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tinmop/src/bs-tree.lisp

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Common Lisp
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2020-09-06 11:32:08 +02:00
;; tinmop: an humble gemini and pleroma client
2020-05-08 15:45:43 +02:00
;; Copyright (C) 2020 cage
;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
(in-package :bs-tree)
(defclass node ()
((parent
:initarg :parent
:initform nil
:accessor parent)
(data
:initarg :data
:initform nil
:accessor data)
(left
:initarg :left
:initform nil
:accessor left)
(right
:initarg :right
:initform nil
:accessor right)))
(defgeneric node->string (object))
(defgeneric search (object datum &key key key-datum compare equal))
(defgeneric search-opt (object datum &key key key-datum compare equal candidate))
(defgeneric insert (object datum &key key key-datum compare equal &allow-other-keys))
(defgeneric leafp (object))
(defgeneric all-children-leaf-p (object))
(defgeneric map (object function))
(defgeneric map-node (object function))
(defgeneric %walk (object function args))
(defgeneric walk (object function &rest args))
(defgeneric bstp (object &key comp-fn key))
(defgeneric node->dot (object))
(defgeneric reconstruct-parent (object &optional parent))
(defgeneric find-max-node (object))
(defmethod data ((object (eql nil)))
nil)
(defmethod parent ((object (eql nil)))
nil)
(defmethod print-object ((object node) stream)
(format stream "~a" (node->string object)))
(defmethod node->string ((object (eql nil)))
"nil")
(defmethod node->string ((object node))
(if (null (data object))
""
(format nil "~a ~% [~a] [~a]"
(data object)
(node->string (left object))
(node->string (right object)))))
(defmethod leafp ((object node))
(null (data object)))
(defmethod all-children-leaf-p ((object node))
(and (leafp (left object))
(leafp (right object))))
(defmethod search ((object node) datum &key (key #'identity)
(key-datum #'identity) (compare #'<) (equal #'=))
(if (leafp object)
nil
(cond
((funcall equal (%key key (data object)) (%key key-datum datum))
object)
((funcall compare (%key key-datum datum) (%key key (data object)))
(search (left object) datum :key key :key-datum key-datum
:compare compare :equal equal))
(t
(search (right object) datum :key key :key-datum key-datum
:compare compare :equal equal)))))
(defmethod search-opt ((object node) datum &key (key #'identity)
(key-datum #'identity) (compare #'<) (equal #'=)
(candidate nil))
(if (leafp object)
(if (and candidate (funcall equal (%key key (data candidate)) (%key key-datum datum)))
candidate
nil)
(cond
((funcall compare (%key key (data object)) (%key key-datum datum))
(search-opt (left object) datum :key key :key-datum key-datum
:compare compare :equal equal :candidate candidate))
(t
(search-opt (right object) datum :key key :key-datum key-datum
:compare compare :equal equal :candidate object)))))
(defun make-node (data left right parent)
(make-instance 'node :left left :right right :data data :parent parent))
(defun make-leaf (parent)
(make-instance 'node :parent parent :left nil :right nil))
(defun make-root-node (datum)
(let* ((tree (make-node datum nil nil nil))
(l-leaf (make-leaf tree))
(r-leaf (make-leaf tree)))
(setf (left tree) l-leaf
(right tree) r-leaf)
tree))
(defun %key (key-fn a)
(funcall key-fn a))
(alexandria:define-constant +data+ :data :test #'eq)
(alexandria:define-constant +left+ :left :test #'eq)
(alexandria:define-constant +right+ :right :test #'eq)
(alexandria:define-constant +parent+ :parent :test #'eq)
(defmethod to-sexp ((object node))
(let ((*print-circle* t))
(list +data+ (to-sexp (data object))
+left+ (to-sexp (left object))
+right+ (to-sexp (right object))
+parent+ (to-sexp (data (parent object))))))
(defmethod from-sexp ((object node) sexp)
(declare (ignorable object))
(labels ((%from-sexp (sexp)
(if (null sexp)
(make-leaf nil)
(make-node (getf sexp +data+)
(from-sexp object (getf sexp +left+))
(from-sexp object (getf sexp +right+)) nil))))
(let ((new-tree (%from-sexp sexp)))
(reconstruct-parent new-tree))))
(defmacro %make-new-node (make-node-fn node data left right parent args)
`(,make-node-fn ,data ,left ,right ,parent
,@(loop for i in args collect
`(,i ,node))))
(defmacro with-insert-local-function ((make-left-node-fn
make-right-node-fn
make-leaf-node-fn
make-leaf-fn
left-descend-fn
right-descend-fn)
&body body)
(let ((insert-fn (alexandria:format-symbol t "%INSERT")))
`(labels ((,insert-fn (node datum key key-datum compare equal)
(if (leafp node)
(let* ((new-node (,make-leaf-node-fn
datum nil nil (parent node)))
(l-leaf (,make-leaf-fn new-node))
(r-leaf (,make-leaf-fn new-node)))
(setf (data new-node) datum
(left new-node) l-leaf
(right new-node) r-leaf)
new-node)
(cond
((funcall equal (%key key (data node)) (%key key-datum datum))
node)
((funcall compare (%key key-datum datum) (%key key (data node)))
