echo-bar/echo-bar-engine.el at main · chenanton/echo-bar · GitHub

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;;; echo-bar-engine.el --- Update engine and hook management -*- lexical-binding: t -*-

;; Author: Anton Chen <mail@antonchen.ca>
;; Version: 0.1.0
;; Package-Requires: ((emacs "29.1"))
;; Keywords: frames, convenience
;; URL: https://github.com/chenanton/echo-bar
;; SPDX-License-Identifier: GPL-3.0-or-later
;; Copyright (C) 2026 Anton Chen

;;; Commentary:
;; The core update loop: dirty tracking, coalescing, hook/advice
;; registration.  Nothing here knows about layout or overlays --
;; it calls into echo-bar-render.el for those.

;;; Code:

(require 'cl-lib)
(require 'echo-bar-segments)
(require 'echo-bar-render)

;;; State

(defvar echo-bar--update-pending nil
  "Non-nil when an update is already scheduled.")

(defvar echo-bar--last-display nil
  "The last display string written to overlays.")

(defvar echo-bar--idle-timer nil
  "Idle timer for safety-net full refresh.")

(defvar echo-bar--segment-timers nil
  "List of active segment timers.")

(defvar echo-bar--registered-hooks nil
  "Alist of (HOOK . FUNCTION) pairs registered by echo-bar.")

(defvar echo-bar--registered-advice nil
  "Alist of (SYMBOL . FUNCTION) pairs for advice registered by echo-bar.")

;;; Dirty tracking

(defun echo-bar--mark-dirty (name)
  "Mark segment NAME as dirty and schedule an update."
  (when-let* ((seg (gethash name echo-bar--segments)))
    (puthash name t (if (eq (echo-bar-segment-scope seg) :global)
                        echo-bar--global-dirty
                      (echo-bar--buffer-dirty)))
    (echo-bar--schedule-update)))

(defun echo-bar--mark-dirty-fn (name)
  "Return a function that marks segment NAME dirty."
  (lambda (&rest _) (echo-bar--mark-dirty name)))

(defun echo-bar--mark-all-dirty ()
  "Mark every segment as dirty."
  (let ((buf-dirty (echo-bar--buffer-dirty)))
    (maphash (lambda (name seg)
               (puthash name t (if (eq (echo-bar-segment-scope seg) :global)
                                   echo-bar--global-dirty
                                 buf-dirty)))
             echo-bar--segments)))

;;; Coalescer and update loop

(defun echo-bar--schedule-update ()
  "Schedule a coalesced update for the next event cycle.
Multiple triggers in the same command cycle produce only one update."
  (unless echo-bar--update-pending
    (setq echo-bar--update-pending t)
    (run-at-time 0 nil #'echo-bar--do-update)))

(defun echo-bar--do-update ()
  "Rebuild display from dirty segments, write overlays if changed."
  (setq echo-bar--update-pending nil)
  (when (and echo-bar-mode (not (active-minibuffer-window)))
    ;; Recompute dirty buffer-local segments
    (let ((buf-dirty (echo-bar--buffer-dirty)))
      (maphash (lambda (name _)
                 (echo-bar--recompute-segment name))
               buf-dirty)
      (clrhash buf-dirty))
    ;; Recompute dirty global segments
    (maphash (lambda (name _)
               (echo-bar--recompute-segment name))
             echo-bar--global-dirty)
    (clrhash echo-bar--global-dirty)
    ;; Render and write if changed
    (let ((new-display (echo-bar--render)))
      (unless (equal new-display echo-bar--last-display)
        (setq echo-bar--last-display new-display)
        (echo-bar--write-overlays new-display)))))

;;; Event handlers

(defun echo-bar--post-command-handler ()
  "Single handler for all post-command-hook segments."
  (let ((buf-dirty (echo-bar--buffer-dirty)))
    (dolist (name echo-bar--post-command-segments)
      (when-let* ((seg (gethash name echo-bar--segments)))
        (puthash name t (if (eq (echo-bar-segment-scope seg) :global)
                            echo-bar--global-dirty
                          buf-dirty)))))
  (echo-bar--schedule-update))

(defun echo-bar--on-buffer-change (&rest _)
  "Mark all buffer-local segments dirty on buffer switch."
  (setq echo-bar--last-display nil)
  (let ((buf-dirty (echo-bar--buffer-dirty)))
    (maphash (lambda (name seg)
               (when (eq (echo-bar-segment-scope seg) :buffer)
                 (puthash name t buf-dirty)))
             echo-bar--segments))
  (echo-bar--schedule-update))

