Bump Mapbox GL Native

Bump version.

mapbox-gl-native @ 377a6e42d687c419e6ae1012b8626336f5dfc1b6

24 files changed, 1162 insertions, 96 deletions

diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt.hpp
index ee1bbbca8d..af5bbc3129 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt.hpp
@@ -51,9 +51,6 @@ struct Options : TileOptions {
 
     // max number of points per tile in the tile index
     uint32_t indexMaxPoints = 100000;
-
-    // whether to tile solid square tiles further
-    bool solidChildren = false;
 };
 
 const Tile empty_tile{};
@@ -63,12 +60,12 @@ inline uint64_t toID(uint8_t z, uint32_t x, uint32_t y) {
 }
 
 inline const Tile geoJSONToTile(const geojson& geojson_,
-                         uint8_t z,
-                         uint32_t x,
-                         uint32_t y,
-                         const TileOptions& options = TileOptions(),
-                         bool wrap = false,
-                         bool clip = false) {
+                                uint8_t z,
+                                uint32_t x,
+                                uint32_t y,
+                                const TileOptions& options = TileOptions(),
+                                bool wrap = false,
+                                bool clip = false) {
 
     const auto features_ = geojson::visit(geojson_, ToFeatureCollection{});
     auto z2 = 1u << z;
@@ -83,8 +80,7 @@ inline const Tile geoJSONToTile(const geojson& geojson_,
         const auto left = detail::clip<0>(features, (x - p) / z2, (x + 1 + p) / z2, -1, 2);
         features = detail::clip<1>(left, (y - p) / z2, (y + 1 + p) / z2, -1, 2);
     }
-    return detail::InternalTile({ features, z, x, y, options.extent, options.buffer, tolerance })
-        .tile;
+    return detail::InternalTile({ features, z, x, y, options.extent, tolerance }).tile;
 }
 
 class GeoJSONVT {
@@ -131,10 +127,6 @@ public:
         // if we found a parent tile containing the original geometry, we can drill down from it
         const auto& parent = it->second;
 
-        // parent tile is a solid clipped square, return it instead since it's identical
-        if (parent.is_solid)
-            return parent.tile;
-
         // drill down parent tile up to the requested one
         splitTile(parent.source_features, parent.z, parent.x, parent.y, z, x, y);
 
@@ -146,11 +138,6 @@ public:
         if (it == tiles.end())
             throw std::runtime_error("Parent tile not found");
 
-        // drilling stopped because parent was a solid square; return it instead
-        if (it->second.is_solid)
-            return it->second.tile;
-
-        // otherwise it was an empty tile
         return empty_tile;
     }
 
@@ -198,8 +185,8 @@ private:
                 (z == options.maxZoom ? 0 : options.tolerance / (z2 * options.extent));
 
             it = tiles
-                     .emplace(id, detail::InternalTile{ features, z, x, y, options.extent,
-                                                        options.buffer, tolerance })
+                     .emplace(id,
+                              detail::InternalTile{ features, z, x, y, options.extent, tolerance })
                      .first;
             stats[z] = (stats.count(z) ? stats[z] + 1 : 1);
             total++;
@@ -211,10 +198,6 @@ private:
         if (features.empty())
             return;
 
-        // stop tiling if the tile is solid clipped square
-        if (!options.solidChildren && tile.is_solid)
-            return;
-
         // if it's the first-pass tiling
         if (cz == 0u) {
             // stop tiling if we reached max zoom, or if the tile is too simple
diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/clip.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/clip.hpp
index 212e2979d0..e6f305921f 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/clip.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/clip.hpp
@@ -116,13 +116,13 @@ private:
                     if (i == len - 2)
                         slice.push_back(b); // last point
                 }
-            } else if (ak > k2) {
+            } else if (ak >= k2) {
                 if (bk < k1) { // <--|-----|---
                     slice.push_back(intersect<I>(a, b, k2));
                     slice.push_back(intersect<I>(a, b, k1));
                     slice = newSlice(slices, slice, dist);
 
-                } else if (bk <= k2) { // |  <--|---
+                } else if (bk < k2) { // |  <--|---
                     slice.push_back(intersect<I>(a, b, k2));
                     if (i == len - 2)
                         slice.push_back(b); // last point
@@ -171,8 +171,8 @@ private:
                     else if (i == len - 2)
                         slice.push_back(b); // last point
                 }
-            } else if (ak > k2) {
-                if (bk <= k2) { // |  <--|---
+            } else if (ak >= k2) {
+                if (bk < k2) { // |  <--|---
                     slice.push_back(intersect<I>(a, b, k2));
                     if (bk < k1) // <--|-----|---
                         slice.push_back(intersect<I>(a, b, k1));
@@ -216,10 +216,10 @@ inline vt_features clip(const vt_features& features,
                         const double minAll,
                         const double maxAll) {
 
-    if (minAll >= k1 && maxAll <= k2) // trivial accept
+    if (minAll >= k1 && maxAll < k2) // trivial accept
         return features;
 
-    if (minAll > k2 || maxAll < k1) // trivial reject
+    if (maxAll < k1 || minAll >= k2) // trivial reject
         return {};
 
     vt_features clipped;
@@ -232,10 +232,10 @@ inline vt_features clip(const vt_features& features,
         const double min = get<I>(feature.bbox.min);
         const double max = get<I>(feature.bbox.max);
 
-        if (min >= k1 && max <= k2) { // trivial accept
+        if (min >= k1 && max < k2) { // trivial accept
             clipped.push_back(feature);
 
-        } else if (min > k2 || max < k1) { // trivial reject
+        } else if (max < k1 || min >= k2) { // trivial reject
             continue;
 
         } else {
diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/convert.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/convert.hpp
index ba28f449b3..88c036f02c 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/convert.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/convert.hpp
@@ -99,8 +99,7 @@ inline vt_features convert(const geometry::feature_collection<double>& features,
     for (const auto& feature : features) {
         projected.emplace_back(
             geometry::geometry<double>::visit(feature.geometry, project{ tolerance }),
-            feature.properties,
-            feature.id);
+            feature.properties, feature.id);
     }
     return projected;
 }
diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/simplify.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/simplify.hpp
index be0165b0f1..784f085e7f 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/simplify.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/simplify.hpp
@@ -37,6 +37,8 @@ inline double getSqSegDist(const vt_point& p, const vt_point& a, const vt_point&
 inline void simplify(std::vector<vt_point>& points, size_t first, size_t last, double sqTolerance) {
     double maxSqDist = sqTolerance;
     size_t index = 0;
+    const int64_t mid = (last - first) >> 1;
+    int64_t minPosToMid = last - first;
 
