Handle search with on timestamp

PHRAS-689

lib/Alchemy/Phrasea/SearchEngine/Elastic/AST/KeyValue/TimestampKey.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Alchemy\Phrasea\SearchEngine\Elastic\AST\KeyValue;
+
+use Alchemy\Phrasea\SearchEngine\Elastic\Search\QueryContext;
+
+class TimestampKey implements Key
+{
+    private $type;
+    private $index_field;
+
+    public static function createdOn()
+    {
+        return new self('creation', 'created_on');
+    }
+
+    public static function updatedOn()
+    {
+        return new self('update', 'updated_on');
+    }
+
+    private function __construct($type, $index_field)
+    {
+        $this->type = $type;
+        $this->index_field = $index_field;
+    }
+
+    public function getIndexField(QueryContext $context, $raw = false)
+    {
+        return $this->index_field;
+    }
+
+    public function isValueCompatible($value, QueryContext $context)
+    {
+        return true;
+    }
+
+    public function __toString()
+    {
+        return $this->type;
+    }
+}