86 lines
2.9 KiB
EmacsLisp
86 lines
2.9 KiB
EmacsLisp
;;; clj-watch.el --- A pinned, self-overwriting watch buffer -*- lexical-binding: t -*-
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;;; Commentary:
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;; Polls `watch/render' on a timer and replaces the buffer contents in
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;; place. Unlike `cider-tap', nothing is appended -- the buffer always shows
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;; the current frame's snapshot and nothing else.
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;;
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;; Usage: M-x clj-watch / M-x clj-watch-stop
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;;
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;; Load with: (load "/path/to/project/watch.el")
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;;; Code:
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(require 'cider-client)
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(defvar clj-watch-buffer "*clj-watch*")
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(defvar clj-watch-interval 0.2
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"Seconds between polls. This is the watch rate, not the frame rate.")
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(defvar clj-watch--timer nil)
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(defvar clj-watch--connection nil
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"The CIDER connection buffer to poll, captured when watching starts.")
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(defun clj-watch--paint (text)
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"Replace the watch buffer's contents with TEXT."
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(when-let* ((buf (get-buffer clj-watch-buffer)))
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(let ((tmp (get-buffer-create " *clj-watch-src*")))
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(with-current-buffer tmp
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(erase-buffer)
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(insert text))
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(with-current-buffer buf
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(let ((inhibit-read-only t))
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;; replace-buffer-contents diffs rather than erasing, so point and
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;; scroll position survive every tick. erase-buffer + insert would
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;; yank the cursor back to the top five times a second.
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(replace-buffer-contents tmp))))))
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(defun clj-watch--tick ()
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"Poll the snapshot once, asynchronously."
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(cond
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((not (get-buffer clj-watch-buffer)) (clj-watch-stop))
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((not (buffer-live-p clj-watch--connection))
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(clj-watch--paint "error:\nCIDER connection lost")
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(clj-watch-stop))
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(t
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;; Async, not `cider-nrepl-sync-request': a sync request on a timer blocks
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;; Emacs's UI thread every tick. Pass the connection explicitly -- the
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;; timer fires with no reliable "current buffer" to resolve one from.
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(cider-nrepl-request:eval
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"(watch/render)"
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(lambda (response)
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(nrepl-dbind-response response (value err)
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(cond
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(err (clj-watch--paint (format "error:\n%s" err)))
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(value (clj-watch--paint (car (read-from-string value)))))))
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nil nil nil nil
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clj-watch--connection))))
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(define-derived-mode clj-watch-mode special-mode "clj-watch"
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"Major mode for the pinned watch buffer."
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(setq-local truncate-lines t))
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;;;###autoload
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(defun clj-watch ()
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"Open the pinned watch buffer and start polling."
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(interactive)
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(setq clj-watch--connection (cider-current-repl nil 'ensure))
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(with-current-buffer (get-buffer-create clj-watch-buffer)
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(unless (eq major-mode 'clj-watch-mode)
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(clj-watch-mode)))
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(when clj-watch--timer (cancel-timer clj-watch--timer))
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(setq clj-watch--timer
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(run-with-timer 0 clj-watch-interval #'clj-watch--tick))
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(display-buffer clj-watch-buffer))
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(defun clj-watch-stop ()
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"Stop polling."
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(interactive)
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(when clj-watch--timer
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(cancel-timer clj-watch--timer)
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(setq clj-watch--timer nil)))
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(provide 'clj-watch)
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;;; clj-watch.el ends here
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