add docs & links

doc/filters/batch.rst

@@ -12,8 +12,8 @@ missing items:
     <table>
         {% for row in items|batch(3, 'No item') %}
             <tr>
-                {% for column in row %}
-                    <td>{{ column }}</td>
+                {% for index, column in row %}
+                    <td>{{ index }} - {{ column }}</td>
                 {% endfor %}
             </tr>
         {% endfor %}
@@ -25,14 +25,47 @@ The above example will be rendered as:
 
     <table>
         <tr>
-            <td>a</td>
-            <td>b</td>
-            <td>c</td>
+            <td>0 - a</td>
+            <td>1 - b</td>
+            <td>2 - c</td>
         </tr>
         <tr>
-            <td>d</td>
-            <td>No item</td>
-            <td>No item</td>
+            <td>3 - d</td>
+            <td>4 - No item</td>
+            <td>5 - No item</td>
+        </tr>
+    </table>
+
+If you choose to set the third parameter ``preserve_keys`` to ``false``, the keys will be reset in each loop.
+
+.. code-block:: html+twig
+
+    {% set items = ['a', 'b', 'c', 'd'] %}
+
+    <table>
+        {% for row in items|batch(3, 'No item', false) %}
+            <tr>
+                {% for index, column in row %}
+                    <td>{{ index }} - {{ column }}</td>
+                {% endfor %}
+            </tr>
+        {% endfor %}
+    </table>
+
+The above example will be rendered as:
+
+.. code-block:: html+twig
+
+    <table>
+        <tr>
+            <td>0 - a</td>
+            <td>1 - b</td>
+            <td>2 - c</td>
+        </tr>
+        <tr>
+            <td>0 - d</td>
+            <td>1 - No item</td>
+            <td>2 - No item</td>
         </tr>
     </table>
 
@@ -41,4 +74,4 @@ Arguments
 
 * ``size``: The size of the batch; fractional numbers will be rounded up
 * ``fill``: Used to fill in missing items
-* ``preserve_keys``: Whether to preserve keys or not
+* ``preserve_keys``: Whether to preserve keys or not (defaults to ``true``)

doc/filters/date.rst

@@ -47,7 +47,7 @@ Timezone
 
 By default, the date is displayed by applying the default timezone (the one
 specified in php.ini or declared in Twig -- see below), but you can override
-it by explicitly specifying a timezone:
+it by explicitly specifying a supported `timezone`_:
 
 .. code-block:: twig
 
@@ -68,11 +68,12 @@ The default timezone can also be set globally by calling ``setTimezone()``::
 Arguments
 ---------
 
-* ``format``:   The date format
+* ``format``:   The date format (default format is ``F j, Y H:i``, which will render as ``January 11, 2024 15:17``)
 * ``timezone``: The date timezone
 
 .. _`strtotime`:            https://www.php.net/strtotime
 .. _`DateTime`:             https://www.php.net/DateTime
 .. _`DateInterval`:         https://www.php.net/DateInterval
 .. _`date`:                 https://www.php.net/date
 .. _`DateInterval::format`: https://www.php.net/DateInterval.format
+.. _`timezone`:            https://www.php.net/manual/en/timezones.php

doc/filters/keys.rst

@@ -9,3 +9,9 @@ iterate over the keys of an array:
     {% for key in array|keys %}
         ...
     {% endfor %}
+
+.. note::
+
+    Internally, Twig uses the PHP `array_keys`_ function.
+
+.. _`array_keys`: https://www.php.net/array_keys

doc/filters/lower.rst

@@ -8,3 +8,9 @@ The ``lower`` filter converts a value to lowercase:
     {{ 'WELCOME'|lower }}
 
     {# outputs 'welcome' #}
+
+.. note::
+
+    Internally, Twig uses the PHP `mb_strtolower`_ function.
+
+.. _`mb_strtolower`: https://www.php.net/manual/fr/function.mb-strtolower.php

doc/filters/reduce.rst

@@ -27,3 +27,9 @@ Arguments
 
 * ``arrow``: The arrow function
 * ``initial``: The initial value
+
+.. note::
+
+    Internally, Twig uses the PHP `array_reduce`_ function.
+
+.. _`array_reduce`: https://www.php.net/array_reduce

doc/filters/slice.rst

@@ -54,6 +54,28 @@ negative then the sequence will stop that many elements from the end of the
 variable. If it is omitted, then the sequence will have everything from offset
 up until the end of the variable.
 
+The argument ``preserve_keys`` is used to reset the index during the loop.
+
+.. code-block:: twig
+
+    {% for key, value in [1, 2, 3, 4, 5]|slice(1, 2, true) %}
+        {{ key }} - {{ value }}
+    {% endfor %}
+
+    {# output
+        1 - 2
+        2 - 3
+    #}
+
+    {% for key, value in [1, 2, 3, 4, 5]|slice(1, 2) %}
+        {{ key }} - {{ value }}
+    {% endfor %}
+
+    {# output
+        0 - 2
+        1 - 3
+    #}
+
 .. note::
 
     It also works with objects implementing the `Traversable`_ interface.
@@ -63,7 +85,7 @@ Arguments
 
 * ``start``:         The start of the slice
 * ``length``:        The size of the slice
-* ``preserve_keys``: Whether to preserve key or not (when the input is an array)
+* ``preserve_keys``: Whether to preserve key or not (when the input is an array), by default the value is ``false``.
 
 .. _`Traversable`: https://www.php.net/manual/en/class.traversable.php
 .. _`array_slice`: https://www.php.net/array_slice

doc/filters/upper.rst

@@ -8,3 +8,9 @@ The ``upper`` filter converts a value to uppercase:
     {{ 'welcome'|upper }}
 
     {# outputs 'WELCOME' #}
+
+.. note::
+
+    Internally, Twig uses the PHP `mb_strtoupper`_ function.
+
+.. _`mb_strtoupper`: https://www.php.net/mb_strtoupper