(defun echo-bar--idle-refresh ()
  "Safety net: mark everything dirty and update."
  (let ((buf-dirty (echo-bar--buffer-dirty)))
    (maphash (lambda (name seg)
               (puthash name t (if (eq (echo-bar-segment-scope seg) :global)
                                   echo-bar--global-dirty
                                 buf-dirty)))
             echo-bar--segments))
  (echo-bar--schedule-update))

;;; Hook and advice registration

(defun echo-bar--register-all-hooks ()
  "Register hooks and advice for all segments."
  ;; Combined post-command-hook handler
  (when echo-bar--post-command-segments
    (add-hook 'post-command-hook #'echo-bar--post-command-handler)
    (push (cons 'post-command-hook #'echo-bar--post-command-handler)
          echo-bar--registered-hooks))
  ;; Buffer change
  (add-hook 'window-buffer-change-functions #'echo-bar--on-buffer-change)
  (push (cons 'window-buffer-change-functions #'echo-bar--on-buffer-change)
        echo-bar--registered-hooks)
  ;; Window resize
  (add-hook 'window-size-change-functions #'echo-bar--on-resize)
  (push (cons 'window-size-change-functions #'echo-bar--on-resize)
        echo-bar--registered-hooks)
  ;; Font change
  (when (boundp 'after-setting-font-hook)
    (add-hook 'after-setting-font-hook #'echo-bar--on-font-change)
    (push (cons 'after-setting-font-hook #'echo-bar--on-font-change)
          echo-bar--registered-hooks))
  ;; Per-segment hooks and advice (excluding post-command-hook)
  (maphash
   (lambda (name seg)
     (let ((triggers (echo-bar-segment-triggers seg)))
       ;; Hooks
       (dolist (hook (plist-get triggers :hooks))
         (unless (eq hook 'post-command-hook)
           (let ((fn (echo-bar--mark-dirty-fn name)))
             (add-hook hook fn)
             (push (cons hook fn) echo-bar--registered-hooks))))
       ;; Advice
       (dolist (spec (plist-get triggers :advice))
         (let ((target (car spec))
               (how (cdr spec))
               (fn (echo-bar--mark-dirty-fn name)))
           (advice-add target how fn)
           (push (cons target fn) echo-bar--registered-advice)))
       ;; Timers
       (when-let* ((timer-spec (plist-get triggers :timers)))
         (let* ((idle (plist-get timer-spec :idle))
                (repeat (plist-get timer-spec :repeat))
                (fn (echo-bar--mark-dirty-fn name))
                (timer (run-with-idle-timer (or idle 10) repeat fn)))
           (push timer echo-bar--segment-timers)))))
   echo-bar--segments)
  ;; Message advice
  (advice-add 'message :around #'echo-bar--message-advice)
  ;; Re-apply face remap on minibuffer transitions (Emacs resets
  ;; face-remapping-alist when entering/exiting the minibuffer)
  (add-hook 'minibuffer-inactive-mode-hook #'echo-bar--fontify-echo-area)
  (push (cons 'minibuffer-inactive-mode-hook #'echo-bar--fontify-echo-area)
        echo-bar--registered-hooks)
  (add-hook 'minibuffer-setup-hook #'echo-bar--fontify-echo-area)
  (push (cons 'minibuffer-setup-hook #'echo-bar--fontify-echo-area)
        echo-bar--registered-hooks)
  ;; Idle fallback timer
  (when echo-bar-idle-fallback-interval
    (setq echo-bar--idle-timer
          (run-with-idle-timer echo-bar-idle-fallback-interval t
                               #'echo-bar--idle-refresh))))

(defun echo-bar--remove-all-hooks ()
  "Remove all hooks and advice registered by echo-bar."
  (dolist (entry echo-bar--registered-hooks)
    (remove-hook (car entry) (cdr entry)))
  (setq echo-bar--registered-hooks nil)
  (dolist (entry echo-bar--registered-advice)
    (advice-remove (car entry) (cdr entry)))
  (setq echo-bar--registered-advice nil)
  (advice-remove 'message #'echo-bar--message-advice)
  (dolist (timer echo-bar--segment-timers)
    (when (timerp timer) (cancel-timer timer)))
  (setq echo-bar--segment-timers nil)
  (when (timerp echo-bar--idle-timer)
    (cancel-timer echo-bar--idle-timer)
    (setq echo-bar--idle-timer nil)))

(provide 'echo-bar-engine)
;;; echo-bar-engine.el ends here