XP Language: Null-Safe Object Operator Patch

CoalesceNode.class.php

<?php
/* This class is part of the XP framework
 *
 * $Id$
 */

  uses('xp.compiler.ast.Node');

  /**
   * Coalesce operator
   *
   * Note: The following two are equivalent:
   * <code>
   *   $a= $b ?? $c;
   *   $a= NULL === ($__r= @$b) ? $c : $__r;
   * </code>
   */
  class CoalesceNode extends xp·compiler·ast·Node {
    public $expression = NULL;    
    public $default = NULL;    
  }
?>

nullsafeobjectoperator.diff

diff --git a/compiler/src/main/php/xp/compiler/ast/MemberAccessNode.class.php b/compiler/src/main/php/xp/compiler/ast/MemberAccessNode.class.php
index a19f3e4..f9ae224 100644
--- a/compiler/src/main/php/xp/compiler/ast/MemberAccessNode.class.php
+++ b/compiler/src/main/php/xp/compiler/ast/MemberAccessNode.class.php
@@ -16,16 +16,19 @@
   class MemberAccessNode extends xp·compiler·ast·Node {
     public $target= NULL;
     public $name= '';
+    public $verify= FALSE;
     
     /**
      * Constructor
      *
      * @param   xp.compiler.ast.Node target
      * @param   string name
+     * @param   bool verify 
      */
-    public function __construct($target= NULL, $name= '') {
+    public function __construct($target= NULL, $name= '', $verify= FALSE) {
       $this->target= $target;
       $this->name= $name;
+      $this->verify= $verify;
     }
 
     /**
diff --git a/compiler/src/main/php/xp/compiler/ast/MethodCallNode.class.php b/compiler/src/main/php/xp/compiler/ast/MethodCallNode.class.php
index a8039d3..9918a24 100644
--- a/compiler/src/main/php/xp/compiler/ast/MethodCallNode.class.php
+++ b/compiler/src/main/php/xp/compiler/ast/MethodCallNode.class.php
@@ -17,6 +17,7 @@
     public $target= NULL;
     public $name= '';
     public $arguments= array();
+    public $verify= FALSE;
     
     /**
      * Creates a new InvocationNode object
@@ -24,11 +25,13 @@
      * @param   xp.compiler.ast.Node target
      * @param   string name
      * @param   xp.compiler.ast.Node[] arguments
+     * @param   bool verify 
      */
-    public function __construct($target= NULL, $name= '', $arguments= NULL) {
+    public function __construct($target= NULL, $name= '', $arguments= NULL, $verify= FALSE) {
       $this->target= $target;
       $this->name= $name;
       $this->arguments= $arguments;
+      $this->verify= $verify;
     }
   }
 ?>
diff --git a/compiler/src/main/php/xp/compiler/emit/source/Emitter.class.php b/compiler/src/main/php/xp/compiler/emit/source/Emitter.class.php
index 8338b65..1abd933 100644
--- a/compiler/src/main/php/xp/compiler/emit/source/Emitter.class.php
+++ b/compiler/src/main/php/xp/compiler/emit/source/Emitter.class.php
@@ -421,6 +421,12 @@
 
       // Manually verify as we can then rely on call target type being available
       if (!$this->checks->verify($call, $this->scope[0], $this, TRUE)) return;
+
+      // - $instance?.method()
+      if ($call->verify) {
+        $op->insert('($··r= ', $mark);
+        $op->append(') === NULL ? NULL : $··r');
+      }
       
       // Rewrite for unsupported syntax
       // - new Date().toString() to create(new Date()).toString()
@@ -439,7 +445,7 @@
 
       $op->append('->'.$call->name);
       $this->emitInvocationArguments($op, (array)$call->arguments);
-
+      
       // Record type
       $this->scope[0]->setType($call, $ptr->hasMethod($call->name) ? $ptr->getMethod($call->name)->returns : TypeName::$VAR);
     }
@@ -481,6 +487,12 @@
       // Manually verify as we can then rely on call target type being available
       if (!$this->checks->verify($access, $this->scope[0], $this, TRUE)) return;
 
+      // - $instance?.property
+      if ($access->verify) {
+        $op->insert('($··r= ', $mark);
+        $op->append(') === NULL ? NULL : $··r');
+      }
+
       // Rewrite for unsupported syntax
       // - new Person().name to create(new Person()).name
       // - (<expr>).name to create(<expr>).name
@@ -676,6 +688,20 @@
     }
 
