A permuted index takes an indexing expression and makes an entry for each word in the expression. For example, the index expression run-shell-command (a reference to the function run-shell-command) is thus indexed under R (for run), S (for shell), and C (for command) in the permuted index. The expression What if the system seems to hang is indexed under H (for hang), I (for if), S (for seems and again for system), T (for the and again for to), and W (for what).
Here are some issues when creating a permuted index:
The power of creating a permuted index is shown from the What if the system seems to hang example. As shown, the index entry is in index-i.htm, starting with the text interrupting for sure. In the permuted index, we get additional entries for hang, system (with hang close by), and system tray, among others, automatically. Further, knowing how the permuted index is generated encourages writing main index entries that will generate useful permuted index entries (by having the link text contain useful words).
Now let us look at the code for generating the index. The steps are as follows:
Here is the code. This code should run in Allegro CL 6.1 (but you may hit the Trial version heap limits). Note that the permuted index files generated, named my-permuted-index-*.htm, are somewhat simpler than the ones in the documentation update. They lack the navigation bars at the top and the bottom and other boilerplate information, and they lack the secondary index (links into the list of entries for fast scrolling).
Three parameters must be set. They have been given reasonable defaults, but are likely best set specifically by you. The parameters are:
We have provided the code here. Click here to download a version of the code in a seperate file (cutting and pasting from a browser often results in poorly formated code).
;; Code to generate permuted index files from standard ;; Allegro CL index files. (in-package :user) (eval-when (compile load eval) (require :phtml) (require :aserve)) #| ;; The program works by reading the index pages from a regular ;; doc set and creating permuted index pages. ;; Configure these pathnames as desired. ;; *doc-index-wildcard* is the path of the doc/ directory, followed by ;; the filenames described by index-*.htm ;; (i.e. the standard index files) ;; *index-target-url* the location where the new permuted index files ;; will be placed. The initial value is "/tmp/" ;; *index-base-url* the directory that will be added to a link ;; from an index file into the documentation. If ;; the documentation is the doc/ subdirectory, of ;; (on Windows machines, this is the usual location) ;; "/Program Files/acl61/doc/" and *index-target-url* ;; is "/tmp/", the value should be ;; "../Program Files/acl61/doc/". ;; On UNIX machines, the location is typically /usr/local/acl61 |# ;; This is from where to read the index files to create the permuted index. (defparameter *doc-index-wildcard* #+mswindows "doc/index-*.htm" #-mswindows "/usr/local/acl61/doc/index-*.htm") ;; This is where to write the created my-permuted-index*.htm files. (defparameter *index-target-url* "/tmp/") ;; This is the base for URL references to the generated indexed doc set. (defparameter *index-base-url* #+mswindows "../Program Files/acl61/doc/" #-mswindows "/usr/local/acl61/doc/") ;; The following functions callect information from ;; the doc/index-*.htm files. ;; The first element of an lhtml list is either a tag ;; or a list of a tag and attribute/value pairs. This ;; function extracts the actual tag. (defun element-tag (element) (if (consp element) (car element) element)) (defun find-element (html predicate continuation) (when (consp html) (destructuring-bind (element &rest content) html (if (if (symbolp predicate) (eq (element-tag element) predicate) (funcall predicate element)) (funcall continuation element content) (loop for sub in content do (find-element sub predicate continuation)))))) (defun collect-strings (content) (with-output-to-string (s) (labels ((collect-strings-1 (content) (typecase content (string (write-string content s)) (cons (collect-strings-1 (car content)) (collect-strings-1 (cdr content)))))) (collect-strings-1 content)))) (defun whitespacep (char) (member char '(#\space #\tab #\linefeed #\return))) (defun normalize-whitespace (str) ;; Normalize all space to a single nbsp, dropping leading and trailing space. (with-output-to-string (s) (loop with startedp = nil with last-whitespace = nil for c across str do (if (whitespacep c) (when startedp (setq last-whitespace t)) (progn (when last-whitespace (write-char #\space s) ; #\no-break_space (setq last-whitespace nil)) (setq startedp t) (write-char c s)))))) (defun collect-all-entries () #| This function depends on the known structure of index-*.htm files: the index entries are in a bulleted list, tagged with UL, with entries tagged with LI and links tagged with A. We further know that the only butlleted lists are lists entries. So this function gets the LHTML list from each index-*.htm file, and strats walking through it, finding A tags within LI tags within UL tags and collecing them |# (let ((ret nil)) (loop for letter-index-file in (directory *doc-index-wildcard*) as html = (with-open-file (f letter-index-file) (net.html.parser:parse-html f)) do (find-element (car html) :ul (lambda (e c) (find-element (cons e c) :li (lambda (e c) (find-element (cons e c) :a (lambda (e c) (let ((url (getf (cdr e) :href))) (push (cons url (normalize-whitespace (collect-strings c))) ret))))))))) ;; Delete duplicates. Certain entries for multiple names ;; (e.g. string-upcase, nstring-upcase, etc.) will have ;; been gathered from multiple pages index-letter pages. (loop for x on (sort ret (lambda (x y) (cond ((string< (car x) (car y)) t) ((string> (car x) (car y)) nil) ((string< (cdr x) (cdr y)) t) (t nil)))) unless (equal (car x) (cadr x)) collect (car x)))) ;; Name is a single string with no leading or trailing ;; whitespace and all internal ;; whitespace consisting of only a single space. ;; Returns a list of indexes into the string ;; where permuted entries should start. (defun generate-index-entries (name) ;; Need to delete noise entries. (loop with last-alpha = nil for n from 0 for c across name if (not (alphanumericp c)) do (setf last-alpha nil) else when (null last-alpha) collect n and do (setf last-alpha t))) (defun gen-index-entries () (loop for entries on (stable-sort (sort (loop for (url . name) in (collect-all-entries) as target-url = (concatenate 'string *index-base-url* url) as entry = (cons name target-url) nconc (loop for split on (generate-index-entries name) when (> (- (or (cadr split) (1+ (length name))) (car split)) 2) collect (list* (subseq name (car split) (and (cadr split) (loop for i from (1- (cadr split)) downto (car split) when (alpha-char-p (char name i)) return (1+ i)))) (car split) (cadr split) entry))) #'string-lessp :key #'fourth) #'string-lessp :key #'car) ;; Delete any duplicate entries. unless (equal (car entries) (cadr entries)) collect (car entries))) ;; This function creates a lhtml list for a collection for a single ;; my-permuted-index-*.htm page and returns it. (defun emit-page-table (entries title) (let ((lhtml-list (list :html (list :head (list :title title)))) (table-head (list (list :table "border" "0" "cellpadding" "0" "cellspacing" "0"))) (table-body nil) (body1-list (list (list :h1 title) (append (list :p) (gen-links-list)))) (body2-list (list (append (list :p) (gen-links-list)))) (result nil)) (loop for entry in entries as (item ind1 ind2 text . url) = entry do (setq table-body (append table-body (list (list :tr (list '(:td "align" "right") (if (eql ind1 0) " " (gen-a-entry url ;; If the last char of the left segment ;; is a space, replace it with a nbsp. ;; Otherwise html rendering will remove ;; it entirely. We can't just replace ;; all spaces with nbsp ;; because then the renderer ;; can't fold very long lines. (progn (if (eql #\space (char text (1- ind1))) (let ((str (subseq text 0 ind1))) (setf (char str (1- ind1)) #\no-break_space) str) (subseq text 0 ind1)))))) (list '(:td "align" "left") (gen-a-entry url (concatenate 'string (if ind2 (when ind2 (loop while (> ind2 ind1) until (alpha-char-p (char text (1- ind2))) do (decf ind2))) "") item (if ind2 (subseq text ind2) ""))))) ))) (setq result (append lhtml-list (list (append (list :body) body1-list (list (append table-head table-body)) body2-list))))) result)) ;; This function creates the main permuted index page (with links ;; all other pages. (defun gen-permuted-index-main () (let ((lhtml-list (list :html)) (body-list nil) (links-list (gen-links-list))) (setq lhtml-list (append lhtml-list (list (list :head (list :title "Permuted Index"))))) (setq body-list (list (list :h1 "Permuted Index") (append (list :p) links-list))) (setq lhtml-list (append lhtml-list (list (append (list :body) body-list)))))) ;; This function creates a lhtml :a entry (defun gen-a-entry (href entry) (list (list :a "href" href) entry)) ;; This function creates the lhtml links (to other my-permuted-index-* ;; files). (defun gen-links-list () (let ((links-list nil)) (loop for c across "abcdefghijklmnopqrstuvwxyz" do (setq links-list (append links-list (list (gen-a-entry (format nil "my-permuted-index-~a.htm" c) (list :b (concatenate 'string (string-upcase c) " "))))))) (setq links-list (append links-list (list (gen-a-entry "my-permuted-index-non-alphabetic.htm" (list :b "Non-Alphabetic"))))))) (defun gen-permuted-index-files () ;; writes permuted index files ;; First the main file: (with-open-file (s (format nil "~amy-permuted-index.htm" *index-target-url*) :direction :output :if-exists :supersede) (net.html.generator:html-print (gen-permuted-index-main) s)) ;; Now the individual files: (let ((entries (gen-index-entries))) (flet ((emit (filenamex predicate) (with-open-file (stream (format nil "~amy-permuted-index-~a.htm" *index-target-url* filenamex) :direction :output :if-exists :supersede) (let ((result (funcall 'emit-page-table (loop for entry in entries when (funcall predicate (car entry)) collect entry) (format nil "Permuted Index - ~:(~a~)" filenamex)))) (net.html.generator:html-print result stream))))) (loop for c across "abcdefghijklmnopqrstuvwxyz" do (emit c (lambda (name) (char-equal (char name 0) c)))) (emit "non-alphabetic" (lambda (name) (not (alpha-char-p (char name 0))))) )))
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