merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer' r/1299

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

1 files changed, 45 insertions, 0 deletions

diff --git a/third_party/immer/immer/refcount/no_refcount_policy.hpp b/third_party/immer/immer/refcount/no_refcount_policy.hpp
new file mode 100644
index 000000000000..24f9d489f54d
--- /dev/null
+++ b/third_party/immer/immer/refcount/no_refcount_policy.hpp
@@ -0,0 +1,45 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#pragma once
+
+namespace immer {
+
+struct disowned
+{};
+
+struct no_spinlock
+{
+    bool try_lock() { return true; }
+    void lock() {}
+    void unlock() {}
+
+    struct scoped_lock
+    {
+        scoped_lock(no_spinlock&) {}
+    };
+};
+
+/*!
+ * Disables reference counting, to be used with an alternative garbage
+ * collection strategy like a `gc_heap`.
+ */
+struct no_refcount_policy
+{
+    using spinlock_type = no_spinlock;
+
+    no_refcount_policy(){};
+    no_refcount_policy(disowned) {}
+
+    void inc() {}
+    bool dec() { return false; }
+    void dec_unsafe() {}
+    bool unique() { return false; }
+};
+
+} // namespace immer