     for (auto i = first + 1; i < last; i++) {
         const double sqDist = getSqSegDist(points[i], points[first], points[last]);
@@ -44,6 +46,16 @@ inline void simplify(std::vector<vt_point>& points, size_t first, size_t last, d
         if (sqDist > maxSqDist) {
             index = i;
             maxSqDist = sqDist;
+
+        } else if (sqDist == maxSqDist) {
+            // a workaround to ensure we choose a pivot close to the middle of the list,
+            // reducing recursion depth, for certain degenerate inputs
+            // https://github.com/mapbox/geojson-vt/issues/104
+            auto posToMid = std::abs(static_cast<int64_t>(i) - mid);
+            if (posToMid < minPosToMid) {
+                index = i;
+                minPosToMid = posToMid;
+            }
         }
     }
 
diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/tile.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/tile.hpp
index ccb230bb9c..e382346779 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/tile.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/tile.hpp
@@ -17,12 +17,16 @@ namespace detail {
 
 class InternalTile {
 public:
+    const uint16_t extent;
     const uint8_t z;
     const uint32_t x;
     const uint32_t y;
 
+    const double z2;
+    const double tolerance;
+    const double sq_tolerance;
+
     vt_features source_features;
-    bool is_solid = false;
     mapbox::geometry::box<double> bbox = { { 2, 1 }, { -1, 0 } };
 
     Tile tile;
@@ -32,13 +36,12 @@ public:
                  const uint32_t x_,
                  const uint32_t y_,
                  const uint16_t extent_,
-                 const uint16_t buffer,
                  const double tolerance_)
-        : z(z_),
+        : extent(extent_),
+          z(z_),
           x(x_),
           y(y_),
           z2(std::pow(2, z)),
-          extent(extent_),
           tolerance(tolerance_),
           sq_tolerance(tolerance_ * tolerance_) {
 
@@ -59,59 +62,33 @@ public:
             bbox.max.x = std::max(feature.bbox.max.x, bbox.max.x);
             bbox.max.y = std::max(feature.bbox.max.y, bbox.max.y);
         }
-
-        is_solid = isSolid(buffer);
     }
 
 private:
-    const double z2;
-    const uint16_t extent;
-    const double tolerance;
-    const double sq_tolerance;
-
-    bool isSolid(const uint16_t buffer) {
-        if (tile.features.size() != 1)
-            return false;
-
-        const auto& geom = tile.features.front().geometry;
-        if (!geom.is<mapbox::geometry::polygon<int16_t>>())
-            return false;
-
-        const auto& rings = geom.get<mapbox::geometry::polygon<int16_t>>();
-        if (rings.size() > 1)
-            return false;
-
-        const auto& ring = rings.front();
-        if (ring.size() != 5)
-            return false;
-
-        const int16_t min = -static_cast<int16_t>(buffer);
-        const int16_t max = static_cast<int16_t>(extent + buffer);
-        for (const auto& p : ring) {
-            if ((p.x != min && p.x != max) || (p.y != min && p.y != max))
-                return false;
-        }
-
-        return true;
-    }
-
-    void addFeature(const vt_point& point, const property_map& props, const optional<identifier>& id) {
+    void
+    addFeature(const vt_point& point, const property_map& props, const optional<identifier>& id) {
         tile.features.push_back({ transform(point), props, id });
     }
 
-    void addFeature(const vt_line_string& line, const property_map& props, const optional<identifier>& id) {
+    void addFeature(const vt_line_string& line,
+                    const property_map& props,
+                    const optional<identifier>& id) {
         const auto new_line = transform(line);
         if (!new_line.empty())
             tile.features.push_back({ std::move(new_line), props, id });
     }
 
-    void addFeature(const vt_polygon& polygon, const property_map& props, const optional<identifier>& id) {
+    void addFeature(const vt_polygon& polygon,
+                    const property_map& props,
+                    const optional<identifier>& id) {
         const auto new_polygon = transform(polygon);
         if (!new_polygon.empty())
             tile.features.push_back({ std::move(new_polygon), props, id });
     }
 
-    void addFeature(const vt_geometry_collection& collection, const property_map& props, const optional<identifier>& id) {
+    void addFeature(const vt_geometry_collection& collection,
+                    const property_map& props,
+                    const optional<identifier>& id) {
         for (const auto& geom : collection) {
             vt_geometry::visit(geom, [&](const auto& g) {
                 // `this->` is a workaround for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61636
diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/types.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/types.hpp
index b54357a7b9..b65844f432 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/types.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/types.hpp
@@ -60,13 +60,19 @@ using vt_multi_point = std::vector<vt_point>;
 
 struct vt_line_string : std::vector<vt_point> {
     using container_type = std::vector<vt_point>;
-    using container_type::container_type;
+    vt_line_string() = default;
+    vt_line_string(std::initializer_list<vt_point> args)
+      : container_type(std::move(args)) {}
+
     double dist = 0.0; // line length
 };
 
 struct vt_linear_ring : std::vector<vt_point> {
     using container_type = std::vector<vt_point>;
-    using container_type::container_type;
+    vt_linear_ring() = default;
+    vt_linear_ring(std::initializer_list<vt_point> args)
+      : container_type(std::move(args)) {}
+
     double area = 0.0; // polygon ring area
 };
 
diff --git a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/wrap.hpp b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/wrap.hpp
index 495ccc5800..495ccc5800 100644
--- a/deps/geojsonvt/6.3.0/include/mapbox/geojsonvt/wrap.hpp
+++ b/deps/geojsonvt/6.5.1/include/mapbox/geojsonvt/wrap.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry.hpp b/deps/geometry/0.9.3/include/mapbox/geometry.hpp
index e232453179..e232453179 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/box.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/box.hpp
index bf81b703ec..bf81b703ec 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/box.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/box.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/envelope.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/envelope.hpp
index 8603583985..8603583985 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/envelope.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/envelope.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/feature.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/feature.hpp
index 20d2ddf6b8..685c01229f 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/feature.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/feature.hpp
@@ -84,7 +84,12 @@ struct feature_collection : Cont<feature<T>>
     using coordinate_type = T;
     using feature_type = feature<T>;
     using container_type = Cont<feature_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    feature_collection(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    feature_collection(std::initializer_list<feature_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/for_each_point.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/for_each_point.hpp
index 44d6e77bd0..44d6e77bd0 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/for_each_point.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/for_each_point.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/geometry.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/geometry.hpp
index a9d072be7e..3b86117220 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/geometry.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/geometry.hpp
@@ -46,12 +46,12 @@ struct geometry_collection : Cont<geometry<T>>
     using coordinate_type = T;
     using geometry_type = geometry<T>;
     using container_type = Cont<geometry_type>;
+    using size_type = typename container_type::size_type;
 
