Add emitting support for asymmetric visibility

Author: thekid

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

@@ -0,0 +1,37 @@
+<?php namespace lang\ast\emit;
+
+use lang\ast\Code;
+use lang\ast\nodes\{
+  Assignment,
+  Block,
+  InstanceExpression,
+  Literal,
+  OffsetExpression,
+  ReturnStatement,
+  Variable
+};
+
+trait AsymmetricVisibility {
+
+  protected function emitProperty($result, $property) {
+    $literal= new Literal("'{$property->name}'");
+    $virtual= new InstanceExpression(new Variable('this'), new OffsetExpression(new Literal('__virtual'), $literal));
+
+    if (in_array('private(set)', $property->modifiers)) {
+      $check= (
+        '$scope= debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2)[1]["class"] ?? null;'.
+        'if (__CLASS__ !== $scope && \\lang\\VirtualProperty::class !== $scope)'.
+        'throw new \\Error("Cannot access private property ".__CLASS__."::".$name);'
+      );
+    }
+
+    $scope= $result->codegen->scope[0];
+    $scope->virtual[$property->name]= [
+      new ReturnStatement($virtual),
+      new Block([new Code($check), new Assignment($virtual, '=', new Variable('value'))]),
+    ];
+    if (isset($property->expression)) {
+      $scope->init[sprintf('$this->__virtual["%s"]', $property->name)]= $property->expression;
+    }
+  }
+}

src/main/php/lang/ast/emit/PHP81.class.php

@@ -23,9 +23,9 @@ class PHP81 extends PHP {
     RewriteBlockLambdaExpressions,
     RewriteDynamicClassConstants,
     RewriteStaticVariableInitializations,
+    RewriteProperties,
     ReadonlyClasses,
-    OmitConstantTypes,
-    PropertyHooks
+    OmitConstantTypes
   ;
 
   /** Sets up type => literal mappings */

src/main/php/lang/ast/emit/PHP82.class.php

@@ -23,9 +23,9 @@ class PHP82 extends PHP {
     RewriteBlockLambdaExpressions,
     RewriteDynamicClassConstants,
     RewriteStaticVariableInitializations,
+    RewriteProperties,
     ReadonlyClasses,
-    OmitConstantTypes,
-    PropertyHooks
+    OmitConstantTypes
   ;
 
   /** Sets up type => literal mappings */

src/main/php/lang/ast/emit/PHP83.class.php

@@ -18,7 +18,7 @@
  * @see  https://wiki.php.net/rfc#php_83
  */
 class PHP83 extends PHP {
-  use RewriteBlockLambdaExpressions, ReadonlyClasses, PropertyHooks;
+  use RewriteBlockLambdaExpressions, RewriteProperties, ReadonlyClasses;
 
   /** Sets up type => literal mappings */
   public function __construct() {

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

@@ -1,15 +1,18 @@
 <?php namespace lang\ast\emit;
 
 trait RewriteProperties {
-  use PropertyHooks, ReadonlyProperties {
+  use PropertyHooks, ReadonlyProperties, AsymmetricVisibility {
     PropertyHooks::emitProperty as emitPropertyHooks;
     ReadonlyProperties::emitProperty as emitReadonlyProperties;
+    AsymmetricVisibility::emitProperty as emitAsymmetricVisibility;
   }
 
   protected function emitProperty($result, $property) {
     if ($property->hooks) {
       return $this->emitPropertyHooks($result, $property);
-    } else if (in_array('readonly', $property->modifiers)) {
+    } else if (in_array('private(set)', $property->modifiers)) {
+      return $this->emitAsymmetricVisibility($result, $property);
+    } else if (PHP_VERSION_ID <= 80100 && in_array('readonly', $property->modifiers)) {
       return $this->emitReadonlyProperties($result, $property);
     }
     parent::emitProperty($result, $property);

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

@@ -0,0 +1,28 @@
+<?php namespace lang\ast\unittest\emit;
+
+use lang\Error;
+use test\{Assert, Expect, Test};
+
+/**
+ * Asymmetric visibility tests
+ *
+ * @see  https://wiki.php.net/rfc/asymmetric-visibility-v2
+ */
+class AsymmetricVisibilityTest extends EmittingTest {
+
+  #[Test]
+  public function reading() {
+    $t= $this->declare('class %T {
+      public private(set) $fixture= "Test";
+    }');
+    Assert::equals('Test', $t->newInstance()->fixture);
+  }
+
+  #[Test, Expect(class: Error::class, message: '/Cannot access private property T.+::fixture/')]
+  public function writing() {
+    $t= $this->declare('class %T {
+      public private(set) $fixture= "Test";
+    }');
+    $t->newInstance()->fixture= 'Changed';
+  }
+}