comment on

Thanks, Anonymous Monk ...

The regex debug output does indeed provide lots of feedback ... a look right into the inner workings of the regex engine. I have to admit, however, I am not sure how this information contributes to solving my initial problem - apart, maybe, from the fact that it only contains one Compiling RExstatement statement - contrary to my initial belief that the regex would get compiled anew on each loop-iteration.

Let me know if I am overlooking anything here:
Compiling REx `(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+'
size 25 Got 204 bytes for offset annotations.
first at 5
   1: CURLYX[0] {1,32767}(12)
   3:   OPEN1(5)
   5:     EXACT <a>(7)
   7:     EVAL(9)
   9:   CLOSE1(11)
  11:   WHILEM[1/2](0)
  12: NOTHING(13)
  13: CURLYX[1] {1,32767}(24)
  15:   OPEN2(17)
  17:     EXACT <b>(19)
  19:     EVAL(21)
  21:   CLOSE2(23)
  23:   WHILEM[2/2](0)
  24: NOTHING(25)
  25: END(0)
anchored "a" at 0 floating "ab" at 0..2147483647 (checking floating) m
+inlen 2 with eval 
Offsets: [25]
    23[1] 0[0] 1[1] 0[0] 2[1] 0[0] 3[19] 0[0] 22[1] 0[0] 23[0] 23[0] 4
+6[1] 0[0] 24[1] 0[0] 25[1] 0[0] 26[19] 0[0] 45[1] 0[0] 46[0] 46[0] 47
+[0] 
Guessing start of match, REx "(a(?{$a_counter ++;}))+(b(?{$b_counter +
++;}))+" against "aaabbbb"...
Found floating substr "ab" at offset 2...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+" against 
+"aaabbbb"
  Setting an EVAL scope, savestack=28
   0 <> <aaabbbb>         |  1:  CURLYX[0] {1,32767}
   0 <> <aaabbbb>         | 11:    WHILEM[1/2]
                              0 out of 1..32767  cc=140f960
   0 <> <aaabbbb>         |  3:      OPEN1
   0 <> <aaabbbb>         |  5:      EXACT <a>
   1 <a> <aabbbb>         |  7:      EVAL
  re_eval 0x18472a4
   1 <a> <aabbbb>         |  9:      CLOSE1
   1 <a> <aabbbb>         | 11:      WHILEM[1/2]
                                1 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=41
   1 <a> <aabbbb>         |  3:        OPEN1
   1 <a> <aabbbb>         |  5:        EXACT <a>
   2 <aa> <abbbb>         |  7:        EVAL
  re_eval 0x18472a4
   2 <aa> <abbbb>         |  9:        CLOSE1
   2 <aa> <abbbb>         | 11:        WHILEM[1/2]
                                  2 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=54
   2 <aa> <abbbb>         |  3:          OPEN1
   2 <aa> <abbbb>         |  5:          EXACT <a>
   3 <aaa> <bbbb>         |  7:          EVAL
  re_eval 0x18472a4
   3 <aaa> <bbbb>         |  9:          CLOSE1
   3 <aaa> <bbbb>         | 11:          WHILEM[1/2]
                                    3 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=67
   3 <aaa> <bbbb>         |  3:            OPEN1
   3 <aaa> <bbbb>         |  5:            EXACT <a>
                                      failed...
     restoring \1 to 2(2)..3
     restoring \2..\2 to undef
                                    failed, try continuation...
