Route lexer/parser through optional native classes

Add a small entrypoint in load.php that swaps in WP_MySQL_Native_Lexer /
WP_MySQL_Native_Parser when a native extension has pre-declared them, and
otherwise falls back to the pure-PHP implementations shipped in this package.

The PHP lexer and parser stay where they are with their original class
names. No file moves, no polyfill renames. Native extensions plug in by
declaring WP_MySQL_Native_* before this file is loaded.

Author: adamziel

packages/mysql-on-sqlite/src/load.php

@@ -12,8 +12,24 @@
 require_once __DIR__ . '/parser/class-wp-parser-node.php';
 require_once __DIR__ . '/parser/class-wp-parser-token.php';
 require_once __DIR__ . '/mysql/class-wp-mysql-token.php';
-require_once __DIR__ . '/mysql/class-wp-mysql-lexer.php';
-require_once __DIR__ . '/mysql/class-wp-mysql-parser.php';
+
+/*
+ * The MySQL lexer and parser have an optional native (e.g. Rust) implementation.
+ * When the native extension is loaded, it pre-declares WP_MySQL_Native_Lexer /
+ * WP_MySQL_Native_Parser; otherwise we fall back to the pure-PHP classes shipped
+ * here. WP_MySQL_Lexer / WP_MySQL_Parser is the public entrypoint either way.
+ */
+if ( class_exists( 'WP_MySQL_Native_Lexer', false ) ) {
+	class WP_MySQL_Lexer extends WP_MySQL_Native_Lexer {}
+} else {
+	require_once __DIR__ . '/mysql/class-wp-mysql-lexer.php';
+}
+
+if ( class_exists( 'WP_MySQL_Native_Parser', false ) ) {
+	class WP_MySQL_Parser extends WP_MySQL_Native_Parser {}
+} else {
+	require_once __DIR__ . '/mysql/class-wp-mysql-parser.php';
+}
 require_once __DIR__ . '/sqlite/class-wp-sqlite-connection.php';
 require_once __DIR__ . '/sqlite/class-wp-sqlite-configurator.php';
 require_once __DIR__ . '/sqlite/class-wp-sqlite-driver.php';