added $this autocompletion

fixtures/completion/this.php

@@ -0,0 +1,15 @@
+<?php
+
+class ThisClass
+{
+    private $foo;
+    private $bar;
+
+    protected function method()
+    {
+    }
+    public function test()
+    {
+        $this->
+    }
+}

fixtures/completion/this_with_prefix.php

@@ -0,0 +1,15 @@
+<?php
+
+class ThisClassPrefix extends TestClass
+{
+    private $foo;
+    private $bar;
+
+    protected function method()
+    {
+    }
+    public function test()
+    {
+        $this->m
+    }
+}

src/CompletionProvider.php

@@ -141,9 +141,17 @@ class CompletionProvider
             // If the name is an Error node, just filter by the class
             if ($node instanceof Node\Expr\MethodCall || $node instanceof Node\Expr\PropertyFetch) {
                 // For instances, resolve the variable type
+                $classNode = null;
+                if ($node->var instanceof Node\Expr\Variable && $node->var->name === 'this') {
+                    $classNode = getClosestNode($node, Node\Stmt\Class_::class);
+                }
+                if ($classNode !== null && !$classNode->isAnonymous()) {
+                    $prefixes = [(string)$classNode->namespacedName];
+                } else {
                     $prefixes = DefinitionResolver::getFqnsFromType(
                         $this->definitionResolver->resolveExpressionNodeToType($node->var)
                     );
+                }
             } else {
                 // Static member reference
                 $prefixes = [$node->class instanceof Node\Name ? (string)$node->class : ''];

tests/LanguageServerTest.php

@@ -57,7 +57,7 @@ class LanguageServerTest extends TestCase
             if ($msg->body->method === 'window/logMessage' && $promise->state === Promise::PENDING) {
                 if ($msg->body->params->type === MessageType::ERROR) {
                     $promise->reject(new Exception($msg->body->params->message));
-                } else if (strpos($msg->body->params->message, 'All 25 PHP files parsed') !== false) {
+                } else if (strpos($msg->body->params->message, 'All 27 PHP files parsed') !== false) {
                     $promise->fulfill();
                 }
             }
@@ -103,7 +103,7 @@ class LanguageServerTest extends TestCase
                     if ($promise->state === Promise::PENDING) {
                         $promise->reject(new Exception($msg->body->params->message));
                     }
-                } else if (strpos($msg->body->params->message, 'All 25 PHP files parsed') !== false) {
+                } else if (strpos($msg->body->params->message, 'All 27 PHP files parsed') !== false) {
                     if ($run === 1) {
                         $run++;
                     } else {

tests/Server/TextDocument/CompletionTest.php

@@ -433,4 +433,88 @@ class CompletionTest extends TestCase
             )
         ], true), $items);
     }
+
+    public function testThisWithoutPrefix()
+    {
+        $completionUri = pathToUri(__DIR__ . '/../../../fixtures/completion/this.php');
+        $this->loader->open($completionUri, file_get_contents($completionUri));
+        $items = $this->textDocument->completion(
+            new TextDocumentIdentifier($completionUri),
+            new Position(12, 15)
+        )->wait();
+        $this->assertEquals(new CompletionList([
+            new CompletionItem(
+                'foo',
+                CompletionItemKind::PROPERTY,
+                'mixed', // Type of the property
+                null
+            ),
+            new CompletionItem(
+                'bar',
+                CompletionItemKind::PROPERTY,
+                'mixed', // Type of the property
+                null
+            ),
+            new CompletionItem(
+                'method',
+                CompletionItemKind::METHOD,
+                'mixed', // Return type of the method
+                null
+            ),
+            new CompletionItem(
+                'test',
+                CompletionItemKind::METHOD,
+                'mixed', // Return type of the method
+                null
+            )
+        ], true), $items);
+    }
+
+    public function testThisWithPrefix()
+    {
+        $completionUri = pathToUri(__DIR__ . '/../../../fixtures/completion/this_with_prefix.php');
+        $this->loader->open($completionUri, file_get_contents($completionUri));
+        $items = $this->textDocument->completion(
+            new TextDocumentIdentifier($completionUri),
+            new Position(12, 16)
+        )->wait();
+        $this->assertEquals(new CompletionList([
+            new CompletionItem(
+                'testProperty',
+                CompletionItemKind::PROPERTY,
+                '\TestClass', // Type of the property
+                'Reprehenderit magna velit mollit ipsum do.'
+            ),
+            new CompletionItem(
+                'testMethod',
+                CompletionItemKind::METHOD,
+                '\TestClass', // Return type of the method
+                'Non culpa nostrud mollit esse sunt laboris in irure ullamco cupidatat amet.'
+            ),
+            new CompletionItem(
+                'foo',
+                CompletionItemKind::PROPERTY,
+                'mixed', // Type of the property
+                null
+            ),
+            new CompletionItem(
+                'bar',
+                CompletionItemKind::PROPERTY,
+                'mixed', // Type of the property
+                null
+            ),
+            new CompletionItem(
+                'method',
+                CompletionItemKind::METHOD,
+                'mixed', // Return type of the method
+                null
+            ),
+            new CompletionItem(
+                'test',
+                CompletionItemKind::METHOD,
+                'mixed', // Return type of the method
+                null
+            )
+        ], true), $items);
+    }
 }