[wp-trac] [WordPress Trac] #41526: Remove usage of each() from Text_Diff_Engine_native

[WordPress Trac]

#41526: Remove usage of each() from Text_Diff_Engine_native
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 Reporter:  johnbillion         |      Owner:
     Type:  task (blessed)      |     Status:  new
 Priority:  normal              |  Milestone:  4.9
Component:  External Libraries  |    Version:
 Severity:  normal              |   Keywords:  needs-patch needs-unit-tests
  Focuses:                      |
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 Ticket split out from #40109.

 `Text_Diff_Engine_native::_diag()` uses `each()`, which is deprecated in
 PHP 7.2 and therefore should be removed.

 The `each()` function exhibits two pieces of behaviour which mean it can't
 simply be replaced with `foreach()`:

 1. After `each()` has executed, the array cursor will be left on the next
 element of the array, or past the last element if it hits the end of the
 array. This means you can break out of an each loop, and continue the
 iteration at a later point. `Text_Diff_Engine_native::_diag()` does just
 this.
 2. With the `while ( each( $array ) )` pattern, it's possible to alter the
 elements in the array during iteration.

 ----

 `Text_Diff_Engine_native::_diag()` iterates over `$matches` with `each()`
 until the condition which causes the `break` clause is met, upon which the
 second call to `each()` continues iteration from the same point in the
 array. Lovely.

 The `Text_Diff` library is a complex, third-party script with no test
 coverage, so changes here need to be made carefully. Unit tests probably
 could be introduced to demonstrate no regressions when `each()` is
 replaced.

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Ticket URL: <https://core.trac.wordpress.org/ticket/41526>
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