     /**
+     * Emit coalesce
+     *
+     * @param   resource op
+     * @param   xp.compiler.ast.CoalesceNode coalesce
+     */
+    protected function emitCoalesce($op, CoalesceNode $coalesce) {
+      $op->append('NULL === ($··r= @');
+      $this->emitOne($op, $coalesce->expresssion);
+      $op->append(') ? ');
+      $this->emitOne($op, $coalesce->default);
+      $op->append(': $··r');
+    }
+
+    /**
      * Emit ternary operator node
      *
      * Note: The following two are equivalent:
diff --git a/compiler/src/main/php/xp/compiler/grammar/xp.jay b/compiler/src/main/php/xp/compiler/grammar/xp.jay
index 024099e..6278529 100644
--- a/compiler/src/main/php/xp/compiler/grammar/xp.jay
+++ b/compiler/src/main/php/xp/compiler/grammar/xp.jay
@@ -54,6 +54,7 @@
     'xp.compiler.ast.BinaryOpNode',
     'xp.compiler.ast.BooleanOpNode',
     'xp.compiler.ast.UnaryOpNode',
+    'xp.compiler.ast.CoalesceNode',
     'xp.compiler.ast.TernaryNode',
     'xp.compiler.ast.SwitchNode',
     'xp.compiler.ast.CaseNode',
@@ -74,6 +75,7 @@
 %left ','
 %left T_BOOLEAN_OR
 %left T_BOOLEAN_AND
+%left T_COALESCE
 %right '=' T_ADD_EQUAL T_SUB_EQUAL T_MUL_EQUAL T_DIV_EQUAL T_CONCAT_EQUAL T_MOD_EQUAL T_AND_EQUAL T_OR_EQUAL T_XOR_EQUAL
 %left '?' ':'
 %left '|'
@@ -124,6 +126,8 @@
 %token T_AS 331
 %token T_THIS 332
 %token T_CONST 334
+%token T_SOAK 335
+%token T_COALESCE 336
 
 %token T_VARIABLE 340
 %token T_RETURN 341
@@ -466,6 +470,7 @@ parameters:
 parameter:
 	paramtyperef T_VARIABLE initialization_opt { $$= array_merge(array('name' => $2), $1); $3 && $$['default']= $3; }
   | paramtyperef T_DOTS '.' T_VARIABLE { $$= array_merge(array('name' => $4, 'vararg' => TRUE), $1); }
+  | paramtyperef T_SOAK T_DOTS T_VARIABLE { $$= array_merge(array('name' => $4, 'vararg' => TRUE, 'check' => FALSE), $1); }
 ;
 
 paramtyperef:
@@ -780,6 +785,11 @@ expression:
       $$->expression= $3;
       $$->conditional= $5;
     }
+  | expression T_COALESCE expression { 
+      $$= $yyLex->create(new CoalesceNode()); 
+      $$->expresssion= $1; 
+      $$->default= $3; 
+    }
   | expression T_BOOLEAN_OR expression { 
       $$= $yyLex->create(new BinaryOpNode()); 
       $$->lhs= $1; 
@@ -949,17 +959,22 @@ chain:
     '[' { $1= $yyLex->create(new ArrayAccessNode(NULL)); } expression_opt ']' { 
       $1->offset= $3;
     }
-  | '.' member {
-      $$= $yyLex->create(new MemberAccessNode(NULL, $2)); 
+  | access member {
+      $$= $yyLex->create(new MemberAccessNode(NULL, $2, $1)); 
     }
-  | '.' member '(' { $1= $yyLex->create(new MethodCallNode(NULL, $2)); } expressionlist_opt ')' { 
+  | access member '(' { $1= $yyLex->create(new MethodCallNode(NULL, $2, NULL, $1)); } expressionlist_opt ')' { 
       $1->arguments= $5;
     }
-  | '.' '(' { $1= $yyLex->create(new InstanceCallNode(NULL)); } expressionlist_opt ')' { 
+  | access '(' { $1= $yyLex->create(new InstanceCallNode(NULL)); } expressionlist_opt ')' { 
       $1->arguments= $4;
     }
 ;
 
