From 12dad6b328adc643289487abb894f1057c72f0bc Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Sun, 6 Feb 2022 23:17:57 +0100
Subject: [PATCH 01/10] Move responsibility for creating result to emitter

---
 src/main/php/lang/ast/Compiled.class.php      |  9 ++----
 src/main/php/lang/ast/Emitter.class.php       | 27 ++++++++++++++++++
 src/main/php/lang/ast/Result.class.php        | 24 ++++++++++++----
 src/main/php/lang/ast/emit/PHP.class.php      | 12 +++++++-
 .../php/xp/compiler/CompileRunner.class.php   | 11 +++-----
 .../lang/ast/unittest/EmitterTest.class.php   | 20 ++++++-------
 .../lang/ast/unittest/ResultTest.class.php    | 28 +++++++++++++------
 7 files changed, 90 insertions(+), 41 deletions(-)

diff --git a/src/main/php/lang/ast/Compiled.class.php b/src/main/php/lang/ast/Compiled.class.php
index 853a3b02..82b7de6a 100755
--- a/src/main/php/lang/ast/Compiled.class.php
+++ b/src/main/php/lang/ast/Compiled.class.php
@@ -22,14 +22,9 @@ private static function language($name, $emitter) {
   }
 
   private static function parse($lang, $in, $version, $out, $file) {
-    $language= isset(self::$lang[$lang])
-      ? self::$lang[$lang]
-      : self::$lang[$lang]= self::language($lang, self::$emit[$version])
-    ;
-
+    $language= self::$lang[$lang] ?? self::$lang[$lang]= self::language($lang, self::$emit[$version]);
     try {
-      self::$emit[$version]->emitAll(new Result($out), $language->parse(new Tokens($in, $file))->stream());
-      return $out;
+      return self::$emit[$version]->write($language->parse(new Tokens($in, $file))->stream(), $out);
     } finally {
       $in->close();
     }
diff --git a/src/main/php/lang/ast/Emitter.class.php b/src/main/php/lang/ast/Emitter.class.php
index c7cc5b1a..fc89857b 100755
--- a/src/main/php/lang/ast/Emitter.class.php
+++ b/src/main/php/lang/ast/Emitter.class.php
@@ -1,5 +1,6 @@
 <?php namespace lang\ast;
 
+use io\streams\OutputStream;
 use lang\ast\{Node, Error, Errors};
 use lang\reflect\Package;
 use lang\{IllegalArgumentException, IllegalStateException, ClassLoader, XPClass};
@@ -154,4 +155,30 @@ public function emitOne($result, $node) {
     }
     $this->{'emit'.$node->kind}($result, $node);
   }
+
+  /**
+   * Creates result
+   *
+   * @param  io.streams.OutputStream $target
+   * @return lang.ast.Result
+   */
+  protected abstract function result($target);
+
+  /**
+   * Emitter entry point, takes nodes and emits them to the given target.
+   * 
+   * @param  iterable $nodes
+   * @param  io.streams.OutputStream $target
+   * @return io.streams.OutputStream
+   * @throws lang.ast.Errors
+   */
+  public function write(iterable $nodes, OutputStream $target) {
+    $result= $this->result($target);
+    try {
+      $this->emitAll($result, $nodes);
+      return $target;
+    } finally {
+      $result->close();
+    }
+  }
 }
\ No newline at end of file
diff --git a/src/main/php/lang/ast/Result.class.php b/src/main/php/lang/ast/Result.class.php
index 958145b0..23360b06 100755
--- a/src/main/php/lang/ast/Result.class.php
+++ b/src/main/php/lang/ast/Result.class.php
@@ -1,8 +1,9 @@
 <?php namespace lang\ast;
 
+use lang\Closeable;
 use lang\ast\emit\{Declaration, Reflection};
 
-class Result {
+class Result implements Closeable {
   public $out;
   public $codegen;
   public $line= 1;
@@ -10,16 +11,19 @@ class Result {
   public $locals= [];
   public $stack= [];
   public $type= [];
+  private $epilog;
 
   /**
-   * Starts a result stream, including a preamble
+   * Starts a result stream, including an optional prolog and epilog
    *
    * @param io.streams.Writer $out
-   * @param string $preamble
+   * @param string $prolog
+   * @param string $epilog
    */
-  public function __construct($out, $preamble= '<?php ') {
+  public function __construct($out, $prolog= '', $epilog= '') {
     $this->out= $out;
-    $this->out->write($preamble);
+    $this->out->write($prolog);
+    $this->epilog= $epilog;
     $this->codegen= new CodeGen();
   }
 
@@ -65,4 +69,14 @@ public function lookup($type) {
 
     return new Reflection($type);
   }
+
+  /** @return void */
+  public function close() {
+    if (null === $this->out) return;
+
+    // Write epilog, then close and ensure this doesn't happen twice
+    '' === $this->epilog || $this->out->write($this->epilog);
+    $this->out->close();
+    unset($this->out);
+  }
 }
\ No newline at end of file
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
index c0971156..8d5160d7 100755
--- a/src/main/php/lang/ast/emit/PHP.class.php
+++ b/src/main/php/lang/ast/emit/PHP.class.php
@@ -15,7 +15,7 @@
   Variable
 };
 use lang\ast\types\{IsUnion, IsFunction, IsArray, IsMap, IsNullable};
-use lang\ast\{Emitter, Node, Type};
+use lang\ast\{Emitter, Node, Type, Result};
 
 abstract class PHP extends Emitter {
   const PROPERTY = 0;
@@ -23,6 +23,16 @@ abstract class PHP extends Emitter {
 
   protected $literals= [];
 
+  /**
+   * Creates result
+   *
+   * @param  io.streams.OutputStream $target
+   * @return lang.ast.Result
+   */
+  protected function result($target) {
+    return new Result($target, '<?php ');
+  }
+
   /**
    * Emit type literal or NULL if no type should be emitted
    *
diff --git a/src/main/php/xp/compiler/CompileRunner.class.php b/src/main/php/xp/compiler/CompileRunner.class.php
index d311e920..03cc7341 100755
--- a/src/main/php/xp/compiler/CompileRunner.class.php
+++ b/src/main/php/xp/compiler/CompileRunner.class.php
@@ -65,13 +65,13 @@ private static function emitter(string $name): XPClass {
   public static function main(array $args) {
     if (empty($args)) return Usage::main($args);
 
-    $target= 'php:'.PHP_MAJOR_VERSION.'.'.PHP_MINOR_VERSION.'.'.PHP_RELEASE_VERSION;
+    $emitter= 'php:'.PHP_MAJOR_VERSION.'.'.PHP_MINOR_VERSION.'.'.PHP_RELEASE_VERSION;
     $in= $out= '-';
     $quiet= false;
     $augment= [];
     for ($i= 0; $i < sizeof($args); $i++) {
       if ('-t' === $args[$i]) {
-        $target= $args[++$i];
+        $emitter= $args[++$i];
       } else if ('-q' === $args[$i]) {
         $quiet= true;
       } else if ('-o' === $args[$i]) {
@@ -92,7 +92,7 @@ public static function main(array $args) {
     }
 
