Differentiate between closures

src/Backtrace.php

@@ -7,9 +7,13 @@ class Backtrace
     /** @var array */
     protected $trace;
 
+    /** @var array */
+    protected $zeroStack;
+
     public function __construct(array $trace)
     {
-        $this->trace = $trace;
+        $this->trace = $trace[1];
+        $this->zeroStack = $trace[0];
     }
 
     public function getArguments(): array
@@ -36,7 +40,12 @@ public function getHash(): string
             return is_object($argument) ? spl_object_hash($argument) : $argument;
         }, $this->getArguments());
 
-        return md5($this->getFunctionName().serialize($normalizedArguments));
+        $prefix = $this->getFunctionName();
+        if (strpos($prefix, '{closure}') !== false) {
+            $prefix = $this->zeroStack['line'];
+        }
+
+        return md5($prefix.serialize($normalizedArguments));
     }
 
     protected function staticCall()

src/functions.php

@@ -7,11 +7,11 @@ function once($callback)
 {
     $trace = debug_backtrace(
         DEBUG_BACKTRACE_PROVIDE_OBJECT, 2
-    )[1];
+    );
 
     $backtrace = new Backtrace($trace);
 
-    if ($trace['function'] === 'eval') {
+    if ($backtrace->getFunctionName() === 'eval') {
         return call_user_func($callback);
     }
 

tests/OnceTest.php

@@ -224,4 +224,57 @@ public function it_will_not_throw_error_with_eval()
 
         $this->assertTrue(in_array($result, range(1, 1000)));
     }
+
+    /** @test */
+    public function it_will_differentiate_between_closures()
+    {
+        $testClass = new class() {
+            public function getNumber()
+            {
+                $closure = function () {
+                    return once(function () {
+                        return random_int(1, 1000);
+                    });
+                };
+
+                return $closure();
+            }
+
+            public function secondNumber()
+            {
+                $closure = function () {
+                    return once(function () {
+                        return random_int(1001, 2000);
+                    });
+                };
+
+                return $closure();
+            }
+        };
+
+        $this->assertNotEquals($testClass->getNumber(), $testClass->secondNumber());
+    }
+
+    /** @test */
+    public function it_will_run_callback_once_for_closure_called_on_differemt_lines()
+    {
+        $testClass = new class() {
+            public function getNumbers()
+            {
+                $closure = function () {
+                    return once(function () {
+                        return random_int(1, 10000000);
+                    });
+                };
+
+                $numbers[] = $closure();
+                $numbers[] = $closure();
+
+                return $numbers;
+            }
+        };
+
+        $results = $testClass->getNumbers();
+        $this->assertEquals($results[0], $results[1]);
+    }
 }