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common-lisp
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anonymous
2019.11.21 05:17:52
(defclass generator () ((thread :initarg :thread :reader generator-thread) (user->generator :initarg :user->generator :reader generator-user->generator-mailbox) (generator->user :initarg :generator->user :reader generator-generator->user-mailbox) (disable-gc :initarg :disable-gc :initform nil :reader generator-disable-gc-p))) (defmethod initialize-instance :after ((generator generator) &key) (unless (generator-disable-gc-p generator) (let ((thread-to-destroy (generator-thread generator))) (trivial-garbage:finalize generator (lambda () (bt:destroy-thread thread-to-destroy)))))) (defgeneric next (generator) (:method ((generator generator)) (safe-queue:mailbox-send-message (generator-user->generator-mailbox generator) :next) (values-list (safe-queue:mailbox-receive-message (generator-generator->user-mailbox generator))))) (defun yield (&rest values) (declare (ignore values)) "Yield all the values VALUES, but only in a WITH-GENERATOR form." (error "Please only use YIELD in a WITH-GENERATOR form")) (defmacro with-generator ((&optional (class ''generator) &rest initargs) &body body) (alexandria:with-gensyms (user->generator generator->user) `(let ((,user->generator (safe-queue:make-mailbox)) (,generator->user (safe-queue:make-mailbox))) (make-instance ,class :user->generator ,user->generator :generator->user ,generator->user :thread (bt:make-thread (lambda () (flet ((yield (&rest values) (safe-queue:mailbox-send-message ,generator->user values) (safe-queue:mailbox-receive-message ,user->generator) (values))) (safe-queue:mailbox-receive-message ,user->generator) ,@body)) :name "generator thread") ,@initargs)))) (with-generator () (yield 42) (yield :hello) (yield "Excuse me" "what the fuck"))
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