Added support for css_class function

CHANGELOG

@@ -118,6 +118,7 @@
    Twig\Environment::setBaseTemplateClass() methods
  * changed internal code to use the namespaced classes as much as possible
  * deprecated Twig_Parser::isReservedMacroName()
+ * Added support for `css_class` function
 
 * 2.6.2 (2019-01-14)
 

doc/functions/css_class.rst

@@ -0,0 +1,12 @@
+``css_class``
+=============
+
+``css_class`` returns a string by conditionally joining class names together.
+
+.. code-block:: jinja
+
+    {{ css_class('a-class', 'another-class', {
+        'errored': object.errored,
+        'finished': object.finished,
+        'pending': object.pending,
+    }) }}

doc/functions/index.rst

@@ -7,6 +7,7 @@ Functions
     attribute
     block
     constant
+    css_class
     cycle
     date
     dump

src/Extension/CoreExtension.php

@@ -269,6 +269,7 @@ final class CoreExtension extends AbstractExtension
             new TwigFunction('date', 'twig_date_converter', ['needs_environment' => true]),
             new TwigFunction('include', 'twig_include', ['needs_environment' => true, 'needs_context' => true, 'is_safe' => ['all']]),
             new TwigFunction('source', 'twig_source', ['needs_environment' => true, 'is_safe' => ['all']]),
+            new TwigFunction('css_class', 'twig_css_class'),
         ];
     }
 
@@ -1548,4 +1549,29 @@ function twig_array_reduce($array, $arrow, $initial = null)
 
     return array_reduce($array, $arrow, $initial);
 }
+
+function twig_css_class(...$args): string
+{
+    $classes = [];
+    foreach ($args as $i => $arg) {
+        if (is_string($arg)) {
+            $classes[] = $arg;
+        } elseif (is_array($arg)) {
+            foreach ($arg as $class => $condition) {
+                if (!is_string($class)) {
+                    throw new RuntimeError(sprintf('Key %d of argument %d should be a string. Got "%s".', $class, $i, gettype($class)));
+                }
+                if (!$condition) {
+                    continue;
+                }
+                $classes[] = $class;
+            }
+        } else {
+            throw new RuntimeError(sprintf('Argument %d should be either a string or an array. Got "%s".', $i, gettype($arg)));
+        }
+    }
+    $classes = array_unique($classes);
+
+    return implode(' ', $classes);
+}
 }

test/Twig/Tests/Fixtures/functions/classes.test

@@ -0,0 +1,12 @@
+--TEST--
+"css_class" function
+--TEMPLATE--
+{{ css_class('a', {'b': true, 'c': false}, 'd') }}
+{% set class_a = 'a' %}
+{% set class_b = 'b' %}
+{{ css_class(class_a, {(class_b): true})}}
+--DATA--
+return []
+--EXPECT--
+a b d
+a b

test/Twig/Tests/Fixtures/functions/classes_with_unsupported_arg.test

@@ -0,0 +1,8 @@
+--TEST--
+"css_class" function
+--TEMPLATE--
+{{ css_class(true) }}
+--DATA--
+return []
+--EXCEPTION--
+Twig\Error\RuntimeError: Argument 0 should be either a string or an array. Got "boolean" in "index.twig" at line 2.

test/Twig/Tests/Fixtures/functions/classes_with_unsupported_key.test

@@ -0,0 +1,8 @@
+--TEST--
+"css_class" function
+--TEMPLATE--
+{{ css_class(['foo']) }}
+--DATA--
+return []
+--EXCEPTION--
+Twig\Error\RuntimeError: Key 0 of argument 0 should be a string. Got "integer" in "index.twig" at line 2.