30 lines
728 B
Common Lisp
30 lines
728 B
Common Lisp
;;;; cl-scopes/util/iter
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;;;; iterators, queues, and other sequentially accessible stuff
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;;;; producing items (objects) like: numbers, strings, symbols, lists, ...
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(defpackage :scopes/util/iter
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(:use :common-lisp)
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(:export #:next #:value
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#:list-iterator))
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(in-package :scopes/util/iter)
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;;;; iterators
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(defgeneric next (it))
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(defgeneric value (it))
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(defclass list-iterator ()
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((data :reader data :initarg :data :initform nil)
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(cur :accessor cur)))
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(defmethod initialize-instance :after ((it list-iterator) &key &allow-other-keys)
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(setf (cur it) (cons nil (data it))))
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(defmethod next ((it list-iterator))
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(pop (cur it))
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(null (cur it)))
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(defmethod value ((it list-iterator))
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(car (cur it)))
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