Add support for regex strings as values

fixes #104

Author: fredemmott

src/key-value-render/HackBuilderRegexRenderer.php

@@ -0,0 +1,34 @@
+<?hh // strict
+/*
+ *  Copyright (c) 2015-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+namespace Facebook\HackCodegen\_Private;
+
+use type Facebook\HackCodegen\{IHackBuilderValueRenderer, IHackCodegenConfig};
+
+use namespace HH\Lib\{Str, Regex};
+
+final class HackBuilderRegexRenderer<T>
+  implements IHackBuilderValueRenderer<Regex\Pattern<T>> {
+
+  final public function render(
+    IHackCodegenConfig $_,
+    Regex\Pattern<T> $value,
+  ): string {
+    return 're"'.
+      Str\replace_every(
+        (string) $value,
+        dict[
+          '$' => '\\$',
+          '"' => '\\"',
+        ],
+      ).
+      '"';
+  }
+}

src/key-value-render/HackBuilderValues.php

@@ -32,6 +32,14 @@ public static function export(): IHackBuilderValueRenderer<mixed> {
     return new _Private\HackBuilderValueExportRenderer();
   }
 
+  /**
+   * Render a regex literal, e.g. `re"/foo/"`.
+   */
+  public static function regex<T>(
+  ): IHackBuilderValueRenderer<\HH\Lib\Regex\Pattern<T>> {
+    return new _Private\HackBuilderRegexRenderer();
+  }
+
   /**
    * Render a Codegen* value to code, and use it as the value.
    */

tests/HackBuilderTest.codegen

@@ -30,6 +30,10 @@ if ($do_that) {
     );
 }
 
+!@#$%codegentest:testAsValue
+dict[
+  'foo' => bar,
+]
 !@#$%codegentest:testClassnameMap
 Map {
   \Facebook\HackCodegen\HackBuilderTest::class => \stdClass::class,

tests/HackBuilderTest.php

@@ -74,7 +74,18 @@ public function testAsValue(): void {
         HackBuilderKeys::export(),
         HackBuilderValues::literal(),
       ),
-    );
+    )->getCode();
+    expect_with_context(static::class, $dict)->toBeUnchanged();
+  }
+
+  public function testRegex(): void {
+    $make_code = $re ==> $this->getHackBuilder()
+      ->addValue($re, HackBuilderValues::regex())
+      ->getCode();
+    expect($make_code(re"/foo/"))->toBeSame('re"/foo/"');
+    expect($make_code(re"/\$foo/"))->toBeSame('re"/\$foo/"');
+    expect($make_code(re"/a\"b/"))->toBeSame('re"/a\"b/"');
+    expect($make_code(re"/a?b/"))->toBeSame('re"/a?b/"');
   }
 
   public function testShapeWithUniformRendering(): void {