   3 <aaa> <bbbb>         | 12:            NOTHING
   3 <aaa> <bbbb>         | 13:            CURLYX[1] {1,32767}
   3 <aaa> <bbbb>         | 23:              WHILEM[2/2]
                                        0 out of 1..32767  cc=140f384
   3 <aaa> <bbbb>         | 15:                OPEN2
   3 <aaa> <bbbb>         | 17:                EXACT <b>
   4 <aaab> <bbb>         | 19:                EVAL
  re_eval 0x18471e8
   4 <aaab> <bbb>         | 21:                CLOSE2
   4 <aaab> <bbb>         | 23:                WHILEM[2/2]
                                          1 out of 1..32767  cc=140f38
+4
  Setting an EVAL scope, savestack=70
   4 <aaab> <bbb>         | 15:                  OPEN2
   4 <aaab> <bbb>         | 17:                  EXACT <b>
   5 <aaabb> <bb>         | 19:                  EVAL
  re_eval 0x18471e8
   5 <aaabb> <bb>         | 21:                  CLOSE2
   5 <aaabb> <bb>         | 23:                  WHILEM[2/2]
                                            2 out of 1..32767  cc=140f
+384
  Setting an EVAL scope, savestack=83
   5 <aaabb> <bb>         | 15:                    OPEN2
   5 <aaabb> <bb>         | 17:                    EXACT <b>
   6 <aaabbb> <b>         | 19:                    EVAL
  re_eval 0x18471e8
   6 <aaabbb> <b>         | 21:                    CLOSE2
   6 <aaabbb> <b>         | 23:                    WHILEM[2/2]
                                              3 out of 1..32767  cc=14
+0f384
  Setting an EVAL scope, savestack=96
   6 <aaabbb> <b>         | 15:                      OPEN2
   6 <aaabbb> <b>         | 17:                      EXACT <b>
   7 <aaabbbb> <>         | 19:                      EVAL
  re_eval 0x18471e8
   7 <aaabbbb> <>         | 21:                      CLOSE2
   7 <aaabbbb> <>         | 23:                      WHILEM[2/2]
                                                4 out of 1..32767  cc=
+140f384
  Setting an EVAL scope, savestack=109
   7 <aaabbbb> <>         | 15:                        OPEN2
   7 <aaabbbb> <>         | 17:                        EXACT <b>
                                                  failed...
     restoring \2 to 6(6)..7
                                                failed, try continuati
+on...
   7 <aaabbbb> <>         | 24:                        NOTHING
   7 <aaabbbb> <>         | 25:                        END
Match successful!
Guessing start of match, REx "(a(?{$a_counter ++;}))+(b(?{$b_counter +
++;}))+" against "ab"...
Found floating substr "ab" at offset 0...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+" against 
+"ab"
  Setting an EVAL scope, savestack=28
   0 <> <ab>              |  1:  CURLYX[0] {1,32767}
   0 <> <ab>              | 11:    WHILEM[1/2]
                              0 out of 1..32767  cc=140f960
   0 <> <ab>              |  3:      OPEN1
   0 <> <ab>              |  5:      EXACT <a>
   1 <a> <b>              |  7:      EVAL
  re_eval 0x18472a4
   1 <a> <b>              |  9:      CLOSE1
   1 <a> <b>              | 11:      WHILEM[1/2]
                                1 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=41
   1 <a> <b>              |  3:        OPEN1
   1 <a> <b>              |  5:        EXACT <a>
                                  failed...
     restoring \1 to 0(0)..1
     restoring \2..\2 to undef
                                failed, try continuation...
   1 <a> <b>              | 12:        NOTHING
   1 <a> <b>              | 13:        CURLYX[1] {1,32767}
   1 <a> <b>              | 23:          WHILEM[2/2]
                                    0 out of 1..32767  cc=140f5dc
   1 <a> <b>              | 15:            OPEN2
   1 <a> <b>              | 17:            EXACT <b>
   2 <ab> <>              | 19:            EVAL
  re_eval 0x18471e8
   2 <ab> <>              | 21:            CLOSE2
   2 <ab> <>              | 23:            WHILEM[2/2]
                                      1 out of 1..32767  cc=140f5dc
  Setting an EVAL scope, savestack=44
   2 <ab> <>              | 15:              OPEN2
   2 <ab> <>              | 17:              EXACT <b>
                                        failed...
     restoring \2 to 1(1)..2
                                      failed, try continuation...
   2 <ab> <>              | 24:              NOTHING
   2 <ab> <>              | 25:              END
Match successful!
Guessing start of match, REx "(a(?{$a_counter ++;}))+(b(?{$b_counter +
++;}))+" against "abb"...
