Perl Version: v5.14.2
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*** NO look-ahead ***
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Prematch:  'www '
Match:     'xxx-A-B-C-D'
Postmatch: ' yyy zzz-E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy '
Match:     'zzz-E-F-G-H'
Postmatch: ''
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*** USING look-ahead ***
============================================================
Prematch:  'www '
Match:     ''
Postmatch: 'xxx-A-B-C-D yyy zzz-E-F-G-H'
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Prematch:  'www x'
Match:     ''
Postmatch: 'xx-A-B-C-D yyy zzz-E-F-G-H'
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Prematch:  'www xx'
Match:     ''
Postmatch: 'x-A-B-C-D yyy zzz-E-F-G-H'
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Prematch:  'www xxx'
Match:     ''
Postmatch: '-A-B-C-D yyy zzz-E-F-G-H'
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Prematch:  'www xxx-'
Match:     ''
Postmatch: 'A-B-C-D yyy zzz-E-F-G-H'
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Prematch:  'www xxx-A'
Match:     ''
Postmatch: '-B-C-D yyy zzz-E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy '
Match:     ''
Postmatch: 'zzz-E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy z'
Match:     ''
Postmatch: 'zz-E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy zz'
Match:     ''
Postmatch: 'z-E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy zzz'
Match:     ''
Postmatch: '-E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy zzz-'
Match:     ''
Postmatch: 'E-F-G-H'
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Prematch:  'www xxx-A-B-C-D yyy zzz-E'
Match:     ''
Postmatch: '-F-G-H'
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