I want to use a regex to match double-quoted strings of arbitrary length. But the regex recommended in perlre(1) seems to use recursion even though greedy *+ is used, which that man page seems to say should prevent backtracking.

Any expression of the form  ( A | B )*+ seems to use recursion.
Can someone explain why recursion, rather than iteration, is used by the regex engine for this?

Here is a demo script showing the problem:

#!/usr/bin/perl
use strict; use warnings;

$_ = '"' . ('\"' x 100000) . '"';

print "NOT MATCHED!\n" unless
  /^ " (?: [^"\\]++ | \\. )*+ " /x ;  # as recommended by perlre(1)

# why does this use recursion (rather than iteration)?

#Output under perl v5.24.1:
# Complex regular subexpression recursion limit (32766) exceeded at li
+ne 6.
# NOT MATCHED!

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In reply to What regex can match arbitrary-length quoted string? by jimav

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