use Text::Balanced qw(extract_codeblock);

# get source code in this variable
my $source = ....;

# regexp finds where method is defined and sets "pos" (see perldoc -f 
+pos),
# than extract_codeblock extracts following codeblock
if($source =~ /public \s+ void \s+ readExternal \s+ \( .*? \) \s+ /gx)
+ {
    my $sub_source = extract_codeblock($source);
    print $sub_source;
}
[download]

--
Ilya Martynov, ilya@iponweb.net
CTO IPonWEB (UK) Ltd
Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net
Personal website - http://martynov.org

Although counting curlies might succeed quite foten, it will fail if you somehwre have a string constant containing a an unbalanced curly or acomment.

public void readExternal () {
    ... '}' /* this } is NOT the end as well */
}
[download]

So it seems you can't get around a basic tokenizer that can differenciate code curlies from string-constant curlies. At least Java syntax is not as hard to parse as Perl, the only way to create a place where a curly does not close a block is in "" and '', after // and between /* and */, there's no qq,q,qr,qw or s///,m//,tr/// ....

A quick solution (demonstrating only basic functionaility):

use Regexp::Common;

local $_ = join '',<>;

my $code = '';
my $curlies = 1; #one curly open

while( m# \G ( [^{}'"/]* ) #xg ){

        $code .= $1;

        my $p = pos;

        # '' + ""
        if( m# \G ( $RE{quoted} ) #xg ){

                $code .= $1;
                next;
        }

        pos = $p;

        # /* */
        if( m# \G ( $RE{balanced}{-begin=>'/*'}{-end=>'*/'} ) #xg ){

                $code .= $1;
                next;
        }

        pos = $p;

        #//

        if( m# \G ( // [^\n]* ) #xg ){

                $code .= $1;
                next;
        }

        pos = $p;

        # {
        if( m# \G \{ #xg ){

                $code .= '{';
                ++ $curlies;
                next;
        }

        pos = $p;

        # }
        if( m# \G \} #xg ){

                $code .= '}';
                -- $curlies;

                last unless $curlies;
                next;
        }

        pos = $p;

        m# \G ( . ) #sxg or last;

        $code .= $1;
}
print "CODE\n$code\n";
[download]

he only way to end the search is to use the ultimate closeing brace. Perhaps using increment and decrement on 1st open and last close braces?

You could use a recursive regex. Easiest way to get one is Regexp::Common.

use Regexp::Common;

$_ = q{
    public void readExternal() {
        this { is } not {
            { real } java
        } code but an {
            {
                { example }
            }
        }
    }
};

my ($function) =
    /( public \s+ void \s+ readExternal [^{]+ $RE{balanced}{-parens=>'
+{}'} )/x;
[download]

- Yes, I reinvent wheels.
- Spam: Visit eurotraQ.

Or try Text::Balanced