On 09/29/2013 06:10 PM, David Thompson wrote: > Guile-2D needs a REPL that runs within its event loop without blocking > when reading user input. Mark Weaver has helped me add a new REPL > option, read-wrapper, that can be used by Guile-2D to push the read > operation into another thread while the main thread's event loop > continues to run as normal. This avoids the problem of thread safety > with the normal REPL server. > > I think that this could be useful for other programs that run in an > event loop. Perhaps Emacsy? > > - Dave Thompson
Here is an updated patch. I've updated prompting-meta-read to preserve the REPL stack when the reader thunk is called, in the case of the thunk being called outside of the current thread.
>From b7cae3fb33d2cc059c4016709e4d0630eee1610d Mon Sep 17 00:00:00 2001 From: David Thompson <dthomps...@worcester.edu> Date: Sun, 29 Sep 2013 18:01:31 -0400 Subject: [PATCH] Add read-wrapper REPL option. * module/system/repl/common.scm (repl-default-options): Add read-wrapper REPL option. * module/system/repl/repl.scm (prompting-meta-read): Use read-wrapper REPL option. --- module/system/repl/common.scm | 4 ++++ module/system/repl/repl.scm | 35 ++++++++++++++++++++++------------- 2 files changed, 26 insertions(+), 13 deletions(-) diff --git a/module/system/repl/common.scm b/module/system/repl/common.scm index 5da7c48..030d5de 100644 --- a/module/system/repl/common.scm +++ b/module/system/repl/common.scm @@ -125,6 +125,10 @@ See <http://www.gnu.org/licenses/lgpl.html>, for more details.") ((not print) #f) ((procedure? print) print) (else (error "Invalid print procedure" print))))) + (read-wrapper + ,(lambda (thunk) + (thunk)) + #f) (value-history ,(value-history-enabled?) ,(lambda (x) diff --git a/module/system/repl/repl.scm b/module/system/repl/repl.scm index 1649556..97adf72 100644 --- a/module/system/repl/repl.scm +++ b/module/system/repl/repl.scm @@ -107,20 +107,29 @@ ;; to be able to re-use the existing readline machinery. ;; ;; Catches read errors, returning *unspecified* in that case. +;; +;; The reader thunk is passed into the read-wrapper procedure. The state +;; of the stack is maintained, in case of the thunk being called outside +;; of the current thread. (define (prompting-meta-read repl) - (catch #t - (lambda () - (repl-reader (lambda () (repl-prompt repl)) - (meta-reader (repl-language repl) (current-module)))) - (lambda (key . args) - (case key - ((quit) - (apply throw key args)) - (else - (format (current-output-port) "While reading expression:\n") - (print-exception (current-output-port) #f key args) - (flush-all-input) - *unspecified*))))) + (let ((read-wrapper (repl-option-ref repl 'read-wrapper)) + (stack (fluid-ref *repl-stack*))) + (read-wrapper + (lambda () + (with-fluids ((*repl-stack* stack)) + (catch #t + (lambda () + (repl-reader (lambda () (repl-prompt repl)) + (meta-reader (repl-language repl) (current-module)))) + (lambda (key . args) + (case key + ((quit) + (apply throw key args)) + (else + (format (current-output-port) "While reading expression:\n") + (print-exception (current-output-port) #f key args) + (flush-all-input) + *unspecified*))))))))) -- 1.8.4.rc3
