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<!doctype html public "-//W3C//DTD HTML 3.2 Final//EN">
<html>
<head>
<title>Parsed Document Syntax for the WN Server</title>
<link rev="made" href="mailto:john@math.nwu.edu">
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
<meta http-equiv="last-modified" content="Fri, 09 Oct 1998 18:18:09 GMT">
<meta http-equiv="keywords" content="WN parsing syntax">
</head>
<body bgcolor="#FFFFFF">
<p>
<a href="http://hopf.math.nwu.edu/"><img
src="images/powered.jpg"
border="0"
width="190"
height="41"
align="right"
alt="WN home page"
></a>
</p>
<strong>Version 2.0.3</strong>
<br>
<!-- pnuts --> <a href="appendixB.html">[Previous]</a> <a href="appendixD.html">[Next]</a> <a href="manual.html">[Up]</a> <a href="manual.html">[Top]</a> <a href="dosearch.html">[Search]</a> <a href="docindex.html">[Index]</a>
<br clear="right">
<hr size="4">
<!-- #start -->
<h2 align="center">Parsed Document Syntax for the <em>WN</em> Server</h2>
<hr size="4">
<p>
This is a list of all parsing instructions recognized by <em>WN</em>
while parsing a text document. They all use one of the two equivalent
forms:
</p>
<blockquote>
<code>
<!-- #something -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<?WN something>
</code>
</blockquote>
<p>
There is a maximum allowed size of 2K bytes for the entire
"<code><!-- #something --></code>" expression. Current
versions of <em>WN</em> no longer require this expression to be on a line
by itself.
</p>
<p>
The second form is considered more <a
href="http://www.sil.org/sgml/">SGML/XML</a> friendly by many as
"<code><?WN something ></code>" indicates a processing
instruction specific to <em>WN</em> rather than a comment. For
historical reasons this manual describes the other form, but either may
be used. With the first form the '<code>#</code>' is required but with
the other you may use either:
</p>
<blockquote>
<code>
<?WN #something>
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<?WN something>
</code>
</blockquote>
<p>
Also "<code><?wn #something></code>" is fine. The case of the
<code>WN</code> is not significant.
</p>
<h3>C.1 <a name="match">Matching Regular Expressions: <code>#if</code> and
<code>#elif</code></a></h3>
<p>
This section describes the use of conditionally included text of the
form:
</p>
<blockquote>
<code>
<!-- #if some_condition -->
<br>
Some conditional text goes here.
<br>
<!-- #elif another_condition -->
<br>
Some other conditional text goes here.
<br>
<!-- #else -->
<br>
Alternate text.
<br>
<!-- #endif -->
</code>
</blockquote>
<p>
Which will insert the first conditional text only if
<code>some_condition</code> is satisfied. The
"<code><!-- #elif another_condition --></code>" and
"<code><!-- #else ></code>" are optional. There may be
multiple "<code>#elif</code>" lines.
</p>
<p>
In all the examples below the use of the equal-tilde string
'<code>=~</code>' to indicate a matching regular expression can be
replaced with the two characters '<code>!~</code>' in which case the if
clause will be true when the regular expression fails to match.
</p>
<p>
Also in the examples of the form
"<code><-- #if accept file="foo" --></code>"
the file <code>foo</code> is assumed to be relative to the current
directory unless it begins with a '<code>/</code>' in which case it is
taken relative to the <em>WN</em> data hierarchy root. The format of
these files is a list of <code>grep(1)</code> like regular expressions,
one per line with any white space being taken as part of the expression.
Lines beginning with '<code>#</code>' are taken to be comments. If a
regular expression is preceded with the character '<code>!</code>' then
that character is skipped but the truth value of any matches with the
expression is reversed.
</p>
<p>
The regular expressions recognized by the <em>WN</em> server are the same
as those of the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility (though this utility is not used as the server has its own
regular expression functions). The more general regular expressions used
for example in the UNIX <code><a
href="http://linux-howto.com/man/man1/egrep.1.html">egrep(1)</a></code>
utility are not supported by <em>WN</em>.
