#!/usr/bin/env perl 
use strict;
use warnings;
my $ls = '';

my $str2 = "(schema1.table1(ratio:1.2-1.5))
union(column)
(schema2.table2(ratio:1.3-1.6))
union(column)
(schema3.table3(ratio:1.4-1.8))
";


my $re = '
  ^
    [\s\n]*

    # group 1
    (
        [(]
            ([\w]+)            # schema name
            [.]
            ([\w]+)            # table name
            (?:
                 [(] 
                      ( ratio | unique )           # condition
                      [:=]
                      ([\d.]+)
                      (?:-([\d.]+) )?
                 [)] 
            )
        [)]
        [\n]
    )
  
    (?:

          (?: ( union | intersect | except | minus ) )
          [(]
                ([\w]+)
          [)]
          [\n]

    (
        [(]
            ([\w]+)            # schema name
            [.]
            ([\w]+)            # table name
            (?:
                 [(] 
                      ( ratio | unique )           # condition
                      [:=]
                      ([\d.]+)
                      (?:-([\d.]+) )?
                 [)] 
            )
        [)]
        [\n]
    )
#         \g{1}

    )+

#   [\n*]*

  $

';

for my $s ($str2) {
  if ($s =~ m/${re}/xsm) {
    for (my$i=0;$i<scalar(@-);$i++) {
      $ls .= "-- $i:   [" . $+[$i] ."]    [" . substr($s, $-[$i], $+[$i]  - $-[$i] ) . "]\n";
    }
    print $ls, "\n";
  }
  else {
    print "-- no match\n";
  }
  print "\n";
  print ">>>", $s, "<<<\n";
}


# captured output:
-- 0:   [124]    [(schema1.table1(ratio:1.2-1.5))
union(column)
(schema2.table2(ratio:1.3-1.6))
union(column)
(schema3.table3(ratio:1.4-1.8))
]
-- 1:   [32]    [(schema1.table1(ratio:1.2-1.5))
]
-- 2:   [8]    [schema1]
-- 3:   [15]    [table1]
-- 4:   [21]    [ratio]
-- 5:   [25]    [1.2]
-- 6:   [29]    [1.5]
-- 7:   [83]    [union]
-- 8:   [90]    [column]
-- 9:   [124]    [(schema3.table3(ratio:1.4-1.8))
]
-- 10:   [100]    [schema3]
-- 11:   [107]    [table3]
-- 12:   [113]    [ratio]
-- 13:   [117]    [1.4]
-- 14:   [121]    [1.8]

# note: schema2 and its detail is missing