[core] Implement data-driven styling for {text,icon}-{color,opacity,halo-color,halo-blur,halo-width} (#7939)

* Add symbol dds attributes and adapt style code generation

* Update to mapbox-gl-js/master

* Refactor SymbolFeature as a subclass of GeometryTileFeature

Prepares for enabling DDS on symbol paint properties by allowing the
SymbolFeatures, which we keep around after constructing SymbolLayout,
to be used in evaluating data-driven paint properties later in the
layout process.

* Draft approach for splitting icon/text paint properties

The `Program` types are set up to bind GL attributes to each of the
data-driven paint properties specified in the `PaintProperties` type
provided.  Since `SymbolPaintProperties` specifies both `Text*` and
`Icon*` properties, the symbolIcon, symbolIconSDF, and symbolGlyph
programs each attempt to bind roughly double the number of attributes
that they actually need.

This change addresses this by:
- Adding the more specific `IconPaintProperties` and `TextPaintProperties` types, which are subsets of the full `SymbolPaintProperties`.
- The symbol layer continues to use its `SymbolPaintProperties paint` member to track layer property state, but it provides helpers that construct objects of each the specific `{Icon,Text}PaintProperties::Evaluated` type, for use by the painter.
- The three symbol programs instantiate `Program<>` using the appropriate `{Icon,Text}PaintProperties` type.

* check in generated style code

* Populate paint buffers for symbol DDS properties

* Address first round of review comments

* Refactor VectorTile{Layer,Feature} to explicitly share data

* Update submodule

1 files changed, 86 insertions, 50 deletions

diff --git a/test/util/merge_lines.test.cpp b/test/util/merge_lines.test.cpp
index 0a39419b70..8a3a400887 100644
--- a/test/util/merge_lines.test.cpp
+++ b/test/util/merge_lines.test.cpp
@@ -8,95 +8,131 @@ const std::u16string bbb = u"b";
 
 using namespace mbgl;
 
-TEST(MergeLines, SameText) {
-    // merges lines with the same text
-    std::vector<mbgl::SymbolFeature> input1 = {
-        { FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{4, 0}, {5, 0}, {6, 0}}}, bbb, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{8, 0}, {9, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{2, 0}, {3, 0}, {4, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{6, 0}, {7, 0}, {8, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{5, 0}, {6, 0}}}, aaa, {}, {{0, 0}}, 0, 0 }
+class GeometryTileFeatureStub : public GeometryTileFeature {
+public:
+    GeometryTileFeatureStub(optional<FeatureIdentifier> id_, FeatureType type_, GeometryCollection geometry_,
+                  std::unordered_map<std::string, Value> properties_) :
+        id(id_),
+        type(type_),
+        geometry(geometry_),
+        properties(properties_)
+    {}
+    
+    FeatureType getType() const override { return type; }
+    optional<Value> getValue(const std::string& key) const override {
+        auto it = properties.find(key);
+        if (it != properties.end()) {
+            return it->second;
+        }
+        return {};
     };
+    std::unordered_map<std::string,Value> getProperties() const override { return properties; };
+    optional<FeatureIdentifier> getID() const override { return id; };
+    GeometryCollection getGeometries() const override { return geometry; };
+    
+    optional<FeatureIdentifier> id;
+    FeatureType type;
+    GeometryCollection geometry;
+    std::unordered_map<std::string,Value> properties;
+};
+
+class SymbolFeatureStub : public SymbolFeature {
+public:
+    SymbolFeatureStub(optional<FeatureIdentifier> id_, FeatureType type_, GeometryCollection geometry_,
+                            std::unordered_map<std::string, Value> properties_, optional<std::u16string> text_,
+                            optional<std::string> icon_, std::size_t index_) :
+        SymbolFeature(std::make_unique<GeometryTileFeatureStub>(id_, type_, geometry_, properties_))
+    {
+        text = text_;
+        icon = icon_;
+        index = index_;
+    }
+};
 
-    const std::vector<mbgl::SymbolFeature> expected1 = {
-        { FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{4, 0}, {5, 0}, {6, 0}}}, bbb, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{5, 0}, {6, 0}, {7, 0}, {8, 0}, {9, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 }
+TEST(MergeLines, SameText) {
+    // merges lines with the same text
+    std::vector<mbgl::SymbolFeature> input1;
+    input1.push_back(SymbolFeatureStub({}, FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}}}, {}, aaa, {}, 0));
+    input1.push_back(SymbolFeatureStub({}, FeatureType::LineString, {{{4, 0}, {5, 0}, {6, 0}}}, {}, bbb, {}, 0));
+    input1.push_back(SymbolFeatureStub({}, FeatureType::LineString, {{{8, 0}, {9, 0}}}, {}, aaa, {}, 0));
+    input1.push_back(SymbolFeatureStub({}, FeatureType::LineString, {{{2, 0}, {3, 0}, {4, 0}}}, {}, aaa, {}, 0));
+    input1.push_back(SymbolFeatureStub({}, FeatureType::LineString, {{{6, 0}, {7, 0}, {8, 0}}}, {}, aaa, {}, 0));
+    input1.push_back(SymbolFeatureStub({}, FeatureType::LineString, {{{5, 0}, {6, 0}}}, {}, aaa, {}, 0));
+
+    const std::vector<GeometryTileFeatureStub> expected1 = {
+        { {}, FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}}}, {} },
+        { {}, FeatureType::LineString, {{{4, 0}, {5, 0}, {6, 0}}}, {} },
+        { {}, FeatureType::LineString, {{{5, 0}, {6, 0}, {7, 0}, {8, 0}, {9, 0}}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} }
     };
-
+    
     mbgl::util::mergeLines(input1);
 