</p>
<p>
The condition in the "<code>#if</code>" or "<code>#elif</code>" tags can
be made more complex than those described above by combining simple
conditions using the logical operations '<code>&&</code>' for
'<code>and</code>', '<code>||</code>' for '<code>or</code>' and
'<code>!</code>' for '<code>not</code>'. Parentheses may be used for
grouping. For example:
</p>
<blockquote>
<code>
<!-- #if cond_1 && cond_2 -->
<br>
Text to show if cond_1 and cond_2 are satisfied.
<br>
<!-- #endif -->
</code>
</blockquote>
<p>
Other examples are:
</p>
<blockquote>
<code>
<!-- #if cond_1 || cond_2 -->
<br>
<!-- #if !cond_1 -->
<br>
<!-- #if (cond_1 || cond_2) && !cond_3 -->
</code>
</blockquote>
<p>
The '<code>&&</code>' and '<code>||</code>' operations have equal
precedence and associate from right to left.
</p>
<h4>C.1.1 <a name="match.conditions"><code>#if</code> and
<code>#elif</code> Conditions</a></h4>
<dl>
<dt>
<a name="match.conditions.accept"><code>#if accept</code></a> -- Match
client's <code>Accept</code> headers
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if accept =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if accept file = "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if (in the first
case) the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches any of
the <code>Accept</code> headers supplied by the client. Or for the
second line if the file "<code>foo</code>" contains a regular
expression matching any of the <code>Accept</code> headers.
</p>
</dd>
<dt>
<a name="match.conditions.after"><code>#if after</code> and
<code>#if before</code></a> -- Select text based on date
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if after "date" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if before "date" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the current time
is after (or before) the specified date. That is, the line:
</p>
<blockquote>
<code>
<!-- #if after "22 Oct 1996 17:41:26" -->
</code>
</blockquote>
<p>
will cause the text segment to be served only after
"<code>22 Oct 1996 17:41:26</code>" local time. The
date format is rather rigid. It must be in precisely the format
shown above (specified by <a
href="http://linux-howto.com/rfc/rfc1000-1499/rfc1123.txt">RFC
1123</a>) and with a single space between each field. Only local
time of the server is supported.
</p>
</dd>
<dt>
<a name="match.conditions.cookie"><code>#if cookie</code></a> --
Match client's <code>Cookie</code> headers
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if cookie =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if cookie file= "foo" -->
</code>
</blockquote>
<p>
specifies that this text segment should be served if the UNIX
<code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression <code>regexp</code> matches any of
the <code>Cookie</code> headers supplied by the client.
</p>
<p>
More information about the proposed HTTP <code>Set-Cookie</code>
header is available at <a
href="http://home.netscape.com/newsref/std/cookie_spec.html">http://home.netscape.com/newsref/std/cookie_spec.html</a>.
</p>
</dd>
<dt>
<a name="match.conditions.field"><code>#if field</code></a> --
Match document's user defined field
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if field3 =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if field3 file= "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
contents of the <a href="field.html">user defined field</a> number 3
(in the first case) or if the file "<code>foo</code>" contains a
matching regular expression (in the second) case. Any valid field
number may be used in place of 3.
</p>
</dd>
<dt>
<a name="match.conditions.hostname"><code>#if hostname</code></a>
-- Match client's hostname
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if hostname =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if hostname file= "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
hostname of the client (in the first case) or if the file
"<code>foo</code>" contains a matching regular expression (in the
second) case. For an alternate method of doing this see the "<a
href="#match.control"><code>#if accessfile</code></a>" syntax
described below.
</p>
<p>
Be aware that the character '<code>.</code>' (dot) has a special
meaning in regular expressions and must be escaped with a
'<code>\</code>' to have its usual meaning.