-    geometry_collection() = default;
-    geometry_collection(geometry_collection const&) = default;
-    geometry_collection(geometry_collection &&) = default;
-    geometry_collection(std::initializer_list<geometry_type> && args)
-      : container_type(std::forward<std::initializer_list<geometry_type>>(args)) {};
+    template <class... Args>
+    geometry_collection(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    geometry_collection(std::initializer_list<geometry_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/line_string.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/line_string.hpp
index 6d811ce221..d11d06bd84 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/line_string.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/line_string.hpp
@@ -14,7 +14,12 @@ struct line_string : Cont<point<T> >
     using coordinate_type = T;
     using point_type = point<T>;
     using container_type = Cont<point_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    line_string(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    line_string(std::initializer_list<point_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/multi_line_string.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/multi_line_string.hpp
index 07a7a1d609..7dfefd8ffa 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/multi_line_string.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/multi_line_string.hpp
@@ -14,7 +14,12 @@ struct multi_line_string : Cont<line_string<T>>
     using coordinate_type = T;
     using line_string_type = line_string<T>;
     using container_type = Cont<line_string_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    multi_line_string(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    multi_line_string(std::initializer_list<line_string_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/multi_point.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/multi_point.hpp
index a3c73cff91..d2d7a6768a 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/multi_point.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/multi_point.hpp
@@ -14,7 +14,12 @@ struct multi_point : Cont<point<T>>
     using coordinate_type = T;
     using point_type = point<T>;
     using container_type = Cont<point_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    multi_point(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    multi_point(std::initializer_list<point_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/multi_polygon.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/multi_polygon.hpp
index ad230a04c8..0e3cb321a4 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/multi_polygon.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/multi_polygon.hpp
@@ -14,7 +14,12 @@ struct multi_polygon : Cont<polygon<T>>
     using coordinate_type = T;
     using polygon_type = polygon<T>;
     using container_type = Cont<polygon_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    multi_polygon(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    multi_polygon(std::initializer_list<polygon_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/point.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/point.hpp
index 0cba4996e7..0cba4996e7 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/point.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/point.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/point_arithmetic.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/point_arithmetic.hpp
index 0c4c63278a..0c4c63278a 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/point_arithmetic.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/point_arithmetic.hpp
diff --git a/deps/geometry/0.9.2/include/mapbox/geometry/polygon.hpp b/deps/geometry/0.9.3/include/mapbox/geometry/polygon.hpp
index 99a66aa125..0c7e1161cb 100644
--- a/deps/geometry/0.9.2/include/mapbox/geometry/polygon.hpp
+++ b/deps/geometry/0.9.3/include/mapbox/geometry/polygon.hpp
@@ -15,7 +15,12 @@ struct linear_ring : Cont<point<T>>
     using coordinate_type = T;
     using point_type = point<T>;
     using container_type = Cont<point_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    linear_ring(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    linear_ring(std::initializer_list<point_type> args)
+        : container_type(std::move(args)) {}
 };
 
 template <typename T, template <typename...> class Cont = std::vector>
@@ -24,7 +29,12 @@ struct polygon : Cont<linear_ring<T>>
     using coordinate_type = T;
     using linear_ring_type = linear_ring<T>;
     using container_type = Cont<linear_ring_type>;
-    using container_type::container_type;
+    using size_type = typename container_type::size_type;
+
+    template <class... Args>
+    polygon(Args&&... args) : container_type(std::forward<Args>(args)...) {}
+    polygon(std::initializer_list<linear_ring_type> args)
+        : container_type(std::move(args)) {}
 };
 
