[core, ios, macos] Added layers and sources properties to MGLStyle

Added new layers and sources properties to MGLStyle that contain all the style’s layers and sources, respectively. These properties are KVC-compliant with all the mutable to-many methods. Layers are ordered from topmost to bottommost, for consistency with Cocoa APIs where front/first means top and back/last means bottom.

Also added storage for mbgl::style::Source in MGLSource proper for wrapping AnnotationSource. Until the style finishes loading, its name property is set to nil.

Fixes #6003.

include/mbgl/map/map.hpp

@@ -157,11 +157,13 @@ public:
     void removeAnnotation(AnnotationID);
 
     // Sources
+    std::vector<style::Source*> getSources();
     style::Source* getSource(const std::string& sourceID);
     void addSource(std::unique_ptr<style::Source>);
     std::unique_ptr<style::Source> removeSource(const std::string& sourceID);
 
     // Layers
+    std::vector<style::Layer*> getLayers();
     style::Layer* getLayer(const std::string& layerID);
     void addLayer(std::unique_ptr<style::Layer>, const optional<std::string>& beforeLayerID = {});
     std::unique_ptr<style::Layer> removeLayer(const std::string& layerID);

platform/darwin/src/MGLBackgroundStyleLayer.mm

@@ -51,6 +51,9 @@
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::BackgroundLayer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLCircleStyleLayer.mm

@@ -83,6 +83,9 @@ namespace mbgl {
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::CircleLayer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLFillStyleLayer.mm

@@ -78,6 +78,9 @@ namespace mbgl {
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::FillLayer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLLineStyleLayer.mm

@@ -90,6 +90,9 @@ namespace mbgl {
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::LineLayer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLRasterStyleLayer.mm

@@ -50,6 +50,9 @@
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::RasterLayer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLSource.mm

@@ -2,6 +2,14 @@
 
 #include <mbgl/style/source.hpp>
 
+@interface MGLSource ()
+
+// Even though this class is abstract, MGLStyle uses it to represent some
+// special internal source types like mbgl::AnnotationSource.
+@property (nonatomic) mbgl::style::Source *rawSource;
+
+@end
+
 @implementation MGLSource
 
 - (instancetype)initWithIdentifier:(NSString *)identifier
@@ -12,6 +20,20 @@
     return self;
 }
 
+- (void)addToMapView:(MGLMapView *)mapView {
+    [NSException raise:NSInvalidArgumentException format:
+     @"The source %@ cannot be added to the style. "
+     @"Make sure the source was created as a member of a concrete subclass of MGLSource.",
+     self];
+}
+
+- (void)removeFromMapView:(MGLMapView *)mapView {
+    [NSException raise:NSInvalidArgumentException format:
+     @"The source %@ cannot be removed from the style. "
+     @"Make sure the source was created as a member of a concrete subclass of MGLSource.",
+     self];
+}
+
 - (NSString *)description {
     return [NSString stringWithFormat:@"<%@: %p; identifier = %@>",
             NSStringFromClass([self class]), (void *)self, self.identifier];

platform/darwin/src/MGLStyle.h

@@ -176,6 +176,11 @@ static const NSInteger MGLStyleDefaultVersion = 9;
 
 #pragma mark Managing Sources
 
+/**
+ A set containing the style’s sources.
+ */
+@property (nonatomic, strong) NS_MUTABLE_SET_OF(MGLSource *) *sources;
+
 /**
  Returns a source with the given identifier in the current style.
 
@@ -200,6 +205,12 @@ static const NSInteger MGLStyleDefaultVersion = 9;
 
 #pragma mark Managing Style Layers
 
+/**
+ The layers included in the style, arranged according to their front-to-back
+ ordering on the screen.
+ */
+@property (nonatomic, strong) NS_MUTABLE_ARRAY_OF(MGLStyleLayer *) *layers;
+
 /**
  Returns a style layer with the given identifier in the current style.
  
