From 4dcee54de4d6e749f33d8ebf85696cd0786ee014 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 17 Dec 2021 20:37:34 -0800
Subject: tree-count: new function.

* tree.c (tree_count): New function.
(tree_init): tree-count intrinsic registered.

* tree.h (tree_count): Declared.

* lib.c (length): Support search tree argument via tree_count.

* tests/010/tree.tl: Test cases for tree-count, indirectly via len.

* txr.1: Documented.
---
 lib.c             |  2 ++
 tests/010/tree.tl | 12 ++++++++++--
 tree.c            |  8 ++++++++
 tree.h            |  1 +
 txr.1             | 12 ++++++++++++
 5 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/lib.c b/lib.c
index dca7474d..1bcd9ffc 100644
--- a/lib.c
+++ b/lib.c
@@ -12253,6 +12253,8 @@ val length(val seq)
       return hash_count(seq);
     if (seq->co.cls == carray_cls)
       return length_carray(seq);
+    if (seq->co.cls == tree_cls)
+      return tree_count(seq);
     if (obj_struct_p(seq)) {
       val length_meth = get_special_slot(seq, length_m);
 
diff --git a/tests/010/tree.tl b/tests/010/tree.tl
index 06d02ce6..f5bfac42 100644
--- a/tests/010/tree.tl
+++ b/tests/010/tree.tl
@@ -5,8 +5,16 @@
 
 (test tr #T(()))
 
-(test (treep tr) t)
-(test (treep 42) nil)
+(mtest
+  (treep tr) t
+  (treep 42) nil)
+
+(mtest
+  (len #T()) 0
+  (len #T(() 1)) 1
+  (len #T(() 1 2)) 2
+  (len #T(() 1 2 3)) 3
+  (len #T(() 1 1 1)) 3)
 
 (each ((n keys))
   (tree-insert tr n))
diff --git a/tree.c b/tree.c
index 3df5ddf6..6adcdd7d 100644
--- a/tree.c
+++ b/tree.c
@@ -769,6 +769,13 @@ val treep(val obj)
   return tnil(type(obj) == COBJ && obj->co.cls == tree_cls);
 }
 
+val tree_count(val tree)
+{
+  val self = lit("tree-count");
+  struct tree *tr = coerce(struct tree *, cobj_handle(self, tree, tree_cls));
+  return unum(tr->size);
+}
+
 static void tree_iter_mark(val tree_iter)
 {
   struct tree_diter *tdi = coerce(struct tree_diter *, tree_iter->co.handle);
@@ -991,6 +998,7 @@ void tree_init(void)
   reg_fun(intern(lit("copy-search-tree"), user_package), func_n1(copy_search_tree));
   reg_fun(intern(lit("make-similar-tree"), user_package), func_n1(make_similar_tree));
   reg_fun(intern(lit("treep"), user_package), func_n1(treep));
+  reg_fun(intern(lit("tree-count"), user_package), func_n1(tree_count));
   reg_fun(intern(lit("tree-insert-node"), user_package), func_n2(tree_insert_node));
   reg_fun(intern(lit("tree-insert"), user_package), func_n2(tree_insert));
   reg_fun(intern(lit("tree-lookup-node"), user_package), func_n2(tree_lookup_node));
diff --git a/tree.h b/tree.h
index 1443a73f..b0b85801 100644
--- a/tree.h
+++ b/tree.h
@@ -44,6 +44,7 @@ val tree(val keys, val key_fn, val less_fn, val equal_fn);
 val copy_search_tree(val tree);
 val make_similar_tree(val tree);
 val treep(val obj);
+val tree_count(val tree);
 val tree_insert_node(val tree, val node);
 val tree_insert(val tree, val key);
 val tree_lookup_node(val tree, val key);
diff --git a/txr.1 b/txr.1
index 92e322bb..990b9522 100644
--- a/txr.1
+++ b/txr.1
@@ -54083,6 +54083,18 @@ if
 is a tree. Otherwise, it returns
 .codn nil .
 
+.coNP Function @ tree-count
+.synb
+.mets (tree-count << tree )
+.syne
+.desc
+The
+.code tree-count
+function returns an integer indicating the number of nodes currently
+inserted into
+.metn tree ,
+which must be a search tree object.
+
 .coNP Function @ tree-insert-node
 .synb
 .mets (tree-insert-node < tree << node )
-- 
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