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)))))
    (('rdf-literal ('string-pat _) ("^^" iri))
     (let* ((res (parse-iri iri state))
            (iri (assoc-ref res "iri"))
            (state (assoc-ref res "state"))
            (object (make-rdf-literal "" 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 _) ('langtag lang))
     (let ((object
           (make-rdf-literal
             ""
             "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)))))
    (('rdf-literal ('string-pat _))
     (let ((object
           (make-rdf-literal
             ""
             "http://www.w3.org/1999/02/22-rdf-syntax-ns#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)))))
    (('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	(('rdf-literal ('string-pat _) ("^^" iri))
163	(let* ((res (parse-iri iri state))
164	(iri (assoc-ref res "iri"))
165	(state (assoc-ref res "state"))
166	(object (make-rdf-literal "" iri #f)))
167	(update-parser-state state
168	#:cur-object object
169	#:result
170	(cons
171	(make-rdf-triple
172	(parser-state-cur-subject state)
173	(parser-state-cur-predicate state)
174	object)
175	(parser-state-result state)))))
176	(('rdf-literal ('string-pat _) ('langtag lang))
177	(let ((object
178	(make-rdf-literal
179	""
180	"http://www.w3.org/1999/02/22-rdf-syntax-ns#langString"
181	lang)))
182	(update-parser-state state
183	#:cur-object object
184	#:result
185	(cons
186	(make-rdf-triple
187	(parser-state-cur-subject state)
188	(parser-state-cur-predicate state)
189	object)
190	(parser-state-result state)))))
191	(('rdf-literal ('string-pat _))
192	(let ((object
193	(make-rdf-literal
194	""
195	"http://www.w3.org/1999/02/22-rdf-syntax-ns#string"
196	#f)))
197	(update-parser-state state
198	#:cur-object object
199	#:result
200	(cons
201	(make-rdf-triple
202	(parser-state-cur-subject state)
203	(parser-state-cur-predicate state)
204	object)
205	(parser-state-result state)))))
206	(('numeric-literal ('decimal num))
207	(let ((object
208	(make-rdf-literal num "http://www.w3.org/2001/XMLSchema#decimal" #f)))
209	(update-parser-state state
210	#:cur-object object
211	#:result
212	(cons
213	(make-rdf-triple
214	(parser-state-cur-subject state)
215	(parser-state-cur-predicate state)
216	object)
217	(parser-state-result state)))))
218	(('numeric-literal ('integer int))
219	(let ((object
220	(make-rdf-literal int "http://www.w3.org/2001/XMLSchema#integer" #f)))
221	(update-parser-state state
222	#:cur-object object
223	#:result
224	(cons
225	(make-rdf-triple
226	(parser-state-cur-subject state)
227	(parser-state-cur-predicate state)
228	object)
229	(parser-state-result state)))))
230	(('numeric-literal ('double num))
231	(let ((object
232	(make-rdf-literal num "http://www.w3.org/2001/XMLSchema#double" #f)))
233	(update-parser-state state
234	#:cur-object object
235	#:result
236	(cons
237	(make-rdf-triple
238	(parser-state-cur-subject state)
239	(parser-state-cur-predicate state)
240	object)
241	(parser-state-result state)))))
242	(('boolean-literal bool)
243	(let ((object
244	(make-rdf-literal bool "http://www.w3.org/2001/XMLSchema#boolean" #f)))
245	(update-parser-state state
246	#:cur-object object
247	#:result
248	(cons
249	(make-rdf-triple
250	(parser-state-cur-subject state)
251	(parser-state-cur-predicate state)
252	object)
253	(parser-state-result state)))))
254	(('blank-node ('anon _))
255	(let ((node ((parser-state-blank-node-gen state))))
256	(update-parser-state state
257	#:cur-object node
258	#:result
259	(cons
260	(make-rdf-triple
261	(parser-state-cur-subject state)
262	(parser-state-cur-predicate state)
263	node)
264	(parser-state-result state)))))
265	(('blank-node ('blank-node-label label))
266	(let* ((node
267	(or (assoc-ref (parser-state-bnode-labels state) label)
268	((parser-state-blank-node-gen state))))
269	(state
270	(if (assoc-ref (parser-state-bnode-labels state) label)
271	state
272	(update-parser-state state
273	#:bnode-labels
274	(cons
275	(cons label node)
276	(parser-state-bnode-labels state))))))
277	(update-parser-state state
278	#:cur-object node
279	#:result
280	(cons
281	(make-rdf-triple
282	(parser-state-cur-subject state)
283	(parser-state-cur-predicate state)
284	node)
285	(parser-state-result state)))))
286	(('blank-node-property-list ('predicate-object-list po ...))
