Reputation: 1019
Perl Regular expression to insert string at specific places
I have the following piece of code:
#!/usr/bin/perl
use strict;
use warnings;
use URI qw( );
my @insert_words = qw( HELLO );
while (<DATA>) {
chomp;
my $url = URI->new($_);
my $path = $url->path();
for (@insert_words) {
# Use package vars to communicate with /(?{})/ blocks.
my $insert_word = $_;
local our @paths;
$path =~ m{
^(.*/)([^/]*)((?:/.*)?)\z
(?{
push @paths, "$1$insert_word$2$3";
if (length($2)) {
push @paths, "$1$insert_word$3";
push @paths, "$1$2$insert_word$3";
}
})
(?!)
}x;
for (@paths) {
$url->path($_);
print "$url\n";
}
}
}
__DATA__
http://www.bagandboxfactory.com/index.php?route=checkout/
http://www.stackoverflow.com/dog/cat/rabbit/
http://www.superuser.co.uk/dog/cat/rabbit/hamster/
At the moment the above piece of code works perfectly for the stackoverflow and superuser urls in __DATA__. It gives the following output for the stackoverflow url:
http://www.stackoverflow.com/dog/cat/rabbit/HELLO
http://www.stackoverflow.com/dog/cat/HELLOrabbit/
http://www.stackoverflow.com/dog/cat/HELLO/
http://www.stackoverflow.com/dog/cat/rabbitHELLO/
http://www.stackoverflow.com/dog/HELLOcat/rabbit/
http://www.stackoverflow.com/dog/HELLO/rabbit/
http://www.stackoverflow.com/dog/catHELLO/rabbit/
http://www.stackoverflow.com/HELLOdog/cat/rabbit/
http://www.stackoverflow.com/HELLO/cat/rabbit/
http://www.stackoverflow.com/dogHELLO/cat/rabbit/
As you can see it inserts the string HELLO at specific places when it comes across a slash (/).
The problem I am having:
I want the same thing to happen when an equals sign (=) is found in the url.
Using http://www.bagandboxfactory.com/index.php?route=checkout as an example, I want the output to give me the following:
http://www.bagandboxfactory.com/index.php?route=HELLOcheckout/ <- puts HELLO before the string after the equals
http://www.bagandboxfactory.com/index.php?route=HELLO/ <- replaces the string after the equals with HELLO
http://www.bagandboxfactory.com/index.php?route=checkoutHELLO/ <- puts HELLO after the string that is after the equals
I thought that changing the regular expression from
^(.*/)([^/]*)((?:/.*)?)\z
to
^(.*[/=])([^/=]*)((?:[/=].*)?)\z would work but it does not.
What would I need to change to the regular expression to make it do this?
Your help is much appreciated, many thanks
__UPDATE___
It needs to be able to handle multiple parameters, for example if I had the url http://www.example.com/dog/cat=2&foo=5 the output I should get is as follows:
http://www.example.com/HELLOdog/cat=2&foo=5
http://www.example.com/HELLO/cat=2&foo=5
http://www.example.com/dogHELLO/cat=2&foo=5
http://www.example.com/dog/cat=HELLO2&foo=5
http://www.example.com/dog/cat=HELLO&foo=5
http://www.example.com/dog/cat=2HELLO&foo=5
http://www.example.com/dog/cat=2&foo=HELLO5
http://www.example.com/dog/cat=2&foo=HELLO
http://www.example.com/dog/cat=2&foo=5HELLO
The code I already have works correctly and does this for every slash it comes across in the url, but I now want it to do it when it comes across an = in the url as well (or any other character I choose to specify in the regex e.g [/=@-]).
Upvotes: 1
Views: 313
Answers (1)
Reputation: 139661
Putting the regex engine to work to perform the backtracking for you is a clever technique.
The main problem is the part after a question mark is the query, available through $url->query. $url->path returns the path component without the query.
Modifying your code to
#!/usr/bin/perl
use strict;
use warnings;
use URI qw( );
my @insert_words = qw( HELLO );
while (<DATA>) {
chomp;
my $url = URI->new($_);
my $path = $url->path();
my $query = $url->query;
for (@insert_words) {
# Use package vars to communicate with /(?{})/ blocks.
my $insert_word = $_;
local our @paths;
$path =~ m{
^(.*/)([^/]*)((?:/.*)?)\z
(?{
push @paths, "$1$insert_word$2$3";
if (length($2)) {
push @paths, "$1$insert_word$3";
push @paths, "$1$2$insert_word$3";
}
})
(?!)