     $lang= Language::named('PHP');
-    $emit= Emitter::forRuntime($target, $augment)->newInstance();
+    $emit= Emitter::forRuntime($emitter, $augment)->newInstance();
     foreach ($lang->extensions() as $extension) {
       $extension->setup($lang, $emit);
     }
@@ -107,9 +107,7 @@ public static function main(array $args) {
       $file= $path->toString('/');
       $t->start();
       try {
-        $parse= $lang->parse(new Tokens($source, $file));
-        $target= $output->target((string)$path);
-        $emit->emitAll(new Result($target), $parse->stream());
+        $emit->write($lang->parse(new Tokens($source, $file))->stream(), $output->target((string)$path));
 
         $t->stop();
         $quiet || Console::$err->writeLinef('> %s (%.3f seconds)', $file, $t->elapsedTime());
@@ -121,7 +119,6 @@ public static function main(array $args) {
         $total++;
         $time+= $t->elapsedTime();
         $source->close();
-        $target->close();
       }
     }
 
diff --git a/src/test/php/lang/ast/unittest/EmitterTest.class.php b/src/test/php/lang/ast/unittest/EmitterTest.class.php
index 76844908..3ed5b28e 100755
--- a/src/test/php/lang/ast/unittest/EmitterTest.class.php
+++ b/src/test/php/lang/ast/unittest/EmitterTest.class.php
@@ -74,39 +74,35 @@ public function emit_node_without_kind() {
   public function transform_modifying_node() {
     $fixture= $this->newEmitter();
     $fixture->transform('variable', function($codegen, $var) { $var->name= '_'.$var->name; return $var; });
-    $out= new MemoryOutputStream();
-    $fixture->emitOne(new Result($out), new Variable('a'));
+    $out= $fixture->write([new Variable('a')], new MemoryOutputStream());
 
-    Assert::equals('<?php $_a', $out->bytes());
+    Assert::equals('<?php $_a;', $out->bytes());
   }
 
   #[Test]
   public function transform_to_node() {
     $fixture= $this->newEmitter();
     $fixture->transform('variable', function($codegen, $var) { return new Code('$variables["'.$var->name.'"]'); });
-    $out= new MemoryOutputStream();
-    $fixture->emitOne(new Result($out), new Variable('a'));
+    $out= $fixture->write([new Variable('a')], new MemoryOutputStream());
 
-    Assert::equals('<?php $variables["a"]', $out->bytes());
+    Assert::equals('<?php $variables["a"];', $out->bytes());
   }
 
   #[Test]
   public function transform_to_array() {
     $fixture= $this->newEmitter();
     $fixture->transform('variable', function($codegen, $var) { return [new Code('$variables["'.$var->name.'"]')]; });
-    $out= new MemoryOutputStream();
-    $fixture->emitOne(new Result($out), new Variable('a'));
+    $out= $fixture->write([new Variable('a')], new MemoryOutputStream());
 
-    Assert::equals('<?php $variables["a"];', $out->bytes());
+    Assert::equals('<?php $variables["a"];;', $out->bytes());
   }
 
   #[Test]
   public function transform_to_null() {
     $fixture= $this->newEmitter();
     $fixture->transform('variable', function($codegen, $var) { return null; });
-    $out= new MemoryOutputStream();
-    $fixture->emitOne(new Result($out), new Variable('a'));
+    $out= $fixture->write([new Variable('a')], new MemoryOutputStream());
 
-    Assert::equals('<?php $a', $out->bytes());
+    Assert::equals('<?php $a;', $out->bytes());
   }
 }
\ No newline at end of file
diff --git a/src/test/php/lang/ast/unittest/ResultTest.class.php b/src/test/php/lang/ast/unittest/ResultTest.class.php
index f15bf8f9..f31d72f5 100755
--- a/src/test/php/lang/ast/unittest/ResultTest.class.php
+++ b/src/test/php/lang/ast/unittest/ResultTest.class.php
@@ -21,23 +21,33 @@ public function creates_unique_temporary_variables() {
   }
 
   #[Test]
-  public function writes_php_open_tag_as_default_preamble() {
+  public function prolog_and_epilog_default_to_emtpy_strings() {
     $out= new MemoryOutputStream();
     $r= new Result(new StringWriter($out));
-    Assert::equals('<?php ', $out->bytes());
+    Assert::equals('', $out->bytes());
   }
 
   #[Test, Values(['', '<?php '])]
-  public function writes_preamble($preamble) {
+  public function writes_prolog($prolog) {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), $preamble);
-    Assert::equals($preamble, $out->bytes());
+    $r= new Result(new StringWriter($out), $prolog);
+    $r->close();
+    Assert::equals($prolog, $out->bytes());
+  }
+
+  #[Test]
+  public function writes_epilog_on_closing() {
+    $out= new MemoryOutputStream();
+    $r= new Result(new StringWriter($out), '<?php ', '?>');
+    $r->close();
+
+    Assert::equals('<?php ?>', $out->bytes());
   }
 
   #[Test]
   public function write() {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out));
+    $r= new Result(new StringWriter($out), '<?php ');
     $r->out->write('echo "Hello";');
     Assert::equals('<?php echo "Hello";', $out->bytes());
   }
@@ -45,7 +55,7 @@ public function write() {
   #[Test]
   public function write_escaped() {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out));
+    $r= new Result(new StringWriter($out), '<?php ');
 
     $r->out->write("'");
     $r->out->redirect(new Escaping($out, ["'" => "\\'"]));
@@ -102,7 +112,7 @@ public function line_number_initially_1() {
   #[Test, Values([[1, '<?php test'], [2, "<?php \ntest"], [3, "<?php \n\ntest"]])]
   public function write_at_line($line, $expected) {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out));
+    $r= new Result(new StringWriter($out), '<?php ');
     $r->at($line)->out->write('test');
 
     Assert::equals($expected, $out->bytes());
@@ -112,7 +122,7 @@ public function write_at_line($line, $expected) {
   #[Test]
   public function at_cannot_go_backwards() {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out));
+    $r= new Result(new StringWriter($out), '<?php ');
     $r->at(0)->out->write('test');
 
     Assert::equals('<?php test', $out->bytes());

From 29effe32a701a46e283aa0c646a21c44dbc5d878 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Sun, 6 Feb 2022 23:21:05 +0100
Subject: [PATCH 02/10] Restore PHP 7.0 compatibility

