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  1. use strict;
  2. use warnings;
  3.  
  4. my $re = qr~
  5. {if:\s*+
  6. 	(?<condition>
  7. 		[^{}]++
  8. 	)
  9. }
  10.  
  11. (?<then>
  12. 	(?:
  13. 		(?:(?!{if:[^{}]++}|{else}|{/endif}).)*+
  14. 		(?R)*+
  15. 	)*+
  16. )
  17.  
  18. (?:
  19. 	{else}
  20. 	(?<else>
  21. 		(?:
  22. 			(?:(?!{if:[^{}]++}|{else}|{/endif}).)*+
  23. 			(?R)*+
  24. 		)*+
  25. 	)
  26. )?+
  27.  
  28. {/endif}
  29. ~six;
  30.  
  31.  
  32. my $txt = <<'_STR_';
  33. {if: "'x' == 'y'"}
  34.     a
  35. {else}
  36.     b
  37. {/endif}
  38.  
  39. {if: "'x' == 'y'"}
  40.     c
  41. {/endif}
  42.  
  43. {if:minimal}{else}{/endif}
  44.  
  45. {if: "'nested' == 'things'"}
  46.     {if: "'x' == 'y'"}x{if:minimal}{else}{/endif}x{/endif}
  47. {else}
  48.     b{if: "'x' == 'y'"}c{/endif}{if: "'x' == 'y'"}c{/endif}
  49. {/endif}
  50.  
  51. {if:foo} unbalanced {if:bar}ignores first if{/endif}
  52.  
  53. _STR_
  54.  
  55.  
  56. while($txt =~ /$re/g){
  57. 	print "*** matched if:\n";
  58. 	print "  * cond: $+{condition}\n";
  59. 	print "  * then: $+{then}\n";
  60. 	print "  * else: $+{else}\n" if defined $+{else};
  61. }
  62.  
Success #stdin #stdout 0s 4724KB
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*** matched if:
  * cond: "'x' == 'y'"
  * then: 
    a

  * else: 
    b

*** matched if:
  * cond: "'x' == 'y'"
  * then: 
    c

*** matched if:
  * cond: minimal
  * then: 
  * else: 
*** matched if:
  * cond: "'nested' == 'things'"
  * then: 
    {if: "'x' == 'y'"}x{if:minimal}{else}{/endif}x{/endif}

  * else: 
    b{if: "'x' == 'y'"}c{/endif}{if: "'x' == 'y'"}c{/endif}

*** matched if:
  * cond: bar
  * then: ignores first if
https://ideone.com/aDG3z
language:
Perl (perl 5.28.1)
created:
11 years ago
visibility:
public

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