Found floating substr "ab" at offset 0...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+" against 
+"abb"
  Setting an EVAL scope, savestack=28
   0 <> <abb>             |  1:  CURLYX[0] {1,32767}
   0 <> <abb>             | 11:    WHILEM[1/2]
                              0 out of 1..32767  cc=140f960
   0 <> <abb>             |  3:      OPEN1
   0 <> <abb>             |  5:      EXACT <a>
   1 <a> <bb>             |  7:      EVAL
  re_eval 0x18472a4
   1 <a> <bb>             |  9:      CLOSE1
   1 <a> <bb>             | 11:      WHILEM[1/2]
                                1 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=41
   1 <a> <bb>             |  3:        OPEN1
   1 <a> <bb>             |  5:        EXACT <a>
                                  failed...
     restoring \1 to 0(0)..1
     restoring \2..\2 to undef
                                failed, try continuation...
   1 <a> <bb>             | 12:        NOTHING
   1 <a> <bb>             | 13:        CURLYX[1] {1,32767}
   1 <a> <bb>             | 23:          WHILEM[2/2]
                                    0 out of 1..32767  cc=140f5dc
   1 <a> <bb>             | 15:            OPEN2
   1 <a> <bb>             | 17:            EXACT <b>
   2 <ab> <b>             | 19:            EVAL
  re_eval 0x18471e8
   2 <ab> <b>             | 21:            CLOSE2
   2 <ab> <b>             | 23:            WHILEM[2/2]
                                      1 out of 1..32767  cc=140f5dc
  Setting an EVAL scope, savestack=44
   2 <ab> <b>             | 15:              OPEN2
   2 <ab> <b>             | 17:              EXACT <b>
   3 <abb> <>             | 19:              EVAL
  re_eval 0x18471e8
   3 <abb> <>             | 21:              CLOSE2
   3 <abb> <>             | 23:              WHILEM[2/2]
                                        2 out of 1..32767  cc=140f5dc
  Setting an EVAL scope, savestack=57
   3 <abb> <>             | 15:                OPEN2
   3 <abb> <>             | 17:                EXACT <b>
                                          failed...
     restoring \2 to 2(2)..3
                                        failed, try continuation...
   3 <abb> <>             | 24:                NOTHING
   3 <abb> <>             | 25:                END
Match successful!
Guessing start of match, REx "(a(?{$a_counter ++;}))+(b(?{$b_counter +
++;}))+" against "aabb"...
Found floating substr "ab" at offset 1...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+" against 
+"aabb"
  Setting an EVAL scope, savestack=28
   0 <> <aabb>            |  1:  CURLYX[0] {1,32767}
   0 <> <aabb>            | 11:    WHILEM[1/2]
                              0 out of 1..32767  cc=140f960
   0 <> <aabb>            |  3:      OPEN1
   0 <> <aabb>            |  5:      EXACT <a>
   1 <a> <abb>            |  7:      EVAL
  re_eval 0x18472a4
   1 <a> <abb>            |  9:      CLOSE1
   1 <a> <abb>            | 11:      WHILEM[1/2]
                                1 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=41
   1 <a> <abb>            |  3:        OPEN1
   1 <a> <abb>            |  5:        EXACT <a>
   2 <aa> <bb>            |  7:        EVAL
  re_eval 0x18472a4
   2 <aa> <bb>            |  9:        CLOSE1
   2 <aa> <bb>            | 11:        WHILEM[1/2]
                                  2 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=54
   2 <aa> <bb>            |  3:          OPEN1
   2 <aa> <bb>            |  5:          EXACT <a>
                                    failed...
     restoring \1 to 1(1)..2
     restoring \2..\2 to undef
                                  failed, try continuation...