PHP 7.0 does not have the `iterable` type
---
 src/main/php/lang/ast/Emitter.class.php          | 2 +-
 src/main/php/xp/compiler/CompileRunner.class.php | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/main/php/lang/ast/Emitter.class.php b/src/main/php/lang/ast/Emitter.class.php
index fc89857b..2943bc76 100755
--- a/src/main/php/lang/ast/Emitter.class.php
+++ b/src/main/php/lang/ast/Emitter.class.php
@@ -172,7 +172,7 @@ protected abstract function result($target);
    * @return io.streams.OutputStream
    * @throws lang.ast.Errors
    */
-  public function write(iterable $nodes, OutputStream $target) {
+  public function write($nodes, OutputStream $target) {
     $result= $this->result($target);
     try {
       $this->emitAll($result, $nodes);
diff --git a/src/main/php/xp/compiler/CompileRunner.class.php b/src/main/php/xp/compiler/CompileRunner.class.php
index 03cc7341..4858ad20 100755
--- a/src/main/php/xp/compiler/CompileRunner.class.php
+++ b/src/main/php/xp/compiler/CompileRunner.class.php
@@ -65,13 +65,13 @@ private static function emitter(string $name): XPClass {
   public static function main(array $args) {
     if (empty($args)) return Usage::main($args);
 
-    $emitter= 'php:'.PHP_MAJOR_VERSION.'.'.PHP_MINOR_VERSION.'.'.PHP_RELEASE_VERSION;
+    $target= 'php:'.PHP_MAJOR_VERSION.'.'.PHP_MINOR_VERSION.'.'.PHP_RELEASE_VERSION;
     $in= $out= '-';
     $quiet= false;
     $augment= [];
     for ($i= 0; $i < sizeof($args); $i++) {
       if ('-t' === $args[$i]) {
-        $emitter= $args[++$i];
+        $target= $args[++$i];
       } else if ('-q' === $args[$i]) {
         $quiet= true;
       } else if ('-o' === $args[$i]) {
@@ -92,7 +92,7 @@ public static function main(array $args) {
     }
 
     $lang= Language::named('PHP');
-    $emit= Emitter::forRuntime($emitter, $augment)->newInstance();
+    $emit= Emitter::forRuntime($target, $augment)->newInstance();
     foreach ($lang->extensions() as $extension) {
       $extension->setup($lang, $emit);
     }

From fd48145e6309918456ac728666ecbf556d868e06 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Tue, 15 Feb 2022 22:10:52 +0100
Subject: [PATCH 03/10] Make lang.ast.Result a slimmer base class, extract code
 generation

---
 src/main/php/lang/ast/Result.class.php        | 42 +--------
 .../php/lang/ast/emit/GeneratedCode.class.php | 60 ++++++++++++
 src/main/php/lang/ast/emit/PHP.class.php      |  8 +-
 .../lang/ast/unittest/EmitterTest.class.php   |  5 +-
 .../lang/ast/unittest/ResultTest.class.php    | 94 +++----------------
 .../unittest/emit/EmitterTraitTest.class.php  |  5 +-
 .../ast/unittest/emit/EmittingTest.class.php  | 10 +-
 .../unittest/emit/GeneratedCodeTest.class.php | 82 ++++++++++++++++
 8 files changed, 174 insertions(+), 132 deletions(-)
 create mode 100755 src/main/php/lang/ast/emit/GeneratedCode.class.php
 create mode 100755 src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php

diff --git a/src/main/php/lang/ast/Result.class.php b/src/main/php/lang/ast/Result.class.php
index 23360b06..0b3e5175 100755
--- a/src/main/php/lang/ast/Result.class.php
+++ b/src/main/php/lang/ast/Result.class.php
@@ -1,7 +1,7 @@
 <?php namespace lang\ast;
 
+use io\streams\OutputStream;
 use lang\Closeable;
-use lang\ast\emit\{Declaration, Reflection};
 
 class Result implements Closeable {
   public $out;
@@ -11,31 +11,17 @@ class Result implements Closeable {
   public $locals= [];
   public $stack= [];
   public $type= [];
-  private $epilog;
 
   /**
    * Starts a result stream, including an optional prolog and epilog
    *
-   * @param io.streams.Writer $out
-   * @param string $prolog
-   * @param string $epilog
+   * @param io.streams.OutputStream $out
    */
-  public function __construct($out, $prolog= '', $epilog= '') {
+  public function __construct(OutputStream $out) {
     $this->out= $out;
-    $this->out->write($prolog);
-    $this->epilog= $epilog;
     $this->codegen= new CodeGen();
   }
 
-  /**
-   * Creates a temporary variable and returns its name
-   *
-   * @return string
-   */
-  public function temp() {
-    return '$'.$this->codegen->symbol();
-  }
-
   /**
    * Forwards output line to given line number
    *
@@ -50,32 +36,10 @@ public function at($line) {
     return $this;
   }
 
-  /**
-   * Looks up a given type 
-   *
-   * @param  string $type
-   * @return lang.ast.emit.Type
-   */
-  public function lookup($type) {
-    if ('self' === $type || 'static' === $type) {
-      return new Declaration($this->type[0], $this);
-    } else if ('parent' === $type) {
-      return $this->lookup($this->type[0]->parent);
-    }
-
-    foreach ($this->type as $enclosing) {
-      if ($type === $enclosing->name) return new Declaration($enclosing, $this);
-    }
-
-    return new Reflection($type);
-  }
-
   /** @return void */
   public function close() {
     if (null === $this->out) return;
 
-    // Write epilog, then close and ensure this doesn't happen twice
-    '' === $this->epilog || $this->out->write($this->epilog);
     $this->out->close();
     unset($this->out);
   }
diff --git a/src/main/php/lang/ast/emit/GeneratedCode.class.php b/src/main/php/lang/ast/emit/GeneratedCode.class.php
new file mode 100755
index 00000000..f986b502
--- /dev/null
+++ b/src/main/php/lang/ast/emit/GeneratedCode.class.php
@@ -0,0 +1,60 @@
+<?php namespace lang\ast\emit;
+
+use lang\ast\Result;
+
+class GeneratedCode extends Result {
+  private $epilog;
+
+  /**
+   * Starts a result stream, including an optional prolog and epilog
+   *
+   * @param io.streams.OutputStream $out
+   * @param string $prolog
+   * @param string $epilog
+   */
+  public function __construct($out, $prolog= '', $epilog= '') {
+    parent::__construct($out);
+
+    $out->write($prolog);
+    $this->epilog= $epilog;
+  }
+
+  /**
+   * Creates a temporary variable and returns its name
+   *
+   * @return string
+   */
+  public function temp() {
+    return '$'.$this->codegen->symbol();
+  }
+
+  /**
+   * Looks up a given type 
+   *
+   * @param  string $type
+   * @return lang.ast.emit.Type
+   */
+  public function lookup($type) {
+    if ('self' === $type || 'static' === $type) {
+      return new Declaration($this->type[0], $this);
+    } else if ('parent' === $type) {
+      return $this->lookup($this->type[0]->parent);
+    }
+
+    foreach ($this->type as $enclosing) {
+      if ($type === $enclosing->name) return new Declaration($enclosing, $this);
+    }
+
+    return new Reflection($type);
+  }
+
+  /** @return void */
+  public function close() {
+    if (null === $this->out) return;
+
+    // Write epilog, then close and ensure this doesn't happen twice
+    '' === $this->epilog || $this->out->write($this->epilog);
+    $this->out->close();
+    unset($this->out);
+  }
+}
\ No newline at end of file
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
index 8d5160d7..0e401e86 100755
--- a/src/main/php/lang/ast/emit/PHP.class.php
+++ b/src/main/php/lang/ast/emit/PHP.class.php
@@ -30,7 +30,7 @@ abstract class PHP extends Emitter {
    * @return lang.ast.Result
    */
   protected function result($target) {
-    return new Result($target, '<?php ');
+    return new GeneratedCode($target, '<?php ');
   }
 