}x;
local our @queries;
if (defined $query) {
$query =~ m{
^(.*[/=])([^/=&]*)((?:[/=&].*)?)\z
(?{
if (length $2) {
push @queries, "$1$insert_word$2$3";
push @queries, "$1$insert_word$3";
push @queries, "$1$2$insert_word$3";
}
})
(?!)
}x;
}
for (@paths) {
$url->path($_);
if (@queries) {
for (@queries) {
$url->query($_);
print $url, "\n";
}
}
else {
print $url, "\n";
}
}
}
}
__DATA__
http://www.bagandboxfactory.com/index.php?route=checkout/
http://www.stackoverflow.com/dog/cat/rabbit/
http://www.superuser.co.uk/dog/cat/rabbit/hamster/
http://www.example.com/index.php?route=9&other=7/
gives the following output. The logic for query replacements is slightly different because it would append each @insert_words after the trailing slash in the query, if present.
http://www.bagandboxfactory.com/HELLOindex.php?route=HELLOcheckout/ http://www.bagandboxfactory.com/HELLOindex.php?route=HELLO/ http://www.bagandboxfactory.com/HELLOindex.php?route=checkoutHELLO/ http://www.bagandboxfactory.com/HELLO?route=HELLOcheckout/ http://www.bagandboxfactory.com/HELLO?route=HELLO/ http://www.bagandboxfactory.com/HELLO?route=checkoutHELLO/ http://www.bagandboxfactory.com/index.phpHELLO?route=HELLOcheckout/ http://www.bagandboxfactory.com/index.phpHELLO?route=HELLO/ http://www.bagandboxfactory.com/index.phpHELLO?route=checkoutHELLO/ http://www.stackoverflow.com/dog/cat/rabbit/HELLO http://www.stackoverflow.com/dog/cat/HELLOrabbit/ http://www.stackoverflow.com/dog/cat/HELLO/ http://www.stackoverflow.com/dog/cat/rabbitHELLO/ http://www.stackoverflow.com/dog/HELLOcat/rabbit/ http://www.stackoverflow.com/dog/HELLO/rabbit/ http://www.stackoverflow.com/dog/catHELLO/rabbit/ http://www.stackoverflow.com/HELLOdog/cat/rabbit/ http://www.stackoverflow.com/HELLO/cat/rabbit/ http://www.stackoverflow.com/dogHELLO/cat/rabbit/ http://www.superuser.co.uk/dog/cat/rabbit/hamster/HELLO http://www.superuser.co.uk/dog/cat/rabbit/HELLOhamster/ http://www.superuser.co.uk/dog/cat/rabbit/HELLO/ http://www.superuser.co.uk/dog/cat/rabbit/hamsterHELLO/ http://www.superuser.co.uk/dog/cat/HELLOrabbit/hamster/ http://www.superuser.co.uk/dog/cat/HELLO/hamster/ http://www.superuser.co.uk/dog/cat/rabbitHELLO/hamster/ http://www.superuser.co.uk/dog/HELLOcat/rabbit/hamster/ http://www.superuser.co.uk/dog/HELLO/rabbit/hamster/ http://www.superuser.co.uk/dog/catHELLO/rabbit/hamster/ http://www.superuser.co.uk/HELLOdog/cat/rabbit/hamster/ http://www.superuser.co.uk/HELLO/cat/rabbit/hamster/ http://www.superuser.co.uk/dogHELLO/cat/rabbit/hamster/ http://www.example.com/HELLOindex.php?route=9&other=HELLO7/ http://www.example.com/HELLOindex.php?route=9&other=HELLO/ http://www.example.com/HELLOindex.php?route=9&other=7HELLO/ http://www.example.com/HELLOindex.php?route=HELLO9&other=7/ http://www.example.com/HELLOindex.php?route=HELLO&other=7/ http://www.example.com/HELLOindex.php?route=9HELLO&other=7/ http://www.example.com/HELLO?route=9&other=HELLO7/ http://www.example.com/HELLO?route=9&other=HELLO/ http://www.example.com/HELLO?route=9&other=7HELLO/ http://www.example.com/HELLO?route=HELLO9&other=7/ http://www.example.com/HELLO?route=HELLO&other=7/ http://www.example.com/HELLO?route=9HELLO&other=7/ http://www.example.com/index.phpHELLO?route=9&other=HELLO7/ http://www.example.com/index.phpHELLO?route=9&other=HELLO/ http://www.example.com/index.phpHELLO?route=9&other=7HELLO/ http://www.example.com/index.phpHELLO?route=HELLO9&other=7/ http://www.example.com/index.phpHELLO?route=HELLO&other=7/ http://www.example.com/index.phpHELLO?route=9HELLO&other=7/
Upvotes: 1
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