   2 <aa> <bb>            | 12:          NOTHING
   2 <aa> <bb>            | 13:          CURLYX[1] {1,32767}
   2 <aa> <bb>            | 23:            WHILEM[2/2]
                                      0 out of 1..32767  cc=140f4b0
   2 <aa> <bb>            | 15:              OPEN2
   2 <aa> <bb>            | 17:              EXACT <b>
   3 <aab> <b>            | 19:              EVAL
  re_eval 0x18471e8
   3 <aab> <b>            | 21:              CLOSE2
   3 <aab> <b>            | 23:              WHILEM[2/2]
                                        1 out of 1..32767  cc=140f4b0
  Setting an EVAL scope, savestack=57
   3 <aab> <b>            | 15:                OPEN2
   3 <aab> <b>            | 17:                EXACT <b>
   4 <aabb> <>            | 19:                EVAL
  re_eval 0x18471e8
   4 <aabb> <>            | 21:                CLOSE2
   4 <aabb> <>            | 23:                WHILEM[2/2]
                                          2 out of 1..32767  cc=140f4b
+0
  Setting an EVAL scope, savestack=70
   4 <aabb> <>            | 15:                  OPEN2
   4 <aabb> <>            | 17:                  EXACT <b>
                                            failed...
     restoring \2 to 3(3)..4
                                          failed, try continuation...
   4 <aabb> <>            | 24:                  NOTHING
   4 <aabb> <>            | 25:                  END
Match successful!
Guessing start of match, REx "(a(?{$a_counter ++;}))+(b(?{$b_counter +
++;}))+" against "aaabb"...
Found floating substr "ab" at offset 2...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+" against 
+"aaabb"
  Setting an EVAL scope, savestack=28
   0 <> <aaabb>           |  1:  CURLYX[0] {1,32767}
   0 <> <aaabb>           | 11:    WHILEM[1/2]
                              0 out of 1..32767  cc=140f960
   0 <> <aaabb>           |  3:      OPEN1
   0 <> <aaabb>           |  5:      EXACT <a>
   1 <a> <aabb>           |  7:      EVAL
  re_eval 0x18472a4
   1 <a> <aabb>           |  9:      CLOSE1
   1 <a> <aabb>           | 11:      WHILEM[1/2]
                                1 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=41
   1 <a> <aabb>           |  3:        OPEN1
   1 <a> <aabb>           |  5:        EXACT <a>
   2 <aa> <abb>           |  7:        EVAL
  re_eval 0x18472a4
   2 <aa> <abb>           |  9:        CLOSE1
   2 <aa> <abb>           | 11:        WHILEM[1/2]
                                  2 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=54
   2 <aa> <abb>           |  3:          OPEN1
   2 <aa> <abb>           |  5:          EXACT <a>
   3 <aaa> <bb>           |  7:          EVAL
  re_eval 0x18472a4
   3 <aaa> <bb>           |  9:          CLOSE1
   3 <aaa> <bb>           | 11:          WHILEM[1/2]
                                    3 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=67
   3 <aaa> <bb>           |  3:            OPEN1
   3 <aaa> <bb>           |  5:            EXACT <a>
                                      failed...
     restoring \1 to 2(2)..3
     restoring \2..\2 to undef
                                    failed, try continuation...
   3 <aaa> <bb>           | 12:            NOTHING
   3 <aaa> <bb>           | 13:            CURLYX[1] {1,32767}
   3 <aaa> <bb>           | 23:              WHILEM[2/2]
                                        0 out of 1..32767  cc=140f384
   3 <aaa> <bb>           | 15:                OPEN2
   3 <aaa> <bb>           | 17:                EXACT <b>
   4 <aaab> <b>           | 19:                EVAL
  re_eval 0x18471e8
   4 <aaab> <b>           | 21:                CLOSE2
   4 <aaab> <b>           | 23:                WHILEM[2/2]
                                          1 out of 1..32767  cc=140f38
+4
  Setting an EVAL scope, savestack=70
   4 <aaab> <b>           | 15:                  OPEN2
   4 <aaab> <b>           | 17:                  EXACT <b>
   5 <aaabb> <>           | 19:                  EVAL
  re_eval 0x18471e8
   5 <aaabb> <>           | 21:                  CLOSE2
   5 <aaabb> <>           | 23:                  WHILEM[2/2]
                                            2 out of 1..32767  cc=140f
+384
  Setting an EVAL scope, savestack=83
   5 <aaabb> <>           | 15:                    OPEN2
   5 <aaabb> <>           | 17:                    EXACT <b>
                                              failed...
     restoring \2 to 4(4)..5
                                            failed, try continuation..
+.