</p>
</dd>
<dt>
<a
name="match.conditions.host_header"><code>#if host_header</code></a>
-- Match server's virtual hostname from client's HTTP Host header
</dt>
<dd>
<p>
The line:
</p>
<blockquote>
<code>
<!-- #if host_header =~ "regexp" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
contents of the HTTP "<code>Host:</code>" header supplied by the
client in its request.
</p>
<p>
Be aware that the character '<code>.</code>' (dot) has a special
meaning in regular expressions and must be escaped with a
'<code>\</code>' to have its usual meaning.
</p>
</dd>
<dt>
<a name="match.conditions.ip"><code>#if IP</code></a> -- Match
client's IP address
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if IP =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if IP file= "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the IP
address of the client (in the first case) or if the file
"<code>foo</code>" contains a matching regular expression (in the
second case). For an alternate method of doing this see the "<a
href="#match.control"><code>#if accessfile</code></a>" syntax
described below.
</p>
<p>
Be aware that the character '<code>.</code>' (dot) has a special
meaning in regular expressions and must be escaped with a
'<code>\</code>' to have its usual meaning.
</p>
</dd>
<dt>
<a name="match.conditions.language"><code>#if language</code></a>
-- Match client's <code>Accept-Language</code> headers
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if language =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if language file = "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if (in the first
case) the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches any of
the <code>Accept-Language</code> headers supplied by the client. Or
for the second line if the file "<code>foo</code>" contains a regular
expression matching any of the <code>Accept-Language</code> headers.
</p>
</dd>
<dt>
<a name="match.conditions.query"><code>#if query</code></a> --
Match query string supplied in request URL
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if query =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if query file = "foo" -->
</code>
</blockquote>
<p>
specifies that this text segment should be served if the UNIX
<code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
query string supplied by the client in the URL (in the first case) or
if the file "<code>foo</code>" contains a matching regular expression
(in the second case).
</p>
</dd>
<dt>
<a name="match.conditions.request"><code>#if request</code></a> --
Match client's request
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if request =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if request file = "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
contents of the full text of the request supplied by the client (in
the first case) or if the file "<code>foo</code>" contains a matching
regular expression (in the second case). The full request contains
the "method" (<code>GET</code> or <code>POST</code>) followed by the
URL requested with the "<code>http://host</code>" part having been
removed (by the client).
</p>
</dd>
<dt>
<a name="match.conditions.referer"><code>#if referer</code></a> --
Match client supplied <code>Referer:</code> header
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if referer =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if referer file = "foo" -->
</code>
</blockquote>
<p>
specify that this text segment should be served if the UNIX <code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
contents of the <code>Referer:</code> header supplied by the client
or if the file "<code>foo</code>" contains a matching regular
expression (in the second case). The <code>Referer:</code> header
contains the URL of the document containing the link accessed to
obtain the current document.
</p>
</dd>
<dt>
<a name="match.conditions.ua"><code>#if UA</code></a> -- Match
client's <code>User-Agent:</code> header
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #if UA =~ "regexp" -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #if UA file = "foo" -->
</code>
</blockquote>
<p>
specifies that this text segment should be served if the UNIX
<code><a
href="http://linux-howto.com/man/man1/grep.1.html">grep(1)</a></code>
utility like regular expression "<code>regexp</code>" matches the
<code>User-Agent:</code> header supplied by the client (in the first
case) or if the file "<code>foo</code>" contains a matching regular
expression (in the second case).
</p>
</dd>
<dt>
<a name="match.conditions.true"><code>#if true</code> and
<code>#if false</code></a> -- Include or exclude text segment
</dt>
<dd>
<p>
The line:
</p>
<blockquote>
<code>
<!-- #if false -->
</code>
</blockquote>
<p>
specifies that the corresponding text segment should not be served.
It may be useful for "commenting out" a part of a document which is
under construction. The "<code>#if true</code>" construct is
present for logical completeness.
