Add m-esr52 at 52.6.0

1 files changed, 86 insertions, 0 deletions

diff --git a/js/src/jshashutil.h b/js/src/jshashutil.h
new file mode 100644
index 0000000000..44cce57187
--- /dev/null
+++ b/js/src/jshashutil.h
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jshashutil_h
+#define jshashutil_h
+
+#include "jscntxt.h"
+
+#include "gc/Zone.h"
+
+namespace js {
+
+/*
+ * Used to add entries to a js::HashMap or HashSet where the key depends on a GC
+ * thing that may be moved by generational or compacting GC between the call to
+ * lookupForAdd() and relookupOrAdd().
+ */
+template <class T>
+struct DependentAddPtr
+{
+    typedef typename T::AddPtr AddPtr;
+    typedef typename T::Entry Entry;
+
+    template <class Lookup>
+    DependentAddPtr(const ExclusiveContext* cx, const T& table, const Lookup& lookup)
+      : addPtr(table.lookupForAdd(lookup))
+      , originalGcNumber(cx->zone()->gcNumber())
+    {}
+
+    DependentAddPtr(DependentAddPtr&& other)
+      : addPtr(other.addPtr)
+      , originalGcNumber(other.originalGcNumber)
+    {}
+
+    template <class KeyInput, class ValueInput>
+    bool add(ExclusiveContext* cx, T& table, const KeyInput& key, const ValueInput& value) {
+        refreshAddPtr(cx, table, key);
+        if (!table.relookupOrAdd(addPtr, key, value)) {
+            ReportOutOfMemory(cx);
+            return false;
+        }
+        return true;
+    }
+
+    template <class KeyInput>
+    void remove(ExclusiveContext* cx, T& table, const KeyInput& key) {
+        refreshAddPtr(cx, table, key);
+        table.remove(addPtr);
+    }
+
+    bool found() const                 { return addPtr.found(); }
+    explicit operator bool() const     { return found(); }
+    const Entry& operator*() const     { return *addPtr; }
+    const Entry* operator->() const    { return &*addPtr; }
+
+  private:
+    AddPtr addPtr ;
+    const uint64_t originalGcNumber;
+
+    template <class KeyInput>
+    void refreshAddPtr(ExclusiveContext* cx, T& table, const KeyInput& key) {
+        bool gcHappened = originalGcNumber != cx->zone()->gcNumber();
+        if (gcHappened)
+            addPtr = table.lookupForAdd(key);
+    }
+
+    DependentAddPtr() = delete;
+    DependentAddPtr(const DependentAddPtr&) = delete;
+    DependentAddPtr& operator=(const DependentAddPtr&) = delete;
+};
+
+template <typename T, typename Lookup>
+inline auto
+MakeDependentAddPtr(const ExclusiveContext* cx, T& table, const Lookup& lookup)
+  -> DependentAddPtr<typename mozilla::RemoveReference<decltype(table)>::Type>
+{
+    using Ptr = DependentAddPtr<typename mozilla::RemoveReference<decltype(table)>::Type>;
+    return Ptr(cx, table, lookup);
+}
+
+} // namespace js
+
+#endif