about summary refs log tree commit diff
path: root/emacs/.emacs.d/wpc/buffer.el
blob: e91b7712149a494c06c4b9c2796ee66ab7f0816a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
;;; buffer.el --- Working with Emacs buffers -*- lexical-binding: t -*-
;; Author: William Carroll <wpcarro@gmail.com>

;;; Commentary:
;; Utilities for CRUDing buffers in Emacs.
;;
;; Many of these functions may seem unnecessary especially when you consider
;; there implementations.  In general I believe that Elisp suffers from a
;; library disorganization problem.  Providing simple wrapper functions that
;; rename functions or reorder parameters is worth the effort in my opinion if
;; it improves discoverability (via intuition) and improve composability.
;;
;; I support three ways for switching between what I'm calling "source code
;; buffers":
;; 1. Toggling previous: <SPC><SPC>
;; 2. Using `ivy-read': <SPC>b
;; TODO: These obscure evil KBDs. Maybe a hydra definition would be best?
;; 3. Cycling (forwards/backwards): C-f, C-b

;;; Code:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Dependencies
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(require 'prelude)
(require 'maybe)
(require 'set)
(require 'cycle)
(require 'struct)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Library
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defconst buffer/enable-tests? t
  "When t, run the test suite.")

(defconst buffer/install-kbds? t
  "When t, install the keybindings defined herein.")

(defconst buffer/source-code-blacklist
  (set/new 'dired-mode
           'erc-mode
           'vterm-mode
           'magit-status-mode
           'magit-process-mode
           'magit-log-mode
           'magit-diff-mode
           'org-mode
           'fundamental-mode)
  "A blacklist of major-modes to ignore for listing source code buffers.")

(defconst buffer/source-code-timeout 2
  "Number of seconds to wait before invalidating the cycle.")

(cl-defstruct source-code-cycle cycle last-called)

(defun buffer/emacs-generated? (name)
  "Return t if buffer, NAME, is an Emacs-generated buffer.
Some buffers are Emacs-generated but are surrounded by whitespace."
  (let ((trimmed (s-trim name)))
    (and (s-starts-with? "*" trimmed))))

(defun buffer/find (buffer-or-name)
  "Find a buffer by its BUFFER-OR-NAME."
  (get-buffer buffer-or-name))

(defun buffer/major-mode (name)
  "Return the active `major-mode' in buffer, NAME."
  (with-current-buffer (buffer/find name)
    major-mode))

(defun buffer/source-code-buffers ()
  "Return a list of source code buffers.
This will ignore Emacs-generated buffers, like *Messages*.  It will also ignore
  any buffer whose major mode is defined in `buffer/source-code-blacklist'."
  (->> (buffer-list)
       (list/map #'buffer-name)
       (list/reject #'buffer/emacs-generated?)
       (list/reject (lambda (name)
                      (set/contains? (buffer/major-mode name)
                                     buffer/source-code-blacklist)))))

(defvar buffer/source-code-cycle-state
  (make-source-code-cycle
   :cycle (cycle/from-list (buffer/source-code-buffers))
   :last-called (ts-now))
  "State used to manage cycling between source code buffers.")

(defun buffer/exists? (name)
  "Return t if buffer, NAME, exists."
  (maybe-some? (buffer/find name)))

(defun buffer/new (name)
  "Return a newly created buffer NAME."
  (generate-new-buffer name))

(defun buffer/find-or-create (name)
  "Find or create buffer, NAME.
Return a reference to that buffer."
  (let ((x (buffer/find name)))
    (if (maybe-some? x)
        x
      (buffer/new name))))

;; TODO: Should this consume: `display-buffer' or `switch-to-buffer'?
(defun buffer/show (buffer-or-name)
  "Display the BUFFER-OR-NAME, which is either a buffer reference or its name."
  (display-buffer buffer-or-name))

;; TODO: Move this and `buffer/cycle-prev' into a separate module that
;; encapsulates all of this behavior.

(defun buffer/cycle (cycle-fn)
  "Cycle forwards or backwards through `buffer/source-code-buffers'."
  (let ((last-called (source-code-cycle-last-called
                      buffer/source-code-cycle-state))
        (cycle (source-code-cycle-cycle
                buffer/source-code-cycle-state)))
    (if (> (ts-diff (ts-now) last-called)
           buffer/source-code-timeout)
        (progn
          (struct/set! source-code-cycle
                       cycle
                       (cycle/from-list (buffer/source-code-buffers))
                       buffer/source-code-cycle-state)
          (let ((cycle (source-code-cycle-cycle
                        buffer/source-code-cycle-state)))
            (funcall cycle-fn cycle)
            (switch-to-buffer (cycle/current cycle)))
          (struct/set! source-code-cycle
                       last-called
                       (ts-now)
                       buffer/source-code-cycle-state))
      (progn
        (funcall cycle-fn cycle)
        (switch-to-buffer (cycle/current cycle))))))

(defun buffer/cycle-next ()
  "Cycle forward through the `buffer/source-code-buffers'."
  (interactive)
  (buffer/cycle #'cycle/next))

(defun buffer/cycle-prev ()
  "Cycle backward through the `buffer/source-code-buffers'."
  (interactive)
  (buffer/cycle #'cycle/prev))

(defun buffer/ivy-source-code ()
  "Use `ivy-read' to choose among all open source code buffers."
  (interactive)
  (ivy-read "Source code buffer: "
            (-drop 1 (buffer/source-code-buffers))
            :sort nil
            :action #'switch-to-buffer))

(defun buffer/show-previous ()
  "Call `switch-to-buffer' on the previously visited buffer.
This function ignores Emacs-generated buffers, i.e. the ones that look like
  this: *Buffer*.  It also ignores buffers that are `dired-mode' or `erc-mode'.
  This blacklist can easily be changed."
  (interactive)
  (let* ((xs (buffer/source-code-buffers))
         (candidate (list/get 1 xs)))
    (prelude-assert (maybe-some? candidate))
    (switch-to-buffer candidate)))

(when buffer/install-kbds?
  (general-define-key
   :states '(normal)
   "C-f" #'buffer/cycle-next
   "C-b" #'buffer/cycle-prev)
  (general-define-key
   :prefix "<SPC>"
   :states '(normal)
   "b" #'buffer/ivy-source-code
   "<SPC>" #'buffer/show-previous
   "k" #'kill-buffer))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Tests
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(when buffer/enable-tests?
  (prelude-assert
   (list/all? #'buffer/emacs-generated?
              '("*scratch*"
                "*Messages*"
                "*shell*"
                "*Shell Command Output*"
                "*Occur*"
                "*Warnings*"
                "*Help*"
                "*Completions*"
                "*Apropos*"
                "*info*"))))

(provide 'buffer)
;;; buffer.el ends here