@@ -217,13 +228,31 @@ static const NSInteger MGLStyleDefaultVersion = 9;
  */
 - (void)addLayer:(MGLStyleLayer *)layer;
 
+/**
+ Inserts a new layer into the style at the given index.
+ 
+ @param layer The layer to insert.
+ @param index The index at which to insert the layer. An index of 0 would send
+    the layer to the back; an index equal to the number of objects in the
+    `layers` property would bring the layer to the front.
+ */
+- (void)insertLayer:(MGLStyleLayer *)layer atIndex:(NSUInteger)index;
+
 /**
  Inserts a new layer below another layer.
 
- @param layer Layer to be inserted.
- @param belowLayer A layer that's already on the map view.
+ @param layer The layer to insert.
+ @param sibling An existing layer in the style.
  */
-- (void)insertLayer:(MGLStyleLayer *)layer belowLayer:(MGLStyleLayer *)otherLayer;
+- (void)insertLayer:(MGLStyleLayer *)layer belowLayer:(MGLStyleLayer *)sibling;
+
+/**
+ Inserts a new layer above another layer.
+
+ @param layer The layer to insert.
+ @param sibling An existing layer in the style.
+ */
+- (void)insertLayer:(MGLStyleLayer *)layer aboveLayer:(MGLStyleLayer *)sibling;
 
 /**
  Removes a layer from the map view.

platform/darwin/src/MGLStyle.mm

@@ -101,7 +101,8 @@ static NSURL *MGLStyleURL_emerald;
 #pragma mark Metadata
 
 - (NSString *)name {
-    return @(self.mapView.mbglMap->getStyleName().c_str());
+    std::string name = self.mapView.mbglMap->getStyleName();
+    return name.empty() ? nil : @(name.c_str());
 }
 
 - (NSURL *)URL {
@@ -110,13 +111,43 @@ static NSURL *MGLStyleURL_emerald;
 
 #pragma mark Sources
 
+- (NS_MUTABLE_SET_OF(MGLSource *) *)sources {
+    auto rawSources = self.mapView.mbglMap->getSources();
+    NSMutableSet *sources = [NSMutableSet setWithCapacity:rawSources.size()];
+    for (auto rawSource = rawSources.begin(); rawSource != rawSources.end(); ++rawSource) {
+        MGLSource *source = [self sourceFromMBGLSource:*rawSource];
+        [sources addObject:source];
+    }
+    return sources;
+}
+
+- (void)setSources:(NS_MUTABLE_SET_OF(MGLSource *) *)sources {
+    for (MGLSource *source in self.sources) {
+        [self removeSource:source];
+    }
+    for (MGLSource *source in sources) {
+        [self addSource:source];
+    }
+}
+
+- (NSUInteger)countOfSources {
+    auto rawSources = self.mapView.mbglMap->getSources();
+    return rawSources.size();
+}
+
+- (MGLSource *)memberOfSources:(MGLSource *)object {
+    return [self sourceWithIdentifier:object.identifier];
+}
+
 - (MGLSource *)sourceWithIdentifier:(NSString *)identifier
 {
-    auto mbglSource = self.mapView.mbglMap->getSource(identifier.UTF8String);
-    if (!mbglSource) {
-        return nil;
-    }
+    auto rawSource = self.mapView.mbglMap->getSource(identifier.UTF8String);
+    return rawSource ? [self sourceFromMBGLSource:rawSource] : nil;
+}
 
+- (MGLSource *)sourceFromMBGLSource:(mbgl::style::Source *)mbglSource {
+    NSString *identifier = @(mbglSource->getID().c_str());
+    
     // TODO: Fill in options specific to the respective source classes
     // https://github.com/mapbox/mapbox-gl-native/issues/6584
     MGLSource *source;
@@ -160,13 +191,93 @@ static NSURL *MGLStyleURL_emerald;
 
