add LazySchemaHasher (#606)

src/DbSchema/LazySchemaHasher.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace staabm\PHPStanDba\DbSchema;
+
+class LazySchemaHasher implements SchemaHasher
+{
+    /**
+     * @var callable():SchemaHasher
+     */
+    private $schemaHasherFactory;
+
+    /**
+     * @var SchemaHasher|null
+     */
+    private $schemaHasher;
+
+    /**
+     * @param callable():SchemaHasher $schemaHasherFactory
+     */
+    public function __construct(callable $schemaHasherFactory)
+    {
+        $this->schemaHasherFactory = $schemaHasherFactory;
+    }
+
+    public function hashDb(): string
+    {
+        if (null === $this->schemaHasher) {
+            $this->schemaHasher = ($this->schemaHasherFactory)();
+        }
+
+        return $this->schemaHasher->hashDb();
+    }
+}

src/DbSchema/SchemaHasher.php

@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace staabm\PHPStanDba\DbSchema;
+
+interface SchemaHasher
+{
+    public function hashDb(): string;
+}

src/DbSchema/SchemaHasherMysql.php

@@ -8,7 +8,7 @@
 use PDO;
 use PHPStan\ShouldNotHappenException;
 
-final class SchemaHasherMysql
+final class SchemaHasherMysql implements SchemaHasher
 {
     /**
      * @var PDO|mysqli

src/QueryReflection/PdoMysqlQueryReflector.php

@@ -8,7 +8,6 @@
 use PDO;
 use PDOException;
 use PHPStan\ShouldNotHappenException;
-use PHPStan\Type\Type;
 use staabm\PHPStanDba\TypeMapping\MysqlTypeMapper;
 use staabm\PHPStanDba\TypeMapping\TypeMapper;
 

src/QueryReflection/ReplayAndRecordingQueryReflector.php

@@ -5,7 +5,7 @@
 namespace staabm\PHPStanDba\QueryReflection;
 
 use PHPStan\Type\Type;
-use staabm\PHPStanDba\DbSchema\SchemaHasherMysql;
+use staabm\PHPStanDba\DbSchema\SchemaHasher;
 use staabm\PHPStanDba\Error;
 
 final class ReplayAndRecordingQueryReflector implements QueryReflector, RecordingReflector
@@ -31,11 +31,11 @@ final class ReplayAndRecordingQueryReflector implements QueryReflector, Recordin
     private $reflectionCache;
 
     /**
-     * @var SchemaHasherMysql
+     * @var SchemaHasher
      */
     private $schemaHasher;
 
-    public function __construct(ReflectionCache $reflectionCache, QueryReflector $queryReflector, SchemaHasherMysql $schemaHasher)
+    public function __construct(ReflectionCache $reflectionCache, QueryReflector $queryReflector, SchemaHasher $schemaHasher)
     {
         $this->replayReflector = new ReplayQueryReflector($reflectionCache);