Add m-esr52 at 52.6.0

1 files changed, 191 insertions, 0 deletions

diff --git a/js/public/UbiNodePostOrder.h b/js/public/UbiNodePostOrder.h
new file mode 100644
index 000000000..a50426776
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+++ b/js/public/UbiNodePostOrder.h
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+/* -*- 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 js_UbiNodePostOrder_h
+#define js_UbiNodePostOrder_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Move.h"
+
+#include "jsalloc.h"
+
+#include "js/UbiNode.h"
+#include "js/Utility.h"
+#include "js/Vector.h"
+
+namespace JS {
+namespace ubi {
+
+/**
+ * A post-order depth-first traversal of `ubi::Node` graphs.
+ *
+ * No GC may occur while an instance of `PostOrder` is live.
+ *
+ * The `NodeVisitor` type provided to `PostOrder::traverse` must have the
+ * following member:
+ *
+ *   bool operator()(Node& node)
+ *
+ *     The node visitor method. This method is called once for each `node`
+ *     reachable from the start set in post-order.
+ *
+ *     This visitor function should return true on success, or false if an error
+ *     occurs. A false return value terminates the traversal immediately, and
+ *     causes `PostOrder::traverse` to return false.
+ *
+ * The `EdgeVisitor` type provided to `PostOrder::traverse` must have the
+ * following member:
+ *
+ *   bool operator()(Node& origin, Edge& edge)
+ *
+ *     The edge visitor method. This method is called once for each outgoing
+ *     `edge` from `origin` that is reachable from the start set.
+ *
+ *     NB: UNLIKE NODES, THERE IS NO GUARANTEED ORDER IN WHICH EDGES AND THEIR
+ *     ORIGINS ARE VISITED!
+ *
+ *     This visitor function should return true on success, or false if an error
+ *     occurs. A false return value terminates the traversal immediately, and
+ *     causes `PostOrder::traverse` to return false.
+ */
+struct PostOrder {
+  private:
+    struct OriginAndEdges {
+        Node                 origin;
+        EdgeVector           edges;
+
+        OriginAndEdges(const Node& node, EdgeVector&& edges)
+          : origin(node)
+          , edges(mozilla::Move(edges))
+        { }
+
+        OriginAndEdges(const OriginAndEdges& rhs) = delete;
+        OriginAndEdges& operator=(const OriginAndEdges& rhs) = delete;
+
+        OriginAndEdges(OriginAndEdges&& rhs)
+          : origin(rhs.origin)
+          , edges(mozilla::Move(rhs.edges))
+        {
+            MOZ_ASSERT(&rhs != this, "self-move disallowed");
+        }
+
+        OriginAndEdges& operator=(OriginAndEdges&& rhs) {
+            this->~OriginAndEdges();
+            new (this) OriginAndEdges(mozilla::Move(rhs));
+            return *this;
+        }
+    };
+
+    using Stack = js::Vector<OriginAndEdges, 256, js::SystemAllocPolicy>;
+    using Set = js::HashSet<Node, js::DefaultHasher<Node>, js::SystemAllocPolicy>;
+
+    JSContext*               cx;
+    Set                      seen;
+    Stack                    stack;
+#ifdef DEBUG
+    bool                     traversed;
+#endif
+
+  private:
+    MOZ_MUST_USE bool fillEdgesFromRange(EdgeVector& edges, js::UniquePtr<EdgeRange>& range) {
+        MOZ_ASSERT(range);
+        for ( ; !range->empty(); range->popFront()) {
+            if (!edges.append(mozilla::Move(range->front())))
+                return false;
+        }
+        return true;
+    }
+
+    MOZ_MUST_USE bool pushForTraversing(const Node& node) {
+        EdgeVector edges;
+        auto range = node.edges(cx, /* wantNames */ false);
+        return range &&
+            fillEdgesFromRange(edges, range) &&
+            stack.append(OriginAndEdges(node, mozilla::Move(edges)));
+    }
+
+
+  public:
+    // Construct a post-order traversal object.
+    //
+    // The traversal asserts that no GC happens in its runtime during its
+    // lifetime via the `AutoCheckCannotGC&` parameter. We do nothing with it,
+    // other than require it to exist with a lifetime that encloses our own.
+    PostOrder(JSContext* cx, AutoCheckCannotGC&)
+      : cx(cx)
+      , seen()
+      , stack()
+#ifdef DEBUG
+      , traversed(false)
+#endif
+    { }
+
+    // Initialize this traversal object. Return false on OOM.
+    MOZ_MUST_USE bool init() { return seen.init(); }
+
+    // Add `node` as a starting point for the traversal. You may add
+    // as many starting points as you like. Returns false on OOM.
+    MOZ_MUST_USE bool addStart(const Node& node) {
+        if (!seen.put(node))
+            return false;
+        return pushForTraversing(node);
+    }
+
+    // Traverse the graph in post-order, starting with the set of nodes passed
+    // to `addStart` and applying `onNode::operator()` for each node in the
+    // graph and `onEdge::operator()` for each edge in the graph, as described
+    // above.
+    //
+    // This should be called only once per instance of this class.
+    //
+    // Return false on OOM or error return from `onNode::operator()` or
+    // `onEdge::operator()`.
+    template<typename NodeVisitor, typename EdgeVisitor>
+    MOZ_MUST_USE bool traverse(NodeVisitor onNode, EdgeVisitor onEdge) {
+#ifdef DEBUG
+        MOZ_ASSERT(!traversed, "Can only traverse() once!");
+        traversed = true;
+#endif
+
+        while (!stack.empty()) {
+            auto& origin = stack.back().origin;
+            auto& edges = stack.back().edges;
+
+            if (edges.empty()) {
+                if (!onNode(origin))
+                    return false;
+                stack.popBack();
+                continue;
+            }
+
+            Edge edge = mozilla::Move(edges.back());
+            edges.popBack();
+
+            if (!onEdge(origin, edge))
+                return false;
+
+            auto ptr = seen.lookupForAdd(edge.referent);
+            // We've already seen this node, don't follow its edges.
+            if (ptr)
+                continue;
+
+            // Mark the referent as seen and follow its edges.
+            if (!seen.add(ptr, edge.referent) ||
+                !pushForTraversing(edge.referent))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+};
+
+} // namespace ubi
+} // namespace JS
+
+#endif // js_UbiNodePostOrder_h