 #pragma mark Style layers
 
-- (MGLStyleLayer *)layerWithIdentifier:(NSString *)identifier
+- (NS_MUTABLE_ARRAY_OF(MGLStyleLayer *) *)layers
 {
-    auto mbglLayer = self.mapView.mbglMap->getLayer(identifier.UTF8String);
-    if (!mbglLayer) {
+    auto layers = self.mapView.mbglMap->getLayers();
+    NSMutableArray *styleLayers = [NSMutableArray arrayWithCapacity:layers.size()];
+    for (auto layer = layers.rbegin(); layer != layers.rend(); ++layer) {
+        MGLStyleLayer *styleLayer = [self layerFromMBGLLayer:*layer];
+        [styleLayers addObject:styleLayer];
+    }
+    return styleLayers;
+}
+
+- (void)setLayers:(NS_MUTABLE_ARRAY_OF(MGLStyleLayer *) *)layers {
+    for (MGLStyleLayer *layer in self.layers.reverseObjectEnumerator) {
+        [self removeLayer:layer];
+    }
+    for (MGLStyleLayer *layer in layers.reverseObjectEnumerator) {
+        [self addLayer:layer];
+    }
+}
+
+- (NSUInteger)countOfLayers
+{
+    return self.mapView.mbglMap->getLayers().size();
+}
+
+- (MGLStyleLayer *)objectInLayersAtIndex:(NSUInteger)index
+{
+    auto layers = self.mapView.mbglMap->getLayers();
+    if (index > layers.size() - 1) {
+        [NSException raise:NSRangeException
+                    format:@"No style layer at index %lu.", (unsigned long)index];
         return nil;
     }
+    auto layer = layers.at(layers.size() - 1 - index);
+    return [self layerFromMBGLLayer:layer];
+}
 
+- (void)getLayers:(MGLStyleLayer **)buffer range:(NSRange)inRange
+{
+    auto layers = self.mapView.mbglMap->getLayers();
+    if (NSMaxRange(inRange) > layers.size()) {
+        [NSException raise:NSRangeException
+                    format:@"Style layer range %@ is out of bounds.", NSStringFromRange(inRange)];
+    }
+    NSUInteger i = 0;
+    for (auto layer = *(layers.rbegin() + inRange.location); i < inRange.length; ++layer, ++i) {
+        MGLStyleLayer *styleLayer = [self layerFromMBGLLayer:layer];
+        buffer[i] = styleLayer;
+    }
+}
+
+- (void)insertObject:(MGLStyleLayer *)styleLayer inLayersAtIndex:(NSUInteger)index
+{
+    if (!styleLayer.rawLayer) {
+        [NSException raise:NSInvalidArgumentException format:
+         @"The style layer %@ cannot be inserted into the style. "
+         @"Make sure the style layer was created as a member of a concrete subclass of MGLStyleLayer.",
+         styleLayer];
+    }
+    auto layers = self.mapView.mbglMap->getLayers();
+    if (index > layers.size()) {
+        [NSException raise:NSRangeException
+                    format:@"Cannot insert style layer at out-of-bounds index %lu.", (unsigned long)index];
+    } else if (index == 0) {
+        [styleLayer addToMapView:self.mapView];
+    } else {
+        MGLStyleLayer *sibling = [self layerFromMBGLLayer:layers.at(layers.size() - index)];
+        [styleLayer addToMapView:self.mapView belowLayer:sibling];
+    }
+}
+
+- (void)removeObjectFromLayersAtIndex:(NSUInteger)index
+{
+    auto layers = self.mapView.mbglMap->getLayers();
+    if (index > layers.size() - 1) {
+        [NSException raise:NSRangeException
+                    format:@"Cannot remove style layer at out-of-bounds index %lu.", (unsigned long)index];
+    }
+    auto layer = layers.at(layers.size() - 1 - index);
+    self.mapView.mbglMap->removeLayer(layer->getID());
+}
+
+- (MGLStyleLayer *)layerFromMBGLLayer:(mbgl::style::Layer *)mbglLayer
+{
+    NSParameterAssert(mbglLayer);
+    
+    NSString *identifier = @(mbglLayer->getID().c_str());
     MGLStyleLayer *styleLayer;
     if (auto fillLayer = mbglLayer->as<mbgl::style::FillLayer>()) {
         MGLSource *source = [self sourceWithIdentifier:@(fillLayer->getSourceID().c_str())];
@@ -195,6 +306,12 @@ static NSURL *MGLStyleURL_emerald;
     return styleLayer;
 }
 
