[core] Adjust layer source properties to better reflect reality

* Layer source ID is immutable; must be provided to the constructor
* Layer source layer is mutable
* Layers with GeoJSON sources do not have a source layer

While here, make Layer::copy impl-private.

14 files changed, 87 insertions, 80 deletions

diff --git a/src/mbgl/annotation/annotation_manager.cpp b/src/mbgl/annotation/annotation_manager.cpp
index dd2467e34f..7e1984a3c8 100644
--- a/src/mbgl/annotation/annotation_manager.cpp
+++ b/src/mbgl/annotation/annotation_manager.cpp
@@ -157,9 +157,9 @@ void AnnotationManager::updateStyle(Style& style) {
         source->baseImpl->enabled = true;
         style.addSource(std::move(source));
 
-        std::unique_ptr<SymbolLayer> layer = std::make_unique<SymbolLayer>(PointLayerID);
+        std::unique_ptr<SymbolLayer> layer = std::make_unique<SymbolLayer>(PointLayerID, SourceID);
 
-        layer->setSource(SourceID, PointLayerID);
+        layer->setSourceLayer(PointLayerID);
         layer->setIconImage({"{sprite}"});
         layer->setIconAllowOverlap(true);
 
diff --git a/src/mbgl/annotation/fill_annotation_impl.cpp b/src/mbgl/annotation/fill_annotation_impl.cpp
index cbd76ede97..8146c68a53 100644
--- a/src/mbgl/annotation/fill_annotation_impl.cpp
+++ b/src/mbgl/annotation/fill_annotation_impl.cpp
@@ -16,9 +16,8 @@ void FillAnnotationImpl::updateStyle(Style& style) const {
     if (style.getLayer(layerID))
         return;
 
-    std::unique_ptr<FillLayer> layer = std::make_unique<FillLayer>(layerID);
-    layer->setSource(AnnotationManager::SourceID, layerID);
-
+    std::unique_ptr<FillLayer> layer = std::make_unique<FillLayer>(layerID, AnnotationManager::SourceID);
+    layer->setSourceLayer(layerID);
     layer->setFillOpacity(annotation.opacity);
     layer->setFillColor(annotation.color);
     layer->setFillOutlineColor(annotation.outlineColor);
diff --git a/src/mbgl/annotation/line_annotation_impl.cpp b/src/mbgl/annotation/line_annotation_impl.cpp
index e689c3240d..bc7b8df50e 100644
--- a/src/mbgl/annotation/line_annotation_impl.cpp
+++ b/src/mbgl/annotation/line_annotation_impl.cpp
@@ -16,8 +16,8 @@ void LineAnnotationImpl::updateStyle(Style& style) const {
     if (style.getLayer(layerID))
         return;
 
-    std::unique_ptr<LineLayer> layer = std::make_unique<LineLayer>(layerID);
-    layer->setSource(AnnotationManager::SourceID, layerID);
+    std::unique_ptr<LineLayer> layer = std::make_unique<LineLayer>(layerID, AnnotationManager::SourceID);
+    layer->setSourceLayer(layerID);
     layer->setLineJoin(LineJoinType::Round);
     layer->setLineOpacity(annotation.opacity);
     layer->setLineWidth(annotation.width);
diff --git a/src/mbgl/annotation/style_sourced_annotation_impl.cpp b/src/mbgl/annotation/style_sourced_annotation_impl.cpp
index d828014606..d3212da12d 100644
--- a/src/mbgl/annotation/style_sourced_annotation_impl.cpp
+++ b/src/mbgl/annotation/style_sourced_annotation_impl.cpp
@@ -2,6 +2,7 @@
 #include <mbgl/annotation/annotation_manager.hpp>
 #include <mbgl/style/style.hpp>
 #include <mbgl/style/layer.hpp>
+#include <mbgl/style/layer_impl.hpp>
 #include <mbgl/style/layers/line_layer.hpp>
 #include <mbgl/style/layers/fill_layer.hpp>
 
