1 files changed, 77 insertions, 0 deletions
diff --git a/vendor/opentracing/opentracing/src/OpenTracing/Reference.php b/vendor/opentracing/opentracing/src/OpenTracing/Reference.php
new file mode 100644
index 000000000..7dadf1785
--- /dev/null
+++ b/vendor/opentracing/opentracing/src/OpenTracing/Reference.php
@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTracing;
+
+use OpenTracing\InvalidReferenceArgumentException;
+
+final class Reference
+{
+    /**
+     * A Span may be the ChildOf a parent Span. In a ChildOf reference,
+     * the parent Span depends on the child Span in some capacity.
+     */
+    public const CHILD_OF = 'child_of';
+
+    /**
+     * Some parent Spans do not depend in any way on the result of their
+     * child Spans. In these cases, we say merely that the child Span
+     * FollowsFrom the parent Span in a causal sense.
+     */
+    public const FOLLOWS_FROM = 'follows_from';
+
+    /**
+     * @var string
+     */
+    private $type;
+
+    /**
+     * @var SpanContext
+     */
+    private $spanContext;
+
+    /**
+     * @param string $type
+     * @param SpanContext $spanContext
+     */
+    public function __construct(string $type, SpanContext $spanContext)
+    {
+        if (empty($type)) {
+            throw InvalidReferenceArgumentException::forEmptyType();
+        }
+
+        $this->type = $type;
+        $this->spanContext = $spanContext;
+    }
+
+    /**
+     * @param string $type
+     * @param Span $span
+     * @return Reference when context is invalid
+     * @throws InvalidReferenceArgumentException on empty type
+     */
+    public static function createForSpan(string $type, Span $span): Reference
+    {
+        return new self($type, $span->getContext());
+    }
+
+    /**
+     * @return SpanContext
+     */
+    public function getSpanContext(): SpanContext
+    {
+        return $this->spanContext;
+    }
+
+    /**
+     * Checks whether a Reference is of one type.
+     *
+     * @param string $type the type for the reference
+     * @return bool
+     */
+    public function isType(string $type): bool
+    {
+        return $this->type === $type;
+    }
+}