287	(let* ((node ((parser-state-blank-node-gen state)))
288	(new-state (parse-predicate-object
289	po (update-parser-state state #:cur-subject node))))
290	(update-parser-state new-state
291	#:cur-object node
292	#:cur-subject (parser-state-cur-subject state)
293	#:cur-predicate (parser-state-cur-predicate state)
294	#:result
295	(cons
296	(make-rdf-triple
297	(parser-state-cur-subject state)
298	(parser-state-cur-predicate state)
299	node)
300	(parser-state-result new-state)))))
301	('collection
302	(let ((object "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil"))
303	(update-parser-state state
304	#:cur-object object
305	#:result
306	(cons
307	(make-rdf-triple
308	(parser-state-cur-subject state)
309	(parser-state-cur-predicate state)
310	object)
311	(parser-state-result state)))))
312	(('collection objects ...)
313	(let ((state (parse-collection objects state)))
314	(update-parser-state state
315	#:result
316	(cons
317	(make-rdf-triple
318	(parser-state-cur-subject state)
319	(parser-state-cur-predicate state)
320	(parser-state-cur-object state))
321	(parser-state-result state)))))
322	(('iri _)
323	(let* ((res (parse-iri object state))
324	(iri (assoc-ref res "iri"))
325	(state (assoc-ref res "state")))
326	(update-parser-state state
327	#:cur-object iri
328	#:result
329	(cons
330	(make-rdf-triple
331	(parser-state-cur-subject state)
332	(parser-state-cur-predicate state)
333	iri)
334	(parser-state-result state)))))))
335
336	(define (parse-collection collection state)
337	(let ((node ((parser-state-blank-node-gen state))))
338	(let loop ((objects collection)
339	(new-state
340	(update-parser-state state
341	#:cur-subject node
342	#:cur-predicate
343	"http://www.w3.org/1999/02/22-rdf-syntax-ns#first"))
344	(previous-object #nil))
345	(match objects
346	('()
347	(update-parser-state new-state
348	#:cur-object node
349	#:cur-subject (parser-state-cur-subject state)
350	#:cur-predicate (parser-state-cur-predicate state)
351	#:result
352	(cons
353	(make-rdf-triple
354	previous-object
355	"http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
356	"http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
357	(parser-state-result new-state))))
358	((('object object) objects ...)
359	(if (equal? previous-object #nil)
360	(let ((new-state (parse-object object new-state)))
361	(loop objects new-state node))
362	(let* ((node ((parser-state-blank-node-gen new-state)))
363	(new-state
364	(update-parser-state new-state
365	#:cur-subject node))
366	(new-state (parse-object object new-state)))
367	(loop
368	objects
369	(update-parser-state new-state
370	#:result
371	(cons
372	(make-rdf-triple
373	previous-object
374	"http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"
375	node)
376	(parser-state-result new-state)))
377	node))))))))
378
379	(define (parse-object-list ol state)
380	(let loop ((ol ol) (state state))
381	(match ol
382	('() state)
383	((('object object) ol ...)
384	(loop ol (parse-object object state)))
385	((ol)
386	(loop ol state)))))
387
388	(define (parse-predicate-object po state)
389	(let loop ((po po) (state state))
390	(match po
391	((('verb verb) ('object-list ol ...) po)
392	(let* ((verb (parse-verb verb state))
393	(state (assoc-ref verb "state"))
394	(verb (assoc-ref verb "verb"))
395	(new-state (update-parser-state state #:cur-predicate verb))
396	(res (parse-object-list ol new-state)))
397	(loop po res)))
398	((('verb verb) ('object-list ol ...))
399	(let* ((verb (parse-verb verb state))
400	(state (assoc-ref verb "state"))
401	(verb (assoc-ref verb "verb"))
402	(new-state (update-parser-state state #:cur-predicate verb))
403	(res (parse-object-list ol new-state)))
404	res))
405	(((('verb verb) ('object-list ol ...)) po ...)
406	(let* ((verb (parse-verb verb state))
407	(state (assoc-ref verb "state"))
408	(verb (assoc-ref verb "verb"))
409	(new-state (update-parser-state state #:cur-predicate verb))
410	(res (parse-object-list ol new-state)))
411	(loop po res)))
412	('() state)
413	((po)
414	(loop po state)))))
415
416	(define (parse-subject s state)
417	(match s
418	(('iri _ ...)
