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
|
<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
-
- This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
- project.
-
- Copyright (C) 1998-2018 OpenLink Software
-
- This project is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by the
- Free Software Foundation; only version 2 of the License, dated June 1991.
-
- This program 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
- General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-
-
-->
<refentry id="xpf_or">
<refmeta>
<refentrytitle>or</refentrytitle>
<refmiscinfo>XPATH</refmiscinfo>
</refmeta>
<refnamediv>
<refname>or</refname>
<refpurpose>Returns true if a value of some argument is true, otherwise returns false.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="xpf_syn_or">
<funcprototype id="xpf_proto_or">
<funcdef>boolean <function>or</function></funcdef>
<paramdef><parameter>val1</parameter> boolean</paramdef>
<paramdef><parameter>val2</parameter> boolean</paramdef>
<paramdef><parameter>...</parameter></paramdef>
<paramdef><parameter>valN</parameter> boolean</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="xpf_desc_or"><title>Description</title>
<para>
This function calculates values of its arguments, from left to right.
If the value of calculated parameter is true, the function returns true immediately,
without calculating of the remaining parameters.
If the list of arguments ends without any true value calculated, the function
returns false (Thus it returns true when called without arguments).
</para>
<para>
The name of this function is the same as name of "or" XPATH and XQUERY operator.
Thus it must be surrounded by double quotes when used in XPATH or XQUERY expressions.
Moreover, this function is not a part of XPATH standard, so it cannot be used if
portability is important.
</para>
</refsect1>
<refsect1 id="xpf_params_or"><title>Parameters</title>
<refsect2><title>valI</title>
<para>Value of boolean expression argument</para></refsect2>
</refsect1>
<refsect1 id="xpf_ret_or"><title>Return Types</title><para>boolean</para></refsect1>
<refsect1 id="xpf_examples_or"><title>Examples</title>
<example id="xpf_ex_and"><title>Control over sequence of search operations</title>
<para>If two conditions must be checked, where one is simple and
another is hard to calculate, then "and" may be used to calculate
second condition only if first is false, to reduce average time of processing</para>
<screen>
"or" ( empty(authors),
document(concat('http://www.lib20.org/findxml.cgi?isbn=',@isbn))/status[@outofprint='YES'] )
</screen>
</example>
</refsect1>
<refsect1 id="xpf_seealso_or"><title>See Also</title>
<para><link linkend="xpf_not">not</link><link linkend="xpf_and">and</link><link linkend="xpf_some">some</link></para>
</refsect1>
</refentry>
|