@@ -23,13 +24,13 @@ void StyleSourcedAnnotationImpl::updateStyle(Style& style) const {
         return;
 
     if (sourceLayer->is<LineLayer>()) {
-        std::unique_ptr<Layer> layer = sourceLayer->copy(layerID, "");
-        layer->as<LineLayer>()->setSource(AnnotationManager::SourceID, layerID);
+        std::unique_ptr<Layer> layer = sourceLayer->baseImpl->copy(layerID, "", AnnotationManager::SourceID);
+        layer->as<LineLayer>()->setSourceLayer(layerID);
         layer->as<LineLayer>()->setVisibility(VisibilityType::Visible);
         style.addLayer(std::move(layer), sourceLayer->getID());
     } else if (sourceLayer->is<FillLayer>()) {
-        std::unique_ptr<Layer> layer = sourceLayer->copy(layerID, "");
-        layer->as<FillLayer>()->setSource(AnnotationManager::SourceID, layerID);
+        std::unique_ptr<Layer> layer = sourceLayer->baseImpl->copy(layerID, "", AnnotationManager::SourceID);
+        layer->as<FillLayer>()->setSourceLayer(layerID);
         layer->as<FillLayer>()->setVisibility(VisibilityType::Visible);
         style.addLayer(std::move(layer), sourceLayer->getID());
     }
diff --git a/src/mbgl/style/layer.cpp b/src/mbgl/style/layer.cpp
index 342699a2c9..6eff64ae09 100644
--- a/src/mbgl/style/layer.cpp
+++ b/src/mbgl/style/layer.cpp
@@ -38,13 +38,5 @@ void Layer::setMaxZoom(float maxZoom) const {
     baseImpl->maxZoom = maxZoom;
 }
 
-std::unique_ptr<Layer> Layer::copy(const std::string& id,
-                                   const std::string& ref) const {
-    std::unique_ptr<Layer> result = baseImpl->clone();
-    result->baseImpl->id = id;
-    result->baseImpl->ref = ref;
-    return result;
-}
-
 } // namespace style
 } // namespace mbgl
diff --git a/src/mbgl/style/layer_impl.cpp b/src/mbgl/style/layer_impl.cpp
index 74cc80d253..b345297027 100644
--- a/src/mbgl/style/layer_impl.cpp
+++ b/src/mbgl/style/layer_impl.cpp
@@ -3,6 +3,16 @@
 namespace mbgl {
 namespace style {
 
+std::unique_ptr<Layer> Layer::Impl::copy(const std::string& id_,
+                                         const std::string& ref_,
+                                         const std::string& source_) const {
+    std::unique_ptr<Layer> result = clone();
+    result->baseImpl->id = id_;
+    result->baseImpl->ref = ref_;
+    result->baseImpl->source = source_;
+    return result;
+}
+
 const std::string& Layer::Impl::bucketName() const {
     return ref.empty() ? id : ref;
 }
diff --git a/src/mbgl/style/layer_impl.hpp b/src/mbgl/style/layer_impl.hpp
index 34fc6b2735..33ad2e32ac 100644
--- a/src/mbgl/style/layer_impl.hpp
+++ b/src/mbgl/style/layer_impl.hpp
@@ -37,6 +37,12 @@ class Layer::Impl {
 public:
     virtual ~Impl() = default;
 
+    // Create a new layer with the specified `id`, `ref`, and `sourceID`. All other properties
+    // are copied from this layer.
+    std::unique_ptr<Layer> copy(const std::string& id,
+                                const std::string& ref,
+                                const std::string& sourceID) const;
+
     // Create an identical copy of this layer.
     virtual std::unique_ptr<Layer> clone() const = 0;
 
diff --git a/src/mbgl/style/layers/circle_layer.cpp b/src/mbgl/style/layers/circle_layer.cpp
index bdfbf629e6..8066d7fd3c 100644
--- a/src/mbgl/style/layers/circle_layer.cpp
+++ b/src/mbgl/style/layers/circle_layer.cpp
@@ -6,10 +6,11 @@
 namespace mbgl {
 namespace style {
 
-CircleLayer::CircleLayer(const std::string& layerID)
+CircleLayer::CircleLayer(const std::string& layerID, const std::string& sourceID)
     : Layer(Type::Circle, std::make_unique<Impl>())
     , impl(static_cast<Impl*>(baseImpl.get())) {
     impl->id = layerID;
+    impl->source = sourceID;
 }
 