 } // namespace geometry
diff --git a/deps/optional/f27e7908/include/experimental/optional b/deps/optional/f27e7908/include/experimental/optional
new file mode 100644
index 0000000000..7b9148f3a7
--- /dev/null
+++ b/deps/optional/f27e7908/include/experimental/optional
@@ -0,0 +1,1052 @@
+// Copyright (C) 2011 - 2012 Andrzej Krzemienski.
+//
+// Use, modification, and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// The idea and interface is based on Boost.Optional library
+// authored by Fernando Luis Cacciola Carballal
+
+# ifndef ___OPTIONAL_HPP___
+# define ___OPTIONAL_HPP___
+
+# include <utility>
+# include <type_traits>
+# include <initializer_list>
+# include <cassert>
+# include <functional>
+# include <string>
+# include <stdexcept>
+
+# define TR2_OPTIONAL_REQUIRES(...) typename enable_if<__VA_ARGS__::value, bool>::type = false
+
+# if defined __GNUC__ // NOTE: GNUC is also defined for Clang
+#   if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)
+#     define TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
+#   elif (__GNUC__ > 4)
+#     define TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
+#   endif
+#
+#   if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)
+#     define TR2_OPTIONAL_GCC_4_7_AND_HIGHER___
+#   elif (__GNUC__ > 4)
+#     define TR2_OPTIONAL_GCC_4_7_AND_HIGHER___
+#   endif
+#
+#   if (__GNUC__ == 4) && (__GNUC_MINOR__ == 8) && (__GNUC_PATCHLEVEL__ >= 1)
+#     define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
+#   elif (__GNUC__ == 4) && (__GNUC_MINOR__ >= 9)
+#     define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
+#   elif (__GNUC__ > 4)
+#     define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
+#   endif
+# endif
+#
+# if defined __clang_major__
+#   if (__clang_major__ == 3 && __clang_minor__ >= 5)
+#     define TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
+#   elif (__clang_major__ > 3)
+#     define TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
+#   endif
+#   if defined TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
+#     define TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
+#   elif (__clang_major__ == 3 && __clang_minor__ == 4 && __clang_patchlevel__ >= 2)
+#     define TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
+#   endif
+# endif
+#
+# if defined _MSC_VER
+#   if (_MSC_VER >= 1900)
+#     define TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
+#   endif
+# endif
+
+# if defined __clang__
+#   if (__clang_major__ > 2) || (__clang_major__ == 2) && (__clang_minor__ >= 9)
+#     define OPTIONAL_HAS_THIS_RVALUE_REFS 1
+#   else
+#     define OPTIONAL_HAS_THIS_RVALUE_REFS 0
+#   endif
+# elif defined TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
+#   define OPTIONAL_HAS_THIS_RVALUE_REFS 1
+# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
+#   define OPTIONAL_HAS_THIS_RVALUE_REFS 1
+# else
+#   define OPTIONAL_HAS_THIS_RVALUE_REFS 0
+# endif
+
+
+# if defined TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
+#   define OPTIONAL_HAS_CONSTEXPR_INIT_LIST 1
+#   define OPTIONAL_CONSTEXPR_INIT_LIST constexpr
+# else
+#   define OPTIONAL_HAS_CONSTEXPR_INIT_LIST 0
+#   define OPTIONAL_CONSTEXPR_INIT_LIST
+# endif
+
+# if defined TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_ && (defined __cplusplus) && (__cplusplus != 201103L)
+#   define OPTIONAL_HAS_MOVE_ACCESSORS 1
+# else
+#   define OPTIONAL_HAS_MOVE_ACCESSORS 0
+# endif
+
+# // In C++11 constexpr implies const, so we need to make non-const members also non-constexpr
+# if (defined __cplusplus) && (__cplusplus == 201103L)
+#   define OPTIONAL_MUTABLE_CONSTEXPR
+# else
+#   define OPTIONAL_MUTABLE_CONSTEXPR constexpr
+# endif
+
+namespace std{
+
+namespace experimental{
+
+// BEGIN workaround for missing is_trivially_destructible
+# if defined TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
+    // leave it: it is already there
+# elif defined TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
+    // leave it: it is already there
+# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
+    // leave it: it is already there
+# elif defined TR2_OPTIONAL_DISABLE_EMULATION_OF_TYPE_TRAITS
+    // leave it: the user doesn't want it
+# else
+	template <typename T>
+	using is_trivially_destructible = std::has_trivial_destructor<T>;
+# endif
+// END workaround for missing is_trivially_destructible
+
+# if (defined TR2_OPTIONAL_GCC_4_7_AND_HIGHER___)
+    // leave it; our metafunctions are already defined.
+# elif defined TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
+    // leave it; our metafunctions are already defined.
+# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
+    // leave it: it is already there
+# elif defined TR2_OPTIONAL_DISABLE_EMULATION_OF_TYPE_TRAITS
+    // leave it: the user doesn't want it
+# else
+
+
+// workaround for missing traits in GCC and CLANG
+template <class T>
+struct is_nothrow_move_constructible
+{
+  constexpr static bool value = std::is_nothrow_constructible<T, T&&>::value;
+};
+
+
+template <class T, class U>
+struct is_assignable
+{
+  template <class X, class Y>
+  constexpr static bool has_assign(...) { return false; }
+
+  template <class X, class Y, size_t S = sizeof((std::declval<X>() = std::declval<Y>(), true)) >
+  // the comma operator is necessary for the cases where operator= returns void
+  constexpr static bool has_assign(bool) { return true; }
+
+  constexpr static bool value = has_assign<T, U>(true);
+};
+
+
+template <class T>
+struct is_nothrow_move_assignable
+{
+  template <class X, bool has_any_move_assign>
+  struct has_nothrow_move_assign {
+    constexpr static bool value = false;
+  };
+
+  template <class X>
+  struct has_nothrow_move_assign<X, true> {
+    constexpr static bool value = noexcept( std::declval<X&>() = std::declval<X&&>() );
+  };
+
+  constexpr static bool value = has_nothrow_move_assign<T, is_assignable<T&, T&&>::value>::value;
+};
+// end workaround
+
+
+# endif
+
+
+
+// 20.5.4, optional for object types
+template <class T> class optional;
+
+// 20.5.5, optional for lvalue reference types
+template <class T> class optional<T&>;
+
+
+// workaround: std utility functions aren't constexpr yet
+template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type& t) noexcept
+{
+  return static_cast<T&&>(t);
+}
+
+template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type&& t) noexcept
+{
+    static_assert(!std::is_lvalue_reference<T>::value, "!!");
+    return static_cast<T&&>(t);
+}
+
+template <class T> inline constexpr typename std::remove_reference<T>::type&& constexpr_move(T&& t) noexcept
+{
+    return static_cast<typename std::remove_reference<T>::type&&>(t);
+}
+
+
+#if defined NDEBUG
+# define TR2_OPTIONAL_ASSERTED_EXPRESSION(CHECK, EXPR) (EXPR)
+#else
+# define TR2_OPTIONAL_ASSERTED_EXPRESSION(CHECK, EXPR) ((CHECK) ? (EXPR) : ([]{assert(!#CHECK);}(), (EXPR)))
+#endif
+
+
+namespace detail_
+{
+
+// static_addressof: a constexpr version of addressof
+template <typename T>
+struct has_overloaded_addressof
+{
+  template <class X>
+  constexpr static bool has_overload(...) { return false; }
+  
+  template <class X, size_t S = sizeof(std::declval<X&>().operator&()) >
+  constexpr static bool has_overload(bool) { return true; }
+
+  constexpr static bool value = has_overload<T>(true);
+};
+
+template <typename T, TR2_OPTIONAL_REQUIRES(!has_overloaded_addressof<T>)>
+constexpr T* static_addressof(T& ref)
+{
+  return &ref;
+}
+
+template <typename T, TR2_OPTIONAL_REQUIRES(has_overloaded_addressof<T>)>
+T* static_addressof(T& ref)