   /**
@@ -463,8 +463,8 @@ protected function emitAnnotation($result, $annotation) {
 
       // Found first non-constant argument, enclose in `eval`
       $result->out->write('(eval: \'');
-      $out= $result->out->stream();
-      $result->out->redirect(new Escaping($out, ["'" => "\\'", '\\' => '\\\\']));
+      $out= $result->out;
+      $result->out= new Escaping($out, ["'" => "\\'", '\\' => '\\\\']);
 
       // If exactly one unnamed argument exists, emit its value directly
       if (1 === sizeof($annotation->arguments) && 0 === key($annotation->arguments)) {
@@ -479,7 +479,7 @@ protected function emitAnnotation($result, $annotation) {
         $result->out->write(']');
       }
 
-      $result->out->redirect($out);
+      $result->out= $out;
       $result->out->write('\')');
       return;
     }
diff --git a/src/test/php/lang/ast/unittest/EmitterTest.class.php b/src/test/php/lang/ast/unittest/EmitterTest.class.php
index 3ed5b28e..e4c4476f 100755
--- a/src/test/php/lang/ast/unittest/EmitterTest.class.php
+++ b/src/test/php/lang/ast/unittest/EmitterTest.class.php
@@ -65,9 +65,10 @@ public function remove_unsets_empty_kind() {
 
   #[Test, Expect(IllegalStateException::class)]
   public function emit_node_without_kind() {
-    $this->newEmitter()->emitOne(new Result(new MemoryOutputStream()), new class() extends Node {
+    $node= new class() extends Node {
       public $kind= null;
-    });
+    };
+    $this->newEmitter()->write([$node], new MemoryOutputStream());
   }
 
   #[Test]
diff --git a/src/test/php/lang/ast/unittest/ResultTest.class.php b/src/test/php/lang/ast/unittest/ResultTest.class.php
index f31d72f5..3ded288c 100755
--- a/src/test/php/lang/ast/unittest/ResultTest.class.php
+++ b/src/test/php/lang/ast/unittest/ResultTest.class.php
@@ -1,6 +1,6 @@
 <?php namespace lang\ast\unittest;
 
-use io\streams\{StringWriter, MemoryOutputStream};
+use io\streams\MemoryOutputStream;
 use lang\ast\Result;
 use lang\ast\emit\{Declaration, Escaping, Reflection};
 use lang\ast\nodes\ClassDeclaration;
@@ -11,108 +11,42 @@ class ResultTest {
 
   #[Test]
   public function can_create() {
-    new Result(new StringWriter(new MemoryOutputStream()));
-  }
-
-  #[Test]
-  public function creates_unique_temporary_variables() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
-    Assert::equals(['$_0', '$_1', '$_2'], [$r->temp(), $r->temp(), $r->temp()]);
-  }
-
-  #[Test]
-  public function prolog_and_epilog_default_to_emtpy_strings() {
-    $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out));
-    Assert::equals('', $out->bytes());
-  }
-
-  #[Test, Values(['', '<?php '])]
-  public function writes_prolog($prolog) {
-    $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), $prolog);
-    $r->close();
-    Assert::equals($prolog, $out->bytes());
-  }
-
-  #[Test]
-  public function writes_epilog_on_closing() {
-    $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), '<?php ', '?>');
-    $r->close();
-
-    Assert::equals('<?php ?>', $out->bytes());
+    new Result(new MemoryOutputStream());
   }
 
   #[Test]
   public function write() {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), '<?php ');
+    $r= new Result($out);
     $r->out->write('echo "Hello";');
-    Assert::equals('<?php echo "Hello";', $out->bytes());
+    Assert::equals('echo "Hello";', $out->bytes());
   }
 
   #[Test]
   public function write_escaped() {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), '<?php ');
+    $r= new Result($out);
 
     $r->out->write("'");
-    $r->out->redirect(new Escaping($out, ["'" => "\\'"]));
+    $r->out= new Escaping($out, ["'" => "\\'"]);
     $r->out->write("echo 'Hello'");
-    $r->out->redirect($out);
-    $r->out->write("'");
-
-    Assert::equals("<?php 'echo \'Hello\''", $out->bytes());
-  }
-
-  #[Test]
-  public function lookup_self() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
-    $r->type[0]= new ClassDeclaration([], '\\T', null, [], [], null, null, 1);
-
-    Assert::equals(new Declaration($r->type[0], $r), $r->lookup('self'));
-  }
-
-  #[Test]
-  public function lookup_parent() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
-    $r->type[0]= new ClassDeclaration([], '\\T', '\\lang\\Value', [], [], null, null, 1);
-
-    Assert::equals(new Reflection(Value::class), $r->lookup('parent'));
-  }
 
-  #[Test]
-  public function lookup_named() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
-    $r->type[0]= new ClassDeclaration([], '\\T', null, [], [], null, null, 1);
-
-    Assert::equals(new Declaration($r->type[0], $r), $r->lookup('\\T'));
-  }
-
-  #[Test]
-  public function lookup_value_interface() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
-
-    Assert::equals(new Reflection(Value::class), $r->lookup('\\lang\\Value'));
-  }
+    $r->out= $out;
+    $r->out->write("'");
 
-  #[Test, Expect(ClassNotFoundException::class)]
-  public function lookup_non_existant() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
-    $r->lookup('\\NotFound');
+    Assert::equals("'echo \'Hello\''", $out->bytes());
   }
 
   #[Test]
   public function line_number_initially_1() {
-    $r= new Result(new StringWriter(new MemoryOutputStream()));
+    $r= new Result(new MemoryOutputStream());
     Assert::equals(1, $r->line);
   }
 
