core: drop support for php5.4

Author: adhocore

.travis.yml

@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 5.4
   - 5.5
   - 5.6
   - 7.0

readme.md

@@ -10,7 +10,7 @@
 
 ## Installation
 
-Requires PHP5.4 or later.
+Requires PHP5.5 or later.
 
 ```bash
 composer require adhocore/underscore

src/Helper.php

@@ -35,66 +35,4 @@ public static function asArray($data)
 
         return (array) $data;
     }
-
-    public static function arrayColumn($array, $columnKey, $indexKey = null)
-    {
-        $result = [];
-
-        if (!\is_array($array)) {
-            \trigger_error('array_column() expects parameter 1 to be array', E_USER_WARNING);
-
-            return;
-        }
-
-        if (null !== $columnKey) {
-            if (\is_object($columnKey) && !\method_exists($columnKey, '__toString')) {
-                \trigger_error('array_column() expects parameter 2 to be number/string/null', E_USER_WARNING);
-
-                return;
-            }
-
-            $columnKey = \is_float($columnKey) ? (int) $columnKey : (string) $columnKey;
-        }
-
-        if (null !== $indexKey) {
-            if (\is_object($indexKey) && !\method_exists($indexKey, '__toString')) {
-                \trigger_error('array_column() expects parameter 3 to be number/string/null', E_USER_WARNING);
-
-                return;
-            }
-
-            $indexKey = \is_float($indexKey) ? (int) $indexKey : (string) $indexKey;
-        }
-
-        foreach ($array as $value) {
-            $objectVars = \is_object($value) ? \get_object_vars($value) : [];
-
-            $key = null;
-            if (null !== $indexKey) {
-                if (\is_array($value) && \array_key_exists($indexKey, $value)) {
-                    $key = $value[$indexKey];
-                } elseif (\array_key_exists($indexKey, $objectVars) || isset($value->{$indexKey})) {
-                    $key = $value->{$indexKey};
-                }
-            }
-
-            if (null !== $columnKey) {
-                if (\is_array($value) && \array_key_exists($columnKey, $value)) {
-                    $value = $value[$columnKey];
-                } elseif (\array_key_exists($columnKey, $objectVars) || isset($value->{$columnKey})) {
-                    $value = $value->{$columnKey};
-                } else {
-                    continue;
-                }
-            }
-
-            if (null === $key) {
-                $result[] = $value;
-            } else {
-                $result[$key] = $value;
-            }
-        }
-
-        return $result;
-    }
 }