guile-rdf

tordf.scm

;;;; Copyright (C) 2020 Julien Lepiller <julien@lepiller.eu>
;;;; 
;;;; 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 3 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;; 

(define-module (turtle tordf)
  #:use-module (ice-9 match)
  #:use-module (ice-9 textual-ports)
  #:use-module (iri iri)
  #:use-module (turtle parser)
  #:use-module (srfi srfi-9)
  #:use-module (rdf rdf)
  #:export (turtle->rdf))

(define-record-type parser-state
  (make-parser-state base-uri namespaces bnode-labels cur-subject cur-predicate
                     cur-object blank-node-gen result)
  parser-state?
  (base-uri       parser-state-base-uri)
  (namespaces     parser-state-namespaces)
  (bnode-labels   parser-state-bnode-labels)
  (cur-subject    parser-state-cur-subject)
  (cur-predicate  parser-state-cur-predicate)
  (cur-object     parser-state-cur-object)
  (blank-node-gen parser-state-blank-node-gen)
  (result         parser-state-result))

(define* (update-parser-state
           state #:key (base-uri (parser-state-base-uri state))
                       (namespaces (parser-state-namespaces state))
                       (bnode-labels (parser-state-bnode-labels state))
                       (cur-subject (parser-state-cur-subject state))
                       (cur-predicate (parser-state-cur-predicate state))
                       (cur-object (parser-state-cur-object state))
                       (blank-node-gen (parser-state-blank-node-gen state))
                       (result (parser-state-result state)))
  (make-parser-state base-uri namespaces bnode-labels cur-subject cur-predicate
                     cur-object blank-node-gen result))

(define (create-generate-blank-node)
  (define num 0)
  (lambda ()
    (set! num (+ num 1))
    num))

(define (add-ns-to-state state ns iri)
  (update-parser-state state
    #:namespaces (cons (cons ns iri) (parser-state-namespaces state))))

(define (parse-string str)
  (match str
    ((? string? str) str)
    ((component str ...)
     (match component
       ((? string? str1)
        (string-append str1 (parse-string str)))
       (('uchar n)
        (string-append (string (integer->char (string->number n 16)))
                       (parse-string str)))
       (('echar e)
        (string-append
          (match e
            ("\\t" "\t")
            ("\\b" "\b")
            ("\\n" "\n")
            ("\\r" "\r")
            ("\\f" "\f")
            ("\\\\" "\\")
            ("\\\"" "\"")
            ("\\'" "'"))
          (parse-string str)))))
    (() "")))

(define (parse-iri iri state)
  (match iri
    (('iri ('prefixed-name ('pname-ln ('pname-ns ns) ('pn-local suffix))))
     `(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) ns)
                                suffix))
       ("state" . ,state)))
    (('iri ('prefixed-name ('pname-ln ('pname-ns ('pn-local suffix)))))
     `(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) "")
                                suffix))
       ("state" . ,state)))
    (('iri ('prefixed-name ('pname-ns ns)))
     `(("iri" . ,(assoc-ref (parser-state-namespaces state) ns))
       ("state" . ,state)))
    (('iri ('prefixed-name 'pname-ns))
     `(("iri" . ,(assoc-ref (parser-state-namespaces state) ""))
       ("state" . ,state)))
    (('iri 'iriref)
     `(("iri" . ,(resolve-iri (parser-state-base-uri state) ""))
       ("state" . ,state)))
    (('iri ('iriref iri ...))
     `(("iri" . ,(resolve-iri (parser-state-base-uri state) (parse-string iri)))
       ("state" . ,state)))))

(define (parse-verb verb state)
  (match verb
    ("a" `(("verb" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#type")
           ("state" . ,state)))
    (('predicate iri)
     (let ((res (parse-iri iri state)))
       `(("verb" . ,(assoc-ref res "iri"))
         ("state" . ,(assoc-ref res "state")))))))

(define (parse-object object state)
  (match object
    (('rdf-literal ('string-pat (_ str ...)))
     (let ((object
             (make-rdf-literal (parse-string str)
                               "http://www.w3.org/2001/XMLSchema#string" #f)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('rdf-literal ('string-pat (_ str ...)) ("^^" iri))
     (let* ((res (parse-iri iri state))
            (iri (assoc-ref res "iri"))
            (state (assoc-ref res "state"))
            (object (make-rdf-literal (parse-string str) iri #f)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('rdf-literal ('string-pat (_ str ...)) ('langtag lang))
     (let ((object
           (make-rdf-literal
             (parse-string str)
             "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString"
             lang)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('numeric-literal ('decimal num))
     (let ((object
            (make-rdf-literal num "http://www.w3.org/2001/XMLSchema#decimal" #f)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('numeric-literal ('integer int))
     (let ((object
           (make-rdf-literal int "http://www.w3.org/2001/XMLSchema#integer" #f)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('numeric-literal ('double num))
     (let ((object
            (make-rdf-literal num "http://www.w3.org/2001/XMLSchema#double" #f)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('boolean-literal bool)
     (let ((object
             (make-rdf-literal bool "http://www.w3.org/2001/XMLSchema#boolean" #f)))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('blank-node ('anon _))
     (let ((node ((parser-state-blank-node-gen state))))
       (update-parser-state state
         #:cur-object node
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             node)
           (parser-state-result state)))))
    (('blank-node ('blank-node-label label))
     (let* ((node
              (or (assoc-ref (parser-state-bnode-labels state) label)
                  ((parser-state-blank-node-gen state))))
            (state
              (if (assoc-ref (parser-state-bnode-labels state) label)
                  state
                  (update-parser-state state
                    #:bnode-labels
                    (cons
                      (cons label node)
                      (parser-state-bnode-labels state))))))
       (update-parser-state state
         #:cur-object node
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             node)
           (parser-state-result state)))))
    (('blank-node-property-list ('predicate-object-list po ...))
     (let* ((node ((parser-state-blank-node-gen state)))
            (new-state (parse-predicate-object
                         po (update-parser-state state #:cur-subject node))))
       (update-parser-state new-state
         #:cur-object node
         #:cur-subject (parser-state-cur-subject state)
         #:cur-predicate (parser-state-cur-predicate state)
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             node)
           (parser-state-result new-state)))))
    ('collection
     (let ((object "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil"))
       (update-parser-state state
         #:cur-object object
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             object)
           (parser-state-result state)))))
    (('collection objects ...)
     (let ((state (parse-collection objects state)))
       (update-parser-state state
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             (parser-state-cur-object state))
           (parser-state-result state)))))
    (('iri _)
     (let* ((res (parse-iri object state))
            (iri (assoc-ref res "iri"))
            (state (assoc-ref res "state")))
       (update-parser-state state
         #:cur-object iri
         #:result
         (cons
           (make-rdf-triple
             (parser-state-cur-subject state)
             (parser-state-cur-predicate state)
             iri)
           (parser-state-result state)))))))

(define (parse-collection collection state)
  (let ((node ((parser-state-blank-node-gen state))))
    (let loop ((objects collection)
               (new-state
                 (update-parser-state state
                   #:cur-subject node
                   #:cur-predicate
                   "http://www.w3.org/1999/02/22-rdf-syntax-ns#first"))
               (previous-object #nil))
      (match objects
        ('()
         (update-parser-state new-state
           #:cur-object node
           #:cur-subject (parser-state-cur-subject state)
           #:cur-predicate (parser-state-cur-predicate state)
           #:result
           (cons
             (make-rdf-triple
               previous-object
               "http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
               "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
             (parser-state-result new-state))))
        ((('object object) objects ...)
         (if (equal? previous-object #nil)
             (let ((new-state (parse-object object new-state)))
               (loop objects new-state node))
             (let* ((node ((parser-state-blank-node-gen new-state)))
                    (new-state
                      (update-parser-state new-state
                        #:cur-subject node))
                    (new-state (parse-object object new-state)))
               (loop
                 objects
                 (update-parser-state new-state
                   #:result
                   (cons
                     (make-rdf-triple
                       previous-object
                       "http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
                       node)
                     (parser-state-result new-state)))
                 node))))))))

(define (parse-object-list ol state)
  (let loop ((ol ol) (state state))
    (match ol
      ('() state)
      ((('object object) ol ...)
       (loop ol (parse-object object state)))
      ((ol)
       (loop ol state)))))

(define (parse-predicate-object po state)
  (let loop ((po po) (state state))
    (match po
      ((('verb verb) ('object-list ol ...) po)
       (let* ((verb (parse-verb verb state))
              (state (assoc-ref verb "state"))
              (verb (assoc-ref verb "verb"))
              (new-state (update-parser-state state #:cur-predicate verb))
              (res (parse-object-list ol new-state)))
         (loop po res)))
      ((('verb verb) ('object-list ol ...))
       (let* ((verb (parse-verb verb state))
              (state (assoc-ref verb "state"))
              (verb (assoc-ref verb "verb"))
              (new-state (update-parser-state state #:cur-predicate verb))
              (res (parse-object-list ol new-state)))
         res))
      (((('verb verb) ('object-list ol ...)) po ...)
       (let* ((verb (parse-verb verb state))
              (state (assoc-ref verb "state"))
              (verb (assoc-ref verb "verb"))
              (new-state (update-parser-state state #:cur-predicate verb))
              (res (parse-object-list ol new-state)))
         (loop po res)))
      ('() state)
      ((po)
       (loop po state)))))

(define (parse-subject s state)
  (match s
    (('iri _ ...)
     (let ((res (parse-iri s state)))
       `(("subject" . ,(assoc-ref res "iri"))
         ("state" . ,(assoc-ref res "state")))))
    (('collection objects ...)
     (let ((res (parse-collection objects state)))
       `(("subject" . ,(parser-state-cur-object res))
         ("state" . ,res))))
    ('collection
     `(("subject" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
       ("state" . ,state)))
    (('blank-node ('anon _))
     (let ((node ((parser-state-blank-node-gen state))))
       `(("subject" . ,node)
         ("state" . ,state))))
    (('blank-node ('blank-node-label label))
     (if (assoc-ref (parser-state-bnode-labels state) label)
         `(("subject" . ,(assoc-ref (parser-state-bnode-labels state) label))
           ("state" . ,state))
         (let ((node ((parser-state-blank-node-gen state))))
           `(("subject" . ,node)
             ("state" . ,(update-parser-state state
                           #:bnode-labels
                           (cons
                             (cons label node)
                             (parser-state-bnode-labels state))))))))))

(define (parse-triples t state)
  (match t
    ((('subject subject) ('predicate-object-list predicate-object ...))
     (let* ((res (parse-subject subject state))
            (subject (assoc-ref res "subject"))
            (state (assoc-ref res "state"))
            (state (update-parser-state state
                    #:cur-subject subject)))
       (parse-predicate-object predicate-object state)))
    ((('blank-node-property-list ('predicate-object-list po ...))
      ('predicate-object-list predicate-object ...))
     (let* ((subject ((parser-state-blank-node-gen state)))
            (new-state (parse-predicate-object
                         po (update-parser-state state #:cur-subject subject))))
       (parse-predicate-object predicate-object new-state)))
    ((('blank-node-property-list ('predicate-object-list po ...)))
     (let* ((subject ((parser-state-blank-node-gen state))))
       (parse-predicate-object po (update-parser-state state
                                    #:cur-subject subject))))))

(define (parse-turtle-doc parse-tree state)
  (let loop ((parse-tree parse-tree) (state state))
    (match parse-tree
      ('() (parser-state-result state))
      ((('prefix-id ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
       (loop parse-tree
             (add-ns-to-state
               state ns (resolve-iri (parser-state-base-uri state)
                                     (parse-string iri)))))
      ((('prefix-id ('pname-ns ('iriref iri ...))) parse-tree ...)
       (loop parse-tree
             (add-ns-to-state
               state "" (resolve-iri (parser-state-base-uri state)
                                     (parse-string iri)))))
      ((('sparql-prefix ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
       (loop parse-tree
             (add-ns-to-state
               state ns (resolve-iri (parser-state-base-uri state)
                                     (parse-string iri)))))
      ((('sparql-prefix ('pname-ns ('iriref iri ...))) parse-tree ...)
       (loop parse-tree
             (add-ns-to-state
               state "" (resolve-iri (parser-state-base-uri state)
                                     (parse-string iri)))))
      ((('base ('iriref iri ...)) parse-tree ...)
       (loop parse-tree
             (update-parser-state
               state #:base-uri (resolve-iri (parser-state-base-uri state)
                                             (parse-string iri)))))
      ((('sparql-base ('iriref iri ...)) parse-tree ...)
       (loop parse-tree
             (update-parser-state
               state #:base-uri (resolve-iri (parser-state-base-uri state)
                                             (parse-string iri)))))
      ((('triples t ...) parse-tree ...)
       (let ((res (parse-triples t state)))
         (loop parse-tree (parse-triples t state))))
      ;; otherwise, it's a single element, not a list of statements
      (((? symbol? _) _ ...) (loop (list parse-tree) state)))))

(define (tordf parse-tree base)
  (define state
    (make-parser-state base '() '() #f #f #f (create-generate-blank-node) '()))
  (parse-turtle-doc parse-tree state))

(define (turtle->rdf str-or-file base)
  (define str
    (cond
      ((file-exists? str-or-file) (call-with-input-file str-or-file get-string-all))
      ((string? str-or-file) str-or-file)))
      
  (let ((parse-tree (parse-turtle str)))
    (tordf parse-tree base)))


1	;;;; Copyright (C) 2020 Julien Lepiller <julien@lepiller.eu>
2	;;;;
3	;;;; This library is free software; you can redistribute it and/or
4	;;;; modify it under the terms of the GNU Lesser General Public
5	;;;; License as published by the Free Software Foundation; either
6	;;;; version 3 of the License, or (at your option) any later version.
7	;;;;
8	;;;; This library is distributed in the hope that it will be useful,
9	;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
10	;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11	;;;; Lesser General Public License for more details.
12	;;;;
13	;;;; You should have received a copy of the GNU Lesser General Public
14	;;;; License along with this library; if not, write to the Free Software
15	;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16	;;;;
17
18	(define-module (turtle tordf)
19	#:use-module (ice-9 match)
20	#:use-module (ice-9 textual-ports)
21	#:use-module (iri iri)
22	#:use-module (turtle parser)
23	#:use-module (srfi srfi-9)
24	#:use-module (rdf rdf)
25	#:export (turtle->rdf))
26
27	(define-record-type parser-state
28	(make-parser-state base-uri namespaces bnode-labels cur-subject cur-predicate
29	cur-object blank-node-gen result)
30	parser-state?
31	(base-uri parser-state-base-uri)
32	(namespaces parser-state-namespaces)
33	(bnode-labels parser-state-bnode-labels)
34	(cur-subject parser-state-cur-subject)
35	(cur-predicate parser-state-cur-predicate)
36	(cur-object parser-state-cur-object)
37	(blank-node-gen parser-state-blank-node-gen)
38	(result parser-state-result))
39
40	(define* (update-parser-state
41	state #:key (base-uri (parser-state-base-uri state))
42	(namespaces (parser-state-namespaces state))
43	(bnode-labels (parser-state-bnode-labels state))
44	(cur-subject (parser-state-cur-subject state))
45	(cur-predicate (parser-state-cur-predicate state))
46	(cur-object (parser-state-cur-object state))
47	(blank-node-gen (parser-state-blank-node-gen state))
48	(result (parser-state-result state)))
49	(make-parser-state base-uri namespaces bnode-labels cur-subject cur-predicate
50	cur-object blank-node-gen result))
51
52	(define (create-generate-blank-node)
53	(define num 0)
54	(lambda ()
55	(set! num (+ num 1))
56	num))
57
58	(define (add-ns-to-state state ns iri)
59	(update-parser-state state
60	#:namespaces (cons (cons ns iri) (parser-state-namespaces state))))
61
62	(define (parse-string str)
63	(match str
64	((? string? str) str)
65	((component str ...)
66	(match component
67	((? string? str1)
68	(string-append str1 (parse-string str)))
69	(('uchar n)
70	(string-append (string (integer->char (string->number n 16)))
71	(parse-string str)))
72	(('echar e)
73	(string-append
74	(match e
75	("\\t" "\t")
76	("\\b" "\b")
77	("\\n" "\n")
78	("\\r" "\r")
79	("\\f" "\f")
80	("\\\\" "\\")
81	("\\\"" "\"")
82	("\\'" "'"))
83	(parse-string str)))))
84	(() "")))
85
86	(define (parse-iri iri state)
87	(match iri
88	(('iri ('prefixed-name ('pname-ln ('pname-ns ns) ('pn-local suffix))))
89	`(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) ns)
90	suffix))
91	("state" . ,state)))
92	(('iri ('prefixed-name ('pname-ln ('pname-ns ('pn-local suffix)))))
93	`(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) "")
94	suffix))
95	("state" . ,state)))
96	(('iri ('prefixed-name ('pname-ns ns)))
97	`(("iri" . ,(assoc-ref (parser-state-namespaces state) ns))
98	("state" . ,state)))
99	(('iri ('prefixed-name 'pname-ns))
100	`(("iri" . ,(assoc-ref (parser-state-namespaces state) ""))
101	("state" . ,state)))
102	(('iri 'iriref)
103	`(("iri" . ,(resolve-iri (parser-state-base-uri state) ""))
104	("state" . ,state)))
105	(('iri ('iriref iri ...))
106	`(("iri" . ,(resolve-iri (parser-state-base-uri state) (parse-string iri)))
107	("state" . ,state)))))
108
109	(define (parse-verb verb state)
110	(match verb
111	("a" `(("verb" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#type")
112	("state" . ,state)))
113	(('predicate iri)
114	(let ((res (parse-iri iri state)))
115	`(("verb" . ,(assoc-ref res "iri"))
116	("state" . ,(assoc-ref res "state")))))))
117
118	(define (parse-object object state)
119	(match object
120	(('rdf-literal ('string-pat (_ str ...)))
121	(let ((object
122	(make-rdf-literal (parse-string str)
123	"http://www.w3.org/2001/XMLSchema#string" #f)))
124	(update-parser-state state
125	#:cur-object object
126	#:result
127	(cons
128	(make-rdf-triple
129	(parser-state-cur-subject state)
130	(parser-state-cur-predicate state)
131	object)
132	(parser-state-result state)))))
133	(('rdf-literal ('string-pat (_ str ...)) ("^^" iri))
134	(let* ((res (parse-iri iri state))
135	(iri (assoc-ref res "iri"))
136	(state (assoc-ref res "state"))
137	(object (make-rdf-literal (parse-string str) iri #f)))
138	(update-parser-state state
139	#:cur-object object
140	#:result
141	(cons
142	(make-rdf-triple
143	(parser-state-cur-subject state)
144	(parser-state-cur-predicate state)
145	object)
146	(parser-state-result state)))))
147	(('rdf-literal ('string-pat (_ str ...)) ('langtag lang))
148	(let ((object
149	(make-rdf-literal
150	(parse-string str)
151	"http://www.w3.org/1999/02/22-rdf-syntax-ns#langString"
152	lang)))
153	(update-parser-state state
154	#:cur-object object
155	#:result
156	(cons
157	(make-rdf-triple
158	(parser-state-cur-subject state)
159	(parser-state-cur-predicate state)
160	object)
161	(parser-state-result state)))))
162	(('numeric-literal ('decimal num))
163	(let ((object
164	(make-rdf-literal num "http://www.w3.org/2001/XMLSchema#decimal" #f)))
165	(update-parser-state state
166	#:cur-object object
167	#:result
168	(cons
169	(make-rdf-triple
170	(parser-state-cur-subject state)
171	(parser-state-cur-predicate state)
172	object)
173	(parser-state-result state)))))
174	(('numeric-literal ('integer int))
175	(let ((object
176	(make-rdf-literal int "http://www.w3.org/2001/XMLSchema#integer" #f)))
177	(update-parser-state state
178	#:cur-object object
179	#:result
180	(cons
181	(make-rdf-triple
182	(parser-state-cur-subject state)
183	(parser-state-cur-predicate state)
184	object)
185	(parser-state-result state)))))
186	(('numeric-literal ('double num))
187	(let ((object
188	(make-rdf-literal num "http://www.w3.org/2001/XMLSchema#double" #f)))
189	(update-parser-state state
190	#:cur-object object
191	#:result
192	(cons
193	(make-rdf-triple
194	(parser-state-cur-subject state)
195	(parser-state-cur-predicate state)
196	object)
197	(parser-state-result state)))))
198	(('boolean-literal bool)
199	(let ((object
200	(make-rdf-literal bool "http://www.w3.org/2001/XMLSchema#boolean" #f)))
201	(update-parser-state state
202	#:cur-object object
203	#:result
204	(cons
205	(make-rdf-triple
206	(parser-state-cur-subject state)
207	(parser-state-cur-predicate state)
208	object)
209	(parser-state-result state)))))
210	(('blank-node ('anon _))
211	(let ((node ((parser-state-blank-node-gen state))))
212	(update-parser-state state
213	#:cur-object node
214	#:result
215	(cons
216	(make-rdf-triple
217	(parser-state-cur-subject state)
218	(parser-state-cur-predicate state)
219	node)
220	(parser-state-result state)))))
221	(('blank-node ('blank-node-label label))
222	(let* ((node
223	(or (assoc-ref (parser-state-bnode-labels state) label)
224	((parser-state-blank-node-gen state))))
225	(state
226	(if (assoc-ref (parser-state-bnode-labels state) label)
227	state
228	(update-parser-state state
229	#:bnode-labels
230	(cons
231	(cons label node)
232	(parser-state-bnode-labels state))))))
233	(update-parser-state state
234	#:cur-object node
235	#:result
236	(cons
237	(make-rdf-triple
238	(parser-state-cur-subject state)
239	(parser-state-cur-predicate state)
240	node)
241	(parser-state-result state)))))
242	(('blank-node-property-list ('predicate-object-list po ...))
243	(let* ((node ((parser-state-blank-node-gen state)))
244	(new-state (parse-predicate-object
245	po (update-parser-state state #:cur-subject node))))
246	(update-parser-state new-state
247	#:cur-object node
248	#:cur-subject (parser-state-cur-subject state)
249	#:cur-predicate (parser-state-cur-predicate state)
250	#:result
251	(cons
252	(make-rdf-triple
253	(parser-state-cur-subject state)
254	(parser-state-cur-predicate state)
255	node)
256	(parser-state-result new-state)))))
257	('collection
258	(let ((object "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil"))
259	(update-parser-state state
260	#:cur-object object
261	#:result
262	(cons
263	(make-rdf-triple
264	(parser-state-cur-subject state)
265	(parser-state-cur-predicate state)
266	object)
267	(parser-state-result state)))))
268	(('collection objects ...)
269	(let ((state (parse-collection objects state)))
270	(update-parser-state state
271	#:result
272	(cons
273	(make-rdf-triple
274	(parser-state-cur-subject state)
275	(parser-state-cur-predicate state)
276	(parser-state-cur-object state))
277	(parser-state-result state)))))
278	(('iri _)
279	(let* ((res (parse-iri object state))
280	(iri (assoc-ref res "iri"))
281	(state (assoc-ref res "state")))
282	(update-parser-state state
283	#:cur-object iri
284	#:result
285	(cons
286	(make-rdf-triple
287	(parser-state-cur-subject state)
288	(parser-state-cur-predicate state)
289	iri)
290	(parser-state-result state)))))))
291
292	(define (parse-collection collection state)
293	(let ((node ((parser-state-blank-node-gen state))))
294	(let loop ((objects collection)
295	(new-state
296	(update-parser-state state
297	#:cur-subject node
298	#:cur-predicate
299	"http://www.w3.org/1999/02/22-rdf-syntax-ns#first"))
300	(previous-object #nil))
301	(match objects
302	('()
303	(update-parser-state new-state
304	#:cur-object node
305	#:cur-subject (parser-state-cur-subject state)
306	#:cur-predicate (parser-state-cur-predicate state)
307	#:result
308	(cons
309	(make-rdf-triple
310	previous-object
311	"http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
312	"http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
313	(parser-state-result new-state))))
314	((('object object) objects ...)
315	(if (equal? previous-object #nil)
316	(let ((new-state (parse-object object new-state)))
317	(loop objects new-state node))
318	(let* ((node ((parser-state-blank-node-gen new-state)))
319	(new-state
320	(update-parser-state new-state
321	#:cur-subject node))
322	(new-state (parse-object object new-state)))
323	(loop
324	objects
325	(update-parser-state new-state
326	#:result
327	(cons
328	(make-rdf-triple
329	previous-object
330	"http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
331	node)
332	(parser-state-result new-state)))
333	node))))))))
334
335	(define (parse-object-list ol state)
336	(let loop ((ol ol) (state state))
337	(match ol
338	('() state)
339	((('object object) ol ...)
340	(loop ol (parse-object object state)))
341	((ol)
342	(loop ol state)))))
343
344	(define (parse-predicate-object po state)
345	(let loop ((po po) (state state))
346	(match po
347	((('verb verb) ('object-list ol ...) po)
348	(let* ((verb (parse-verb verb state))
349	(state (assoc-ref verb "state"))
350	(verb (assoc-ref verb "verb"))
351	(new-state (update-parser-state state #:cur-predicate verb))
352	(res (parse-object-list ol new-state)))
353	(loop po res)))
354	((('verb verb) ('object-list ol ...))
355	(let* ((verb (parse-verb verb state))
356	(state (assoc-ref verb "state"))
357	(verb (assoc-ref verb "verb"))
358	(new-state (update-parser-state state #:cur-predicate verb))
359	(res (parse-object-list ol new-state)))
360	res))
361	(((('verb verb) ('object-list ol ...)) po ...)
362	(let* ((verb (parse-verb verb state))
363	(state (assoc-ref verb "state"))
364	(verb (assoc-ref verb "verb"))
365	(new-state (update-parser-state state #:cur-predicate verb))
366	(res (parse-object-list ol new-state)))
367	(loop po res)))
368	('() state)
369	((po)
370	(loop po state)))))
371
372	(define (parse-subject s state)
373	(match s
374	(('iri _ ...)
375	(let ((res (parse-iri s state)))
376	`(("subject" . ,(assoc-ref res "iri"))
377	("state" . ,(assoc-ref res "state")))))
378	(('collection objects ...)
379	(let ((res (parse-collection objects state)))
380	`(("subject" . ,(parser-state-cur-object res))
381	("state" . ,res))))
382	('collection
383	`(("subject" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
384	("state" . ,state)))
385	(('blank-node ('anon _))
386	(let ((node ((parser-state-blank-node-gen state))))
387	`(("subject" . ,node)
388	("state" . ,state))))
389	(('blank-node ('blank-node-label label))
390	(if (assoc-ref (parser-state-bnode-labels state) label)
391	`(("subject" . ,(assoc-ref (parser-state-bnode-labels state) label))
392	("state" . ,state))
393	(let ((node ((parser-state-blank-node-gen state))))
394	`(("subject" . ,node)
395	("state" . ,(update-parser-state state
396	#:bnode-labels
397	(cons
398	(cons label node)
399	(parser-state-bnode-labels state))))))))))
400
401	(define (parse-triples t state)
402	(match t
403	((('subject subject) ('predicate-object-list predicate-object ...))
404	(let* ((res (parse-subject subject state))
405	(subject (assoc-ref res "subject"))
406	(state (assoc-ref res "state"))
407	(state (update-parser-state state
408	#:cur-subject subject)))
409	(parse-predicate-object predicate-object state)))
410	((('blank-node-property-list ('predicate-object-list po ...))
411	('predicate-object-list predicate-object ...))
412	(let* ((subject ((parser-state-blank-node-gen state)))
413	(new-state (parse-predicate-object
414	po (update-parser-state state #:cur-subject subject))))
415	(parse-predicate-object predicate-object new-state)))
416	((('blank-node-property-list ('predicate-object-list po ...)))
417	(let* ((subject ((parser-state-blank-node-gen state))))
418	(parse-predicate-object po (update-parser-state state
419	#:cur-subject subject))))))
420
421	(define (parse-turtle-doc parse-tree state)
422	(let loop ((parse-tree parse-tree) (state state))
423	(match parse-tree
424	('() (parser-state-result state))
425	((('prefix-id ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
426	(loop parse-tree
427	(add-ns-to-state
428	state ns (resolve-iri (parser-state-base-uri state)
429	(parse-string iri)))))
430	((('prefix-id ('pname-ns ('iriref iri ...))) parse-tree ...)
431	(loop parse-tree
432	(add-ns-to-state
433	state "" (resolve-iri (parser-state-base-uri state)
434	(parse-string iri)))))
435	((('sparql-prefix ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
436	(loop parse-tree
437	(add-ns-to-state
438	state ns (resolve-iri (parser-state-base-uri state)
439	(parse-string iri)))))
440	((('sparql-prefix ('pname-ns ('iriref iri ...))) parse-tree ...)
441	(loop parse-tree
442	(add-ns-to-state
443	state "" (resolve-iri (parser-state-base-uri state)
444	(parse-string iri)))))
445	((('base ('iriref iri ...)) parse-tree ...)
446	(loop parse-tree
447	(update-parser-state
448	state #:base-uri (resolve-iri (parser-state-base-uri state)
449	(parse-string iri)))))
450	((('sparql-base ('iriref iri ...)) parse-tree ...)
451	(loop parse-tree
452	(update-parser-state
453	state #:base-uri (resolve-iri (parser-state-base-uri state)
454	(parse-string iri)))))
455	((('triples t ...) parse-tree ...)
456	(let ((res (parse-triples t state)))
457	(loop parse-tree (parse-triples t state))))
458	;; otherwise, it's a single element, not a list of statements
459	(((? symbol? _) _ ...) (loop (list parse-tree) state)))))
460
461	(define (tordf parse-tree base)
462	(define state
463	(make-parser-state base '() '() #f #f #f (create-generate-blank-node) '()))
464	(parse-turtle-doc parse-tree state))
465
466	(define (turtle->rdf str-or-file base)
467	(define str
468	(cond
469	((file-exists? str-or-file) (call-with-input-file str-or-file get-string-all))
470	((string? str-or-file) str-or-file)))
471
472	(let ((parse-tree (parse-turtle str)))
473	(tordf parse-tree base)))
474