-  #[Test, Values([[1, '<?php test'], [2, "<?php \ntest"], [3, "<?php \n\ntest"]])]
+  #[Test, Values([[1, 'test'], [2, "\ntest"], [3, "\n\ntest"]])]
   public function write_at_line($line, $expected) {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), '<?php ');
+    $r= new Result($out);
     $r->at($line)->out->write('test');
 
     Assert::equals($expected, $out->bytes());
@@ -122,10 +56,10 @@ public function write_at_line($line, $expected) {
   #[Test]
   public function at_cannot_go_backwards() {
     $out= new MemoryOutputStream();
-    $r= new Result(new StringWriter($out), '<?php ');
+    $r= new Result($out);
     $r->at(0)->out->write('test');
 
-    Assert::equals('<?php test', $out->bytes());
+    Assert::equals('test', $out->bytes());
     Assert::equals(1, $r->line);
   }
 }
\ No newline at end of file
diff --git a/src/test/php/lang/ast/unittest/emit/EmitterTraitTest.class.php b/src/test/php/lang/ast/unittest/emit/EmitterTraitTest.class.php
index 722aca93..620eed0a 100755
--- a/src/test/php/lang/ast/unittest/emit/EmitterTraitTest.class.php
+++ b/src/test/php/lang/ast/unittest/emit/EmitterTraitTest.class.php
@@ -1,7 +1,8 @@
 <?php namespace lang\ast\unittest\emit;
 
 use io\streams\MemoryOutputStream;
-use lang\ast\{Node, Result};
+use lang\ast\Node;
+use lang\ast\emit\GeneratedCode;
 use unittest\Before;
 
 abstract class EmitterTraitTest {
@@ -9,7 +10,7 @@ abstract class EmitterTraitTest {
 
   /** Emits a node and returns the emitted code */
   protected function emit(Node $node, array $type= []): string {
-    $result= new Result(new MemoryOutputStream(), '');
+    $result= new GeneratedCode(new MemoryOutputStream(), '');
     $result->type= $type;
 
     $this->emitter->emitOne($result, $node);
diff --git a/src/test/php/lang/ast/unittest/emit/EmittingTest.class.php b/src/test/php/lang/ast/unittest/emit/EmittingTest.class.php
index d1073736..594f9532 100755
--- a/src/test/php/lang/ast/unittest/emit/EmittingTest.class.php
+++ b/src/test/php/lang/ast/unittest/emit/EmittingTest.class.php
@@ -1,7 +1,8 @@
 <?php namespace lang\ast\unittest\emit;
 
-use io\streams\{MemoryOutputStream, StringWriter};
+use io\streams\MemoryOutputStream;
 use lang\DynamicClassLoader;
+use lang\ast\emit\GeneratedCode;
 use lang\ast\emit\php\XpMeta;
 use lang\ast\{CompilingClassLoader, Emitter, Language, Result, Tokens};
 use unittest\{After, Assert, TestCase};
@@ -63,7 +64,7 @@ protected function emit($code) {
     $tree= $this->language->parse(new Tokens(str_replace('<T>', $name, $code), static::class))->tree();
 
     $out= new MemoryOutputStream();
-    $this->emitter->emitAll(new Result(new StringWriter($out), ''), $tree->children());
+    $this->emitter->emitAll(new GeneratedCode($out, ''), $tree->children());
     return $out->bytes();
   }
 
@@ -75,8 +76,6 @@ protected function emit($code) {
    */
   protected function type($code) {
     $name= 'T'.(self::$id++);
-    $out= new MemoryOutputStream();
-
     $tree= $this->language->parse(new Tokens(str_replace('<T>', $name, $code), static::class))->tree();
     if (isset($this->output['ast'])) {
       Console::writeLine();
@@ -84,7 +83,8 @@ protected function type($code) {
       Console::writeLine($tree);
     }
 
-    $this->emitter->emitAll(new Result(new StringWriter($out), ''), $tree->children());
+    $out= new MemoryOutputStream();
+    $this->emitter->emitAll(new GeneratedCode($out, ''), $tree->children());
     if (isset($this->output['code'])) {
       Console::writeLine();
       Console::writeLine('=== ', static::class, ' ===');
diff --git a/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php b/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php
new file mode 100755
index 00000000..2c91574b
--- /dev/null
+++ b/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php
@@ -0,0 +1,82 @@
+<?php namespace lang\ast\unittest\emit;
+
+use io\streams\MemoryOutputStream;
+use lang\ast\emit\{GeneratedCode, Declaration, Escaping, Reflection};
+use lang\ast\nodes\ClassDeclaration;
+use lang\{Value, ClassNotFoundException};
+use unittest\{Assert, Expect, Test};
+
+class GeneratedCodeTest {
+
+  #[Test]
+  public function can_create() {
+    new GeneratedCode(new MemoryOutputStream());
+  }
+
+  #[Test]
+  public function creates_unique_temporary_variables() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+    Assert::equals(['$_0', '$_1', '$_2'], [$r->temp(), $r->temp(), $r->temp()]);
+  }
+
+  #[Test]
+  public function prolog_and_epilog_default_to_emtpy_strings() {
+    $out= new MemoryOutputStream();
+    $r= new GeneratedCode($out);
+    Assert::equals('', $out->bytes());
+  }
+
+  #[Test, Values(['', '<?php '])]
+  public function writes_prolog($prolog) {
+    $out= new MemoryOutputStream();
+    $r= new GeneratedCode($out, $prolog);
+    $r->close();
+    Assert::equals($prolog, $out->bytes());
+  }
+
+  #[Test]
+  public function writes_epilog_on_closing() {
+    $out= new MemoryOutputStream();
+    $r= new GeneratedCode($out, '<?php ', '?>');
+    $r->close();
+
+    Assert::equals('<?php ?>', $out->bytes());
+  }
+
+  #[Test]
+  public function lookup_self() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+    $r->type[0]= new ClassDeclaration([], '\\T', null, [], [], null, null, 1);
+
+    Assert::equals(new Declaration($r->type[0], $r), $r->lookup('self'));
+  }
+
+  #[Test]
+  public function lookup_parent() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+    $r->type[0]= new ClassDeclaration([], '\\T', '\\lang\\Value', [], [], null, null, 1);
+
+    Assert::equals(new Reflection(Value::class), $r->lookup('parent'));
+  }
+
+  #[Test]
+  public function lookup_named() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+    $r->type[0]= new ClassDeclaration([], '\\T', null, [], [], null, null, 1);
+
+    Assert::equals(new Declaration($r->type[0], $r), $r->lookup('\\T'));
+  }
+
+  #[Test]
+  public function lookup_value_interface() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+
+    Assert::equals(new Reflection(Value::class), $r->lookup('\\lang\\Value'));
+  }
+
+  #[Test, Expect(ClassNotFoundException::class)]
+  public function lookup_non_existant() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+    $r->lookup('\\NotFound');
+  }
+}
\ No newline at end of file