,(let ((a `(let ((new-node (,make-left-node-fn
(data node)
(,insert-fn (left node) datum key
key-datum compare equal)
(right node)
(parent node))))
(setf (parent (right new-node)) new-node
(parent (left new-node)) new-node)
new-node)))
(if left-descend-fn
`(,left-descend-fn ,a)
a)))
(t
,(let ((a `(let ((new-node (,make-right-node-fn
(data node)
(left node)
(,insert-fn (right node) datum key
key-datum compare equal)
(parent node))))
(setf (parent (right new-node)) new-node
(parent (left new-node)) new-node)
new-node)))
(if right-descend-fn
`(,right-descend-fn ,a)
a)))))))
,@body)))
(defmethod insert ((object node) datum &key (key #'identity) (key-datum #'identity)
(compare #'<) (equal #'=))
(with-insert-local-function (make-node make-node make-node make-leaf nil nil)
(%insert object datum key key-datum compare equal)))
(defmethod map ((object node) function)
(with-accessors ((data data) (left left) (right right)) object
(if (leafp object)
(make-leaf nil)
(make-node (funcall function data) (map left function)
(map right function) nil))))
(defmethod map-node ((object node) function)
(with-accessors ((color color) (data data) (left left) (right right)) object
(if (leafp object)
(funcall function object (make-leaf object))
(funcall function object (make-node data
(map-node left function)
(map-node right function) nil)))))
(defmethod %walk ((object node) function args)
(with-accessors ((color color) (data data) (left left) (right right)) object
(when (not (leafp object))
(apply function object args)
(%walk left function args)
(%walk right function args))))
(defmethod %walk ((object node) function (args (eql nil)))
(with-accessors ((color color) (data data) (left left) (right right)) object
(when (not (leafp object))
(funcall function object)
(%walk left function args)
(%walk right function args))))
(defmethod %walk ((object (eql nil)) function args)
(apply function object args))
(defmethod walk ((object node) function &rest args)
(with-accessors ((color color) (data data) (left left) (right right)) object
(when (not (leafp object))
(apply function object args)
(%walk left function args)
(%walk right function args))))
(defmethod walk ((object (eql nil)) function &rest args)
(apply function object args))
(defun gather-all (node &key (add-root t))
(let ((res nil))
(when (not (leafp node))
(walk (left node) #'(lambda (n) (push (data n) res)))
(walk (right node) #'(lambda (n) (push (data n) res)))
(and add-root (push (data node) res)))
res))
(defmethod bstp ((object node) &key (comp-fn #'<) (key #'identity))
(labels ((balanced (node)
(with-accessors ((left left) (right right)) node
(if (not (leafp node))
(let ((left-children (and left (gather-all left)))
(right-children (and right (gather-all right)))
(pivot (funcall key (data node))))
(cond
((and (null left-children) (null right-children))
t);; leaf node, always balanced
((and left-children right-children)
(and
(every #'(lambda (a) (funcall comp-fn (funcall key a) pivot))
left-children)
(every #'(lambda (a) (funcall comp-fn pivot (funcall key a)))
right-children)
'a))
((null left-children)
(and (every #'(lambda (a) (funcall comp-fn pivot (funcall key a)))
right-children))
'l)
((null right-children)
(every #'(lambda (a) (funcall comp-fn (funcall key a) pivot))
left-children)
'r)))
(misc:dbg "leaf root ~a" (data node))))))
(let ((res nil))
(walk object #'(lambda (n) (push
(cons (data n) (or (balanced n) '(nil)))
res)))
(every #'cdr res))))
(defmethod node->dot ((object node))
(labels ((nodes ()
(append
(list
`(:node ((:id ,(format nil "~a" (data object)))
(:label ,(format nil "~ap~a" (data object)
(data (parent object)))))))
(if (not (leafp (left object)))
(node->dot (left object))
(list
`(:node ((:id ,(format nil "nil-l~a" (data object)))
(:label "nil")))))
(if (not (leafp (right object)))
(node->dot (right object))
(list
`(:node ((:id ,(format nil "nil-r~a" (data object)))
(:label "nil")))))))
(edges ()
(append
(if (data (left object))
(list `(:edge
((:from ,(format nil "~a" (data object)))
(:to ,(format nil "~a" (data (left object)))))))
(list `(:edge
((:from ,(format nil "~a" (data object)))
(:to ,(format nil "nil-l~a" (data object)))))))
(if (data (right object))
(list `(:edge
((:from ,(format nil "~a" (data object)))
(:to ,(format nil "~a" (data (right object)))))))
(list `(:edge
((:from ,(format nil "~a" (data object)))
(:to ,(format nil "nil-r~a" (data object))))))))))
(append (nodes) (edges))))
(defmethod reconstruct-parent ((object node) &optional (parent (parent object)))
(with-accessors ((data data) (left left) (right right)) object
(if (leafp object)
(make-leaf parent)
(make-node data
(reconstruct-parent left object)
(reconstruct-parent right object) parent))))
(defmethod find-max-node ((object node))
(if (leafp (right object))
object
(find-max-node (right object))))