blob: 91770aaa49b8769c276223df5c454e50bc36193d (
about) (
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
|
;;; Copyright 2024 Masaya Tojo <masaya@tojo.tokyo>
;;;
;;; Licensed under the Apache License, Version 2.0 (the "License");
;;; you may not use this file except in compliance with the License.
;;; You may obtain a copy of the License at
;;;
;;; http://www.apache.org/licenses/LICENSE-2.0
;;;
;;; Unless required by applicable law or agreed to in writing, software
;;; distributed under the License is distributed on an "AS IS" BASIS,
;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;; See the License for the specific language governing permissions and
;;; limitations under the License.
(define-library (qklib infix)
(export infix->prefix
prefix->infix
infix
current-infix-rules)
(import (scheme base)
(scheme case-lambda)
(ice-9 pretty-print)
(only (srfi 1) car+cdr fold break! reverse! append-map)
(only (srfi 26) cut)
(only (srfi 128) make-default-comparator)
(only (srfi 146) mapping? mapping-unfold mapping-adjoin mapping-ref/default))
(begin
(define-record-type <infix-rule>
(%make-operator symbol precedence left? unit inv?)
operator?
(symbol operator-symbol)
(precedence operator-precedence)
(left? operator-left?)
(unit operator-unit)
(inv? operator-inv?))
(define-record-type <unit>
(make-unit value)
unit?
(value unit-value))
(define infix
(case-lambda
((sym)
(infix sym 0))
((sym precedence)
(infix sym precedence 'right))
((sym precedence left-or-right)
(%make-operator sym precedence (eq? 'left left-or-right) #f #f))
((sym precedence left-or-right unit)
(infix sym precedence left-or-right unit #f))
((sym precedence left-or-right unit inv?)
(unless (or (eq? 'left left-or-right)
(eq? 'right left-or-right))
(error "infix: The 3rd argument must be 'left or 'right" left-or-right))
(%make-operator sym precedence (eq? 'left left-or-right) (make-unit unit) inv?))))
(define (infix-rule-list->infix-rule-mapping ops)
(mapping-unfold null?
(lambda (ops)
(values (operator-symbol (car ops))
(car ops)))
cdr
ops
(make-default-comparator)))
(define (make-default-infix-rules)
(list (infix '+ 1 'left 0)
(infix '- 1 'left 0 #t)
(infix '* 2 'left 1)
(infix '/ 2 'left 1 #t)))
(define current-infix-rules
(make-parameter (make-default-infix-rules)
(lambda (x)
(if (mapping? x)
x
(infix-rule-list->infix-rule-mapping x)))))
(define (infix->prefix expr)
(let ((infix-rules (current-infix-rules)))
(map-all-list (cut infix->prefix-1 <> infix-rules)
expr)))
(define (map-all-list f expr)
(f (map-cars f expr)))
(define (map-cars f expr)
(if (pair? expr)
(if (pair? (car expr))
(cons (f (map-cars f (car expr)))
(map-cars f (cdr expr)))
(cons (car expr)
(map-cars f (cdr expr))))
expr))
(define (infix->prefix-1 expr ops)
(if (not (pair? expr))
expr
(let ->prefix ((expr (cons (car expr) (replace-operators (cdr expr) ops)))) ;; all new conses
(define op (minimum-precedence (cdr expr)))
(cond ((operator? op)
(if (operator-left? op)
(let ((rev-expr (reverse! expr)))
(let-values (((rev-lst op+rev-rest) (break! (cut operator=? op <>) rev-expr)))
(let-values (((op rev-rest) (car+cdr op+rev-rest)))
(list (operator-symbol op) (->prefix (reverse! rev-rest)) (->prefix (reverse! rev-lst))))))
(let-values (((lst op+rest) (break! (cut operator=? op <>) expr)))
(let-values (((op rest) (car+cdr op+rest)))
(list (operator-symbol op) (->prefix lst) (->prefix rest))))))
((single? expr) (car expr))
(else expr)))))
(define (prefix->infix expr)
(let ((infix-rules (current-infix-rules)))
(let-values (((result _precedence) (%prefix->infix expr infix-rules)))
result)))
(define (%prefix->infix expr ops)
(let ->infix ((expr expr))
(define (->infix-fst expr)
(let-values (((x _) (->infix expr)))
x))
(if (not (pair? expr))
(values expr -inf.0)
(let-values (((op args) (car+cdr expr)))
(cond ((mapping-ref/default ops op #f)
=> (lambda (op)
(let ((p (operator-precedence op))
(sym (operator-symbol op)))
(cond ((and (null? args)
(not (operator-inv? op))
(operator-unit op))
=> (lambda (u) (values (unit-value u) -inf.0)))
((single? args)
(let-values (((x xp) (->infix (car args))))
(cond ((operator-inv? op)
(values `(,(unit-value (operator-unit op))
,sym
,@(if (<= p xp) x (list x)))
p))
((operator-unit op)
(values x xp))
(else (values (list sym x) -inf.0)))))
((pair? args)
(values (cdr
(append-map (lambda (arg)
(let-values (((x xp) (->infix arg)))
(cons sym (if (<= p xp) x (list x)))))
args))
p))
(else (values (map ->infix-fst expr) -inf.0))))))
(else (values (map ->infix-fst expr) -inf.0)))))))
(define (single? x)
(and (pair? x)
(null? (cdr x))))
(define (replace-operators expr ops)
(map (lambda (x)
(mapping-ref/default ops x x))
expr))
(define (expr-precedence expr)
(if (operator? expr)
(operator-precedence expr)
+inf.0))
(define (minimum-precedence expr)
(fold (lambda (x y) (if (< (expr-precedence x) (expr-precedence y)) x y)) #f expr))
(define (operator=? x y)
(and (operator? x)
(operator? y)
(eq? (operator-symbol x)
(operator-symbol y))))
))
|
