How to use regex to match elements not followed by...?

How can I match this string?

${test {0}}

I need to match everything between ${ and } w开发者_StackOverflow中文版here } is not preceded by a number, so I can retrieve test {0}.

Is it possible to match with a regex pattern alone?

Samples:

${any string}              == any string
${string - {x}             == string - {x
${{0} a}                   == {0} a
${a {1} b {3} c {2} d {0}} == a {1} b {3} c {2} d {0}

You can ensure such a criteria using a negative look behind like this

\$\{(.*)(?<!\d)\}

You can see it online here on Regexr.

Your string is in group 1.

The negative lookahead ensures that it matches only on a } that is not preceded by a digit.

This works for your test case, but you need to be more clear about how the data you need to capture could vary if you want a better general regex

The regex:

/\${(.*[^0-9])}/

In Javascript:

alert( "${test {0}}".match( /\${(.*[^0-9])}/ )[1] )

(Edited following up on your examples...) Like so:

/\$\{((?:.+?|\{\d+\})+?)\}/

Expect gargantuan backtracking, though...

How about : /\$\{(.*)\}/

Here is a perl script that do the job with the given examples :

#!/usr/bin/perl 
use Modern::Perl;

my @l = ('${any string}','${string - {x}','${{0} a}','${a {1} b {3} c {2} d {0}}');
my $re = qr/\$\{(.*)\}/;
foreach(@l) {
  say $1 if $_ =~ $re;
}

output:

any string
string - {x
{0} a
a {1} b {3} c {2} d {0}

Not sure which in which language you need this solution but following works for me in PHP:

$arr = array('${test {0}}', '${any string}', '${string - {x}', '${{0} a}', '${a {1} b {3} c {2} d {0}}');
foreach ($arr as $s) {
   if (preg_match('~\$\{(.+?[^\d])}~', $s, $m ) > 0)
       var_dump($s . ' == ' . $m[1]);
}

OUTPUT

string(23) "${test {0}} == test {0}"
string(27) "${any string} == any string"
string(29) "${string - {x} == string - {x"
string(17) "${{0} a} == {0} a"
string(53) "${a {1} b {3} c {2} d {0}} == a {1} b {3} c {2} d {0}"

(?<={)([^{}]*({\d+})*[^{}]*)+(?=})

It has been tested with RAD Software Regular Expression Designer.. This regex works for .NET and java environment..

You should use this regex for Javascript..

{([^{}]*({\d+})*[^{}]*)+}