47 lines
1.1 KiB
Common Lisp
47 lines
1.1 KiB
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 #:stop #:next #:value #:next-value #:process
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#:list-iterator))
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(in-package :scopes/util/iter)
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;;;; iterators
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(defclass iterator ()
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((stop :accessor stop :initform nil)))
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(defgeneric next (it))
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(defgeneric value (it))
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(defgeneric next-value (it)
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(:method ((it iterator))
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(next it)
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(value it)))
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(defgeneric process (it fn)
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(:method ((it iterator) fn)
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(do ((eoi (next it) (next it)))
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((or eoi (stop it)))
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(funcall fn (value it)))
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(setf (stop it) nil)))
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;;;; list iterator implementation
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(defclass list-iterator (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)
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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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