Can I substitute multiple items in a single regular expression in VIM or Perl?

Question

Let's say I have string "The quick brown fox jumps over the lazy dog" can I change this to "The slow brown fox jumps over the energetic dog" with one regular expression? Currently, I use two sets of regular expressions for this situation. (In this case, I use s/quick/slow/ followed by s/lazy/energetic/.)

thanks.

Answer 1

You can do the following.

:%s/quick\(.*\)lazy/slow\1energetic

The trick is to use the parens to match the text between the two words. You can then reference this text in the substitution string by using \1. You can also use \2 for the second matched paren expression and so on. This allows you to replace multiple words without disturbing the text inbetween.

Answer 2

The second part of a substitution is a double quoted string, so any normal interpolation can occur. This means you can use the value of the capture to index into a hash:

#!/usr/bin/perl

use strict;
use warnings;


my %replace = (
    quick => "slow",
    lazy  => "energetic",
);

my $regex = join "|", keys %replace;
$regex = qr/$regex/;

my $s = "The quick brown fox jumps over the lazy dog";

$s =~ s/($regex)/$replace{$1}/g;

print "$s\n";

Answer 3

In perl:

s/quick(.*)lazy/slow${1}energetic/;

In vim:

s/quick\(.*\)lazy/slow\1energetic/;

Answer 4

There's a neat way to do it in Ruby using gsub with a block:

s = "The quick brown fox jumps over the lazy dog"
subs = {'quick' => 'slow', 'lazy' => 'industrious'}
s.gsub(/quick|lazy/) { |match| subs[match] }
# => "The slow brown fox jumps over the industrious dog"

Answer 5

Use this solution.

Answer 6

Chas's answer is good, the only other thing I'd mention is that if you're doing word swaps you probably want to be matching on

\b(foo|bar|baz|qux)\b

to avoid matching substrings. If you doing a lot of word swapping, you might start to find regexps a bit limiting and want to do something like:

join '', map { exists $subst{$_} ? $subst{$_} : $_ } split /\b/, $string