Initial SQLite development (#1)

Reviewed-on: #1

src/Mapper/StringMapper.php

@@ -0,0 +1,30 @@
+<?php declare(strict_types=1);
+
+namespace BitBadger\PDODocument\Mapper;
+
+/**
+ * Map a string result from the
+ *
+ * @implements Mapper<string>
+ */
+class StringMapper implements Mapper
+{
+    /**
+     * Constructor
+     *
+     * @param string $fieldName The name of the field to be retrieved as a string
+     */
+    public function __construct(public string $fieldName) { }
+
+    /**
+     * @inheritDoc
+     */
+    public function map(array $result): ?string
+    {
+        return match (false) {
+            key_exists($this->fieldName, $result) => null,
+            is_string($result[$this->fieldName])  => "{$result[$this->fieldName]}",
+            default                               => $result[$this->fieldName]
+        };
+    }
+}