01-10-2008
'c-->0;$0~s{if(b)for(c=b+1;c>1;c--)print r[(NR-c+1)%b];print;c=a}b{r[NR%b]=$0}'
has 3 pattern-action statements:
1) c-->0;
2) $0~s{if(b)for(c=b+1;c>1;c--)print r[(NR-c+1)%b];print;c=a}
3) b{r[NR%b]=$0}
The first one has no explicit action so the action is to simply print the entire record. But in this case the semicolon is needed so that it doesn't run in to the second staement. The second statement has an explicit action which is in braces and the braces are enough to separate it from the third. Now consider these statements in reverse order...
3) b{r[NR%b]=$0}
The pattern is b, which is asking if b is equal to zero. If b is non-zero we need to save records in case we need them later. But if b is zero, we can skip this since we do not want any "before" records displayed. If b is, say, 5, we will always have the last 5 records in the r array.
2) $0~s{if(b)for(c=b+1;c>1;c--)print r[(NR-c+1)%b];print;c=a}
The pattern $0~s simply asks if the record matches the search criteria we stored in s. If so and if b is non-zero, we print those records that we saved in step 3 above. Then we print the current record. Then c=a sets up the next step to be explained...
1) c-->0;
c gets set to a (number of "after" records) when we find a match. The c-- part decrements c after we use it. And we use it to see if it is greater than zero. This is how the "after" records are printed.
Last edited by Perderabo; 01-17-2008 at 08:34 AM..
Reason: fix some typos
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LEARN ABOUT DEBIAN
sru::response::searchretrieve
SRU::Response::SearchRetrieve(3pm) User Contributed Perl Documentation SRU::Response::SearchRetrieve(3pm)
NAME
SRU::Response::SearchRetrieve - A class for representing SRU searchRetrieve responses
SYNOPSIS
## create response from the request object
my $response = SRU::Response::SearchRetrieve->new( $request );
## add records to the response
foreach my $record ( @records ) { $response->addRecord( $record ); }
## print out the response as XML
print $response->asXML();
DESCRIPTION
SRU::Response::SearchRetrieve provides a framework for bundling up the response to a searchRetrieve request. You are responsible for
generating the XML representation of the records, and the rest should be taken care of.
METHODS
new()
numberOfRecords()
Returns the number of results associated with the object.
addRecord()
Add a SRU::Response::Record object to the response.
$response->addRecord( $r );
If you don't pass in the right sort of object you'll get back undef and $SRU::Error will be populated appropriately.
records()
Gets or sets all the records associated with the object. Be careful with this one :) You must pass in an array ref, and expect an array ref
back.
resultSetId()
resultSetIdleTime()
nextRecordPosition()
diagnostics()
extraResponseData()
echoedSearchRetrieveRequest()
asXML()
asXML(encoding=>"ISO-8859-1")
Returns the object serialized as XML. UTF-8 and UTF-16 are default encodings if you don't pass the encoding parameter. You can define
different encoding in order to parse you XML document correctly.
perl v5.12.4 2009-11-20 SRU::Response::SearchRetrieve(3pm)