+{
+  return std::addressof(ref);
+}
+
+
+// the call to convert<A>(b) has return type A and converts b to type A iff b decltype(b) is implicitly convertible to A  
+template <class U>
+constexpr U convert(U v) { return v; }
+  
+} // namespace detail
+
+
+constexpr struct trivial_init_t{} trivial_init{};
+
+
+// 20.5.6, In-place construction
+constexpr struct in_place_t{} in_place{};
+
+
+// 20.5.7, Disengaged state indicator
+struct nullopt_t
+{
+  struct init{};
+  constexpr explicit nullopt_t(init){}
+};
+constexpr nullopt_t nullopt{nullopt_t::init()};
+
+
+// 20.5.8, class bad_optional_access
+class bad_optional_access : public logic_error {
+public:
+  explicit bad_optional_access(const string& what_arg) : logic_error{what_arg} {}
+  explicit bad_optional_access(const char* what_arg) : logic_error{what_arg} {}
+};
+
+
+template <class T>
+union storage_t
+{
+  unsigned char dummy_;
+  T value_;
+
+  constexpr storage_t( trivial_init_t ) noexcept : dummy_() {};
+
+  template <class... Args>
+  constexpr storage_t( Args&&... args ) : value_(constexpr_forward<Args>(args)...) {}
+
+  ~storage_t(){}
+};
+
+
+template <class T>
+union constexpr_storage_t
+{
+    unsigned char dummy_;
+    T value_;
+
+    constexpr constexpr_storage_t( trivial_init_t ) noexcept : dummy_() {};
+
+    template <class... Args>
+    constexpr constexpr_storage_t( Args&&... args ) : value_(constexpr_forward<Args>(args)...) {}
+
+    ~constexpr_storage_t() = default;
+};
+
+
+template <class T>
+struct optional_base
+{
+    bool init_;
+    storage_t<T> storage_;
+
+    constexpr optional_base() noexcept : init_(false), storage_(trivial_init) {};
+
+    explicit constexpr optional_base(const T& v) : init_(true), storage_(v) {}
+
+    explicit constexpr optional_base(T&& v) : init_(true), storage_(constexpr_move(v)) {}
+
+    template <class... Args> explicit optional_base(in_place_t, Args&&... args)
+        : init_(true), storage_(constexpr_forward<Args>(args)...) {}
+
+    template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<U>>)>
+    explicit optional_base(in_place_t, std::initializer_list<U> il, Args&&... args)
+        : init_(true), storage_(il, std::forward<Args>(args)...) {}
+
+    ~optional_base() { if (init_) storage_.value_.T::~T(); }
+};
+
+
+template <class T>
+struct constexpr_optional_base
+{
+    bool init_;
+    constexpr_storage_t<T> storage_;
+
+    constexpr constexpr_optional_base() noexcept : init_(false), storage_(trivial_init) {};
+
+    explicit constexpr constexpr_optional_base(const T& v) : init_(true), storage_(v) {}
+
+    explicit constexpr constexpr_optional_base(T&& v) : init_(true), storage_(constexpr_move(v)) {}
+
+    template <class... Args> explicit constexpr constexpr_optional_base(in_place_t, Args&&... args)
+      : init_(true), storage_(constexpr_forward<Args>(args)...) {}
+
+    template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<U>>)>
+    OPTIONAL_CONSTEXPR_INIT_LIST explicit constexpr_optional_base(in_place_t, std::initializer_list<U> il, Args&&... args)
+      : init_(true), storage_(il, std::forward<Args>(args)...) {}
+
+    ~constexpr_optional_base() = default;
+};
+
+template <class T>
+using OptionalBase = typename std::conditional<
+    is_trivially_destructible<T>::value,                          // if possible
+    constexpr_optional_base<typename std::remove_const<T>::type>, // use base with trivial destructor
+    optional_base<typename std::remove_const<T>::type>
+>::type;
+
+
+
+template <class T>
+class optional : private OptionalBase<T>
+{
+  static_assert( !std::is_same<typename std::decay<T>::type, nullopt_t>::value, "bad T" );
+  static_assert( !std::is_same<typename std::decay<T>::type, in_place_t>::value, "bad T" );
+  
+
+  constexpr bool initialized() const noexcept { return OptionalBase<T>::init_; }
+  typename std::remove_const<T>::type* dataptr() {  return std::addressof(OptionalBase<T>::storage_.value_); }
+  constexpr const T* dataptr() const { return detail_::static_addressof(OptionalBase<T>::storage_.value_); }
+  
+# if OPTIONAL_HAS_THIS_RVALUE_REFS == 1
+  constexpr const T& contained_val() const& { return OptionalBase<T>::storage_.value_; }
+#   if OPTIONAL_HAS_MOVE_ACCESSORS == 1
+  OPTIONAL_MUTABLE_CONSTEXPR T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }
+  OPTIONAL_MUTABLE_CONSTEXPR T& contained_val() & { return OptionalBase<T>::storage_.value_; }
+#   else
+  T& contained_val() & { return OptionalBase<T>::storage_.value_; }
+  T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }
+#   endif
+# else
+  constexpr const T& contained_val() const { return OptionalBase<T>::storage_.value_; }
+  T& contained_val() { return OptionalBase<T>::storage_.value_; }
+# endif
+
+  void clear() noexcept {
+    if (initialized()) dataptr()->T::~T();
+    OptionalBase<T>::init_ = false;
+  }
+  
+  template <class... Args>
+  void initialize(Args&&... args) noexcept(noexcept(T(std::forward<Args>(args)...)))
+  {
+    assert(!OptionalBase<T>::init_);
+    ::new (static_cast<void*>(dataptr())) T(std::forward<Args>(args)...);
+    OptionalBase<T>::init_ = true;
+  }
+
+  template <class U, class... Args>
+  void initialize(std::initializer_list<U> il, Args&&... args) noexcept(noexcept(T(il, std::forward<Args>(args)...)))
+  {
+    assert(!OptionalBase<T>::init_);
+    ::new (static_cast<void*>(dataptr())) T(il, std::forward<Args>(args)...);
+    OptionalBase<T>::init_ = true;
+  }
+
+public:
+  typedef T value_type;
+
+  // 20.5.5.1, constructors
+  constexpr optional() noexcept : OptionalBase<T>()  {};
+  constexpr optional(nullopt_t) noexcept : OptionalBase<T>() {};
+
+  optional(const optional& rhs)
+  : OptionalBase<T>()
+  {
+    if (rhs.initialized()) {
+        ::new (static_cast<void*>(dataptr())) T(*rhs);
+        OptionalBase<T>::init_ = true;
+    }
+  }
+
+  optional(optional&& rhs) noexcept(is_nothrow_move_constructible<T>::value)
+  : OptionalBase<T>()
+  {
+    if (rhs.initialized()) {
+        ::new (static_cast<void*>(dataptr())) T(std::move(*rhs));
+        OptionalBase<T>::init_ = true;
+    }
+  }
+
+  constexpr optional(const T& v) : OptionalBase<T>(v) {}
+
+  constexpr optional(T&& v) : OptionalBase<T>(constexpr_move(v)) {}
+
+  template <class... Args>
+  explicit constexpr optional(in_place_t, Args&&... args)
+  : OptionalBase<T>(in_place_t{}, constexpr_forward<Args>(args)...) {}
+
+  template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<U>>)>
+  OPTIONAL_CONSTEXPR_INIT_LIST explicit optional(in_place_t, std::initializer_list<U> il, Args&&... args)
+  : OptionalBase<T>(in_place_t{}, il, constexpr_forward<Args>(args)...) {}
+
+  // 20.5.4.2, Destructor
+  ~optional() = default;
+
+  // 20.5.4.3, assignment
+  optional& operator=(nullopt_t) noexcept
+  {
+    clear();
+    return *this;
+  }
+  
+  optional& operator=(const optional& rhs)
+  {
+    if      (initialized() == true  && rhs.initialized() == false) clear();
+    else if (initialized() == false && rhs.initialized() == true)  initialize(*rhs);
+    else if (initialized() == true  && rhs.initialized() == true)  contained_val() = *rhs;
+    return *this;
+  }
+  
+  optional& operator=(optional&& rhs)
+  noexcept(is_nothrow_move_assignable<T>::value && is_nothrow_move_constructible<T>::value)
+  {
+    if      (initialized() == true  && rhs.initialized() == false) clear();
+    else if (initialized() == false && rhs.initialized() == true)  initialize(std::move(*rhs));
+    else if (initialized() == true  && rhs.initialized() == true)  contained_val() = std::move(*rhs);
+    return *this;
+  }
