1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
|
; Copyright (c) Chris Houser, April 2008. All rights reserved.
; The use and distribution terms for this software are covered by the
; Common Public License 1.0 (http://opensource.org/licenses/cpl.php)
; which can be found in the file CPL.TXT at the root of this distribution.
; By using this software in any fashion, you are agreeing to be bound by
; the terms of this license.
; You must not remove this notice, or any other, from this software.
; System for filtering trees and nodes generated by zip.clj in
; general, and xml trees in particular.
(clojure/in-ns 'zip-filter)
(clojure/refer 'clojure)
(alias 'zip 'clojure.zip)
(defn sequential?
"Returns true if x implements Sequential."
[x] (instance? clojure.lang.Sequential x))
; This uses the negative form (no-auto) so that the result from any
; naive function, including user functions, defaults to "auto".
(defn auto
[v x] (with-meta x ((if v dissoc assoc) ^x :zip-filter/no-auto? true)))
(defn auto?
[x] (not (:zip-filter/no-auto? ^x)))
(defn right-locs
"Returns a lazy sequence of locations to the right of loc, starting with loc."
[loc] (when loc (lazy-cons (auto false loc) (right-locs (zip/right loc)))))
(defn left-locs
"Returns a lazy sequence of locations to the left of loc, starting with loc."
[loc] (when loc (lazy-cons (auto false loc) (left-locs (zip/left loc)))))
(defn leftmost?
"Returns true if there are no more nodes to the left of location loc."
[loc] (nil? (zip/left loc)))
(defn rightmost?
"Returns true if there are no more nodes to the right of location loc."
[loc] (nil? (zip/right loc)))
(defn children
"Returns a lazy sequence of all immediate children of location loc,
left-to-right."
[loc]
(when (zip/branch? loc)
(map #(auto false %) (right-locs (zip/down loc)))))
(defn children-auto
"Returns a lazy sequence of all immediate children of location loc,
left-to-right, marked so that a following tag= predicate will auto-descend."
#^{:private true}
[loc]
(when (zip/branch? loc)
(map #(auto true %) (right-locs (zip/down loc)))))
(defn descendants
"Returns a lazy sequence of all descendants of location loc, in
depth-first order, left-to-right, starting with loc."
[loc] (lazy-cons (auto false loc) (mapcat descendants (children loc))))
(defn ancestors
"Returns a lazy sequence of all ancestors of location loc, starting
with loc and proceeding to loc's parent node and on through to the
root of the tree."
[loc] (when loc (lazy-cons (auto false loc) (ancestors (zip/up loc)))))
(defn fixup-apply
"Calls (pred loc), and then converts the result to the 'appropriate'
sequence."
#^{:private true}
[pred loc]
(let [rtn (pred loc)]
(cond (and (map? ^rtn) (:zip-filter/is-node? ^rtn)) (list rtn)
(= rtn true) (list loc)
(= rtn false) nil
(nil? rtn) nil
(sequential? rtn) rtn
:else (list rtn))))
(defn mapcat-chain
#^{:private true}
[loc preds mkpred]
(reduce (fn [prevseq expr]
(mapcat #(fixup-apply (or (mkpred expr) expr) %) prevseq))
(list (with-meta loc (assoc ^loc :zip-filter/is-node? true)))
preds))
; === specialization for xml filtering ===
(clojure/in-ns 'zip-filter-xml)
(clojure/refer 'clojure)
(alias 'zip 'clojure.zip)
(alias 'xml 'clojure.xml)
(refer 'zip-filter)
(def xml->)
(defn attr
"Returns the xml attribute named attrname, of the xml node at location loc."
([attrname] (fn [loc] (attr loc attrname)))
([loc attrname] (when (zip/branch? loc) (-> loc zip/node :attrs attrname))))
(defn attr=
"Returns a query predicate that matches a node when it has an
attribute named attrname whose value is attrval."
[attrname attrval] (fn [loc] (= attrval (attr loc attrname))))
(defn tag=
"Returns a query predicate that matches a node when its is a tag
named tagname."
