mem_t *data);
 val init_borrowed_buf(obj_t *buf, val len, mem_t *data);
 val make_duplicate_buf(val len, mem_t *data);
+val copy_buf(val buf);
 val buf_trim(val buf);
 val buf_set_length(val obj, val len, val init_val);
 val length_buf(val buf);
diff --git a/lib.c b/lib.c
index 4070ce4e..f86576b9 100644
--- a/lib.c
+++ b/lib.c
@@ -9939,6 +9939,8 @@ val copy(val seq)
     return copy_str(seq);
   case VEC:
     return copy_vec(seq);
+  case BUF:
+    return copy_buf(seq);
   case COBJ:
     if (seq->co.cls == hash_s)
       return copy_hash(seq);
diff --git a/txr.1 b/txr.1
index 1aa8f26f..f1c71f4c 100644
--- a/txr.1
+++ b/txr.1
@@ -26177,6 +26177,12 @@ is a structure, it returns
 .cble
 If
 .meta object
+is a buffer, it returns
+.cblk
+.meti (copy-buf << object ).
+.cble
+If
+.meta object
 is a
 .codn carray ,
 it returns
@@ -56985,6 +56991,22 @@ If
 is specified, its value must be in the range 0 to 255.
 It defaults to zero.
 
+.coNP Function @ copy-buf
+.synb
+.mets (copy-buf << buf )
+.syne
+.desc
+The
+.code copy-buf
+function returns a duplicate of
+.metn buf :
+an object distinct from
+.meta buf
+which has the same length and contents, and compares
+.code equal
+to
+.metn buf .
+
 .coNP Function @ buf-put-i8
 .synb
 .mets (buf-put-i8 < buf < pos << val )
-- 
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