From d0923e437b00977c09b7ef1a54677ccf4d3e00ab Mon Sep 17 00:00:00 2001 From: David Kastrup Date: Thu, 3 Jun 2004 19:53:53 +0000 Subject: [PATCH] (woman-mapcan): More concise code. (woman-topic-all-completions, woman-topic-all-completions-1) (woman-topic-all-completions-merge): Replace by a simpler and much faster implementation based on O(n log n) sort/merge instead of the old O(n^2) behavior. --- lisp/woman.el | 104 +++++++++++++++++++++++++------------------------- 1 file changed, 53 insertions(+), 51 deletions(-) diff --git a/lisp/woman.el b/lisp/woman.el index d69c631f27b..ba511bca1ae 100644 --- a/lisp/woman.el +++ b/lisp/woman.el @@ -1,6 +1,6 @@ ;;; woman.el --- browse UN*X manual pages `wo (without) man' -;; Copyright (C) 2000, 2002 Free Software Foundation, Inc. +;; Copyright (C) 2000, 2002, 2004 Free Software Foundation, Inc. ;; Author: Francis J. Wright ;; Maintainer: Francis J. Wright @@ -402,6 +402,7 @@ ;; Alexander Hinds ;; Stefan Hornburg ;; Theodore Jump +;; David Kastrup ;; Paul Kinnucan ;; Jonas Linde ;; Andrew McRae @@ -438,7 +439,8 @@ "Return concatenated list of FN applied to successive `car' elements of X. FN must return a list, cons or nil. Useful for splicing into a list." ;; Based on the Standard Lisp function MAPCAN but with args swapped! - (and x (nconc (funcall fn (car x)) (woman-mapcan fn (cdr x))))) + ;; More concise implementation than the recursive one. -- dak + (apply #'nconc (mapcar fn x))) (defun woman-parse-colon-path (paths) "Explode search path string PATHS into a list of directory names. @@ -1367,15 +1369,16 @@ The cdr of each alist element is the path-index / filename." ;; is re-processed by `woman-topic-all-completions-merge'. (let (dir files (path-index 0)) ; indexing starts at zero (while path - (setq dir (car path) - path (cdr path)) + (setq dir (pop path)) (if (woman-not-member dir path) ; use each directory only once! - (setq files - (nconc files - (woman-topic-all-completions-1 dir path-index)))) + (push (woman-topic-all-completions-1 dir path-index) + files)) (setq path-index (1+ path-index))) ;; Uniquefy topics: - (woman-topic-all-completions-merge files))) + ;; Concate all lists with a single nconc call to + ;; avoid retraversing the first lists repeatedly -- dak + (woman-topic-all-completions-merge + (apply #'nconc files)))) (defun woman-topic-all-completions-1 (dir path-index) "Return an alist of the man topics in directory DIR with index PATH-INDEX. @@ -1388,55 +1391,54 @@ of the first `woman-cache-level' elements from the following list: ;; unnecessary. So let us assume that `woman-file-regexp' will ;; filter out any directories, which probably should not be there ;; anyway, i.e. it is a user error! - (mapcar - (lambda (file) - (cons - (file-name-sans-extension - (if (string-match woman-file-compression-regexp file) - (file-name-sans-extension file) - file)) - (if (> woman-cache-level 1) - (cons - path-index - (if (> woman-cache-level 2) - (cons file nil)))))) - (directory-files dir nil woman-file-regexp))) + ;; + ;; Don't sort files: we do that when merging, anyway. -- dak + (let (newlst (lst (directory-files dir nil woman-file-regexp t)) + ;; Make an explicit regexp for stripping extension and + ;; compression extension: file-name-sans-extension is a + ;; far too costly function. -- dak + (ext (format "\\(\\.[^.\\/]*\\)?\\(%s\\)?\\'" + woman-file-compression-regexp))) + ;; Use a loop instead of mapcar in order to avoid the speed + ;; penalty of binding function arguments. -- dak + (dolist (file lst newlst) + (push + (cons + (if (string-match ext file) + (substring file 0 (match-beginning 0)) + file) + (and (> woman-cache-level 1) + (cons + path-index + (and (> woman-cache-level 2) + (list file))))) + newlst)))) (defun woman-topic-all-completions-merge (alist) "Merge the alist ALIST so that the keys are unique. Also make each path-info component into a list. \(Note that this function changes the value of ALIST.)" - ;; Intended to be fast by avoiding recursion and list copying. - (if (> woman-cache-level 1) - (let ((newalist alist)) - (while newalist - (let ((tail newalist) (topic (car (car newalist)))) - ;; Make the path-info into a list: - (setcdr (car newalist) (list (cdr (car newalist)))) - (while tail - (while (and tail (not (string= topic (car (car (cdr tail)))))) - (setq tail (cdr tail))) - (if tail ; merge path-info into (car newalist) - (let ((path-info (cdr (car (cdr tail))))) - (if (member path-info (cdr (car newalist))) - () - ;; Make the path-info into a list: - (nconc (car newalist) (list path-info))) - (setcdr tail (cdr (cdr tail)))) - )) - (setq newalist (cdr newalist)))) - alist) + ;; Replaces unreadably "optimized" O(n^2) implementation. + ;; Instead we use sorting to merge stuff efficiently. -- dak + (let (elt newalist) + ;; Sort list into reverse order + (setq alist (sort alist (lambda(x y) (string< (car y) (car x))))) + ;; merge duplicate keys. + (if (> woman-cache-level 1) + (while alist + (setq elt (pop alist)) + (if (equal (car elt) (caar newalist)) + (unless (member (cdr elt) (cdar newalist)) + (setcdr (car newalist) (cons (cdr elt) + (cdar newalist)))) + (setcdr elt (list (cdr elt))) + (push elt newalist))) ;; woman-cache-level = 1 => elements are single-element lists ... - (while (and alist (member (car alist) (cdr alist))) - (setq alist (cdr alist))) - (if alist - (let ((newalist alist) cdr_alist) - (while (setq cdr_alist (cdr alist)) - (if (not (member (car cdr_alist) (cdr cdr_alist))) - (setq alist cdr_alist) - (setcdr alist (cdr cdr_alist))) - ) - newalist)))) + (while alist + (setq elt (pop alist)) + (unless (equal (car elt) (caar newalist)) + (push elt newalist)))) + newalist)) (defun woman-file-name-all-completions (topic) "Return an alist of the files in all man directories that match TOPIC." -- 2.39.5