   5 <aaabb> <>           | 24:                    NOTHING
   5 <aaabb> <>           | 25:                    END
Match successful!
Guessing start of match, REx "(a(?{$a_counter ++;}))+(b(?{$b_counter +
++;}))+" against "aabbb"...
Found floating substr "ab" at offset 1...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+" against 
+"aabbb"
  Setting an EVAL scope, savestack=28
   0 <> <aabbb>           |  1:  CURLYX[0] {1,32767}
   0 <> <aabbb>           | 11:    WHILEM[1/2]
                              0 out of 1..32767  cc=140f960
   0 <> <aabbb>           |  3:      OPEN1
   0 <> <aabbb>           |  5:      EXACT <a>
   1 <a> <abbb>           |  7:      EVAL
  re_eval 0x18472a4
   1 <a> <abbb>           |  9:      CLOSE1
   1 <a> <abbb>           | 11:      WHILEM[1/2]
                                1 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=41
   1 <a> <abbb>           |  3:        OPEN1
   1 <a> <abbb>           |  5:        EXACT <a>
   2 <aa> <bbb>           |  7:        EVAL
  re_eval 0x18472a4
   2 <aa> <bbb>           |  9:        CLOSE1
   2 <aa> <bbb>           | 11:        WHILEM[1/2]
                                  2 out of 1..32767  cc=140f960
  Setting an EVAL scope, savestack=54
   2 <aa> <bbb>           |  3:          OPEN1
   2 <aa> <bbb>           |  5:          EXACT <a>
                                    failed...
     restoring \1 to 1(1)..2
     restoring \2..\2 to undef
                                  failed, try continuation...
   2 <aa> <bbb>           | 12:          NOTHING
   2 <aa> <bbb>           | 13:          CURLYX[1] {1,32767}
   2 <aa> <bbb>           | 23:            WHILEM[2/2]
                                      0 out of 1..32767  cc=140f4b0
   2 <aa> <bbb>           | 15:              OPEN2
   2 <aa> <bbb>           | 17:              EXACT <b>
   3 <aab> <bb>           | 19:              EVAL
  re_eval 0x18471e8
   3 <aab> <bb>           | 21:              CLOSE2
   3 <aab> <bb>           | 23:              WHILEM[2/2]
                                        1 out of 1..32767  cc=140f4b0
  Setting an EVAL scope, savestack=57
   3 <aab> <bb>           | 15:                OPEN2
   3 <aab> <bb>           | 17:                EXACT <b>
   4 <aabb> <b>           | 19:                EVAL
  re_eval 0x18471e8
   4 <aabb> <b>           | 21:                CLOSE2
   4 <aabb> <b>           | 23:                WHILEM[2/2]
                                          2 out of 1..32767  cc=140f4b
+0
  Setting an EVAL scope, savestack=70
   4 <aabb> <b>           | 15:                  OPEN2
   4 <aabb> <b>           | 17:                  EXACT <b>
   5 <aabbb> <>           | 19:                  EVAL
  re_eval 0x18471e8
   5 <aabbb> <>           | 21:                  CLOSE2
   5 <aabbb> <>           | 23:                  WHILEM[2/2]
                                            3 out of 1..32767  cc=140f
+4b0
  Setting an EVAL scope, savestack=83
   5 <aabbb> <>           | 15:                    OPEN2
   5 <aabbb> <>           | 17:                    EXACT <b>
                                              failed...
     restoring \2 to 4(4)..5
                                            failed, try continuation..
+.
   5 <aabbb> <>           | 24:                    NOTHING
   5 <aabbb> <>           | 25:                    END
Match successful!
In aaabbbb there were 3 'a's and 4 'b's.
In ab there were 0 'a's and 0 'b's.
In abb there were 0 'a's and 0 'b's.
In aabb there were 0 'a's and 0 'b's.
In aaabb there were 0 'a's and 0 'b's.
In aabbb there were 0 'a's and 0 'b's.
Freeing REx: `"(a(?{$a_counter ++;}))+(b(?{$b_counter ++;}))+"'
[download]
In reply to Re^4: Extracting the number of repetitions by pat_mc
in thread Extracting the number of repetitions from a regex by pat_mc
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