company-same-mode-buffers.el / complete-same-mode-buffers.el

Company / completion-at-point backend to complete symbols in same mode buffers (like ac-source-words-in-same-mode-buffers)

with following features:

• Optional flex matching
• Good performance powered by radix-tree
• History mechanism to share candidates across sessions

Installation

load and initialize this package, and,

company

add to company-backends.

(require 'company-same-mode-buffers)
(company-same-mode-buffers-initialize)
(push 'company-same-mode-buffers company-backends)

completion-at-point (corfu)

add to completion-at-point-functions.

(require complete-same-mode-buffers)
(company-same-mode-buffers-initialize)
(push 'complete-same-mode-buffers (default-value 'completion-at-point-functions))

History file

You may optionally save current candidates to a file, to share across sessions.

;; this line must be put before "company-same-mode-buffers-initialize"
(setq company-same-mode-buffers-history-file "~/.emacs.d/.company-same-mode-buffers-history")

History file internals (v2)

Format

An alist of the form alist[timestamp => alist[major-mode => list[symbol]]] is saved to the history file.

((TIMESTAMP (MAJOR_MODE SYMBOL ...) ...) ...)

Load

For each history record (of the form cons[timestamp, alist[major-mode => symbol]]), symbols are inserted into temporary buffer with appropreate major-mode.

;; sample history
((<timestamp>
  (emacs-lisp-mode "save-excursion" "defun" "defvar")
  (js-mode "function" "return"))
 (<timestamp>
  (emacs-lisp-mode "defconst")
  (css-mode "margin")))

;; a temporary buffer with emacs-lisp-mode
save-excursion defun defvar defconst

;; a temporary buffer with js-mode
function return

;; a temporary buffer with css-mode
margin

Note that each history records' timestamp is compared to company-same-mode-buffers-history-store-limit, and if it's older than the threshold, the record is skipped.

Save

When killing Emacs, company-same-mode-buffers visits all buffers (that derives prog-mode, including temporary buffers created by company-same-mode-buffers) and collect all symbols. If a symbol appears in more than two buffers, then the symbols is saved to the history file with new timestamp.

This way, we can store symbols ONLY IF it's useful across buffers, and save memory. We don't need file-specific symbols (like internal variable names) to be saved.

Downside: If a buffer is killed before killing Emacs, symbols in that buffer are NOT saved.

Matching algorithms

You may disable some of these matching algorithms, if you don't need them.

(setq company-same-mode-buffers-matchers
      '(company-same-mode-buffers-matcher-basic
        company-same-mode-buffers-matcher-partial
        company-same-mode-buffers-matcher-exact-first-letter-flex-rest
        ;; company-same-mode-buffers-matcher-flex
        ))

• company-same-mode-buffers-matcher-basic

  compan -> compan* -> company-backends

• company-same-mode-buffers-matcher-partial

  co-ba -> co*-ba* -> company-backends

• company-same-mode-buffers-matcher-exact-first-letter-flex-rest

  cbns -> c*n*b*s* -> company-backends

• company-same-mode-buffers-matcher-flex

  pbns -> *p*n*b*s* -> company-backends