Joseph Ferano
7ce1d09900
A different primitive from redefining a name. There is no name to install a body into, so the expression is wrapped in a function with nowhere to be called from; the module exports flan_reload_call to say "run this once", and the agent calls it after the install - on the game thread, at a frame boundary, so an expression that reads the program's state sees a point the program agrees is consistent. Nothing is marshalled back because nothing could be. A Flan value carries no header, so no code at run time can say what it is; the compiler knows the type and renders it there, in the thunk. That is the layout decision's bill, and it is why the printer set is the scalars rather than everything. The rendering does not go through stdout. Stdout belongs to the program, it is in the hot path for anything that prints, and a dev-only feature must not put a branch in it - so flan_rt.c is untouched and the value goes to flan_dev_result, read back over the agent's socket. Safe without a handshake because the generation counter is bumped last: the daemon waits for it to move rather than assuming the program has reached a frame boundary. u64 refuses by name, because i64->bytes is signed and anything past 2^63 would come back negative. Everything without a derived printer refuses the same way. A number that is quietly wrong is the failure this whole thing exists to prevent. An evaluation is not a declaration: the thunk is built against the program and never spliced into it, so describe does not fill up with an eval/N for every expression ever typed. The test that matters is the same expression twice. The fixture increments ticks every frame, so two evaluations must disagree - a value computed in the compiler, or read from a copy of the program's state, would not.
236 lines
9.6 KiB
EmacsLisp
236 lines
9.6 KiB
EmacsLisp
;;; flan-dev.el --- Talk to a running Flan program -*- lexical-binding: t; -*-
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;; The editor half of Flan's dev loop. `flan dev program.flan' compiles the
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;; program, launches it, and listens on .flan-dev.sock beside the source; this
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;; connects to that socket and sends it forms.
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;;
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;; C-c C-c recompiles the top-level form at point and installs it in the
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;; running program, at that program's next frame boundary. Call sites compiled
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;; before the new body existed follow it, and the program's state — its globals
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;; — is untouched. C-c C-k does the same for a whole buffer.
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;;
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;; The protocol is one s-expression per message, length framed. That is why
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;; there is no parser here: `prin1' writes a request and `read' reads a reply.
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;;
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;; C-x C-e evaluates the expression before point *in the running program* and
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;; shows its value. That is a different primitive from redefining a name:
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;; there is nothing to install a body into, so the expression is wrapped in a
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;; thunk the program runs at its next frame boundary. Only scalars, bool and
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;; strings render so far — a Flan value carries no header, so a printer has to
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;; be derived per type at compile time, and the ones that are not derived yet
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;; say so rather than guessing.
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;;; Code:
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(require 'subr-x)
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(defgroup flan-dev nil
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"Talking to a running Flan program."
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:group 'flan
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:prefix "flan-dev-")
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(defcustom flan-dev-socket-name ".flan-dev.sock"
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"Name of the socket `flan dev' listens on, looked for up from the buffer."
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:type 'string)
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(defcustom flan-dev-echo-result t
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"Whether a successful evaluation reports in the echo area."
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:type 'boolean)
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(defvar flan-dev--connection nil
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"The open connection, or nil.")
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(defvar flan-dev--socket nil
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"Path of the socket `flan-dev--connection' is connected to.")
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;;; Wire
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;; Framing is a decimal byte count, a newline, then that many bytes. A message
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;; carries Flan source, which contains newlines, so a line-oriented protocol
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;; would need an escape layer that this does not. Lengths are in *bytes*, so
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;; every measurement goes through `string-bytes' and the process is raw-text —
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;; a multibyte identifier would otherwise put the reply stream out of step by
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;; exactly as many bytes as the payload has non-ASCII characters.
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(defun flan-dev--send (proc form)
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"Send FORM to PROC as one framed message."
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(let* ((payload (encode-coding-string (prin1-to-string form) 'utf-8 t)))
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(process-send-string proc (format "%d\n%s" (length payload) payload))))
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(defun flan-dev--read-reply (proc)
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"Block until PROC sends one complete framed message, and read it."
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(with-current-buffer (process-buffer proc)
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(let ((deadline (+ (float-time) 30)))
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;; The header first: digits up to a newline.
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(while (and (not (save-excursion (goto-char (point-min))
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(re-search-forward "\\`\\([0-9]+\\)\n" nil t)))
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(< (float-time) deadline))
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(accept-process-output proc 0.05))
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(goto-char (point-min))
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(unless (re-search-forward "\\`\\([0-9]+\\)\n" nil t)
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(error "flan dev: no reply"))
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(let* ((n (string-to-number (match-string 1)))
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(body-start (point)))
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(while (and (< (- (position-bytes (point-max)) (position-bytes body-start)) n)
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(< (float-time) deadline))
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(accept-process-output proc 0.05))
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(let* ((end (byte-to-position (+ (position-bytes body-start) n)))
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(text (decode-coding-string
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(encode-coding-string (buffer-substring-no-properties
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body-start end)
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'utf-8 t)
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'utf-8))
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(form (car (read-from-string text))))
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(delete-region (point-min) end)
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form)))))
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(defun flan-dev--request (form)
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"Send FORM to the connected program and return its reply."
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(let ((proc (flan-dev--live-connection)))
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(flan-dev--send proc form)
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(flan-dev--read-reply proc)))
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;;; Connection
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(defun flan-dev--find-socket ()
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"Find the daemon's socket by walking up from the current buffer."
