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
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
(in-package #:monparser)
(defun parse-string (p input)
(let ((result (funcall p (from-string input))))
(if (parsing-p result)
(parsing-tree result)
result)))
(defun parse-file (p input)
(let ((result (funcall p (from-file input))))
(if (parsing-p result)
(parsing-tree result)
result)))
(defstruct parsing
tree
left
limit)
(defun lazy-parsing-p (r)
(or (functionp r)
(parsing-p r)))
(defstruct failure
place
message)
(defmethod print-object ((obj failure) stream)
(let ((file (file (failure-place obj))))
(if file
(multiple-value-bind (line column) (line-and-column (failure-place obj))
(format stream "~a:~a:~a: ~a" line column file (failure-message obj)))
(format stream "~a: ~a" (cursor (failure-place obj)) (failure-message obj)))))
(defun new (tree)
(lambda (input &key limit lazy)
(declare (ignore lazy))
(if (and limit (> limit 0))
(make-failure :place input
:message (format nil "Didn't reach expected limit: ~a." limit))
(make-parsing :tree tree :left input))))
(defun bind (p f &key (greedy t))
(lambda (input &key limit lazy)
(let (r)
(if greedy
(setf r (funcall p input :limit limit))
(let ((next-parser (funcall f nil input))
(limit -1))
(do ((sweep-input input (advance sweep-input)))
((or (not (has-data? sweep-input))
(> limit -1)) nil)
(when (lazy-parsing-p (funcall next-parser sweep-input :lazy t))
(setf limit (input-sub sweep-input input))))
(if (< limit 0)
(setf r (make-failure :place input
:message "Reached end of input while sweeping."))
(setf r (funcall p input :limit limit)))))
(if (parsing-p r)
(if lazy
(lambda (ignored-input &key lazy limit)
(declare (ignore ignored-input limit))
(funcall (funcall f (parsing-tree r) input)
(parsing-left r)
:lazy lazy
:limit (if greedy (parsing-limit r))))
(funcall (funcall f (parsing-tree r) input)
(parsing-left r)
:limit (if greedy (parsing-limit r))))
r))))
(defmacro comp (bindings &body body)
(if (null bindings)
`(new (progn ,@body))
(let ((var (first (car bindings)))
(parser (second (car bindings)))
(lazy (third (car bindings)))
(unused (gensym)))
(if (symbolp var)
(if (string= (symbol-name var) "_")
`(bind ,parser
(lambda (&rest ,unused)
(declare (ignore ,unused))
(comp ,(cdr bindings) ,@body))
:greedy ,(not lazy))
`(bind ,parser
(lambda (,var &rest ,unused)
(declare (ignore ,unused))
(comp ,(cdr bindings) ,@body))
:greedy ,(not lazy)))
(if (and (consp var) (symbolp (car var)) (symbolp (cdr var)))
`(bind ,parser
(lambda (,(car var) ,(cdr var) &rest ,unused)
(declare (ignore ,unused))
(comp ,(cdr bindings) ,@body))
:greedy ,(not lazy))
(error "Binding must be either a symbol or a cons of symbols."))))))
(defun one-of (first-parser second-parser &rest other-parsers)
(lambda (input &key limit lazy)
(declare (ignore lazy))
(labels ((one-of-rec (parsers)
(let ((intermediate-parsers '())
(result nil))
(dolist (p parsers)
(let ((r (funcall p
input
:lazy (> (length parsers) 1)
:limit limit)))
(cond ((functionp r)
(push r intermediate-parsers))
((parsing-p r)
(when (or (not (parsing-p result))
(> (cursor (parsing-left r))
(cursor (parsing-left result))))
(setf result r)))
((failure-p r)
(when (or (failure-p result)
(= (length parsers) 1))
(setf result r))))))
(if intermediate-parsers
(one-of-rec intermediate-parsers)
result))))
(one-of-rec (cons first-parser (cons second-parser other-parsers))))))
(defun fail (message)
(lambda (input &key limit lazy)
(make-failure :place input :message message)))
(defmacro unit (&optional predicate)
(cond ((null predicate)
(setf predicate '(characterp it)))
((symbolp predicate)
(setf predicate `(,predicate it)))
((characterp predicate)
(setf predicate `(char-equal ,predicate it)))
(t (setf predicate
(nsubst-if 'it
(lambda (x)
(and (symbolp x)
(string-equal (symbol-name x) "IT"))) predicate))))
`(lambda (input &key limit lazy)
(declare (ignore lazy))
(if (and limit (<= limit 0))
(make-failure :place input :message "Reached established limit.")
(if (has-data? input)
(let ((it (peek input)))
(if ,predicate
(make-parsing :tree it :left (advance input) :limit (if limit (1- limit)))
(make-failure :place input
:message (format nil "Expected: ~a, Got: ~a" ',predicate it))))
(make-failure :place input :message "Reached end of input.")))))
(defmacro literal (word)
(when (not (stringp word))
(error "Literal only accepts strings as input."))
(let ((binding-list '())
(name-list '()))
(loop :for c :across word :do
(when c
(let ((name (gensym)))
(push name name-list)
(push `(,name (unit ,c)) binding-list))))
`(comp ,(reverse binding-list)
(coerce ,(cons 'list (reverse name-list)) 'string))))
(defparameter nothing
(new nil))
(defun optional (p)
(one-of p nothing))
(defun many (p)
(comp ((x p)
(xs (if (not x)
(fail "Parsing result is empty.")
(optional (many p)))))
(cons x xs)))
(defun repeat (p min &optional (max 0))
(if (> min 0)
(comp ((x p)
(xs (repeat p (1- min) (1- max))))
(cons x xs))
(if (> max 0)
(comp ((x (optional p))
(xs (repeat p 0 (if x (1- max) 0))))
(if x (cons x xs) x))
nothing)))
(defun whitespace? (x)
(some (lambda (y) (char= x y)) '(#\Space #\Newline #\Tab)))
(defparameter whitespace
(comp ((_ (optional (many (unit whitespace?)))))
:whitespace))
(defun separated-list (p separator &key include-separator)
(comp ((v p)
(sep (optional separator))
(vn (if sep
(separated-list p separator)
nothing)))
(if include-separator
(cons v (cons sep vn))
(cons v vn))))
(defun surrounded (left p right &key include-surrounding)
(comp ((l left)
(body p :lazy)
(r right))
(if include-surrounding
(list l body r)
body)))
|