From 6ba6343c167d58611ea6b2a15aec5fe998f6d5c6 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Wed, 16 Feb 2022 18:09:40 +0100
Subject: [PATCH 04/10] Fix PHP 7 compatibility

---
 src/main/php/lang/ast/emit/AttributesAsComments.class.php | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/php/lang/ast/emit/AttributesAsComments.class.php b/src/main/php/lang/ast/emit/AttributesAsComments.class.php
index 2b3cd209..5282490b 100755
--- a/src/main/php/lang/ast/emit/AttributesAsComments.class.php
+++ b/src/main/php/lang/ast/emit/AttributesAsComments.class.php
@@ -33,13 +33,13 @@ protected function emitAnnotations($result, $annotations) {
     $line= $annotations->line;
     $result->out->write('#[');
 
-    $out= $result->out->stream();
-    $result->out->redirect(new Escaping($out, ["\n" => " "]));
+    $out= $result->out;
+    $result->out= new Escaping($out, ["\n" => " "]);
     foreach ($annotations->named as $annotation) {
       $this->emitOne($result, $annotation);
       $result->out->write(',');
     }
-    $result->out->redirect($out);
+    $result->out= $out;
 
     $result->out->write("]\n");
     $result->line= $line + 1;

From 00687835ee10dc54218af4943003c2dcb1ac0304 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Wed, 16 Feb 2022 18:12:53 +0100
Subject: [PATCH 05/10] Remove need for temporary variables

---
 src/main/php/lang/ast/emit/AttributesAsComments.class.php | 5 ++---
 src/main/php/lang/ast/emit/Escaping.class.php             | 4 ++++
 src/main/php/lang/ast/emit/PHP.class.php                  | 5 ++---
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/main/php/lang/ast/emit/AttributesAsComments.class.php b/src/main/php/lang/ast/emit/AttributesAsComments.class.php
index 5282490b..8870790c 100755
--- a/src/main/php/lang/ast/emit/AttributesAsComments.class.php
+++ b/src/main/php/lang/ast/emit/AttributesAsComments.class.php
@@ -33,13 +33,12 @@ protected function emitAnnotations($result, $annotations) {
     $line= $annotations->line;
     $result->out->write('#[');
 
-    $out= $result->out;
-    $result->out= new Escaping($out, ["\n" => " "]);
+    $result->out= new Escaping($result->out, ["\n" => " "]);
     foreach ($annotations->named as $annotation) {
       $this->emitOne($result, $annotation);
       $result->out->write(',');
     }
-    $result->out= $out;
+    $result->out= $result->out->original();
 
     $result->out->write("]\n");
     $result->line= $line + 1;
diff --git a/src/main/php/lang/ast/emit/Escaping.class.php b/src/main/php/lang/ast/emit/Escaping.class.php
index cf3685fa..e096035f 100755
--- a/src/main/php/lang/ast/emit/Escaping.class.php
+++ b/src/main/php/lang/ast/emit/Escaping.class.php
@@ -21,4 +21,8 @@ public function flush() {
   public function close() {
     $this->target->close();
   }
+
+  public function original() {
+    return $this->target;
+  }
 }
\ No newline at end of file
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
index 0e401e86..cf0c0628 100755
--- a/src/main/php/lang/ast/emit/PHP.class.php
+++ b/src/main/php/lang/ast/emit/PHP.class.php
@@ -463,8 +463,7 @@ protected function emitAnnotation($result, $annotation) {
 
       // Found first non-constant argument, enclose in `eval`
       $result->out->write('(eval: \'');
-      $out= $result->out;
-      $result->out= new Escaping($out, ["'" => "\\'", '\\' => '\\\\']);
+      $result->out= new Escaping($result->out, ["'" => "\\'", '\\' => '\\\\']);
 
       // If exactly one unnamed argument exists, emit its value directly
       if (1 === sizeof($annotation->arguments) && 0 === key($annotation->arguments)) {
@@ -479,7 +478,7 @@ protected function emitAnnotation($result, $annotation) {
         $result->out->write(']');
       }
 
-      $result->out= $out;
+      $result->out= $result->out->original();
       $result->out->write('\')');
       return;
     }

From e3470da2fba4b80f2df34bec9edcdeea0be8db48 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Thu, 17 Feb 2022 19:51:00 +0100
Subject: [PATCH 06/10] Move at() to GeneratedCode class

---
 src/main/php/lang/ast/Result.class.php        | 17 ++++-------
 .../php/lang/ast/emit/GeneratedCode.class.php | 29 ++++++++++++++-----
 .../lang/ast/unittest/ResultTest.class.php    | 26 -----------------
 .../unittest/emit/GeneratedCodeTest.class.php | 26 +++++++++++++++++
 4 files changed, 54 insertions(+), 44 deletions(-)

diff --git a/src/main/php/lang/ast/Result.class.php b/src/main/php/lang/ast/Result.class.php
index 0b3e5175..e3a8978c 100755
--- a/src/main/php/lang/ast/Result.class.php
+++ b/src/main/php/lang/ast/Result.class.php
@@ -6,11 +6,9 @@
 class Result implements Closeable {
   public $out;
   public $codegen;
-  public $line= 1;
   public $meta= [];
   public $locals= [];
   public $stack= [];
-  public $type= [];
 
   /**
    * Starts a result stream, including an optional prolog and epilog
@@ -23,23 +21,20 @@ public function __construct(OutputStream $out) {
   }
 
   /**
-   * Forwards output line to given line number
+   * Finalize result. Guaranteed to be called *once* from within `close()`.
+   * Without implementation here - overwrite in subclasses.
    *
-   * @param  int $line
-   * @return self
+   * @return void
    */
-  public function at($line) {
-    if ($line > $this->line) {
-      $this->out->write(str_repeat("\n", $line - $this->line));
-      $this->line= $line;
-    }
-    return $this;
+  protected function finalize() {
+    // NOOP
   }
 
   /** @return void */
   public function close() {
     if (null === $this->out) return;
 
+    $this->finalize();
     $this->out->close();
     unset($this->out);
   }
diff --git a/src/main/php/lang/ast/emit/GeneratedCode.class.php b/src/main/php/lang/ast/emit/GeneratedCode.class.php
index f986b502..6d4fad51 100755
--- a/src/main/php/lang/ast/emit/GeneratedCode.class.php
+++ b/src/main/php/lang/ast/emit/GeneratedCode.class.php
@@ -4,6 +4,8 @@
 
 class GeneratedCode extends Result {
   private $epilog;
+  public $line= 1;
+  public $type= [];
 