+
+  template <class U>
+  auto operator=(U&& v)
+  -> typename enable_if
+  <
+    is_same<typename decay<U>::type, T>::value,
+    optional&
+  >::type
+  {
+    if (initialized()) { contained_val() = std::forward<U>(v); }
+    else               { initialize(std::forward<U>(v));  }
+    return *this;
+  }
+  
+  
+  template <class... Args>
+  void emplace(Args&&... args)
+  {
+    clear();
+    initialize(std::forward<Args>(args)...);
+  }
+  
+  template <class U, class... Args>
+  void emplace(initializer_list<U> il, Args&&... args)
+  {
+    clear();
+    initialize<U, Args...>(il, std::forward<Args>(args)...);
+  }
+  
+  // 20.5.4.4, Swap
+  void swap(optional<T>& rhs) noexcept(is_nothrow_move_constructible<T>::value && noexcept(swap(declval<T&>(), declval<T&>())))
+  {
+    if      (initialized() == true  && rhs.initialized() == false) { rhs.initialize(std::move(**this)); clear(); }
+    else if (initialized() == false && rhs.initialized() == true)  { initialize(std::move(*rhs)); rhs.clear(); }
+    else if (initialized() == true  && rhs.initialized() == true)  { using std::swap; swap(**this, *rhs); }
+  }
+
+  // 20.5.4.5, Observers
+  
+  explicit constexpr operator bool() const noexcept { return initialized(); }
+  constexpr bool has_value() const noexcept { return initialized(); }
+  
+  constexpr T const* operator ->() const {
+    return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), dataptr());
+  }
+  
+# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
+
+  OPTIONAL_MUTABLE_CONSTEXPR T* operator ->() {
+    assert (initialized());
+    return dataptr();
+  }
+  
+  constexpr T const& operator *() const& {
+    return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), contained_val());
+  }
+  
+  OPTIONAL_MUTABLE_CONSTEXPR T& operator *() & {
+    assert (initialized());
+    return contained_val();
+  }
+  
+  OPTIONAL_MUTABLE_CONSTEXPR T&& operator *() && {
+    assert (initialized());
+    return constexpr_move(contained_val());
+  }
+
+  constexpr T const& value() const& {
+    return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
+  }
+  
+  OPTIONAL_MUTABLE_CONSTEXPR T& value() & {
+    return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
+  }
+  
+  OPTIONAL_MUTABLE_CONSTEXPR T&& value() && {
+    if (!initialized()) throw bad_optional_access("bad optional access");
+	return std::move(contained_val());
+  }
+  
+# else
+
+  T* operator ->() {
+    assert (initialized());
+    return dataptr();
+  }
+  
+  constexpr T const& operator *() const {
+    return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), contained_val());
+  }
+  
+  T& operator *() {
+    assert (initialized());
+    return contained_val();
+  }
+  
+  constexpr T const& value() const {
+    return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
+  }
+  
+  T& value() {
+    return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
+  }
+  
+# endif
+  
+# if OPTIONAL_HAS_THIS_RVALUE_REFS == 1
+
+  template <class V>
+  constexpr T value_or(V&& v) const&
+  {
+    return *this ? **this : detail_::convert<T>(constexpr_forward<V>(v));
+  }
+  
+#   if OPTIONAL_HAS_MOVE_ACCESSORS == 1
+
+  template <class V>
+  OPTIONAL_MUTABLE_CONSTEXPR T value_or(V&& v) &&
+  {
+    return *this ? constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<T>(constexpr_forward<V>(v));
+  }
+
+#   else
+ 
+  template <class V>
+  T value_or(V&& v) &&
+  {
+    return *this ? constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<T>(constexpr_forward<V>(v));
+  }
+  
+#   endif
+  
+# else
+  
+  template <class V>
+  constexpr T value_or(V&& v) const
+  {
+    return *this ? **this : detail_::convert<T>(constexpr_forward<V>(v));
+  }
+
+# endif
+
+  // 20.6.3.6, modifiers
+  void reset() noexcept { clear(); }
+};
+
+
+template <class T>
+class optional<T&>
+{
+  static_assert( !std::is_same<T, nullopt_t>::value, "bad T" );
+  static_assert( !std::is_same<T, in_place_t>::value, "bad T" );
+  T* ref;
+  
+public:
+
+  // 20.5.5.1, construction/destruction
+  constexpr optional() noexcept : ref(nullptr) {}
+  
+  constexpr optional(nullopt_t) noexcept : ref(nullptr) {}
+   
+  constexpr optional(T& v) noexcept : ref(detail_::static_addressof(v)) {}
+  
+  optional(T&&) = delete;
+  
+  constexpr optional(const optional& rhs) noexcept : ref(rhs.ref) {}
+  
+  explicit constexpr optional(in_place_t, T& v) noexcept : ref(detail_::static_addressof(v)) {}
+  
+  explicit optional(in_place_t, T&&) = delete;
+  
+  ~optional() = default;
+  
+  // 20.5.5.2, mutation
+  optional& operator=(nullopt_t) noexcept {
+    ref = nullptr;
+    return *this;
+  }
+  
+  // optional& operator=(const optional& rhs) noexcept {
+    // ref = rhs.ref;
+    // return *this;
+  // }
+  
+  // optional& operator=(optional&& rhs) noexcept {
+    // ref = rhs.ref;
+    // return *this;
+  // }
+  
+  template <typename U>
+  auto operator=(U&& rhs) noexcept
+  -> typename enable_if
+  <
+    is_same<typename decay<U>::type, optional<T&>>::value,
+    optional&
+  >::type
+  {
+    ref = rhs.ref;
+    return *this;
+  }
+  
+  template <typename U>
+  auto operator=(U&& rhs) noexcept
+  -> typename enable_if
+  <
+    !is_same<typename decay<U>::type, optional<T&>>::value,
+    optional&
+  >::type
+  = delete;
+  
+  void emplace(T& v) noexcept {
+    ref = detail_::static_addressof(v);
+  }
+  
+  void emplace(T&&) = delete;
+  
+  
+  void swap(optional<T&>& rhs) noexcept
+  {
+    std::swap(ref, rhs.ref);
+  }
+    
+  // 20.5.5.3, observers
+  constexpr T* operator->() const {
+    return TR2_OPTIONAL_ASSERTED_EXPRESSION(ref, ref);
+  }
+  
+  constexpr T& operator*() const {
+    return TR2_OPTIONAL_ASSERTED_EXPRESSION(ref, *ref);
+  }
+  
+  constexpr T& value() const {
+    return ref ? *ref : (throw bad_optional_access("bad optional access"), *ref);
+  }
+  
+  explicit constexpr operator bool() const noexcept {
+    return ref != nullptr;
+  }
+ 
+  constexpr bool has_value() const noexcept {
+    return ref != nullptr;
+  }
+  
+  template <class V>
+  constexpr typename decay<T>::type value_or(V&& v) const
+  {
+    return *this ? **this : detail_::convert<typename decay<T>::type>(constexpr_forward<V>(v));
+  }
+
+  // x.x.x.x, modifiers
+  void reset() noexcept { ref = nullptr; }
+};
+
+
+template <class T>
+class optional<T&&>
+{
+  static_assert( sizeof(T) == 0, "optional rvalue references disallowed" );
+};
+
+
+// 20.5.8, Relational operators
+template <class T> constexpr bool operator==(const optional<T>& x, const optional<T>& y)
+{
+  return bool(x) != bool(y) ? false : bool(x) == false ? true : *x == *y;
+}
+
+template <class T> constexpr bool operator!=(const optional<T>& x, const optional<T>& y)
+{
+  return !(x == y);
+}
+
+template <class T> constexpr bool operator<(const optional<T>& x, const optional<T>& y)
+{
+  return (!y) ? false : (!x) ? true : *x < *y;
+}
+
+template <class T> constexpr bool operator>(const optional<T>& x, const optional<T>& y)
+{
+  return (y < x);
+}
+
+template <class T> constexpr bool operator<=(const optional<T>& x, const optional<T>& y)
+{
+  return !(y < x);
+}
+
+template <class T> constexpr bool operator>=(const optional<T>& x, const optional<T>& y)
+{
+  return !(x < y);
+}
+
+
+// 20.5.9, Comparison with nullopt
+template <class T> constexpr bool operator==(const optional<T>& x, nullopt_t) noexcept
+{
+  return (!x);
+}
+
+template <class T> constexpr bool operator==(nullopt_t, const optional<T>& x) noexcept
+{
+  return (!x);
+}
+
+template <class T> constexpr bool operator!=(const optional<T>& x, nullopt_t) noexcept