 CircleLayer::CircleLayer(const Impl& other)
@@ -25,15 +26,14 @@ std::unique_ptr<Layer> CircleLayer::Impl::clone() const {
 
 // Source
 
-void CircleLayer::setSource(const std::string& sourceID, const std::string& sourceLayer) {
-    impl->source = sourceID;
-    impl->sourceLayer = sourceLayer;
-}
-
 const std::string& CircleLayer::getSourceID() const {
     return impl->source;
 }
 
+void CircleLayer::setSourceLayer(const std::string& sourceLayer) {
+    impl->sourceLayer = sourceLayer;
+}
+
 const std::string& CircleLayer::getSourceLayer() const {
     return impl->sourceLayer;
 }
diff --git a/src/mbgl/style/layers/fill_layer.cpp b/src/mbgl/style/layers/fill_layer.cpp
index 1deaabb5ef..7d7d1a9e27 100644
--- a/src/mbgl/style/layers/fill_layer.cpp
+++ b/src/mbgl/style/layers/fill_layer.cpp
@@ -6,10 +6,11 @@
 namespace mbgl {
 namespace style {
 
-FillLayer::FillLayer(const std::string& layerID)
+FillLayer::FillLayer(const std::string& layerID, const std::string& sourceID)
     : Layer(Type::Fill, std::make_unique<Impl>())
     , impl(static_cast<Impl*>(baseImpl.get())) {
     impl->id = layerID;
+    impl->source = sourceID;
 }
 
 FillLayer::FillLayer(const Impl& other)
@@ -25,15 +26,14 @@ std::unique_ptr<Layer> FillLayer::Impl::clone() const {
 
 // Source
 
-void FillLayer::setSource(const std::string& sourceID, const std::string& sourceLayer) {
-    impl->source = sourceID;
-    impl->sourceLayer = sourceLayer;
-}
-
 const std::string& FillLayer::getSourceID() const {
     return impl->source;
 }
 
+void FillLayer::setSourceLayer(const std::string& sourceLayer) {
+    impl->sourceLayer = sourceLayer;
+}
+
 const std::string& FillLayer::getSourceLayer() const {
     return impl->sourceLayer;
 }
diff --git a/src/mbgl/style/layers/layer.cpp.ejs b/src/mbgl/style/layers/layer.cpp.ejs
index 633d673804..4f78d6b55e 100644
--- a/src/mbgl/style/layers/layer.cpp.ejs
+++ b/src/mbgl/style/layers/layer.cpp.ejs
@@ -11,11 +11,20 @@
 namespace mbgl {
 namespace style {
 
+<% if (type === 'background') { -%>
 <%- camelize(type) %>Layer::<%- camelize(type) %>Layer(const std::string& layerID)
     : Layer(Type::<%- camelize(type) %>, std::make_unique<Impl>())
     , impl(static_cast<Impl*>(baseImpl.get())) {
     impl->id = layerID;
 }
+<% } else { -%>
+<%- camelize(type) %>Layer::<%- camelize(type) %>Layer(const std::string& layerID, const std::string& sourceID)
+    : Layer(Type::<%- camelize(type) %>, std::make_unique<Impl>())
+    , impl(static_cast<Impl*>(baseImpl.get())) {
+    impl->id = layerID;
+    impl->source = sourceID;
+}
+<% } -%>
 
 <%- camelize(type) %>Layer::<%- camelize(type) %>Layer(const Impl& other)
     : Layer(Type::<%- camelize(type) %>, std::make_unique<Impl>(other))
@@ -28,28 +37,18 @@ std::unique_ptr<Layer> <%- camelize(type) %>Layer::Impl::clone() const {
     return std::make_unique<<%- camelize(type) %>Layer>(*this);
 }
 
-<% if (type === 'raster') { -%>
+<% if (type !== 'background') { -%>
 // Source
 
-void <%- camelize(type) %>Layer::setSource(const std::string& sourceID) {
-    impl->source = sourceID;
-}
-
 const std::string& <%- camelize(type) %>Layer::getSourceID() const {
     return impl->source;
 }
-<% } else if (type !== 'background') { -%>
-// Source
 