+- (MGLStyleLayer *)layerWithIdentifier:(NSString *)identifier
+{
+    auto mbglLayer = self.mapView.mbglMap->getLayer(identifier.UTF8String);
+    return mbglLayer ? [self layerFromMBGLLayer:mbglLayer] : nil;
+}
+
 - (void)removeLayer:(MGLStyleLayer *)layer
 {
     if (!layer.rawLayer) {
@@ -217,7 +334,11 @@ static NSURL *MGLStyleURL_emerald;
     [layer addToMapView:self.mapView];
 }
 
-- (void)insertLayer:(MGLStyleLayer *)layer belowLayer:(MGLStyleLayer *)otherLayer
+- (void)insertLayer:(MGLStyleLayer *)layer atIndex:(NSUInteger)index {
+    [self insertObject:layer inLayersAtIndex:index];
+}
+
+- (void)insertLayer:(MGLStyleLayer *)layer belowLayer:(MGLStyleLayer *)sibling
 {
     if (!layer.rawLayer) {
         [NSException raise:NSInvalidArgumentException
@@ -226,14 +347,58 @@ static NSURL *MGLStyleURL_emerald;
          @"Make sure the style layer was created as a member of a concrete subclass of MGLStyleLayer.",
          layer];
     }
-    if (!otherLayer.rawLayer) {
+    if (!sibling.rawLayer) {
         [NSException raise:NSInvalidArgumentException
                     format:
-         @"A style layer cannot be placed before %@ in the style. "
-         @"Make sure otherLayer was obtained using -[MGLStyle layerWithIdentifier:].",
-         otherLayer];
+         @"A style layer cannot be placed below %@ in the style. "
+         @"Make sure sibling was obtained using -[MGLStyle layerWithIdentifier:].",
+         sibling];
     }
-    [layer addToMapView:self.mapView belowLayer:otherLayer];
+    [self willChangeValueForKey:@"layers"];
+    [layer addToMapView:self.mapView belowLayer:sibling];
+    [self didChangeValueForKey:@"layers"];
+}
+
+- (void)insertLayer:(MGLStyleLayer *)layer aboveLayer:(MGLStyleLayer *)sibling {
+    if (!layer.rawLayer) {
+        [NSException raise:NSInvalidArgumentException
+                    format:
+         @"The style layer %@ cannot be added to the style. "
+         @"Make sure the style layer was created as a member of a concrete subclass of MGLStyleLayer.",
+         layer];
+    }
+    if (!sibling.rawLayer) {
+        [NSException raise:NSInvalidArgumentException
+                    format:
+         @"A style layer cannot be placed above %@ in the style. "
+         @"Make sure sibling was obtained using -[MGLStyle layerWithIdentifier:].",
+         sibling];
+    }
+    
+    auto layers = self.mapView.mbglMap->getLayers();
+    std::string siblingIdentifier = sibling.identifier.UTF8String;
+    NSUInteger index = 0;
+    for (auto layer : layers) {
+        if (layer->getID() == siblingIdentifier) {
+            break;
+        }
+        index++;
+    }
+    
+    [self willChangeValueForKey:@"layers"];
+    if (index + 1 > layers.size()) {
+        [NSException raise:NSInvalidArgumentException
+                    format:
+         @"A style layer cannot be placed above %@ in the style. "
+         @"Make sure sibling was obtained using -[MGLStyle layerWithIdentifier:].",
+         sibling];
+    } else if (index + 1 == layers.size()) {
+        [layer addToMapView:self.mapView];
+    } else {
+        MGLStyleLayer *sibling = [self layerFromMBGLLayer:layers.at(index + 1)];
+        [layer addToMapView:self.mapView belowLayer:sibling];
+    }
+    [self didChangeValueForKey:@"layers"];
 }
 
 #pragma mark Style classes
@@ -270,6 +435,11 @@ static NSURL *MGLStyleURL_emerald;
     self.mapView.mbglMap->setClasses(newAppliedClasses);
 }
 
+- (NSUInteger)countOfStyleClasses {
+    const auto &classes = self.mapView.mbglMap->getClasses();
+    return classes.size();
+}
+
 - (BOOL)hasStyleClass:(NSString *)styleClass
 {
     return styleClass && self.mapView.mbglMap->hasClass([styleClass UTF8String]);

platform/darwin/src/MGLStyleLayer.mm.ejs

@@ -120,6 +120,9 @@ namespace mbgl {
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::<%- camelize(type) %>Layer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLSymbolStyleLayer.mm