+{
+  return bool(x);
+}
+
+template <class T> constexpr bool operator!=(nullopt_t, const optional<T>& x) noexcept
+{
+  return bool(x);
+}
+
+template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept
+{
+  return false;
+}
+
+template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept
+{
+  return bool(x);
+}
+
+template <class T> constexpr bool operator<=(const optional<T>& x, nullopt_t) noexcept
+{
+  return (!x);
+}
+
+template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept
+{
+  return true;
+}
+
+template <class T> constexpr bool operator>(const optional<T>& x, nullopt_t) noexcept
+{
+  return bool(x);
+}
+
+template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept
+{
+  return false;
+}
+
+template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept
+{
+  return true;
+}
+
+template <class T> constexpr bool operator>=(nullopt_t, const optional<T>& x) noexcept
+{
+  return (!x);
+}
+
+
+
+// 20.5.10, Comparison with T
+template <class T> constexpr bool operator==(const optional<T>& x, const T& v)
+{
+  return bool(x) ? *x == v : false;
+}
+
+template <class T> constexpr bool operator==(const T& v, const optional<T>& x)
+{
+  return bool(x) ? v == *x : false;
+}
+
+template <class T> constexpr bool operator!=(const optional<T>& x, const T& v)
+{
+  return bool(x) ? *x != v : true;
+}
+
+template <class T> constexpr bool operator!=(const T& v, const optional<T>& x)
+{
+  return bool(x) ? v != *x : true;
+}
+
+template <class T> constexpr bool operator<(const optional<T>& x, const T& v)
+{
+  return bool(x) ? *x < v : true;
+}
+
+template <class T> constexpr bool operator>(const T& v, const optional<T>& x)
+{
+  return bool(x) ? v > *x : true;
+}
+
+template <class T> constexpr bool operator>(const optional<T>& x, const T& v)
+{
+  return bool(x) ? *x > v : false;
+}
+
+template <class T> constexpr bool operator<(const T& v, const optional<T>& x)
+{
+  return bool(x) ? v < *x : false;
+}
+
+template <class T> constexpr bool operator>=(const optional<T>& x, const T& v)
+{
+  return bool(x) ? *x >= v : false;
+}
+
+template <class T> constexpr bool operator<=(const T& v, const optional<T>& x)
+{
+  return bool(x) ? v <= *x : false;
+}
+
+template <class T> constexpr bool operator<=(const optional<T>& x, const T& v)
+{
+  return bool(x) ? *x <= v : true;
+}
+
+template <class T> constexpr bool operator>=(const T& v, const optional<T>& x)
+{
+  return bool(x) ? v >= *x : true;
+}
+
+
+// Comparison of optional<T&> with T
+template <class T> constexpr bool operator==(const optional<T&>& x, const T& v)
+{
+  return bool(x) ? *x == v : false;
+}
+
+template <class T> constexpr bool operator==(const T& v, const optional<T&>& x)
+{
+  return bool(x) ? v == *x : false;
+}
+
+template <class T> constexpr bool operator!=(const optional<T&>& x, const T& v)
+{
+  return bool(x) ? *x != v : true;
+}
+
+template <class T> constexpr bool operator!=(const T& v, const optional<T&>& x)
+{
+  return bool(x) ? v != *x : true;
+}
+
+template <class T> constexpr bool operator<(const optional<T&>& x, const T& v)
+{
+  return bool(x) ? *x < v : true;
+}
+
+template <class T> constexpr bool operator>(const T& v, const optional<T&>& x)
+{
+  return bool(x) ? v > *x : true;
+}
+
+template <class T> constexpr bool operator>(const optional<T&>& x, const T& v)
+{
+  return bool(x) ? *x > v : false;
+}
+
+template <class T> constexpr bool operator<(const T& v, const optional<T&>& x)
+{
+  return bool(x) ? v < *x : false;
+}
+
+template <class T> constexpr bool operator>=(const optional<T&>& x, const T& v)
+{
+  return bool(x) ? *x >= v : false;
+}
+
+template <class T> constexpr bool operator<=(const T& v, const optional<T&>& x)
+{
+  return bool(x) ? v <= *x : false;
+}
+
+template <class T> constexpr bool operator<=(const optional<T&>& x, const T& v)
+{
+  return bool(x) ? *x <= v : true;
+}
+
+template <class T> constexpr bool operator>=(const T& v, const optional<T&>& x)
+{
+  return bool(x) ? v >= *x : true;
+}
+
+// Comparison of optional<T const&> with T
+template <class T> constexpr bool operator==(const optional<const T&>& x, const T& v)
+{
+  return bool(x) ? *x == v : false;
+}
+
+template <class T> constexpr bool operator==(const T& v, const optional<const T&>& x)
+{
+  return bool(x) ? v == *x : false;
+}
+
+template <class T> constexpr bool operator!=(const optional<const T&>& x, const T& v)
+{
+  return bool(x) ? *x != v : true;
+}
+
+template <class T> constexpr bool operator!=(const T& v, const optional<const T&>& x)
+{
+  return bool(x) ? v != *x : true;
+}
+
+template <class T> constexpr bool operator<(const optional<const T&>& x, const T& v)
+{
+  return bool(x) ? *x < v : true;
+}
+
+template <class T> constexpr bool operator>(const T& v, const optional<const T&>& x)
+{
+  return bool(x) ? v > *x : true;
+}
+
+template <class T> constexpr bool operator>(const optional<const T&>& x, const T& v)
+{
+  return bool(x) ? *x > v : false;
+}
+
+template <class T> constexpr bool operator<(const T& v, const optional<const T&>& x)
+{
+  return bool(x) ? v < *x : false;
+}
+
+template <class T> constexpr bool operator>=(const optional<const T&>& x, const T& v)
+{
+  return bool(x) ? *x >= v : false;
+}
+
+template <class T> constexpr bool operator<=(const T& v, const optional<const T&>& x)
+{
+  return bool(x) ? v <= *x : false;
+}
+
+template <class T> constexpr bool operator<=(const optional<const T&>& x, const T& v)
+{
+  return bool(x) ? *x <= v : true;
+}
+
+template <class T> constexpr bool operator>=(const T& v, const optional<const T&>& x)
+{
+  return bool(x) ? v >= *x : true;
+}
+
+
+// 20.5.12, Specialized algorithms
+template <class T>
+void swap(optional<T>& x, optional<T>& y) noexcept(noexcept(x.swap(y)))
+{
+  x.swap(y);
+}
+
+
+template <class T>
+constexpr optional<typename decay<T>::type> make_optional(T&& v)
+{
+  return optional<typename decay<T>::type>(constexpr_forward<T>(v));
+}
+
+template <class X>
+constexpr optional<X&> make_optional(reference_wrapper<X> v)
+{
+  return optional<X&>(v.get());
+}
+
+
+} // namespace experimental
+} // namespace std
+
+namespace std
+{
+  template <typename T>
+  struct hash<std::experimental::optional<T>>
+  {
+    typedef typename hash<T>::result_type result_type;
+    typedef std::experimental::optional<T> argument_type;
+    
+    constexpr result_type operator()(argument_type const& arg) const {
+      return arg ? std::hash<T>{}(*arg) : result_type{};
+    }
+  };
+  
+  template <typename T>
+  struct hash<std::experimental::optional<T&>>
+  {
+    typedef typename hash<T>::result_type result_type;
+    typedef std::experimental::optional<T&> argument_type;
+    
+    constexpr result_type operator()(argument_type const& arg) const {
+      return arg ? std::hash<T>{}(*arg) : result_type{};
+    }
+  };
+}
+
+# undef TR2_OPTIONAL_REQUIRES
+# undef TR2_OPTIONAL_ASSERTED_EXPRESSION
+
+# endif //___OPTIONAL_HPP___
diff --git a/deps/vector-tile/1.0.1/include/mapbox/vector_tile.hpp b/deps/vector-tile/1.0.2/include/mapbox/vector_tile.hpp
index 2308462c68..5ddae485f0 100644
--- a/deps/vector-tile/1.0.1/include/mapbox/vector_tile.hpp
+++ b/deps/vector-tile/1.0.2/include/mapbox/vector_tile.hpp
@@ -23,13 +23,15 @@ using point_type = mapbox::geometry::point<std::int16_t>;
 class points_array_type : public std::vector<point_type> {
 public:
     using coordinate_type = point_type::coordinate_type;
-    using std::vector<point_type>::vector;
+    template <class... Args>
+    points_array_type(Args&&... args) : std::vector<point_type>(std::forward<Args>(args)...) {}
 };
 
