From 8466d8cfa486fb30d1755c4261b781135083787b Mon Sep 17 00:00:00 2001 From: Bryan Newbold Date: Mon, 20 Feb 2017 00:05:29 -0800 Subject: Import Upstream version 3a1 --- tree.txi | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 tree.txi (limited to 'tree.txi') diff --git a/tree.txi b/tree.txi new file mode 100644 index 0000000..3164ae5 --- /dev/null +++ b/tree.txi @@ -0,0 +1,48 @@ +@code{(require 'tree)} +@ftindex tree + +These are operations that treat lists a representations of trees. + + +@defun subst new old tree +@defunx substq new old tree +@defunx substv new old tree + + +@defunx subst new old tree equ? +@code{subst} makes a copy of @var{tree}, substituting @var{new} for +every subtree or leaf of @var{tree} which is @code{equal?} to @var{old} +and returns a modified tree. The original @var{tree} is unchanged, but +may share parts with the result. + +@code{substq} and @code{substv} are similar, but test against @var{old} +using @code{eq?} and @code{eqv?} respectively. If @code{subst} is +called with a fourth argument, @var{equ?} is the equality predicate. + +Examples: +@lisp +(substq 'tempest 'hurricane '(shakespeare wrote (the hurricane))) + @result{} (shakespeare wrote (the tempest)) +(substq 'foo '() '(shakespeare wrote (twelfth night))) + @result{} (shakespeare wrote (twelfth night . foo) . foo) +(subst '(a . cons) '(old . pair) + '((old . spice) ((old . shoes) old . pair) (old . pair))) + @result{} ((old . spice) ((old . shoes) a . cons) (a . cons)) +@end lisp +@end defun + +@defun copy-tree tree + +Makes a copy of the nested list structure @var{tree} using new pairs and +returns it. All levels are copied, so that none of the pairs in the +tree are @code{eq?} to the original ones -- only the leaves are. + +Example: +@lisp +(define bar '(bar)) +(copy-tree (list bar 'foo)) + @result{} ((bar) foo) +(eq? bar (car (copy-tree (list bar 'foo)))) + @result{} #f +@end lisp +@end defun -- cgit v1.2.3