stas 2002/06/19 12:24:42
Modified: src/docs/2.0/user/handlers handlers.pod
Log:
add PerlOutputFilterHandler example
Revision Changes Path
1.2 +75 -11 modperl-docs/src/docs/2.0/user/handlers/handlers.pod
Index: handlers.pod
===================================================================
RCS file: /home/cvs/modperl-docs/src/docs/2.0/user/handlers/handlers.pod,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- handlers.pod 15 Jun 2002 18:26:33 -0000 1.1
+++ handlers.pod 19 Jun 2002 19:24:42 -0000 1.2
@@ -483,27 +483,91 @@
=head2 PerlOutputFilterHandler
-This handler registers an stream-orientered output filter (i.e. it
-works with the response stream). To actually use it the core
-C<AddOutputFilter> directive must be used.
+This handler registers and configures a stream-orientered output
+filter (i.e. it works with the response stream).
This handler is of type C<VOID>.
The handler's configuration scope is C<DIR>.
-Example:
-
-In this example the output filter C<Apache::ReverseFilter>
-
-The following filter reverts XXX
+The output filter in the following example reverses every line of the
+response, preserving the new line characters in their places:
+ file:httpd.conf
+ ---------------
+ PerlModule Apache::ReverseFilter
<Location /reverse>
SetHandler modperl
- PerlOutputFilterHandler TestFilter::reverse
- PerlResponseHandler TestFilter::reverse::response
+ PerlOutputFilterHandler Apache::ReverseFilter::output_filter
+ PerlResponseHandler Apache::ReverseFilter::response
</Location>
-
+ file:Apache/ReverseFilter.pm
+ ----------------------------
+ package Apache::ReverseFilter;
+
+ use strict;
+ use warnings FATAL => 'all';
+
+ use Apache::RequestRec ();
+ use Apache::RequestIO ();
+ use Apache::Filter ();
+
+ use Apache::Const -compile => qw(OK);
+
+ my $clrf = qr/[\r\n]+/;
+
+ sub output_filter {
+ my $filter = shift;
+
+ my $left_over = '';
+ while ($filter->read(my $buffer, 2)) {
+ $buffer = $left_over . $buffer;
+ $left_over = '';
+ while ($buffer =~ /([^\r\n]*)([\r\n]*)/g) {
+ $left_over = $1, last unless $2;
+ $filter->print(scalar(reverse $1), $2);
+ }
+ }
+ $filter->print(scalar reverse $left_over) if length $left_over;
+
+ Apache::OK;
+ }
+
+ sub response {
+ my $r = shift;
+
+ $r->content_type('text/plain');
+ $r->puts(1..9, "0\n");
+ $r->puts('a'..'z', "\n");
+
+ Apache::OK;
+ }
+ 1;
+
+
+In this example when a request to I</reverse> is made, the response
+handler C<Apache::ReverseFilter::response()> sends:
+
+ 1234567890
+ abcdefghijklmnopqrstuvwxyz
+
+as a response and the output filter handler
+C<Apache::ReverseFilter::output_filter> reverses the lines, so the
+client gets:
+
+ 0987654321
+ zyxwvutsrqponmlkjihgfedcba
+
+The reversing filter is quite simple: it reads from the output stream
+in chunks of 1024 characters, and then prints all lines reversed
+preserving the new line control characters at the end of each
+line. The special handling of new lines is needed for cases where an
+input line is longer than the buffer size, (1024 in our example), when
+this happens we store the reminder of the string in C<$left_over> and
+prepend it to the buffer when the next chunk is read. At the end we
+print out the reminder of the input when there is no more data left on
+the stream.
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