 class points_arrays_type : public std::vector<points_array_type> {
 public:
     using coordinate_type = points_array_type::coordinate_type;
-    using std::vector<points_array_type>::vector;
+    template <class... Args>
+    points_arrays_type(Args&&... args) : std::vector<points_array_type>(std::forward<Args>(args)...) {}
 };
 
 class layer;
@@ -137,7 +139,7 @@ inline feature::feature(protozero::data_view const& feature_view, layer const& l
     while (feature_pbf.next()) {
         switch (feature_pbf.tag()) {
         case FeatureType::ID:
-            id = { feature_pbf.get_uint64() };
+            id = optional<mapbox::geometry::identifier>{ feature_pbf.get_uint64() };
             break;
         case FeatureType::TAGS:
             tags_iter = feature_pbf.get_packed_uint32();
diff --git a/deps/vector-tile/1.0.1/include/mapbox/vector_tile/vector_tile_config.hpp b/deps/vector-tile/1.0.2/include/mapbox/vector_tile/vector_tile_config.hpp
index acf1185673..acf1185673 100644
--- a/deps/vector-tile/1.0.1/include/mapbox/vector_tile/vector_tile_config.hpp
+++ b/deps/vector-tile/1.0.2/include/mapbox/vector_tile/vector_tile_config.hpp
diff --git a/deps/vector-tile/1.0.1/include/mapbox/vector_tile/version.hpp b/deps/vector-tile/1.0.2/include/mapbox/vector_tile/version.hpp
index 13b8755d3c..cc1974d63c 100644
--- a/deps/vector-tile/1.0.1/include/mapbox/vector_tile/version.hpp
+++ b/deps/vector-tile/1.0.2/include/mapbox/vector_tile/version.hpp
@@ -7,10 +7,10 @@
 #define VECTOR_TILE_VERSION_MINOR 0
 
 /// The patch number
-#define VECTOR_TILE_VERSION_PATCH 1
+#define VECTOR_TILE_VERSION_PATCH 2
 
 /// The complete version number
 #define VECTOR_TILE_VERSION_CODE (VECTOR_TILE_VERSION_MAJOR * 10000 + VECTOR_TILE_VERSION_MINOR * 100 + VECTOR_TILE_VERSION_PATCH)
 
 /// Version number as string
-#define VECTOR_TILE_VERSION_STRING "1.0.1"
+#define VECTOR_TILE_VERSION_STRING "1.0.2"