Add support for getting references of variables

src/NodeVisitor/VariableReferencesCollector.php

@@ -0,0 +1,50 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\NodeVisitor;
+
+use PhpParser\{NodeVisitorAbstract, Node, NodeTraverser};
+
+/**
+ * Collects all references to a variable
+ */
+class VariableReferencesCollector extends NodeVisitorAbstract
+{
+    /**
+     * Array of references to the variable
+     *
+     * @var Node\Expr\Variable[]
+     */
+    public $references = [];
+
+    /**
+     * @var string
+     */
+    private $name;
+
+    /**
+     * @param string $name The variable name
+     */
+    public function __construct(string $name)
+    {
+        $this->name = $name;
+    }
+
+    public function enterNode(Node $node)
+    {
+        if ($node instanceof Node\Expr\Variable && $node->name === $this->name) {
+            $this->references[] = $node;
+        } else if ($node instanceof Node\FunctionLike) {
+            // If we meet a function node, dont traverse its statements, they are in another scope
+            // except it is a closure that has imported the variable through use
+            if ($node instanceof Node\Expr\Closure) {
+                foreach ($node->uses as $use) {
+                    if ($use->var === $this->name) {
+                        return;
+                    }
+                }
+            }
+            return NodeTraverser::DONT_TRAVERSE_CHILDREN;
+        }
+    }
+}

src/PhpDocument.php

@@ -9,7 +9,8 @@ use LanguageServer\NodeVisitor\{
     ReferencesAdder,
     DefinitionCollector,
     ColumnCalculator,
-    ReferencesCollector
+    ReferencesCollector,
+    VariableReferencesCollector
 };
 use PhpParser\{Error, Node, NodeTraverser, Parser};
 use PhpParser\NodeVisitor\NameResolver;
@@ -58,7 +59,7 @@ class PhpDocument
      *
      * @var Node[]
      */
-    private $statements;
+    private $stmts;
 
     /**
      * Map from fully qualified name (FQN) to Node
@@ -177,7 +178,7 @@ class PhpDocument
                 $this->project->addReferenceDocument($fqn, $this);
             }
 
-            $this->statements = $stmts;
+            $this->stmts = $stmts;
         }
     }
 
@@ -214,6 +215,16 @@ class PhpDocument
         return $this->uri;
     }
 
+    /**
+     * Returns the AST of the document
+     *
+     * @return Node[]
+     */
+    public function getStmts(): array
+    {
+        return $this->stmts;
+    }
+
     /**
      * Returns the node at a specified position
      *
@@ -225,7 +236,7 @@ class PhpDocument
         $traverser = new NodeTraverser;
         $finder = new NodeAtPositionFinder($position);
         $traverser->addVisitor($finder);
-        $traverser->traverse($this->statements);
+        $traverser->traverse($this->stmts);
         return $finder->node;
     }
 
@@ -453,6 +464,53 @@ class PhpDocument
         return $document->getDefinitionByFqn($fqn);
     }
 
+    /**
+     * Returns the reference nodes for any node
+     * The references node MAY be in other documents, check the ownerDocument attribute
+     *
+     * @param Node $node
+     * @return Node[]
+     */
+    public function getReferencesByNode(Node $node)
+    {
+        // Variables always stay in the boundary of the file and need to be searched inside their function scope
+        // by traversing the AST
+        if ($node instanceof Node\Expr\Variable) {
+            if ($node->name instanceof Node\Expr) {
+                return null;
+            }
+            // Find function/method/closure scope
+            $n = $node;
+            while (isset($n) && !($n instanceof Node\FunctionLike)) {
+                $n = $n->getAttribute('parentNode');
+            }
+            if (!isset($n)) {
+                $n = $node->getAttribute('ownerDocument');
+            }
+            $traverser = new NodeTraverser;
+            $refCollector = new VariableReferencesCollector($node->name);
+            $traverser->addVisitor($refCollector);
+            $traverser->traverse($n->getStmts());
+            return $refCollector->references;
+        }
+        // Definition with a global FQN
+        $fqn = $this->getDefinedFqn($node);
+        if ($fqn === null) {
+            return [];
+        }
+        $refDocuments = $this->project->getReferenceDocuments($fqn);
+        $nodes = [];
+        foreach ($refDocuments as $document) {
+            $refs = $document->getReferencesByFqn($fqn);
+            if ($refs !== null) {
+                foreach ($refs as $ref) {
+                    $nodes[] = $ref;
+                }
+            }
+        }
+        return $nodes;
+    }
+
     /**
      * Returns the assignment or parameter node where a variable was defined
      *

src/Server/TextDocument.php

@@ -110,28 +110,19 @@ class TextDocument
      * denoted by the given text document position.
      *
      * @param ReferenceContext $context
-     * @return Location[]|null
+     * @return Location[]
      */
-    public function references(ReferenceContext $context, TextDocumentIdentifier $textDocument, Position $position)
+    public function references(ReferenceContext $context, TextDocumentIdentifier $textDocument, Position $position): array
     {
         $document = $this->project->getDocument($textDocument->uri);
         $node = $document->getNodeAtPosition($position);
         if ($node === null) {
-            return null;
+            return [];
         }
-        $fqn = $document->getDefinedFqn($node);
-        if ($fqn === null) {
-            return null;
-        }
-        $refDocuments = $this->project->getReferenceDocuments($fqn);
+        $refs = $document->getReferencesByNode($node);
         $locations = [];
-        foreach ($refDocuments as $document) {
-            $refs = $document->getReferencesByFqn($fqn);
-            if ($refs !== null) {
-                foreach ($refs as $ref) {
-                    $locations[] = Location::fromNode($ref);
-                }
-            }
+        foreach ($refs as $ref) {
+            $locations[] = Location::fromNode($ref);
         }
         return $locations;
     }

tests/Server/TextDocument/References/NamespacedTest.php

@@ -278,6 +278,19 @@ class NamespacedTest extends TestCase
         // Get definition for $var
         $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($this->referencesUri), new Position(13, 7));
         $this->assertEquals([
+            [
+                'uri' => $this->referencesUri,
+                'range' => [
+                    'start' => [
+                        'line' => 12,
+                        'character' => 0
+                    ],
+                    'end' => [
+                        'line' => 12,
+                        'character' => 4
+                    ]
+                ]
+            ],
             [
                 'uri' => $this->referencesUri,
                 'range' => [
@@ -287,7 +300,20 @@ class NamespacedTest extends TestCase
                     ],
                     'end' => [
                         'line' => 13,
-                        'character' => 8
+                        'character' => 9
+                    ]
+                ]
+            ],
+            [
+                'uri' => $this->referencesUri,
+                'range' => [
+                    'start' => [
+                        'line' => 20,
+                        'character' => 9
+                    ],
+                    'end' => [
+                        'line' => 20,
+                        'character' => 13
                     ]
                 ]
             ]