@@ -137,6 +137,9 @@ namespace mbgl {
 - (void)removeFromMapView:(MGLMapView *)mapView
 {
     auto removedLayer = mapView.mbglMap->removeLayer(self.identifier.UTF8String);
+    if (!removedLayer) {
+        return;
+    }
     _pendingLayer = std::move(reinterpret_cast<std::unique_ptr<mbgl::style::SymbolLayer> &>(removedLayer));
     _rawLayer = _pendingLayer.get();
 }

platform/darwin/src/MGLVectorSource.mm

@@ -18,8 +18,6 @@
     std::unique_ptr<mbgl::style::VectorSource> _pendingSource;
 }
 
-static NSString *MGLVectorSourceType   = @"vector";
-
 - (instancetype)initWithIdentifier:(NSString *)identifier URL:(NSURL *)url
 {
     if (self = [super initWithIdentifier:identifier])

src/mbgl/map/map.cpp

@@ -803,6 +803,10 @@ AnnotationIDs Map::queryPointAnnotations(const ScreenBox& box) {
 
 #pragma mark - Style API
 
+std::vector<style::Source*> Map::getSources() {
+    return impl->style ? impl->style->getSources() : std::vector<style::Source*>();
+}
+
 style::Source* Map::getSource(const std::string& sourceID) {
     if (impl->style) {
         impl->styleMutated = true;
@@ -825,8 +829,12 @@ std::unique_ptr<Source> Map::removeSource(const std::string& sourceID) {
     }
     return nullptr;
 }
+    
+std::vector<style::Layer*> Map::getLayers() {
+    return impl->style ? impl->style->getLayers() : std::vector<style::Layer*>();
+}
 
-style::Layer* Map::getLayer(const std::string& layerID) {
+Layer* Map::getLayer(const std::string& layerID) {
     if (impl->style) {
         impl->styleMutated = true;
         return impl->style->getLayer(layerID);

src/mbgl/style/style.cpp

@@ -165,6 +165,15 @@ std::vector<const Layer*> Style::getLayers() const {
     return result;
 }
 
+std::vector<Layer*> Style::getLayers() {
+    std::vector<Layer*> result;
+    result.reserve(layers.size());
+    for (auto& layer : layers) {
+        result.push_back(layer.get());
+    }
+    return result;
+}
+
 std::vector<std::unique_ptr<Layer>>::const_iterator Style::findLayer(const std::string& id) const {
     return std::find_if(layers.begin(), layers.end(), [&](const auto& layer) {
         return layer->baseImpl->id == id;
@@ -312,6 +321,24 @@ void Style::recalculate(float z, const TimePoint& timePoint, MapMode mode) {
     }
 }
 
+std::vector<const Source*> Style::getSources() const {
+    std::vector<const Source*> result;
+    result.reserve(sources.size());
+    for (const auto& source : sources) {
+        result.push_back(source.get());
+    }
+    return result;
+}
+
+std::vector<Source*> Style::getSources() {
+    std::vector<Source*> result;
+    result.reserve(sources.size());
+    for (auto& source : sources) {
+        result.push_back(source.get());
+    }
+    return result;
+}
+
 Source* Style::getSource(const std::string& id) const {
     const auto it = std::find_if(sources.begin(), sources.end(), [&](const auto& source) {
         return source->getID() == id;

src/mbgl/style/style.hpp

@@ -64,11 +64,14 @@ public:
         return lastError;
     }
 
+    std::vector<const Source*> getSources() const;
+    std::vector<Source*> getSources();
     Source* getSource(const std::string& id) const;
     void addSource(std::unique_ptr<Source>);
     std::unique_ptr<Source> removeSource(const std::string& sourceID);
 
     std::vector<const Layer*> getLayers() const;
+    std::vector<Layer*> getLayers();
     Layer* getLayer(const std::string& id) const;
     Layer* addLayer(std::unique_ptr<Layer>,
                     optional<std::string> beforeLayerID = {});