[tagname]
(fn [loc]
(filter #(and (zip/branch? %) (= tagname ((zip/node %) :tag)))
(if (auto? loc) (children-auto loc) (list (auto true loc))))))
(defn text
"Returns the textual contents of the given location, similar to
xpaths's value-of"
[loc]
(.replaceAll #^String (apply str (xml-> loc descendants zip/node string?))
(str "[\\s" (char 160) "]+") " "))
(defn text=
"Returns a query predicate that matches a node when its textual
content equals s."
[s] (fn [loc] (= (text loc) s)))
(defn seq-test
"Returns a query predicate that matches a node when its xml content
matches the query expresions given."
#^{:private true}
[preds] (fn [loc] (and (apply xml-> loc preds) (list loc))))
(defn xml->
"The loc is passed to the first predicate. If the predicate returns
a collection, each value of the collection is passed to the next
predicate. If it returns a location, the location is passed to the
next predicate. If it returns true, the input location is passed to
the next predicate. If it returns false or nil, the next predicate
is not called.
This process is repeated, passing the processed results of each
predicate to the next predicate. xml-> returns the final sequence.
The entire chain is evaluated lazily.
There are also special predicates: keywords are converted to tag=,
strings to text=, and vectors to sub-queries that return true if
they match.
See the footer of zip-query.clj for examples."
[loc & preds]
(mapcat-chain loc preds
#(cond (keyword? %) (tag= %)
(string? %) (text= %)
(vector? %) (seq-test %))))
(defn xml1->
"Returns the first item from loc based on the query predicates
given. See xml->"
[loc & preds] (first (apply xml-> loc preds)))
; === examples ===
(comment
(defn parse-str [s]
(zip/xml-zip (xml/parse (new org.xml.sax.InputSource
(new java.io.StringReader s)))))
(def atom1 (parse-str "<?xml version='1.0' encoding='UTF-8'?>
<feed xmlns='http://www.w3.org/2005/Atom'>
<id>tag:blogger.com,1999:blog-28403206</id>
<updated>2008-02-14T08:00:58.567-08:00</updated>
<title type='text'>n01senet</title>
<link rel='alternate' type='text/html' href='http://n01senet.blogspot.com/'/>
<entry>
<id>1</id>
<published>2008-02-13</published>
<title type='text'>clojure is the best lisp yet</title>
<author><name>Chouser</name></author>
</entry>
<entry>
<id>2</id>
<published>2008-02-07</published>
<title type='text'>experimenting with vnc</title>
<author><name>agriffis</name></author>
</entry>
</feed>
"))
; simple single-function filter
(assert (= (xml-> atom1 #((zip/node %) :tag))
'(:feed)))
; two-stage filter using helpful query prediates
(assert (= (xml-> atom1 (tag= :title) text)
'("n01senet")))
; same filter as above, this time using keyword shortcut
(assert (= (xml-> atom1 :title text)
'("n01senet")))
; multi-stage filter
(assert (= (xml-> atom1 :entry :author :name text)
'("Chouser" "agriffis")))
; test xml1->
(assert (= (xml1-> atom1 :entry :author :name text)
"Chouser"))
; multi-stage filter with subquery specified using a vector
(assert (= (xml-> atom1 :entry [:author :name (text= "agriffis")]
:id text)
'("2")))
; same filter as above, this time using a string shortcut
(assert (= (xml-> atom1 :entry [:author :name "agriffis"] :id text)
'("2")))
; attribute access
(assert (= (xml-> atom1 :title (attr :type))
'("text")))
; attribute filtering
(assert (= (xml-> atom1 :link [(attr= :rel "alternate")] (attr :type))
'("text/html")))
; ancestors
(assert (= (xml-> atom1 descendants :id "2" ancestors zip/node #(:tag %))
'(:id :entry :feed)))
; ancestors with non-auto tag= (:entry), followed by auto tag= (:id)
(assert (= (xml-> atom1 descendants :name "Chouser" ancestors :entry :id text)
'("1")))
; left-locs and detection of returning a single loc (zip/up)
(assert (= (xml-> atom1 descendants :name "Chouser" zip/up left-locs :id text)
'("1")))
; right-locs
(assert (= (xml-> atom1 descendants :id right-locs :author text)
'("Chouser" "agriffis")))
)
|