-void <%- camelize(type) %>Layer::setSource(const std::string& sourceID, const std::string& sourceLayer) {
-    impl->source = sourceID;
+<% if (type !== 'raster') { -%>
+void <%- camelize(type) %>Layer::setSourceLayer(const std::string& sourceLayer) {
     impl->sourceLayer = sourceLayer;
 }
 
-const std::string& <%- camelize(type) %>Layer::getSourceID() const {
-    return impl->source;
-}
-
 const std::string& <%- camelize(type) %>Layer::getSourceLayer() const {
     return impl->sourceLayer;
 }
@@ -64,6 +63,7 @@ const Filter& <%- camelize(type) %>Layer::getFilter() const {
     return impl->filter;
 }
 <% } -%>
+<% } -%>
 
 // Layout properties
 
diff --git a/src/mbgl/style/layers/line_layer.cpp b/src/mbgl/style/layers/line_layer.cpp
index abe326a672..e720d1fcfb 100644
--- a/src/mbgl/style/layers/line_layer.cpp
+++ b/src/mbgl/style/layers/line_layer.cpp
@@ -6,10 +6,11 @@
 namespace mbgl {
 namespace style {
 
-LineLayer::LineLayer(const std::string& layerID)
+LineLayer::LineLayer(const std::string& layerID, const std::string& sourceID)
     : Layer(Type::Line, std::make_unique<Impl>())
     , impl(static_cast<Impl*>(baseImpl.get())) {
     impl->id = layerID;
+    impl->source = sourceID;
 }
 
 LineLayer::LineLayer(const Impl& other)
@@ -25,15 +26,14 @@ std::unique_ptr<Layer> LineLayer::Impl::clone() const {
 
 // Source
 
-void LineLayer::setSource(const std::string& sourceID, const std::string& sourceLayer) {
-    impl->source = sourceID;
-    impl->sourceLayer = sourceLayer;
-}
-
 const std::string& LineLayer::getSourceID() const {
     return impl->source;
 }
 
+void LineLayer::setSourceLayer(const std::string& sourceLayer) {
+    impl->sourceLayer = sourceLayer;
+}
+
 const std::string& LineLayer::getSourceLayer() const {
     return impl->sourceLayer;
 }
diff --git a/src/mbgl/style/layers/raster_layer.cpp b/src/mbgl/style/layers/raster_layer.cpp
index fb7f08fbe9..cdba19ac4e 100644
--- a/src/mbgl/style/layers/raster_layer.cpp
+++ b/src/mbgl/style/layers/raster_layer.cpp
@@ -6,10 +6,11 @@
 namespace mbgl {
 namespace style {
 
-RasterLayer::RasterLayer(const std::string& layerID)
+RasterLayer::RasterLayer(const std::string& layerID, const std::string& sourceID)
     : Layer(Type::Raster, std::make_unique<Impl>())
     , impl(static_cast<Impl*>(baseImpl.get())) {
     impl->id = layerID;
+    impl->source = sourceID;
 }
 
 RasterLayer::RasterLayer(const Impl& other)
@@ -25,14 +26,11 @@ std::unique_ptr<Layer> RasterLayer::Impl::clone() const {
 
 // Source
 
-void RasterLayer::setSource(const std::string& sourceID) {
-    impl->source = sourceID;
-}
-
 const std::string& RasterLayer::getSourceID() const {
     return impl->source;
 }
 
+
 // Layout properties
 
 
diff --git a/src/mbgl/style/layers/symbol_layer.cpp b/src/mbgl/style/layers/symbol_layer.cpp
index 38a898deca..905caa0310 100644
--- a/src/mbgl/style/layers/symbol_layer.cpp
+++ b/src/mbgl/style/layers/symbol_layer.cpp
@@ -6,10 +6,11 @@
 namespace mbgl {
 namespace style {
 
-SymbolLayer::SymbolLayer(const std::string& layerID)
+SymbolLayer::SymbolLayer(const std::string& layerID, const std::string& sourceID)
     : Layer(Type::Symbol, std::make_unique<Impl>())
     , impl(static_cast<Impl*>(baseImpl.get())) {
     impl->id = layerID;
+    impl->source = sourceID;
 }
 
