tree: support for duplicate keys.

* tree.c (tr_insert): New argument for allowing duplicate.
If it is true, suppresses the case of replacing a node,
causing the logic to fall through to traversing right, so the
duplicate key effectively looks like it is greater than the
existing duplicates, and gets inserted as the rightmost
duplicate.
(tr_do_delete_specific, tr_delete_specific): New static functions.
(tree_insert_node): New parameter, passed to tr_insert.
(tree_insert): New parameter, passed to tree_insert_node.
(tree_delete_specific_node): New function.
(tree): New parameter to allow duplicate keys in the elements
sequence.
(tree_construct): Pass t to tree to allow duplicate elements.
(tree_init): Update registrations of tree, tree-insert and
tree-insert-node. Register tree-delete-specific-node function.

* tree.h (tree, tree_insert_node, tree_insert): Declarations
updated.
(tree_delete_specific_node): Declared.

* lib.c (seq): Pass t argument to tree_insert, allowing
duplicates.

* parser.c (circ_backpatch): Likewise.

* parser.y (tree): Pass t to new argument of tree, so
duplicates are preserved in the element list of the #T
literal.

* y.tab.c.shipped: Updated.

* tests/010/tree.tl: Test cases for duplicate keys.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.

1 files changed, 2 insertions, 0 deletions

diff --git a/stdlib/doc-syms.tl b/stdlib/doc-syms.tl
index 654a3610..80922b42 100644
--- a/stdlib/doc-syms.tl
+++ b/stdlib/doc-syms.tl
@@ -2002,8 +2002,10 @@
       ("tree-bind" "N-021A9008")
       ("tree-case" "N-03D834A5")
       ("tree-clear" "N-03C88274")
+      ("tree-count" "N-032882F2")
       ("tree-delete" "N-022035DF")
       ("tree-delete-node" "N-00772FAE")
+      ("tree-delete-specific-node" "N-009B02CA")
       ("tree-find" "N-0149BC05")
       ("tree-insert" "N-0114FF9E")
       ("tree-insert-node" "N-008B4AD9")