Driver changes to support basic text searching

lib/Db/Driver.php

@@ -73,6 +73,10 @@ interface Driver {
      * 
      * - "greatest": the GREATEST function implemented by PostgreSQL and MySQL
      * - "nocase": the name of a general-purpose case-insensitive collation sequence
+     * - "like": the case-insensitive LIKE operator
      */
     public function sqlToken(string $token): string;
+
+    /** Indicates whether the implementation is capable of full-text searching */
+    public function fulltextEnabled(): bool;
 }

lib/Db/MySQL/Driver.php

@@ -212,4 +212,8 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
     public function prepareArray(string $query, array $paramTypes): \JKingWeb\Arsse\Db\Statement {
         return new Statement($this->db, $query, $paramTypes, $this->packetSize);
     }
+
+    public function fulltextEnabled(): bool {
+        return false;
+    }
 }

lib/Db/PostgreSQL/Driver.php

@@ -120,6 +120,8 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
         switch (strtolower($token)) {
             case "nocase":
                 return '"und-x-icu"';
+            case "like":
+                return "ilike";
             default:
                 return $token;
         }
@@ -219,4 +221,8 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
     public function prepareArray(string $query, array $paramTypes): \JKingWeb\Arsse\Db\Statement {
         return new Statement($this->db, $query, $paramTypes);
     }
+
+    public function fulltextEnabled(): bool {
+        return false;
+    }
 }

lib/Db/SQLite3/Driver.php

@@ -179,4 +179,8 @@ class Driver extends \JKingWeb\Arsse\Db\AbstractDriver {
         $this->exec((!$rollback) ? "COMMIT" : "ROLLBACK");
         return true;
     }
+
+    public function fulltextEnabled(): bool {
+        return false;
+    }
 }