 SymbolLayer::SymbolLayer(const Impl& other)
@@ -25,15 +26,14 @@ std::unique_ptr<Layer> SymbolLayer::Impl::clone() const {
 
 // Source
 
-void SymbolLayer::setSource(const std::string& sourceID, const std::string& sourceLayer) {
-    impl->source = sourceID;
-    impl->sourceLayer = sourceLayer;
-}
-
 const std::string& SymbolLayer::getSourceID() const {
     return impl->source;
 }
 
+void SymbolLayer::setSourceLayer(const std::string& sourceLayer) {
+    impl->sourceLayer = sourceLayer;
+}
+
 const std::string& SymbolLayer::getSourceLayer() const {
     return impl->sourceLayer;
 }
diff --git a/src/mbgl/style/parser.cpp b/src/mbgl/style/parser.cpp
index bbe2fd7862..a0f4dd24c9 100644
--- a/src/mbgl/style/parser.cpp
+++ b/src/mbgl/style/parser.cpp
@@ -219,7 +219,7 @@ void Parser::parseLayer(const std::string& id, const JSValue& value, std::unique
             return;
         }
 
-        layer = reference->copy(id, ref);
+        layer = reference->baseImpl->copy(id, ref, reference->baseImpl->source);
         layer->baseImpl->parsePaints(value);
     } else {
         // Otherwise, parse the source/source-layer/filter/render keys to form the bucket.
@@ -235,17 +235,31 @@ void Parser::parseLayer(const std::string& id, const JSValue& value, std::unique
         }
 
         std::string type { typeVal.GetString(), typeVal.GetStringLength() };
+        std::string source;
+
+        if (value.HasMember("source")) {
+            const JSValue& value_source = value["source"];
+            if (value_source.IsString()) {
+                source = { value_source.GetString(), value_source.GetStringLength() };
+                auto source_it = sourcesMap.find(source);
+                if (source_it == sourcesMap.end()) {
+                    Log::Warning(Event::ParseStyle, "can't find source '%s' required for layer '%s'", source.c_str(), id.c_str());
+                }
+            } else {
+                Log::Warning(Event::ParseStyle, "source of layer '%s' must be a string", id.c_str());
+            }
+        }
 
         if (type == "fill") {
-            layer = std::make_unique<FillLayer>(id);
+            layer = std::make_unique<FillLayer>(id, source);
         } else if (type == "line") {
-            layer = std::make_unique<LineLayer>(id);
+            layer = std::make_unique<LineLayer>(id, source);
         } else if (type == "circle") {
-            layer = std::make_unique<CircleLayer>(id);
+            layer = std::make_unique<CircleLayer>(id, source);
         } else if (type == "symbol") {
-            layer = std::make_unique<SymbolLayer>(id);
+            layer = std::make_unique<SymbolLayer>(id, source);
         } else if (type == "raster") {
-            layer = std::make_unique<RasterLayer>(id);
+            layer = std::make_unique<RasterLayer>(id, source);
         } else if (type == "background") {
             layer = std::make_unique<BackgroundLayer>(id);
         } else {
@@ -255,19 +269,6 @@ void Parser::parseLayer(const std::string& id, const JSValue& value, std::unique
 
         Layer::Impl* impl = layer->baseImpl.get();
 
-        if (value.HasMember("source")) {
-            const JSValue& value_source = value["source"];
-            if (value_source.IsString()) {
-                impl->source = { value_source.GetString(), value_source.GetStringLength() };
-                auto source_it = sourcesMap.find(impl->source);
-                if (source_it == sourcesMap.end()) {
-                    Log::Warning(Event::ParseStyle, "can't find source '%s' required for layer '%s'", impl->source.c_str(), impl->id.c_str());
-                }
-            } else {
-                Log::Warning(Event::ParseStyle, "source of layer '%s' must be a string", impl->id.c_str());
-            }
-        }
-
         if (value.HasMember("source-layer")) {
             const JSValue& value_source_layer = value["source-layer"];
             if (value_source_layer.IsString()) {