blob: cb9b7511e608ca07a1aac727ae2fa7008866ebcf (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
; push-stacks.scm - A stack-like data-type
; Copyright (C) 2005 Jonathan Kraut
; This library is free software; you can redistribute it and/or
; modify it under the terms of the GNU Lesser General Public
; License as published by the Free Software Foundation; either
; version 2.1 of the License, or (at your option) any later version.
; This library 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
; Lesser General Public License for more details.
; You should have received a copy of the GNU Lesser General Public
; License along with this library; if not, write to the Free Software
; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
; Contact:
; Jonathan Kraut
; 4130 43 ST #C2
; Sunnyside, NY 11104
; jak76@columbia.edu
; see file COPYING in the top of Sassy's distribution directory
; module sassy-push-stacks
; import-syntax meta-lambda
; export all
(define make-pushdown-stack #f)
(define make-pushup-stack #f)
(let ((make-push-stack
(lambda (direc)
(define size 0)
(define items '())
(define pointer '())
(define down-stack-base '())
(define (cycle lst siz)
(do ((ls lst (cdr ls))
(c siz (+ c 1)))
((null? (cdr ls)) (set! size c) ls)))
(define push-gs
(if (eqv? 'up direc)
(lambda (itm-or-pr)
(and (not (pair? itm-or-pr))
(set! itm-or-pr (list itm-or-pr)))
(if (null? pointer)
(begin (set! items itm-or-pr)
(set! pointer (cycle itm-or-pr (+ size 1)))
items)
(begin (set-cdr! pointer itm-or-pr)
(let ((old (cdr pointer)))
(set! pointer (cycle pointer size))
old))))
(lambda (itm-or-pr)
(let ((push-one (lambda () ; fast path for non-pairs
(set! items (cons itm-or-pr items))
(set! pointer items)
(set! size (+ size 1)))))
(if (null? pointer)
(if (not (pair? itm-or-pr))
(begin (push-one)
(set! down-stack-base pointer)
pointer)
(begin (set! items itm-or-pr)
(set! down-stack-base
(cycle itm-or-pr (+ size 1)))
(set! pointer items)
pointer))
(if (not (pair? itm-or-pr))
(begin (push-one)
pointer)
(begin (set-cdr! (cycle itm-or-pr (+ size 1)) items)
(set! items itm-or-pr)
(set! pointer itm-or-pr)
pointer)))))))
; (and (not (pair? lst))
; (set! lst (list lst)))
; (if (null? pointer)
; (begin (set! items lst)
; (set! down-stack-base (cycle lst (+ size 1)))
; (set! pointer items)
; pointer)
; (begin (set-cdr! (cycle lst (+ size 1)) items)
; (set! items lst)
; (set! pointer lst)
; pointer)))))
(define (patch-gs pnt lst)
(do ((rst lst (cdr rst))
(loc pnt (cdr loc)))
((null? rst))
(set-car! loc (car rst))))
(define previous '())
(define append-gs
(if (eqv? 'up direc)
(lambda (stk2)
(if (memq stk2 previous)
(error "tried to append! the same stacks twice" stk2)
(begin (set! previous (cons stk2 previous))
(set! size (+ size (stk2 'size)))
(if (null? pointer)
(set! items (stk2 'items))
(set-cdr! pointer (stk2 'items)))
(let ((p (if (eqv? 'up (stk2 'direc))
(stk2 'pointer)
(stk2 'down-base))))
(if (and (not (eq? pointer p))
(not (null? p)))
(set! pointer p))))))
(lambda (stk2)
(if (memq stk2 previous)
(error "tried to append! the same stacks twice" stk2)
(begin (set! previous (cons stk2 previous))
(set! size (+ size (stk2 'size)))
(if (null? pointer)
(begin (set! items (stk2 'items))
(set! pointer items))
(set-cdr! down-stack-base (stk2 'items)))
(let ((d (if (eqv? 'up (stk2 'direc))
(stk2 'pointer)
(stk2 'down-base))))
(if (and (not (eq? down-stack-base d))
(not (null? d)))
(set! down-stack-base d))))))))
(meta-lambda-dot
(or (and 'push ? (lambda (x) (push-gs x)))
(and 'size (begin size))
(and 'patch pair? (or (and pair? (lambda (x y) (patch-gs x y)))
(and ? (lambda (x y) (set-car! x y)))))
(and 'append procedure? (lambda (x) (append-gs x)))
(and 'set-previous procedure? (lambda (x) (set! previous
(cons x previous))))
(and 'pointer (begin pointer))
(and 'down-base (begin down-stack-base))
(and 'items (begin items))
(and 'save (begin
(let ((os size) (op pointer) (oi items))
(lambda ()
(set! size os)
(set! pointer op)
(set! items oi)
(if (and (not (null? pointer)) (eqv? direc 'up))
(set-cdr! pointer '()))))))
(and 'push-proc ? (lambda (x) (let ((t (push-gs x)))
(lambda (new) (patch-gs t new)))))
(and 'direc (begin direc))
; last because it may return #f
(and 'empty (begin (null? items))))))))
(set! make-pushdown-stack (lambda () (make-push-stack 'up)))
(set! make-pushup-stack (lambda () (make-push-stack 'down))))
(define (push-stack-push stk itm) (stk 'push itm))
(define (push-stack-pointer stk) (stk 'pointer))
(define (push-stack-items stk) (stk 'items))
(define (push-stack-patch stk pnt itm) (stk 'patch pnt itm))
(define (push-stack-push->patcher stk itm) (stk 'push-proc itm))
(define (push-stack-save stk) (stk 'save))
(define (push-stack-direction stk) (stk 'direc))
(define (push-stack-size stk) (stk 'size))
(define (push-stack-append! stk1 stk2)
(stk2 'set-previous stk1)
(stk1 'append stk2))
(define (push-stack-empty? stk) (stk 'empty))
(define push-stack-align
(let ((align-to (lambda (count align)
(let ((diff (modulo count align)))
(if (zero? diff)
0
(- align diff))))))
(lambda (stk align fill . offset)
(let ((amount (align-to (+ (stk 'size)
(if (null? offset) 0 (car offset)))
align)))
(if (pair? fill)
(error "can not fill a push-stack with a pair" fill)
(when (not (zero? amount))
(stk 'push (make-list amount fill))))))))
|
