rfc:cyclic-replace

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rfc:cyclic-replace [2015/01/09 13:54] – 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: 2015-01-09+  * 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.
  
-Note that replacements are done in array order. Key values are ignored.+Note that replacements are done in array order. Key values are ignored in replace arrays.
  
 So, features brought by this RFC to str_[i]replace() are : So, features brought by this RFC to str_[i]replace() are :
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 be a string or an array. If it is a string, we have the usual string/string 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. behavior. If it is an array, cyclic replacement is performed.
-So, the 'array search' case can be seen as an implicit loop around the+So, the 'array search' case is an implicit loop around the
 'string search' case, providing exactly the same features. 'string search' case, providing exactly the same features.
-As this is performed using recursion, search can contain any level of imbricated 
-arrays, provided replace provides the corresponding structure. 
  
-Note that, in case of multi-level arrays, replace array can be less deep than +Arbitrarily nested subject arrays are now supported, returning exactly the same 
-search array as, as soon as we find a non-array replace value, this value is +array structure and preserving keys. Only values are replaced.
-used as replacement string for the whole corresponding search subtree. The opposite +
-case is very different : If the replace array tree is deeper than the search tree by more +
-than 1 level, array to string conversion will occur (with E_NOTICE and the +
-wonderful 'Array' result).+
  
 Empty replace arrays are considered as unexpected. When one is provided, an Empty replace arrays are considered as unexpected. When one is provided, an
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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
- +
-Different behavior too when replace is an empty array. Previously, as seen above, an E_NOTICE+
 was raised and the array was converted to 'Array'. Now, an E_WARNING was raised and the array was converted to 'Array'. Now, an E_WARNING
-is raised and the subject is returned unchanged. Minimal break too as giving +is raised and the subject is returned unchanged. 
-an array as replace arg, while supported (with E_NOTICE), had no real sense + 
-(even documentation states that).+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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 ===== 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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