+access:
+    '.' { $$= FALSE; }
+  | T_SOAK { $$= TRUE; }
+;
+
 member:
     T_WORD
   | T_IN
diff --git a/compiler/src/main/php/xp/compiler/syntax/xp/Lexer.class.php b/compiler/src/main/php/xp/compiler/syntax/xp/Lexer.class.php
index 3903f43..a5e2b75 100644
--- a/compiler/src/main/php/xp/compiler/syntax/xp/Lexer.class.php
+++ b/compiler/src/main/php/xp/compiler/syntax/xp/Lexer.class.php
@@ -91,6 +91,7 @@
         '|' => array('||' => xp·compiler·syntax·xp·Parser::T_BOOLEAN_OR, '|=' => xp·compiler·syntax·xp·Parser::T_OR_EQUAL),
         '&' => array('&&' => xp·compiler·syntax·xp·Parser::T_BOOLEAN_AND, '&=' => xp·compiler·syntax·xp·Parser::T_AND_EQUAL),
         '^' => array('^=' => xp·compiler·syntax·xp·Parser::T_XOR_EQUAL),
+        '?' => array('?.' => xp·compiler·syntax·xp·Parser::T_SOAK, '??' => xp·compiler·syntax·xp·Parser::T_COALESCE),
       );
 
     const 
diff --git a/compiler/src/test/php/net/xp_lang/tests/execution/source/OperatorTest.class.php b/compiler/src/test/php/net/xp_lang/tests/execution/source/OperatorTest.class.php
index 7d16d92..5b64afe 100644
--- a/compiler/src/test/php/net/xp_lang/tests/execution/source/OperatorTest.class.php
+++ b/compiler/src/test/php/net/xp_lang/tests/execution/source/OperatorTest.class.php
@@ -324,5 +324,41 @@
     public function conditionalAssignmentResult() {
       $this->assertEquals(1, $this->run('$a= 2; $b= 0; $a && $b+= 1; return $b;'));
     }
+
+    /**
+     * Test coalesce operator
+     *
+     */
+    #[@test]
+    public function coalesce() {
+      $this->assertEquals(2, $this->run('$a= 2; return $a ?? 1;'));
+    }
+
+    /**
+     * Test coalesce operator
+     *
+     */
+    #[@test]
+    public function coalesceWithNull() {
+      $this->assertEquals(1, $this->run('$a= null; return $a ?? 1;'));
+    }
+
+    /**
+     * Test coalesce operator
+     *
+     */
+    #[@test]
+    public function coalesceWithUnset() {
+      $this->assertEquals(1, $this->run('unset($a); return $a ?? 1;'));
+    }
+
+    /**
+     * Test coalesce operator
+     *
+     */
+    #[@test]
+    public function coalesceWithUnsetOffset() {
+      $this->assertEquals(1, $this->run('$a= [1, 2, 3]; return $a[4] ?? 1;'));
+    }
   }
 ?>

NullSafeObjectOperatorTest.class.php

<?php
/* This class is part of the XP framework
 *
 * $Id$
 */

  $package= 'net.xp_lang.tests.execution.source';

  uses('net.xp_lang.tests.execution.source.ExecutionTest');

  /**
   * Tests null-safe object operator ?.
   *
   */
  class net·xp_lang·tests·execution·source·NullSafeObjectOperatorTest extends ExecutionTest {
    
    /**
     * Test
     *
     */
    #[@test]
    public function nullDotMethod() {
      $this->assertNull($this->run('$instance= null; return $instance?.method();'));
    }

    /**
     * Test
     *
     */
    #[@test]
    public function nullReturnedFromMethod() {
      $this->assertNull($this->run('$v= new util.collections.Vector<var>(); $v.add(null); return $v.get(0)?.hashCode();'));
    }

    /**
     * Test
     *
     */
    #[@test]
    public function nullNotReturnedFromMethod() {
      $this->assertNotEquals(NULL, $this->run('$v= new util.collections.Vector<var>(); $v.add($this); return $v.get(0)?.hashCode();'));
    }

    /**
     * Test
     *
     */
    #[@test]
    public function twoNullSafeObjectOperatorsInOneChain() {
      $this->assertNull($this->run('$v= new util.collections.Vector<var>(); $v.add(null); return $v?.get(0)?.hashCode();'));
    }

    /**
     * Test
     *
     */
    #[@test]
    public function nullDotProperty() {
      $this->assertNull($this->run('$instance= null; return $instance?.property;'));
    }

    /**
     * Test
     *
     */
    #[@test, @ignore('Generates syntax error, unexpected ")"')]
    public function nullDotInvoke() {
      $this->compile('$instance= null; return $instance?.();');
    }
  }
?>