   /**
    * Starts a result stream, including an optional prolog and epilog
@@ -19,6 +21,20 @@ public function __construct($out, $prolog= '', $epilog= '') {
     $this->epilog= $epilog;
   }
 
+  /**
+   * Forwards output line to given line number
+   *
+   * @param  int $line
+   * @return self
+   */
+  public function at($line) {
+    if ($line > $this->line) {
+      $this->out->write(str_repeat("\n", $line - $this->line));
+      $this->line= $line;
+    }
+    return $this;
+  }
+
   /**
    * Creates a temporary variable and returns its name
    *
@@ -48,13 +64,12 @@ public function lookup($type) {
     return new Reflection($type);
   }
 
-  /** @return void */
-  public function close() {
-    if (null === $this->out) return;
-
-    // Write epilog, then close and ensure this doesn't happen twice
+  /**
+   * Write epilog
+   *
+   * @return void
+   */
+  protected function finalize() {
     '' === $this->epilog || $this->out->write($this->epilog);
-    $this->out->close();
-    unset($this->out);
   }
 }
\ No newline at end of file
diff --git a/src/test/php/lang/ast/unittest/ResultTest.class.php b/src/test/php/lang/ast/unittest/ResultTest.class.php
index 3ded288c..3847680c 100755
--- a/src/test/php/lang/ast/unittest/ResultTest.class.php
+++ b/src/test/php/lang/ast/unittest/ResultTest.class.php
@@ -36,30 +36,4 @@ public function write_escaped() {
 
     Assert::equals("'echo \'Hello\''", $out->bytes());
   }
-
-  #[Test]
-  public function line_number_initially_1() {
-    $r= new Result(new MemoryOutputStream());
-    Assert::equals(1, $r->line);
-  }
-
-  #[Test, Values([[1, 'test'], [2, "\ntest"], [3, "\n\ntest"]])]
-  public function write_at_line($line, $expected) {
-    $out= new MemoryOutputStream();
-    $r= new Result($out);
-    $r->at($line)->out->write('test');
-
-    Assert::equals($expected, $out->bytes());
-    Assert::equals($line, $r->line);
-  }
-
-  #[Test]
-  public function at_cannot_go_backwards() {
-    $out= new MemoryOutputStream();
-    $r= new Result($out);
-    $r->at(0)->out->write('test');
-
-    Assert::equals('test', $out->bytes());
-    Assert::equals(1, $r->line);
-  }
 }
\ No newline at end of file
diff --git a/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php b/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php
index 2c91574b..3d1ed780 100755
--- a/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php
+++ b/src/test/php/lang/ast/unittest/emit/GeneratedCodeTest.class.php
@@ -79,4 +79,30 @@ public function lookup_non_existant() {
     $r= new GeneratedCode(new MemoryOutputStream());
     $r->lookup('\\NotFound');
   }
+
+  #[Test]
+  public function line_number_initially_1() {
+    $r= new GeneratedCode(new MemoryOutputStream());
+    Assert::equals(1, $r->line);
+  }
+
+  #[Test, Values([[1, 'test'], [2, "\ntest"], [3, "\n\ntest"]])]
+  public function write_at_line($line, $expected) {
+    $out= new MemoryOutputStream();
+    $r= new GeneratedCode($out);
+    $r->at($line)->out->write('test');
+
+    Assert::equals($expected, $out->bytes());
+    Assert::equals($line, $r->line);
+  }
+
+  #[Test]
+  public function at_cannot_go_backwards() {
+    $out= new MemoryOutputStream();
+    $r= new GeneratedCode($out);
+    $r->at(0)->out->write('test');
+
+    Assert::equals('test', $out->bytes());
+    Assert::equals(1, $r->line);
+  }
 }
\ No newline at end of file

From 91850eb9364a8fa078fcf33aa82aa7019d57efcf Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Thu, 17 Feb 2022 19:52:07 +0100
Subject: [PATCH 07/10] Move Result class to lang.ast.emit

---
 src/main/php/lang/ast/emit/GeneratedCode.class.php  | 2 --
 src/main/php/lang/ast/{ => emit}/Result.class.php   | 3 ++-
 src/test/php/lang/ast/unittest/ResultTest.class.php | 3 +--
 3 files changed, 3 insertions(+), 5 deletions(-)
 rename src/main/php/lang/ast/{ => emit}/Result.class.php (93%)

diff --git a/src/main/php/lang/ast/emit/GeneratedCode.class.php b/src/main/php/lang/ast/emit/GeneratedCode.class.php
index 6d4fad51..2950ac45 100755
--- a/src/main/php/lang/ast/emit/GeneratedCode.class.php
+++ b/src/main/php/lang/ast/emit/GeneratedCode.class.php
@@ -1,7 +1,5 @@
 <?php namespace lang\ast\emit;
 
-use lang\ast\Result;
-
 class GeneratedCode extends Result {
   private $epilog;
   public $line= 1;
diff --git a/src/main/php/lang/ast/Result.class.php b/src/main/php/lang/ast/emit/Result.class.php
similarity index 93%
rename from src/main/php/lang/ast/Result.class.php
rename to src/main/php/lang/ast/emit/Result.class.php
index e3a8978c..8562d688 100755
--- a/src/main/php/lang/ast/Result.class.php
+++ b/src/main/php/lang/ast/emit/Result.class.php
@@ -1,7 +1,8 @@
-<?php namespace lang\ast;
+<?php namespace lang\ast\emit;
 
 use io\streams\OutputStream;
 use lang\Closeable;
+use lang\ast\CodeGen;
 
 class Result implements Closeable {
   public $out;
diff --git a/src/test/php/lang/ast/unittest/ResultTest.class.php b/src/test/php/lang/ast/unittest/ResultTest.class.php
index 3847680c..c0ff9ed0 100755
--- a/src/test/php/lang/ast/unittest/ResultTest.class.php
+++ b/src/test/php/lang/ast/unittest/ResultTest.class.php
@@ -1,8 +1,7 @@
 <?php namespace lang\ast\unittest;
 
 use io\streams\MemoryOutputStream;
-use lang\ast\Result;
-use lang\ast\emit\{Declaration, Escaping, Reflection};
+use lang\ast\emit\{Result, Declaration, Escaping, Reflection};
 use lang\ast\nodes\ClassDeclaration;
 use lang\{Value, ClassNotFoundException};
 use unittest\{Assert, Expect, Test};

From bf8353f240c228d97fe5bfe9c997c6b8e280e179 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Thu, 17 Feb 2022 20:04:24 +0100
Subject: [PATCH 08/10] Move output line positioning to GeneratedCode class

