Hi,
inside a framework-/scripting-project we've lately discussed
string-replacements with arrays.
Currently PHP supports either replacing one string by another or
replacing first element from one array with first from another array.
What I'd like to propose is for str_replace and preg_replace to introduce:
- a functionality to replace one string with strings from an array
- to (optionally) allow for rolling replacements (1,2,3, 1,2,3, ...)
- to (optionally) allow to skip strings already replaced
(that means not to accidentially double-replace strings)
This would allow to do things like
$content = str_replace('<li>',
array('<li class="A">', '<li class="B">', '<li class="C">'),
$content);
optionally starting over from A again. (Current default is to stop when
there are no more elements to replace with).
Would such a change/extension find support?
Kind regards,
Stefan Neufeind
Both str_replace and preg_replace already support some array based
replacements, I think adding more options to these functions specifically
would just lead to confusion.
What you're proposing can already be achieved quite easily with
preg_replace_callback and passing your array/options into the anonymous
function with use, I'd personally welcome a str_replace_callback
counterpart.
Hi,
inside a framework-/scripting-project we've lately discussed
string-replacements with arrays.Currently PHP supports either replacing one string by another or
replacing first element from one array with first from another array.What I'd like to propose is for str_replace and preg_replace to introduce:
- a functionality to replace one string with strings from an array
- to (optionally) allow for rolling replacements (1,2,3, 1,2,3, ...)
- to (optionally) allow to skip strings already replaced
(that means not to accidentially double-replace strings)This would allow to do things like
$content = str_replace('<li>',
array('<li class="A">', '<li class="B">', '<li class="C">'),
$content);optionally starting over from A again. (Current default is to stop when
there are no more elements to replace with).Would such a change/extension find support?
Kind regards,
Stefan Neufeind
Hi,
Both str_replace and preg_replace already support some array based
replacements, I think adding more options to these functions
specifically would just lead to confusion.
Well, yes and no. Currently you have to supply either one string to
replace with one other or you have to supply arrays for each of them.
And this wouldn't allow to replace the second, third etc. occurence
different.
Since we already have functionality for replacing with arrays in place,
I wondered if giving it one string to replace and then an array to
choose the replacement from (rotating) would be an option. Currently
that's "unsupported" (either two strings or two arrays).
What you're proposing can already be achieved quite easily with
preg_replace_callback and passing your array/options into the anonymous
function withuse, I'd personally welcome a str_replace_callback
counterpart.
I think you could use a callback-function but would need to add quite a
few more lines to initialise your array first, do a "next()" on the
array inside the callback-function and (how would you pass it that
array?) and still would have to handle starting from beginning of the
array again once you reach the end etc.
Kind regards,
Stefan
On 18 December 2012 12:08, Stefan Neufeind <neufeind@php.net
mailto:neufeind@php.net> wrote:Hi, inside a framework-/scripting-project we've lately discussed string-replacements with arrays. Currently PHP supports either replacing one string by another or replacing first element from one array with first from another array. What I'd like to propose is for str_replace and preg_replace to introduce: * a functionality to replace one string with strings from an array * to (optionally) allow for rolling replacements (1,2,3, 1,2,3, ...) * to (optionally) allow to skip strings already replaced (that means not to accidentially double-replace strings) This would allow to do things like $content = str_replace('<li>', array('<li class="A">', '<li class="B">', '<li class="C">'), $content); optionally starting over from A again. (Current default is to stop when there are no more elements to replace with). Would such a change/extension find support? Kind regards, Stefan Neufeind
Since we already have functionality for replacing with arrays in place,
I wondered if giving it one string to replace and then an array to
choose the replacement from (rotating) would be an option. Currently
that's "unsupported" (either two strings or two arrays).
It's certainly possible to implement, but personally it feels like odd
behaviour. I don't know what other people think about it.
I think you could use a callback-function but would need to add quite a
few more lines to initialise your array first, do a "next()" on the
array inside the callback-function and (how would you pass it that
array?) and still would have to handle starting from beginning of the
array again once you reach the end etc.
You pass the array using "use". You could do it something like this:
$replacements = array(
'one', 'two', 'three'
);
$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements) {
$current = current($replacements);
next($replacements) || reset($replacements);
return $current;
},
'word word word word word'
);
var_dump($result);
Output:
string(21) "one two three one two"
Since we already have functionality for replacing with arrays in place,
I wondered if giving it one string to replace and then an array to
choose the replacement from (rotating) would be an option. Currently
that's "unsupported" (either two strings or two arrays).It's certainly possible to implement, but personally it feels like odd
behaviour. I don't know what other people think about it.I think you could use a callback-function but would need to add quite a
few more lines to initialise your array first, do a "next()" on the
array inside the callback-function and (how would you pass it that
array?) and still would have to handle starting from beginning of the
array again once you reach the end etc.You pass the array using "use". You could do it something like this:
$replacements = array(
'one', 'two', 'three'
);$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements) {
$current = current($replacements);
next($replacements) || reset($replacements);
return $current;
},
'word word word word word'
);var_dump($result);
Output:
string(21) "one two three one two"
You could likely simplify the code even further using an infinite iterator:
http://us1.php.net/infiniteiterator
$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements_iterator) {
return $replacements->next();
},
'word word word word word'
);
--Larry Garfield
You could likely simplify the code even further using an infinite iterator:
http://us1.php.net/infiniteiterator
$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements_iterator) {
return $replacements->next();
},
'word word word word word'
);--Larry Garfield
What am I missing that causes the first call to $replacements_iterator->current() to return NULL
unless the iterator is rewound before use?