</p>
</dd>
</dl>
<h4>C.1.2 <a name="match.control">Access Control Files</a></h4>
<p>
The normal <a href="access.html">access control files</a> used by
<em>WN</em> to limit access to a directory can also be used to
conditionally permit or deny access to text segments.
</p>
<dl>
<dt>
<a
name="match.control.accessfile"><code>#if accessfile="filename"</code></a>
-- Check access control file
</dt>
<dd>
<p>
The line:
</p>
<blockquote>
<code>
<!-- #if accessfile="/dir/accessfile" -->
</code>
</blockquote>
<p>
specifies that the file <code>/dir/accessfile</code> is to be used to
determine access privileges (by hostname or IP address) for this text
segment. The path <code>/dir/accessfile</code> is relative to the
server root directory. If this path does not begin with a
'<code>/</code>' then the path is relative to the directory
containing the file with this text. See the chapter "<a
href="access.html">Limiting Access to Your <em>WN</em> Hierarchy</a>"
in this guide.
</p>
</dd>
</dl>
<h3>C.2 <a name="insert">Inserting the Contents of a File</a></h3>
<dl>
<dt>
<a name="insert.include"><code>#include</code></a> -- Insert the
contents of a file
</dt>
<dd>
<p>
The line:
</p>
<blockquote>
<code>
<!-- #include -->
</code>
</blockquote>
<p>
specifies that the contents of next file listed in the <a
href="parse.html">includes or wrappers</a> should be inserted at this
point. It is permissible to add the name of this file, as in:
</p>
<blockquote>
<code>
<!-- #include foo.txt -->
</code>
</blockquote>
<p>
but this acts only as a comment. The actual file inserted depends
only on the "<code><a
href="appendixD.html#includes">Includes=</a></code>" and "<code><a
href="appendixD.html#wrappers">Wrappers=</a></code>" directives in
the <a href="index_desc.html#index"><code>index</code></a> file (or
more precisely the <code>index.cache</code> file created from it).
</p>
</dd>
<dt>
<a name="insert.section"><code>#section</code></a> -- Insert part of
the contents of a file
</dt>
<dd>
<p>
The line:
</p>
<blockquote>
<code>
<!-- #section -->
</code>
</blockquote>
<p>
specifies that part of the contents of next file listed in the <a
href="parse.html">includes or wrappers</a> should be inserted at this
point. It is permissible to add the name of this file, as in:
</p>
<blockquote>
<code>
<!-- #section foo.txt -->
</code>
</blockquote>
<p>
but this acts only as a comment. The actual file inserted depends
only on the "<code><a
href="appendixD.html#includes">Includes=</a></code>" and "<code><a
href="appendixD.html#wrappers">Wrappers=</a></code>" directives in
the <a href="index_desc.html#index"><code>index</code></a> file (or
more precisely the <code>index.cache</code> file created from it).
</p>
<p>
The part of the file actually included is that portion of the
document between the special comments
"<code><!-- #start --></code>" and
"<code><!-- #end --></code>" inserted in that
document. This requires that these starting and ending comments
occur in the HTML document on lines by themselves. For more
information see the section "<a href="parse.html#section">More on
Including: the <code>section</code> Marker</a>" in this guide.
</p>
</dd>
<dt>
<a name="insert.start"><code>#start</code> and <code>#end</code></a> --
Mark the beginning and end of text to be included
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #start -->
</code>
</blockquote>
<p>
and:
</p>
<blockquote>
<code>
<!-- #end -->
</code>
</blockquote>
<p>
mark the beginning and end of the portion of the text to be inserted
from an include or wrapper in response to encountering
"<code><!-- #section --></code>" in the text of a
document being parsed. There can be more than one
"<code>#start</code>/<code>#end</code>" pair in a document. For more
information see the section "<a href="parse.html#section">More on
Including: the <code>section</code> Marker</a>" in this guide.