---
 src/main/php/lang/ast/Emitter.class.php  | 11 +++--------
 src/main/php/lang/ast/emit/PHP.class.php | 11 +++++++++++
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/main/php/lang/ast/Emitter.class.php b/src/main/php/lang/ast/Emitter.class.php
index 2943bc76..148dd1e9 100755
--- a/src/main/php/lang/ast/Emitter.class.php
+++ b/src/main/php/lang/ast/Emitter.class.php
@@ -129,23 +129,17 @@ public function emitAll($result, $nodes) {
    */
   public function emitOne($result, $node) {
 
-    // Inlined Result::at()
-    if ($node->line > $result->line) {
-      $result->out->write(str_repeat("\n", $node->line - $result->line));
-      $result->line= $node->line;
-    }
-
     // Check for transformations
     if (isset($this->transformations[$node->kind])) {
       foreach ($this->transformations[$node->kind] as $transformation) {
         $r= $transformation($result->codegen, $node);
         if ($r instanceof Node) {
           if ($r->kind === $node->kind) continue;
-          $this->{"emit{$r->kind}"}($result, $r);
+          $this->{'emit'.$r->kind}($result, $r);
           return;
         } else if ($r) {
           foreach ($r as $n) {
-            $this->{"emit{$n->kind}"}($result, $n);
+            $this->{'emit'.$n->kind}($result, $n);
             $result->out->write(';');
           }
           return;
@@ -153,6 +147,7 @@ public function emitOne($result, $node) {
       }
       // Fall through, use default
     }
+
     $this->{'emit'.$node->kind}($result, $node);
   }
 
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
index cf0c0628..e67ab4da 100755
--- a/src/main/php/lang/ast/emit/PHP.class.php
+++ b/src/main/php/lang/ast/emit/PHP.class.php
@@ -1034,4 +1034,15 @@ protected function emitFrom($result, $from) {
     $result->out->write('yield from ');
     $this->emitOne($result, $from->iterable);
   }
+
+  /**
+   * Emit single nodes
+   *
+   * @param  lang.ast.Result $result
+   * @param  lang.ast.Node $node
+   * @return void
+   */
+  public function emitOne($result, $node) {
+    parent::emitOne($result->at($node->line), $node);
+  }
 }
\ No newline at end of file

From ba39d7f7a31a8a29fde8100ff461476a9e0e1134 Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Thu, 17 Feb 2022 20:12:28 +0100
Subject: [PATCH 09/10] Add Result::initialize()

---
 .../php/lang/ast/emit/GeneratedCode.class.php | 33 ++++++++++++-------
 src/main/php/lang/ast/emit/Result.class.php   | 13 +++++++-
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/src/main/php/lang/ast/emit/GeneratedCode.class.php b/src/main/php/lang/ast/emit/GeneratedCode.class.php
index 2950ac45..8fbe4d27 100755
--- a/src/main/php/lang/ast/emit/GeneratedCode.class.php
+++ b/src/main/php/lang/ast/emit/GeneratedCode.class.php
@@ -1,7 +1,7 @@
 <?php namespace lang\ast\emit;
 
 class GeneratedCode extends Result {
-  private $epilog;
+  private $prolog, $epilog;
   public $line= 1;
   public $type= [];
 
@@ -13,10 +13,28 @@ class GeneratedCode extends Result {
    * @param string $epilog
    */
   public function __construct($out, $prolog= '', $epilog= '') {
+    $this->prolog= $prolog;
+    $this->epilog= $epilog;
     parent::__construct($out);
+  }
 
-    $out->write($prolog);
-    $this->epilog= $epilog;
+  /**
+   * Initialize result. Guaranteed to be called *once* from constructor.
+   * Without implementation here - overwrite in subclasses.
+   *
+   * @return void
+   */
+  protected function initialize() {
+    '' === $this->prolog || $this->out->write($this->prolog);
+  }
+
+  /**
+   * Write epilog
+   *
+   * @return void
+   */
+  protected function finalize() {
+    '' === $this->epilog || $this->out->write($this->epilog);
   }
 
   /**
@@ -61,13 +79,4 @@ public function lookup($type) {
 
     return new Reflection($type);
   }
-
-  /**
-   * Write epilog
-   *
-   * @return void
-   */
-  protected function finalize() {
-    '' === $this->epilog || $this->out->write($this->epilog);
-  }
 }
\ No newline at end of file
diff --git a/src/main/php/lang/ast/emit/Result.class.php b/src/main/php/lang/ast/emit/Result.class.php
index 8562d688..a9b7dd58 100755
--- a/src/main/php/lang/ast/emit/Result.class.php
+++ b/src/main/php/lang/ast/emit/Result.class.php
@@ -12,13 +12,24 @@ class Result implements Closeable {
   public $stack= [];
 
   /**
-   * Starts a result stream, including an optional prolog and epilog
+   * Starts a result stream.
    *
    * @param io.streams.OutputStream $out
    */
   public function __construct(OutputStream $out) {
     $this->out= $out;
     $this->codegen= new CodeGen();
+    $this->initialize();
+  }
+
+  /**
+   * Initialize result. Guaranteed to be called *once* from constructor.
+   * Without implementation here - overwrite in subclasses.
+   *
+   * @return void
+   */
+  protected function initialize() {
+    // NOOP
   }
 
   /**

From 192ac0948a2ed732797039206adabae8bacfd3cc Mon Sep 17 00:00:00 2001
From: Timm Friebe <thekid@thekid.de>
Date: Sat, 7 May 2022 12:11:13 +0200
Subject: [PATCH 10/10] MFH

---
 .../lang/ast/unittest/EmitterTest.class.php   | 27 ++++++++++---------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/test/php/lang/ast/unittest/EmitterTest.class.php b/src/test/php/lang/ast/unittest/EmitterTest.class.php
index 87b1a7fc..347ff56e 100755
--- a/src/test/php/lang/ast/unittest/EmitterTest.class.php
+++ b/src/test/php/lang/ast/unittest/EmitterTest.class.php
@@ -109,19 +109,20 @@ public function transform_to_null() {
 
   #[Test]
   public function emit_multiline_comment() {
-    $fixture= $this->newEmitter();
-    $out= new MemoryOutputStream();
-    $fixture->emitAll(new Result($out), [
-      new Comment(
-        "/**\n".
-        " * Doc comment\n".
-        " *\n".
-        " * @see http://example.com/\n".
-        " */",
-        3
-      ),
-      new Variable('a', 8)
-    ]);
+    $out= $this->newEmitter()->write(
+      [
+        new Comment(
+          "/**\n".
+          " * Doc comment\n".
+          " *\n".
+          " * @see http://example.com/\n".
+          " */",
+          3
+        ),
+        new Variable('a', 8)
+      ],
+      new MemoryOutputStream()
+    );
 
     $code= $out->bytes();
     Assert::equals('$a;', explode("\n", $code)[7], $code);