419	(let ((res (parse-iri s state)))
420	`(("subject" . ,(assoc-ref res "iri"))
421	("state" . ,(assoc-ref res "state")))))
422	(('collection objects ...)
423	(let ((res (parse-collection objects state)))
424	`(("subject" . ,(parser-state-cur-object res))
425	("state" . ,res))))
426	('collection
427	`(("subject" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#nil")
428	("state" . ,state)))
429	(('blank-node ('anon _))
430	(let ((node ((parser-state-blank-node-gen state))))
431	`(("subject" . ,node)
432	("state" . ,state))))
433	(('blank-node ('blank-node-label label))
434	(if (assoc-ref (parser-state-bnode-labels state) label)
435	`(("subject" . ,(assoc-ref (parser-state-bnode-labels state) label))
436	("state" . ,state))
437	(let ((node ((parser-state-blank-node-gen state))))
438	`(("subject" . ,node)
439	("state" . ,(update-parser-state state
440	#:bnode-labels
441	(cons
442	(cons label node)
443	(parser-state-bnode-labels state))))))))))
444
445	(define (parse-triples t state)
446	(match t
447	((('subject subject) ('predicate-object-list predicate-object ...))
448	(let* ((res (parse-subject subject state))
449	(subject (assoc-ref res "subject"))
450	(state (assoc-ref res "state"))
451	(state (update-parser-state state
452	#:cur-subject subject)))
453	(parse-predicate-object predicate-object state)))
454	((('blank-node-property-list ('predicate-object-list po ...))
455	('predicate-object-list predicate-object ...))
456	(let* ((subject ((parser-state-blank-node-gen state)))
457	(new-state (parse-predicate-object
458	po (update-parser-state state #:cur-subject subject))))
459	(parse-predicate-object predicate-object new-state)))
460	((('blank-node-property-list ('predicate-object-list po ...)))
461	(let* ((subject ((parser-state-blank-node-gen state))))
462	(parse-predicate-object po (update-parser-state state
463	#:cur-subject subject))))))
464
465	(define (parse-turtle-doc parse-tree state)
466	(let loop ((parse-tree parse-tree) (state state))
467	(match parse-tree
468	('() (parser-state-result state))
469	((('prefix-id ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
470	(loop parse-tree
471	(add-ns-to-state
472	state ns (resolve-iri (parser-state-base-uri state)
473	(parse-string iri)))))
474	((('prefix-id ('pname-ns ('iriref iri ...))) parse-tree ...)
475	(loop parse-tree
476	(add-ns-to-state
477	state "" (resolve-iri (parser-state-base-uri state)
478	(parse-string iri)))))
479	((('sparql-prefix ('pname-ns ns) ('iriref iri ...)) parse-tree ...)
480	(loop parse-tree
481	(add-ns-to-state
482	state ns (resolve-iri (parser-state-base-uri state)
483	(parse-string iri)))))
484	((('sparql-prefix ('pname-ns ('iriref iri ...))) parse-tree ...)
485	(loop parse-tree
486	(add-ns-to-state
487	state "" (resolve-iri (parser-state-base-uri state)
488	(parse-string iri)))))
489	((('base ('iriref iri ...)) parse-tree ...)
490	(loop parse-tree
491	(update-parser-state
492	state #:base-uri (resolve-iri (parser-state-base-uri state)
493	(parse-string iri)))))
494	((('sparql-base ('iriref iri ...)) parse-tree ...)
495	(loop parse-tree
496	(update-parser-state
497	state #:base-uri (resolve-iri (parser-state-base-uri state)
498	(parse-string iri)))))
499	((('triples t ...) parse-tree ...)
500	(let ((res (parse-triples t state)))
501	(loop parse-tree (parse-triples t state))))
502	;; otherwise, it's a single element, not a list of statements
503	(((? symbol? _) _ ...) (loop (list parse-tree) state)))))
504
505	(define (tordf parse-tree base)
506	(define state
507	(make-parser-state base '() '() #f #f #f (create-generate-blank-node) '()))
508	(parse-turtle-doc parse-tree state))
509
510	(define (turtle->rdf str-or-file base)
511	(define str
512	(cond
513	((file-exists? str-or-file) (call-with-input-file str-or-file get-string-all))
514	((string? str-or-file) str-or-file)))
515
516	(let ((parse-tree (parse-turtle str)))
517	(tordf parse-tree base)))
518