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Improve org ref contraction readability and docs
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tecosaur committed Dec 10, 2020
1 parent 7217ab7 commit dc873d35307c0c20f85773ce5bf690c8c5a57e25
Showing with 65 additions and 46 deletions.
  1. +65 −46 config.org
@@ -4225,63 +4225,82 @@ the[[*Window title][Window title]].
#+end_src
**** Nicer generated heading IDs
Thanks to alphapapa's [[https://github.com/alphapapa/unpackaged.el#export-to-html-with-useful-anchors][unpackaged.el]].

By default, ~url-hexify-string~ seemed to cause me some issues. Replacing that in
~a53899~ resolved this for me. To go one step further, I create a function for
producing nice short links, like an inferior version of ~reftex-label~.

#+begin_src emacs-lisp
(defvar org-heading-contraction-max-words 3
"Maximum number of words in a heading")
(defvar org-heading-contraction-max-length 35
"Maximum length of resulting string")
(defvar org-heading-contraction-stripped-words
(defvar org-reference-contraction-max-words 3
"Maximum number of words in a reference reference.")
(defvar org-reference-contraction-max-length 35
"Maximum length of resulting reference reference, including joining characters.")
(defvar org-reference-contraction-stripped-words
'("the" "on" "in" "off" "a" "for" "by" "of" "and" "is" "to")
"Unnecesary words to be removed from a heading")

(defun org-heading-contraction (heading-string)
"Get a contracted form of HEADING-STRING that is onlu contains alphanumeric charachters.
Strips 'joining' words in `org-heading-contraction-stripped-words',
and then limits the result to the first `org-heading-contraction-max-words' words.
If the total length is > `org-heading-contraction-max-length' then individual words are
truncated to fit within the limit"
(let ((heading-words
"Superfluous words to be removed from a reference.")
(defvar org-reference-contraction-joining-char "-"
"Character used to join words in the reference reference.")

(defun org-reference-contraction-truncate-words (words)
"Using `org-reference-contraction-max-length' as the total character 'budget' for the WORDS
and truncate individual words to conform to this budget.

To arrive at a budget that accounts for words undershooting their requisite average length,
the number of charachters in the budget freed by short words is distributed among the words
exceeding the average length. This adjusts the per-word budget to be the maximum feasable for
this particular situation, rather than the universal maximum average.

This budget-adjusted per-word maximum length is given by the mathematical expression below:

max length = \\floor{ \\frac{total length - chars for seperators - \\sum_{word \\leq average length} length(word) }{num(words) > average length} }"
;; trucate each word to a max word length determined by
;;
(let* ((total-length-budget (- org-reference-contraction-max-length ; how many non-separator chars we can use
(1- (length words))))
(word-length-budget (/ total-length-budget ; max length of each word to keep within budget
org-reference-contraction-max-words))
(num-overlong (-count (lambda (word) ; how many words exceed that budget
(> (length word) word-length-budget))
words))
(total-short-length (-sum (mapcar (lambda (word) ; total length of words under that budget
(if (<= (length word) word-length-budget)
(length word) 0))
words)))
(max-length (/ (- total-length-budget total-short-length) ; max(max-length) that we can have to fit within the budget
num-overlong)))
(mapcar (lambda (word)
(if (<= (length word) max-length)
word
(substring word 0 max-length)))
words)))

(defun org-reference-contraction (reference-string)
"Give a contracted form of REFERENCE-STRING that is only contains alphanumeric characters.
Strips 'joining' words present in `org-reference-contraction-stripped-words',
and then limits the result to the first `org-reference-contraction-max-words' words.
If the total length is > `org-reference-contraction-max-length' then individual words are
truncated to fit within the limit using `org-reference-contraction-truncate-words'."
(let ((reference-words
(-filter (lambda (word)
(not (member word org-heading-contraction-stripped-words)))
(not (member word org-reference-contraction-stripped-words)))
(split-string
(->> heading-string
s-downcase
(->> reference-string
downcase
(replace-regexp-in-string "\\[\\[[^]]+\\]\\[\\([^]]+\\)\\]\\]" "\\1") ; get description from org-link
(replace-regexp-in-string "[-/ ]+" " ") ; replace seperator-type chars with space
(replace-regexp-in-string "[^a-z0-9 ]" "") ; strip chars which need %-encoding in a uri
) " "))))
(when (> (length heading-words)
org-heading-contraction-max-words)
(setq heading-words
(cl-subseq heading-words 0 org-heading-contraction-max-words)))

(when (> (+ (-sum (mapcar #'length heading-words))
(1- (length heading-words)))
org-heading-contraction-max-length)
;; trucate each word to a max word length determined by
;; max length = \floor{ \frac{total length - chars for seperators - \sum_{word \leq average length} length(word) }{num(words) > average length} }
(setq heading-words (let* ((total-length-budget (- org-heading-contraction-max-length ; how many non-separator chars we can use
(1- (length heading-words))))
(word-length-budget (/ total-length-budget ; max length of each word to keep within budget
org-heading-contraction-max-words))
(num-overlong (-count (lambda (word) ; how many words exceed that budget
(> (length word) word-length-budget))
heading-words))
(total-short-length (-sum (mapcar (lambda (word) ; total length of words under that budget
(if (<= (length word) word-length-budget)
(length word) 0))
heading-words)))
(max-length (/ (- total-length-budget total-short-length) ; max(max-length) that we can have to fit within the budget
num-overlong)))
(mapcar (lambda (word)
(if (<= (length word) max-length)
word
(substring word 0 max-length)))
heading-words))))
(string-join heading-words "-")))
(when (> (length reference-words)
org-reference-contraction-max-words)
(setq reference-words
(cl-subseq reference-words 0 org-reference-contraction-max-words)))

(when (> (apply #'+ (1- (length reference-words))
(mapcar #'length reference-words))
org-reference-contraction-max-length)
(setq reference-words (org-reference-contraction-truncate-words reference-words)))

(string-join reference-words org-reference-contraction-joining-char)))
#+end_src
Now here's alphapapa's subtly tweaked mode.
#+begin_src emacs-lisp

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