     for (int i = 0; i < 6; i++) {
-        EXPECT_TRUE(input1[i].geometry == expected1[i].geometry);
+        EXPECT_TRUE(input1[i].geometry == expected1[i].getGeometries());
     }
 }
 
 TEST(MergeLines, BothEnds) {
     // mergeLines handles merge from both ends
-    std::vector<mbgl::SymbolFeature> input2 = {
-        { FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{4, 0}, {5, 0}, {6, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{2, 0}, {3, 0}, {4, 0}}}, aaa, {}, {{0, 0}}, 0, 0 }
-    };
-
-    const std::vector<mbgl::SymbolFeature> expected2 = {
-        { FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}, {6, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 }
+    std::vector<mbgl::SymbolFeature> input2;
+    input2.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}}}, {}, aaa, {}, 0 });
+    input2.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{{4, 0}, {5, 0}, {6, 0}}}, {}, aaa, {}, 0 });
+    input2.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{{2, 0}, {3, 0}, {4, 0}}}, {}, aaa, {}, 0 });
+
+    const std::vector<GeometryTileFeatureStub> expected2 = {
+        { {}, FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}, {6, 0}}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} }
     };
 
     mbgl::util::mergeLines(input2);
 
     for (int i = 0; i < 3; i++) {
-        EXPECT_TRUE(input2[i].geometry == expected2[i].geometry);
+        EXPECT_TRUE(input2[i].geometry == expected2[i].getGeometries());
     }
 }
 
 TEST(MergeLines, CircularLines) {
     // mergeLines handles circular lines
-    std::vector<mbgl::SymbolFeature> input3 = {
-        { FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{2, 0}, {3, 0}, {4, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{{4, 0}, {0, 0}}}, aaa, {}, {{0, 0}}, 0, 0 }
-    };
-
-    const std::vector<mbgl::SymbolFeature> expected3 = {
-        { FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}, {0, 0}}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 },
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 }
+    std::vector<mbgl::SymbolFeature> input3;
+    input3.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}}}, {}, aaa, {}, 0 });
+    input3.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{{2, 0}, {3, 0}, {4, 0}}}, {}, aaa, {}, 0 });
+    input3.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{{4, 0}, {0, 0}}}, {}, aaa, {}, 0 });
+
+    const std::vector<GeometryTileFeatureStub> expected3 = {
+        { {}, FeatureType::LineString, {{{0, 0}, {1, 0}, {2, 0}, {3, 0}, {4, 0}, {0, 0}}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} },
+        { {}, FeatureType::LineString, {{}}, {} }
     };
 
     mbgl::util::mergeLines(input3);
 
     for (int i = 0; i < 3; i++) {
-        EXPECT_TRUE(input3[i].geometry == expected3[i].geometry);
+        EXPECT_TRUE(input3[i].geometry == expected3[i].getGeometries());
     }
 }
 
 TEST(MergeLines, EmptyOuterGeometry) {
-    std::vector<mbgl::SymbolFeature> input = {
-        { FeatureType::LineString, {}, aaa, {}, {{0, 0}}, 0, 0 },
-    };
+    std::vector<mbgl::SymbolFeature> input;
+    input.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {}, {}, aaa, {}, 0 });
 
-    const std::vector<mbgl::SymbolFeature> expected = input;
+    const std::vector<GeometryTileFeatureStub> expected = { { {}, FeatureType::LineString, {}, {} } };
 
     mbgl::util::mergeLines(input);
 
-    EXPECT_EQ(expected[0].geometry, input[0].geometry);
+    EXPECT_EQ(input[0].geometry, expected[0].getGeometries());
 }
 
 TEST(MergeLines, EmptyInnerGeometry) {
-    std::vector<mbgl::SymbolFeature> input = {
-        { FeatureType::LineString, {{}}, aaa, {}, {{0, 0}}, 0, 0 },
-    };
+    std::vector<mbgl::SymbolFeature> input;
+    input.push_back(SymbolFeatureStub { {}, FeatureType::LineString, {{}}, {}, aaa, {}, 0 });
 
-    const std::vector<mbgl::SymbolFeature> expected = input;
+    const std::vector<GeometryTileFeatureStub> expected = { { {}, FeatureType::LineString, {{}}, {} } };
 
     mbgl::util::mergeLines(input);
 
-    EXPECT_EQ(expected[0].geometry, input[0].geometry);
+    EXPECT_EQ(input[0].geometry, expected[0].getGeometries());
 }