;; Licensed under a Creative Commons Attribution 4.0 International License.
;; See http://creativecommons.org/licenses/by/4.0/
;;
;; Author: Howard X. Abrams <http://gitlab.com/howardabrams>
;; Maintainer: Howard X. Abrams
;; Created: October 14, 2022
;;
;; While obvious, GNU Emacs does not include this file or project.
;;
;; *NB:* Do not edit this file. Instead, edit the original literate file at:
;; /Users/howard.abrams/other/hamacs/ha-data.org
;; And tangle the file to recreate this one.
;;
;;; Code:
#+end_src
* Introduction
Once upon a time, I [[https://www.youtube.com/watch?v=HKJMDJ4i-XI][gave a talk]] to EmacsConf 2019, about [[http://howardism.org/Technical/Emacs/piper-presentation-transcript.html][an interesting idea]] I called [[https://gitlab.com/howardabrams/emacs-piper][emacs-piper]]. I still like the idea of sometimes editing an Emacs buffer on the entire contents, as if it were a data file. This file contains what I feel are the best functions for that… oh, and a leader to call it (instead of the original Hydra).
#+begin_src emacs-lisp
(ha-leader
"d" '(:ignore t :which-key "data")
"d |" '("pipe to shell" . replace-buffer-with-shell-command)
"d y" '("copy to clipboard" . ha-yank-buffer-contents))
#+end_src
* Line-Oriented Functions
These functions focus on the data in the buffer as a series of lines:
#+begin_src emacs-lisp
(ha-leader
"d l" '(:ignore t :which-key "on lines")
"d l f" '("flush lines" . flush-lines)
"d l k" '("keep lines" . keep-lines)
"d l s" '("sort lines" . ha-sort-lines)
"d l u" '("unique lines" . delete-duplicate-lines)
"d l b" '("flush blanks" . flush-blank-lines))
#+end_src
One issue I have is [[help:keep-lines][keep-lines]] operate on the lines /starting with the point/, not on the entire buffer. Let’s fix that:
"Replace current line after keeping or deleting COLUMNS.
Keep the COLUMNS if KEEP? is non-nil, delete otherwise.
Defined columns as the text between SEPARATOR."
(cl-labels ((keep-oper (idx it) (if keep?
(when (member idx columns) it)
(unless (member idx columns) it))))
(let* ((start (line-beginning-position))
(end (line-end-position))
(line (buffer-substring start end))
(parts (thread-last (split-string line separator)
(--map-indexed (keep-oper it-index it))
(-remove 'null)))
(nline (string-join parts separator)))
(delete-region start end)
(insert nline))))
#+end_src
I like the idea of the shell command, =cut=, where you can have an arbitrary character as a separator, and then either delete or keep the data between them, as columns. But I need a function that can convert a string of “columns”, for instance ="1, 4-7 9"= to an list of numbers, like ='(1 4 5 6 7 9)=:
