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)
  (pk 'iri iri)
  (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)
             (make-rdf-literal str "http://www.w3.org/2001/XMLSchema#string" #f))
           (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)
             (make-rdf-literal str "http://www.w3.org/2001/XMLSchema#string" #f))
           (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)))))
       (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	(pk 'iri iri)
88	(match iri
89	(('iri ('prefixed-name ('pname-ln ('pname-ns ns) ('pn-local suffix))))
90	`(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) ns)
91	suffix))
92	("state" . ,state)))
93	(('iri ('prefixed-name ('pname-ln ('pname-ns ('pn-local suffix)))))
94	`(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) "")
95	suffix))
96	("state" . ,state)))
97	(('iri ('prefixed-name ('pname-ns ns)))
98	`(("iri" . ,(assoc-ref (parser-state-namespaces state) ns))
99	("state" . ,state)))
100	(('iri ('prefixed-name 'pname-ns))
101	`(("iri" . ,(assoc-ref (parser-state-namespaces state) ""))
102	("state" . ,state)))
103	(('iri 'iriref)
104	`(("iri" . ,(resolve-iri (parser-state-base-uri state) ""))
105	("state" . ,state)))
106	(('iri ('iriref iri ...))
107	`(("iri" . ,(resolve-iri (parser-state-base-uri state) (parse-string iri)))
108	("state" . ,state)))))
109
110	(define (parse-verb verb state)
111	(match verb
112	("a" `(("verb" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#type")
113	("state" . ,state)))
114	(('predicate iri)
115	(let ((res (parse-iri iri state)))
116	`(("verb" . ,(assoc-ref res "iri"))
117	("state" . ,(assoc-ref res "state")))))))
118
119	(define (parse-object object state)
120	(match object
121	(('rdf-literal ('string-pat (_ str ...)))
122	(let ((object
123	(make-rdf-literal (parse-string str)
124	"http://www.w3.org/2001/XMLSchema#string" #f)))
125	(update-parser-state state
126	#:cur-object object
127	#:result
128	(cons
129	(make-rdf-triple
130	(parser-state-cur-subject state)
131	(parser-state-cur-predicate state)
132	(make-rdf-literal str "http://www.w3.org/2001/XMLSchema#string" #f))
133	(parser-state-result state)))))
134	(('rdf-literal ('string-pat (_ str ...)) ("^^" iri))
135	(let* ((res (parse-iri iri state))
136	(iri (assoc-ref res "iri"))
137	(state (assoc-ref res "state"))
138	(object (make-rdf-literal (parse-string str) iri #f)))
139	(update-parser-state state
140	#:cur-object object
141	#:result
142	(cons
143	(make-rdf-triple
144	(parser-state-cur-subject state)
145	(parser-state-cur-predicate state)
146	(make-rdf-literal str "http://www.w3.org/2001/XMLSchema#string" #f))
147	(parser-state-result state)))))
148	(('rdf-literal ('string-pat (_ str ...)) ('langtag lang))
149	(let ((object
150	(make-rdf-literal
151	(parse-string str)
152	"http://www.w3.org/1999/02/22-rdf-syntax-ns#langString"
153	lang)))
154	(update-parser-state state
155	#:cur-object object
156	#:result
157	(cons
158	(make-rdf-triple
159	(parser-state-cur-subject state)
160	(parser-state-cur-predicate state)
161	object)
162	(parser-state-result state)))))
163	(('numeric-literal ('decimal num))
164	(let ((object
165	(make-rdf-literal num "http://www.w3.org/2001/XMLSchema#decimal" #f)))
166	(update-parser-state state
167	#:cur-object object
168	#:result
169	(cons
170	(make-rdf-triple
171	(parser-state-cur-subject state)
172	(parser-state-cur-predicate state)
173	object)
174	(parser-state-result state)))))
175	(('numeric-literal ('integer int))
176	(let ((object
177	(make-rdf-literal int "http://www.w3.org/2001/XMLSchema#integer" #f)))
178	(update-parser-state state
179	#:cur-object object
180	#:result
181	(cons
182	(make-rdf-triple
183	(parser-state-cur-subject state)
184	(parser-state-cur-predicate state)
185	object)
186	(parser-state-result state)))))
187	(('numeric-literal ('double num))
188	(let ((object
189	(make-rdf-literal num "http://www.w3.org/2001/XMLSchema#double" #f)))
190	(update-parser-state state
191	#:cur-object object
192	#:result
193	(cons
194	(make-rdf-triple
195	(parser-state-cur-subject state)
196	(parser-state-cur-predicate state)
197	object)
198	(parser-state-result state)))))
199	(('boolean-literal bool)
200	(let ((object
201	(make-rdf-literal bool "http://www.w3.org/2001/XMLSchema#boolean" #f)))
202	(update-parser-state state
203	#:cur-object object
204	#:result
205	(cons
206	(make-rdf-triple
207	(parser-state-cur-subject state)
208	(parser-state-cur-predicate state)
209	object)
210	(parser-state-result state)))))
211	(('blank-node ('anon _))
212	(let ((node ((parser-state-blank-node-gen state))))
213	(update-parser-state state
214	#:cur-object node
215	#:result
216	(cons
217	(make-rdf-triple
218	(parser-state-cur-subject state)
219	(parser-state-cur-predicate state)
220	node)
221	(parser-state-result state)))))
222	(('blank-node ('blank-node-label label))
223	(let* ((node
224	(or (assoc-ref (parser-state-bnode-labels state) label)
225	((parser-state-blank-node-gen state)))))
226	(update-parser-state state
227	#:cur-object node
228	#:result
229	(cons
230	(make-rdf-triple
231	(parser-state-cur-subject state)
232	(parser-state-cur-predicate state)
233	node)
234	(parser-state-result state)))))
235	(('blank-node-property-list ('predicate-object-list po ...))
236	(let* ((node ((parser-state-blank-node-gen state)))
237	(new-state (parse-predicate-object
238	po (update-parser-state state #:cur-subject node))))
239	(update-parser-state new-state
240	#:cur-object node
241	#:cur-subject (parser-state-cur-subject state)
242	#:cur-predicate (parser-state-cur-predicate state)
243	#:result
244	(cons
245	(make-rdf-triple
246	(parser-state-cur-subject state)
247	(parser-state-cur-predicate state)
248	node)
249	(parser-state-result new-state)))))
250	('collection
251	(let ((object "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil"))
252	(update-parser-state state
253	#:cur-object object
254	#:result
255	(cons
256	(make-rdf-triple
257	(parser-state-cur-subject state)
258	(parser-state-cur-predicate state)
259	object)
260	(parser-state-result state)))))
261	(('collection objects ...)
262	(let ((state (parse-collection objects state)))
263	(update-parser-state state
264	#:result
265	(cons
266	(make-rdf-triple
267	(parser-state-cur-subject state)
268	(parser-state-cur-predicate state)
269	(parser-state-cur-object state))
270	(parser-state-result state)))))
271	(('iri _)
272	(let* ((res (parse-iri object state))
273	(iri (assoc-ref res "iri"))
274	(state (assoc-ref res "state")))
275	(update-parser-state state
276	#:cur-object iri
277	#:result
278	(cons
279	(make-rdf-triple
280	(parser-state-cur-subject state)
281	(parser-state-cur-predicate state)
282	iri)
283	(parser-state-result state)))))))
284
285	(define (parse-collection collection state)
286	(let ((node ((parser-state-blank-node-gen state))))
287	(let loop ((objects collection)
288	(new-state
289	(update-parser-state state
290	#:cur-subject node
291	#:cur-predicate
292	"http://www.w3.org/1999/02/22-rdf-syntax-ns#first"))
293	(previous-object #nil))
294	(match objects
295	('()
296	(update-parser-state new-state
297	#:cur-object node
298	#:cur-subject (parser-state-cur-subject state)
299	#:cur-predicate (parser-state-cur-predicate state)
300	#:result
301	(cons
302	(make-rdf-triple
303	previous-object
304	"http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
305	"http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
306	(parser-state-result new-state))))
307	((('object object) objects ...)
308	(if (equal? previous-object #nil)
309	(let ((new-state (parse-object object new-state)))
310	(loop objects new-state node))
311	(let* ((node ((parser-state-blank-node-gen new-state)))
312	(new-state
313	(update-parser-state new-state
314	#:cur-subject node))
315	(new-state (parse-object object new-state)))
316	(loop
317	objects
318	(update-parser-state new-state
319	#:result
320	(cons
321	(make-rdf-triple
322	previous-object
323	"http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
324	node)
325	(parser-state-result new-state)))
326	node))))))))
327
328	(define (parse-object-list ol state)
329	(let loop ((ol ol) (state state))
330	(match ol
331	('() state)
332	((('object object) ol ...)
333	(loop ol (parse-object object state)))
334	((ol)
335	(loop ol state)))))
336
337	(define (parse-predicate-object po state)
338	(let loop ((po po) (state state))
339	(match po
340	((('verb verb) ('object-list ol ...) po)
341	(let* ((verb (parse-verb verb state))
342	(state (assoc-ref verb "state"))
343	(verb (assoc-ref verb "verb"))
344	(new-state (update-parser-state state #:cur-predicate verb))
345	(res (parse-object-list ol new-state)))
346	(loop po res)))
347	((('verb verb) ('object-list ol ...))