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(let ((dir (locate-dominating-file
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(or buffer-file-name default-directory)
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flan-dev-socket-name)))
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(and dir (expand-file-name flan-dev-socket-name dir))))
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(defun flan-dev--live-connection ()
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"The open connection, or signal an error saying how to get one."
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(unless (and flan-dev--connection
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(process-live-p flan-dev--connection))
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(error "Not connected: M-x flan-connect, or start `flan dev program.flan'"))
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flan-dev--connection)
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;;;###autoload
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(defun flan-connect (&optional socket)
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"Connect to a `flan dev' daemon listening on SOCKET.
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With no argument, look for `flan-dev-socket-name' up from this buffer."
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(interactive
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(list (or (flan-dev--find-socket)
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(read-file-name "flan dev socket: "))))
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(unless socket (user-error "No %s found above this buffer" flan-dev-socket-name))
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(when (process-live-p flan-dev--connection)
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(delete-process flan-dev--connection))
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(let ((buf (get-buffer-create " *flan-dev*")))
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(with-current-buffer buf (erase-buffer) (set-buffer-multibyte nil))
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(setq flan-dev--connection
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(make-network-process
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:name "flan-dev" :buffer buf :family 'local :service socket
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:coding 'binary :noquery t))
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(setq flan-dev--socket socket))
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(let ((r (flan-dev--request '(:op "describe"))))
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(message "flan dev: connected to %s (%d functions, %d globals)"
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(abbreviate-file-name socket)
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(length (plist-get r :fns)) (length (plist-get r :globals))))
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flan-dev--connection)
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(defun flan-disconnect ()
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"Close the connection, which also ends the daemon and its program."
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(interactive)
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(when (process-live-p flan-dev--connection)
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(ignore-errors (flan-dev--request '(:op "close")))
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(delete-process flan-dev--connection))
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(setq flan-dev--connection nil)
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(message "flan dev: disconnected"))
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(defun flan-describe ()
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"Report what the running program currently defines."
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(interactive)
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(let ((r (flan-dev--request '(:op "describe"))))
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(message "flan dev: %s, %d functions, %d globals"
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(if (plist-get r :alive) "running" "exited")
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(length (plist-get r :fns)) (length (plist-get r :globals)))))
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;;; Evaluating
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(defun flan-dev--report (reply what)
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"Report REPLY, describing WHAT was sent."
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(if (equal (plist-get reply :status) "ok")
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(let ((fns (plist-get reply :fns))
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(names (plist-get reply :names))
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(note (plist-get reply :note))
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(value (plist-get reply :value)))
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(when flan-dev-echo-result
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(if value
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;; An expression's value, rendered inside the running program —
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;; nothing was marshalled back, because nothing could be.
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(message "=> %s" value)
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(if note
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;; The daemon accepted it and had nothing to send. Say so rather
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;; than claiming an install that did not happen.
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(message "%s: %s" (if names (string-join names ", ") what) note)
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(message "%s installed in %.0fms"
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(if fns (string-join fns ", ")
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(if names (string-join names ", ") what))
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(or (plist-get reply :ms) 0))))))
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;; The daemon reports where, so put point there when it is this buffer.
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(let ((loc (plist-get reply :loc))
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(msg (plist-get reply :message)))
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(when (and loc (string-match "\\`\\(.*\\):\\([0-9]+\\):\\([0-9]+\\)\\'" loc))
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(let ((file (match-string 1 loc))
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(line (string-to-number (match-string 2 loc)))
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(col (string-to-number (match-string 3 loc))))
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(when (and buffer-file-name (file-equal-p file buffer-file-name))
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(goto-char (point-min))
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(forward-line (1- line))
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(forward-char (max 0 (1- col))))))
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(user-error "flan: %s" (or msg "rejected")))))
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(defun flan-dev--eval (code what)
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"Send CODE to the running program. WHAT names it for the echo area."
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(flan-dev--report
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(flan-dev--request
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;; buffer-file-name so an error points at the file being edited rather than
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;; at the daemon's placeholder.
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(list :op "eval" :code code :file (or buffer-file-name "<buffer>")))
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what))
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(defun flan-dev--defun-at-point ()
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"The text of the top-level form containing or preceding point."
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(save-excursion
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(end-of-defun)
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(let ((end (point)))
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(beginning-of-defun)
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(buffer-substring-no-properties (point) end))))
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;;;###autoload
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(defun flan-eval-defun ()
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"Recompile the top-level form at point and install it in the running program."
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(interactive)
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(flan-dev--eval (flan-dev--defun-at-point) "form"))
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;;;###autoload
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(defun flan-eval-buffer ()
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"Recompile every top-level form in this buffer and install them together.
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One module, not one per form: a var and the function that uses it have to
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arrive in the same load or the first refers to storage that does not exist."
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(interactive)
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(flan-dev--eval (buffer-substring-no-properties (point-min) (point-max))
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(buffer-name)))
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;;;###autoload
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(defun flan-eval-last-sexp ()
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"Evaluate the expression before point in the running program and show it."
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(interactive)
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(let ((code (buffer-substring-no-properties
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(save-excursion (backward-sexp) (point))
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(point))))
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(flan-dev--report
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(flan-dev--request
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(list :op "eval-expr" :code code :file (or buffer-file-name "<buffer>")))
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"expression")))
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;;;###autoload
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(defun flan-eval-region (start end)
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"Recompile the top-level forms between START and END."
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(interactive "r")
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(flan-dev--eval (buffer-substring-no-properties start end) "region"))
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(provide 'flan-dev)
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;;; flan-dev.el ends here
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