Chris
<?php
$replacements = array(
'one', 'two', 'three'
);
$replacements_iterator = new InfiniteIterator(new ArrayIterator($replacements));
$replacements_iterator->rewind(); // why is the rewind needed?
$result = preg_replace_callback(
'/word/',
function($matches) use ($replacements_iterator) {
$r = $replacements_iterator->current();
$replacements_iterator->next();
return $r;
},
'word word word word word'
);
var_dump($result);
// Outputs:
// string(21) "one two three one two"
// Without the call to $replacements_iterator->rewind(), the output is:
// string(18) " two three one two"
?>
You could likely simplify the code even further using an infinite
iterator:http://us1.php.net/infiniteiterator
$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements_iterator) {
return $replacements->next();
},
'word word word word word'
);--Larry Garfield
What am I missing that causes the first call to
$replacements_iterator->current() to returnNULL
unless the iterator is rewound before use?
Eh, nothing. You're right, next() doesn't return an element, it just
advances, so you still need the current() call. Which seems kinda silly
to me, but whatev.
--Larry Garfield
You could likely simplify the code even further using an infinite
iterator:http://us1.php.net/infiniteiterator
$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements_iterator) {
return $replacements->next();
},
'word word word word word'
);--Larry Garfield
What am I missing that causes the first call to
$replacements_iterator->current() to returnNULL
unless the iterator is rewound before use?Eh, nothing. You're right,
next()doesn't return an element, it just advances, so you still need thecurrent()call. Which seems kinda silly to me, but whatev.
That is documented, so it's OK. The curiosity (bug?) is the need to call rewind():
$replacements_iterator = new InfiniteIterator(new ArrayIterator($replacements));
$replacements_iterator->rewind(); // why is the rewind needed?
$result = preg_replace_callback(
'/word/',
function($matches) use ($replacements_iterator) {
$r = $replacements_iterator->current();
$replacements_iterator->next();
return $r;
},
'word word word word word word word word'
);
In other (simple) scripts using InfiniteIterator the rewind wasn't needed.
You could likely simplify the code even further using an infinite
iterator:http://us1.php.net/infiniteiterator
$result = preg_replace_callback(
'/word/',
function($matches) use (&$replacements_iterator) {
return $replacements->next();
},
'word word word word word'
);--Larry Garfield
What am I missing that causes the first call to
$replacements_iterator->current() to returnNULL
unless the iterator is rewound before use?Eh, nothing. You're right,
next()doesn't return an element, it just
advances, so you still need thecurrent()call. Which seems kinda
silly to me, but whatev.That is documented, so it's OK. The curiosity (bug?) is the need to
callrewind():$replacements_iterator = new InfiniteIterator(new
ArrayIterator($replacements));
$replacements_iterator->rewind(); // why is the rewind needed?$result = preg_replace_callback(
'/word/',
function($matches) use ($replacements_iterator) {
$r = $replacements_iterator->current();
$replacements_iterator->next();
return $r;
},
'word word word word word word word word'
);In other (simple) scripts using InfiniteIterator the rewind wasn't
needed.
What happens if you do:
$replacements_iterator = new InfiniteIterator(new
ArrayIterator($replacements));
var_dump($replacements_iterator->current());
If I remember correctly, when you pass a traversable into foreach, under
the hood, it basically calls:
$iterator->rewind();
while($iterator->valid()){
$value = $iterator->current();
....(foreach block)....
$iterator->next();
}
So that might explain why it works in "(simple) scripts".
It does seem like a bug that the rewind is required though. A newly
created iterator should already be in a rewound state so the call
shouldn't be needed.
Cheers,
David
The curiosity (bug?) is the need to call
rewind():$replacements_iterator = new InfiniteIterator(new ArrayIterator($replacements));
$replacements_iterator->rewind(); // why is the rewind needed?$result = preg_replace_callback(
'/word/',
function($matches) use ($replacements_iterator) {
$r = $replacements_iterator->current();
$replacements_iterator->next();
return $r;
},
'word word word word word word word word'
);In other (simple) scripts using InfiniteIterator the rewind wasn't needed.
What happens if you do:
$replacements_iterator = new InfiniteIterator(new ArrayIterator($replacements));
var_dump($replacements_iterator->current());If I remember correctly, when you pass a traversable into foreach, under the hood, it basically calls:
$iterator->rewind();
while($iterator->valid()){
$value = $iterator->current();
....(foreach block)....
$iterator->next();
}So that might explain why it works in "(simple) scripts".
It does seem like a bug that the rewind is required though. A newly created iterator should already be in a rewound state so the call shouldn't be needed.
Cheers,
David
I logged a bug so this can be tracked and re-discovered: https://bugs.php.net/bug.php?id=63823
Chris
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