Add method to find out node at position

Keep AST in memory

src/NodeVisitors/NodeAtPositionFinder.php

@@ -0,0 +1,47 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\NodeVisitors;
+
+use PhpParser\{NodeVisitorAbstract, Node};
+use LanguageServer\Protocol\Position;
+
+/**
+ * Finds the Node at a specified position
+ * Depends on ColumnCalculator
+ */
+class NodeAtPositionFinder extends NodeVisitorAbstract
+{
+    /**
+     * The node at the position, if found
+     *
+     * @var Node
+     */
+    public $node;
+
+    /**
+     * @var Position
+     */
+    private $position;
+
+    /**
+     * @param Position $position The position where the node is located
+     */
+    public function __construct(Position $position)
+    {
+        $this->position = $position;
+    }
+
+    public function leaveNode(Node $node)
+    {
+        if (
+            !isset($this->node)
+            && $node->getAttribute('startLine') <= $this->position->line + 1
+            && $node->getAttribute('endLine') >= $this->position->line + 1
+            && $node->getAttribute('startColumn') <= $this->position->character + 1
+            && $node->getAttribute('endColumn') >= $this->position->character + 1
+        ) {
+            $this->node = $node;
+        }
+    }
+}

src/PhpDocument.php

@@ -4,7 +4,7 @@ declare(strict_types = 1);
 namespace LanguageServer;
 
 use LanguageServer\Protocol\{Diagnostic, DiagnosticSeverity, Range, Position, SymbolKind, TextEdit};
-use LanguageServer\NodeVisitors\{ReferencesAdder, SymbolFinder, ColumnCalculator};
+use LanguageServer\NodeVisitors\{NodeAtPositionFinder, ReferencesAdder, SymbolFinder, ColumnCalculator};
 use PhpParser\{Error, Comment, Node, ParserFactory, NodeTraverser, Lexer, Parser};
 use PhpParser\PrettyPrinter\Standard as PrettyPrinter;
 use PhpParser\NodeVisitor\NameResolver;
@@ -104,7 +104,7 @@ class PhpDocument
      * Re-parses a source file, updates symbols, reports parsing errors
      * that may have occured as diagnostics and returns parsed nodes.
      *
-     * @return \PhpParser\Node[]
+     * @return void
      */
     public function parse()
     {
@@ -155,9 +155,9 @@ class PhpDocument
             $traverser->traverse($stmts);
 
             $this->symbols = $symbolFinder->symbols;
-        }
 
-        return $stmts;
+            $this->stmts = $stmts;
+        }
     }
 
     /**
@@ -167,14 +167,13 @@ class PhpDocument
      */
     public function getFormattedText()
     {
-        $stmts = $this->parse();
+        if (empty($this->stmts)) {
-        if (empty($stmts)) {
             return [];
         }
         $prettyPrinter = new PrettyPrinter();
         $edit = new TextEdit();
         $edit->range = new Range(new Position(0, 0), new Position(PHP_INT_MAX, PHP_INT_MAX));
-        $edit->newText = $prettyPrinter->prettyPrintFile($stmts);
+        $edit->newText = $prettyPrinter->prettyPrintFile($this->stmts);
         return [$edit];
     }
 
@@ -187,4 +186,22 @@ class PhpDocument
     {
         return $this->content;
     }
+
+    /**
+     * Returns the node at a specified position
+     *
+     * @param Position $position
+     * @return Node|null
+     */
+    public function getNodeAtPosition(Position $position)
+    {
+        if ($this->stmts === null) {
+            return null;
+        }
+        $traverser = new NodeTraverser;
+        $finder = new NodeAtPositionFinder($position);
+        $traverser->addVisitor($finder);
+        $traverser->traverse($this->stmts);
+        return $finder->node;
+    }
 }

tests/PhpDocumentTest.php

@@ -6,7 +6,9 @@ namespace LanguageServer\Tests\Server;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{LanguageClient, Project};
-use LanguageServer\Protocol\SymbolKind;
+use LanguageServer\NodeVisitors\NodeAtPositionFinder;
+use LanguageServer\Protocol\{SymbolKind, Position};
+use PhpParser\Node;
 
 class PhpDocumentTest extends TestCase
 {
@@ -67,4 +69,13 @@ class PhpDocumentTest extends TestCase
             ]
         ], json_decode(json_encode($symbols), true));
     }
+
+    public function testGetNodeAtPosition()
+    {
+        $document = $this->project->getDocument('whatever');
+        $document->updateContent("<?php\n$\$a = new SomeClass;");
+        $node = $document->getNodeAtPosition(new Position(1, 13));
+        $this->assertInstanceOf(Node\Name\FullyQualified::class, $node);
+        $this->assertEquals('SomeClass', (string)$node);
+    }
 }