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	res))
354	(((('verb verb) ('object-list ol ...)) po ...)
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	(loop po res)))
361	('() state)
362	((po)
363	(loop po state)))))
364
365	(define (parse-subject s state)
366	(match s
367	(('iri _ ...)
368	(let ((res (parse-iri s state)))
369	`(("subject" . ,(assoc-ref res "iri"))
370	("state" . ,(assoc-ref res "state")))))
371	(('collection objects ...)
372	(let ((res (parse-collection objects state)))
373	`(("subject" . ,(parser-state-cur-object res))
374	("state" . ,res))))
375	('collection
376	`(("subject" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
377	("state" . ,state)))
378	(('blank-node ('anon _))
379	(let ((node ((parser-state-blank-node-gen state))))
380	`(("subject" . ,node)
381	("state" . ,state))))
382	(('blank-node ('blank-node-label label))
383	(if (assoc-ref (parser-state-bnode-labels state) label)
384	`(("subject" . ,(assoc-ref (parser-state-bnode-labels state) label))
385	("state" . ,state))
386	(let ((node ((parser-state-blank-node-gen state))))
387	`(("subject" . ,node)
388	("state" . ,(update-parser-state state
389	#:bnode-labels
390	(cons
391	(cons label node)
392	(parser-state-bnode-labels state))))))))))
393
394	(define (parse-triples t state)
395	(match t
396	((('subject subject) ('predicate-object-list predicate-object ...))
397	(let* ((res (parse-subject subject state))
398	(subject (assoc-ref res "subject"))
399	(state (assoc-ref res "state"))
400	(state (update-parser-state state
401	#:cur-subject subject)))
402	(parse-predicate-object predicate-object state)))
403	((('blank-node-property-list ('predicate-object-list po ...))
404	('predicate-object-list predicate-object ...))
405	(let* ((subject ((parser-state-blank-node-gen state)))
406	(new-state (parse-predicate-object
407	po (update-parser-state state #:cur-subject subject))))
408	(parse-predicate-object predicate-object new-state)))
409	((('blank-node-property-list ('predicate-object-list po ...)))
410	(let* ((subject ((parser-state-blank-node-gen state))))
411	(parse-predicate-object po (update-parser-state state
412	#:cur-subject subject))))))
413
414	(define (parse-turtle-doc parse-tree state)
415	(let loop ((parse-tree parse-tree) (state state))
416	(match parse-tree
417	('() (parser-state-result state))
418	((('prefix-id ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
419	(loop parse-tree
420	(add-ns-to-state
421	state ns (resolve-iri (parser-state-base-uri state)
422	(parse-string iri)))))
423	((('prefix-id ('pname-ns ('iriref iri ...))) parse-tree ...)
424	(loop parse-tree
425	(add-ns-to-state
426	state "" (resolve-iri (parser-state-base-uri state)
427	(parse-string iri)))))
428	((('sparql-prefix ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
429	(loop parse-tree
430	(add-ns-to-state
431	state ns (resolve-iri (parser-state-base-uri state)
432	(parse-string iri)))))
433	((('sparql-prefix ('pname-ns ('iriref iri ...))) parse-tree ...)
434	(loop parse-tree
435	(add-ns-to-state
436	state "" (resolve-iri (parser-state-base-uri state)
437	(parse-string iri)))))
438	((('base ('iriref iri ...)) parse-tree ...)
439	(loop parse-tree
440	(update-parser-state
441	state #:base-uri (resolve-iri (parser-state-base-uri state)
442	(parse-string iri)))))
443	((('sparql-base ('iriref iri ...)) parse-tree ...)
444	(loop parse-tree
445	(update-parser-state
446	state #:base-uri (resolve-iri (parser-state-base-uri state)
447	(parse-string iri)))))
448	((('triples t ...) parse-tree ...)
449	(let ((res (parse-triples t state)))
450	(loop parse-tree (parse-triples t state))))
451	;; otherwise, it's a single element, not a list of statements
452	(((? symbol? _) _ ...) (loop (list parse-tree) state)))))
453
454	(define (tordf parse-tree base)
455	(define state
456	(make-parser-state base '() '() #f #f #f (create-generate-blank-node) '()))
457	(parse-turtle-doc parse-tree state))
458
459	(define (turtle->rdf str-or-file base)
460	(define str
461	(cond
462	((file-exists? str-or-file) (call-with-input-file str-or-file get-string-all))
463	((string? str-or-file) str-or-file)))
464
465	(let ((parse-tree (parse-turtle str)))
466	(tordf parse-tree base)))
467