</p>
</dd>
<dt>
<a name="insert.title"><code>#title</code>, <code>#query</code>, and
<code>#field</code></a> -- Insert the title, current search string, or
a user defined field
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #title -->
<br>
<!-- #query -->
</code>
</blockquote>
<p>
or:
</p>
<blockquote>
<code>
<!-- #field 3 -->
</code>
</blockquote>
<p>
in a parsed document instruct the server to include the title of the
current document, the current search term from the client or the
value of user defined "<code>field #3</code>" for the current
document. All of these markers must occur on a line by themselves.
For more information see the section "<a
href="parse.html#section">Including Title, Query, Fields and
Environment Variables</a>" in this guide.
</p>
</dd>
<dt>
<a name="insert.environ"><code>#environ</code></a> -- Insert the
contents of an environment variable
</dt>
<dd>
<p>
The lines:
</p>
<blockquote>
<code>
<!-- #environ = "WHATEVER" -->
</code>
</blockquote>
<p>
in a parsed document instructs the server to include the contents of
the environment variable <code>WHATEVER</code>. Remember to use an
"<code><a
href="appendixB.html#attributes.parse">Attributes=parse</a></code>"
line when using this construct and to use an "<code><a
href="appendixB.html#attributes.parse">Attributes=cgi</a></code>"
when it is a <a href="appendixD.html">CGI variable</a> like <a
href="appendixD.html#http_referer"><code>HTTP_REFERER</code></a>
which is to be included.
</p>
</dd>
</dl>
<h3><a name="redirect">Conditional Redirecting</a></h3>
<dl>
<dt>
<a name="redirect.redirect"><code>#redirect</code></a> -- Redirect to a
different URL
</dt>
<dd>
<p>
The line:
</p>
<blockquote>
<code>
<!-- #redirect = "url" -->
</code>
</blockquote>
<p>
specifies that if no text has yet been sent the server should send an
HTTP redirect to the given URL. This might be used as follows. If
the text:
</p>
<blockquote>
<code>
<!-- #if hostname =~ "\.uk$" -->
<br>
<!-- #redirect = "UK_mirror_url" -->
<br>
<!-- #endif -->
</code>
</blockquote>
<p>
is included at the beginning of an HTML document then any request
from a <code>uk</code> host will automatically be redirected to the
specified URL, the <code>UK_mirror_url</code> in this case. This
mechanism could also be used to redirect text only browsers to a text
only alternative page, etc.
</p>
<p>
There must be no text sent before the
'<code><!-- #redirect = "url" --></code>'
is encountered (not even blank lines) since the server cannot send an
HTTP redirect while in the middle of transmitting a document. Thus
the example above would be an error if there are any blank lines
before the "<code>#if hostname</code>" line or any blank lines
after it before the "<code>#redirect</code>" line. When such an
error occurs it is logged in the <a href="setup.html#logging">error
file</a> and the "<code>#redirect</code>" line is ignored.
</p>
<p>
Note however that:
</p>
<blockquote>
<code>
<!-- #if hostname =~ "\.uk$" -->
<br>
[Lots of text here]
<br>
<!-- #else -->
<br>
<!-- #redirect = "some_URL" -->
<br>
<!-- #endif -->
</code>
</blockquote>
<p>
is correct since when the <code>#redirect</code> line is encountered
no text has been sent.
</p>
<p>
Normally the URL in the
"<code><!-- #redirect = "URL" --></code>"
line is fully qualified, like "<code>http://host/path/foo</code>".
However, it can also be simply "<code>foo</code>" referring to a file
in the same directory as the file being parsed. In this case an HTTP
redirection is not sent, and instead the file "<code>foo</code>" is
returned immediately to the client.
</p>
</dd>
</dl>
<!-- #end -->
<hr size="4">
<address>
<em>WN</em> version 2.0.3
<br>
Copyright © 1998 <a href="mailto:john@math.nwu.edu">John Franks
<john@math.nwu.edu></a>
<br>
licensed under the <a href="http://www.opencontent.org/opl.html">
OpenContent Public License</a>
<br>
last-modified: Fri, 09 Oct 1998 18:18:09 GMT
</address>
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