Merge pull request #131 from xp-framework/refactor/inline-nullable-ch…

…ecks

Inline nullable checks when casting

src/main/php/lang/ast/emit/PHP.class.php

@@ -14,7 +14,7 @@
   UnpackExpression,
   Variable
 };
-use lang\ast\types\{IsUnion, IsFunction, IsArray, IsMap};
+use lang\ast\types\{IsUnion, IsFunction, IsArray, IsMap, IsNullable};
 use lang\ast\{Emitter, Node, Type};
 
 abstract class PHP extends Emitter {
@@ -234,17 +234,26 @@ protected function emitVariable($result, $variable) {
   protected function emitCast($result, $cast) {
     static $native= ['string' => true, 'int' => true, 'float' => true, 'bool' => true, 'array' => true, 'object' => true];
 
-    $name= $cast->type->name();
-    if ('?' === $name[0]) {
-      $result->out->write('cast(');
-      $this->emitOne($result, $cast->expression);
-      $result->out->write(',\''.$name.'\', false)');
-    } else if (isset($native[$name])) {
-      $result->out->write('('.$cast->type->literal().')');
+    // Inline nullable checks using ternaries
+    if ($cast->type instanceof IsNullable) {
+      $t= $result->temp();
+      $result->out->write('null===('.$t.'=');
       $this->emitOne($result, $cast->expression);
+      $result->out->write(')?null:');
+
+      $name= $cast->type->element->name();
+      $expression= new Variable(substr($t, 1));
+    } else {
+      $name= $cast->type->name();
+      $expression= $cast->expression;
+    }
+
+    if (isset($native[$name])) {
+      $result->out->write('('.$name.')');
+      $this->emitOne($result, $expression);
     } else {
       $result->out->write('cast(');
-      $this->emitOne($result, $cast->expression);
+      $this->emitOne($result, $expression);
       $result->out->write(',\''.$name.'\')');
     }
   }

src/test/php/lang/ast/unittest/emit/CastingTest.class.php

@@ -89,6 +89,19 @@ public function run($value) {
     ));
   }
 
+  #[Test, Values([null, 'test'])]
+  public function nullable_string_cast_of_expression_returning($value) {
+    Assert::equals($value, $this->run(
+      'class <T> {
+        public function run($value) {
+          $values= [$value];
+          return (?string)array_pop($values);
+        }
+      }',
+      $value
+    ));
+  }
+
   #[Test]
   public function cast_braced() {
     Assert::equals(['test'], $this->run(