rfc:cyclic-replace

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rfc:cyclic-replace [2015/01/09 02:38] – francoisrfc:cyclic-replace [2015/02/02 18:00] – francois
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 ====== Add cyclic string replacements ====== ====== Add cyclic string replacements ======
-  * Version: 1.0 +  * Version: 1.6 
-  * Date: 2015-01-08+  * Creation date: 2015-01-05 
 +  * Last modification date : 2015-02-02
   * Author: François Laupretre, francois@tekwire.net   * Author: François Laupretre, francois@tekwire.net
   * Status: Under discussion   * Status: Under discussion
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 This is what we name 'cyclic replace'. Purists will note that it is really 'cyclic' This is what we name 'cyclic replace'. Purists will note that it is really 'cyclic'
-only when we set the option to loop in the replace array but I didn't find a better name.+only when we set the option to loop in the replace array.
  
-Features brought by this RFC to str_[i]replace() :+Note that replacements are done in array order. Key values are ignored in replace arrays.
  
- * When search is a string and replace an array, cyclic replace is performed.+So, features brought by this RFC to str_[i]replace() are :
  
- * When search and replace are arrays, each element of the replace array can now be a string or an array. If it is a string, we have the usual string/string behavior. If it is an array, cyclic replacement is performed. So, the 'array search' case is an implicit loop whose body provides exactly the same features as when search is received as a string.+When search is a string and replace an array, cyclic replace is performed. 
 +This is the 'first-level' case. 
 + 
 +When search and replace are arrays, each element of the replace array can 
 +be a string or an array. If it is a string, we have the usual string/string 
 +behavior. If it is an array, cyclic replacement is performed. 
 +So, the 'array search' case is an implicit loop around the 
 +'string search' case, providing exactly the same features. 
 + 
 +Arbitrarily nested subject arrays are now supported, returning exactly the same 
 +array structure and preserving keys. Only values are replaced.
  
 Empty replace arrays are considered as unexpected. When one is provided, an Empty replace arrays are considered as unexpected. When one is provided, an
-E_WARNING error is raised and the input subject is returned as-is.+E_WARNING error is raised and the input subject is returned as-is. If search is 
 +an array, this warning can be raised more than once during a single str_[i]replace() 
 +execution, as we raise it each time we meet an empty replace array.
  
 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
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 php_char_to_str_ex() and php_str_to_str_ex() (defined in ext/standard/php_string.h) php_char_to_str_ex() and php_str_to_str_ex() (defined in ext/standard/php_string.h)
 take an additional //options// take an additional //options//
-argument. This argument is not used at the moment but, this allows their API+argument. This argument is not used at the moment but it allows their API
 to remain compatible with the new new php_str_to_array_ex() function. to remain compatible with the new new php_str_to_array_ex() function.
  
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 Now, this combination of argument types causes the search string to be replaced Now, this combination of argument types causes the search string to be replaced
-with elements from the replace array. So, the behavior is different.+with elements from the replace array.
  
-The BC break is minimal here as I hope very few people ever relied on a replace +Different behavior too each time we meet an empty array as replace value. 
-array being converted to 'Array', especially with an E_NOTICE.+Previously, as seen above, an E_NOTICE 
 +was raised and the array was converted to 'Array'. Now, an E_WARNING 
 +is raised and the subject is returned unchanged. 
 + 
 +The support of arbitrarily-nested subject brings the same 
 +kind of BC because previous implementations supported one array level only. 
 + 
 +All these BC breaks are similar and deal with array to string conversions in 
 +previous implementations. Can be considered as very low impact because 
 +relying on an array-to-string conversion (with E_NOTICE) when calling these 
 +functions, while theoritically supported, is very improbable.
  
 ===== Proposed PHP Version(s) ===== ===== Proposed PHP Version(s) =====
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 ==== To Existing Extensions ==== ==== To Existing Extensions ====
  
-Extensions using one the C functions with a modified API need to be adapted (add +Extensions using one of the C functions with a modified API (see BC changes in C API above) 
-a 0 argument to each call).+need to be adapted (adding a 0 final argument to each call). Only two occurences of such calls exist in 
 +the whole php-src tree (outside of string.c).
  
 ==== To Opcache ==== ==== To Opcache ====
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 are exclusive (they cannot be combined) : are exclusive (they cannot be combined) :
  
- * STR_REPLACE_STOP : Stop replacements (up to count(replace) occurences of needle can be replaced)+ * STR_REPLACE_STOP : Stop replacements (up to count(replace) occurences of needle can be replaced)
  * STR_REPLACE_FIRST : Remaining occurences are replaced with the first element of the replace array.  * STR_REPLACE_FIRST : Remaining occurences are replaced with the first element of the replace array.
  * STR_REPLACE_LAST : Remaining occurences are replaced with the last element of the replace array.  * STR_REPLACE_LAST : Remaining occurences are replaced with the last element of the replace array.
- * STR_REPLACE_LOOP : Loop and restart replacements with the first element of the replace array. Looping occurs as many times as needed.+ * STR_REPLACE_LOOP : Loop and restart replacements with the first element of the replace array. Loop as many times as needed.
  * STR_REPLACE_EMPTY : Remaining occurences are replaced with an empty string.  * STR_REPLACE_EMPTY : Remaining occurences are replaced with an empty string.
  
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 ===== Open Issues ===== ===== Open Issues =====
  
-None+The need for an additional options arg is still under discussion.
  
 ===== Unaffected PHP Functionality ===== ===== Unaffected PHP Functionality =====
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 ===== Future Scope ===== ===== Future Scope =====
  
-Propose the addition of a similar feature to preg_replace() and preg_filter().+Proposed: 
 + 
 + * Add (search=null, replace=array) syntax. Would take search from array_keys(replace). An array of (search => replace) elements would be, IMO, a more intuitive way to specify multiple replacements. 
 + 
 + * Add similar features (cyclic replacement and multi-level array recursion) to preg_replace() and preg_filter().
  
 ===== Proposed Voting Choices ===== ===== Proposed Voting Choices =====
  
-Not sure of required majority for this feature. Probably 2/3.+Required majority : 50%+1.
  
 ===== Patches and Tests ===== ===== Patches and Tests =====
  
-Pull request against current PHP7 branch : [[https://github.com/php/php-src/pull/980]] +Pull request against PHP7 branch : [[https://github.com/php/php-src/pull/980]]
- +
-When implementation will be complete, this PR is intended to be the final patch.+
  
 ===== Implementation ===== ===== Implementation =====
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 Feature request : [[https://bugs.php.net/bug.php?id=38685]] Feature request : [[https://bugs.php.net/bug.php?id=38685]]
 +
 +A similar feature request : [[https://bugs.php.net/bug.php?id=62315]]
  
 PR : [[https://github.com/php/php-src/pull/980]] PR : [[https://github.com/php/php-src/pull/980]]
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 ===== Rejected Features ===== ===== Rejected Features =====
  
-(Keep this updated with features that were discussed on the mail lists)+Support for arbitrarily-nested search/replace arrays is abandoned.
  
rfc/cyclic-replace.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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