If the patterns are all simple, one approach would be to represent each pattern as a list of atoms, and test whether a partial pattern can consume the buffer:

my @re= qw( [abc] b+ c );

my @tests = qw( a ab ba bb bbbbbcdef bbbbbbg );

TEST:
foreach my $buff ( @tests )
{
    my @tre = @re;
    my $tre = "";
    while (@tre > 1)
    {
        $tre .= shift @tre;
        if ( $buff =~ m/^$tre$/ )
        {
            print "Test string '$buff' matched partial pattern, $tre\n
+";
            next TEST;
        }
    }
    $tre .= shift @tre;
    if ( $buff =~ m/^$tre/ )
    {
        print "Test string '$buff' matched whole pattern, $tre\n";
    }
    else
    {
        print "Test string '$buff' did not match pattern $tre\n";
    }
}
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This method will fail if you use alternation, or atoms with a minumum length > 1, such as "a{5}".