From e0a2e36d290f5fd8d97319dfbb40cbb3ebd29fac Mon Sep 17 00:00:00 2001
From: Mikhail Pozdnyakov <mikhail.pozdnyakov@mapbox.com>
Date: Mon, 17 Dec 2018 16:03:38 +0200
Subject: [mac, ios] Enable core-only layers

`LayerManagerDarwin` can add layer types that are enabled only for JSON style.
It allows to exclude the SDK wrappers for these layers from the project and decrease binary size.
---
 .../android/src/style/layers/layer_manager.hpp     |  2 +-
 platform/darwin/src/MGLStyleLayerManager.h         | 16 ++++++++-
 platform/darwin/src/MGLStyleLayerManager.mm        | 38 +++++++++++++++++-----
 3 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/platform/android/src/style/layers/layer_manager.hpp b/platform/android/src/style/layers/layer_manager.hpp
index fb87721dd2..807ded1737 100644
--- a/platform/android/src/style/layers/layer_manager.hpp
+++ b/platform/android/src/style/layers/layer_manager.hpp
@@ -30,7 +30,7 @@ public:
 private:
     LayerManagerAndroid();
     /**
-     * @brief Enables a layer type for both JSON style an runtime API.
+     * @brief Enables a layer type for both JSON style and runtime API.
      */
     void addLayerType(std::unique_ptr<JavaLayerPeerFactory>); 
     /**
diff --git a/platform/darwin/src/MGLStyleLayerManager.h b/platform/darwin/src/MGLStyleLayerManager.h
index cdd30f4fff..95fecd0252 100644
--- a/platform/darwin/src/MGLStyleLayerManager.h
+++ b/platform/darwin/src/MGLStyleLayerManager.h
@@ -20,13 +20,27 @@ public:
 
 private:
     LayerManagerDarwin();
+    /**
+     * Enables a layer type for both JSON style and runtime API.
+     */
     void addLayerType(std::unique_ptr<LayerPeerFactory>);
+    /**
+     * Enables a layer type for JSON style only.
+     *
+     * We might not want to expose runtime API for some layer types
+     * in order to save binary size (the corresponding SDK layer wrappers
+     * should be excluded from the project build).
+     */
+    void addLayerTypeCoreOnly(std::unique_ptr<mbgl::LayerFactory>);
+
+    void registerCoreFactory(LayerFactory*);
     LayerPeerFactory* getPeerFactory(const style::LayerTypeInfo* typeInfo);
     // mbgl::LayerManager overrides.
     LayerFactory* getFactory(const std::string& type) noexcept final;
     LayerFactory* getFactory(const mbgl::style::LayerTypeInfo* info) noexcept final;
 
-    std::vector<std::unique_ptr<LayerPeerFactory>> factories;
+    std::vector<std::unique_ptr<LayerPeerFactory>> peerFactories;
+    std::vector<std::unique_ptr<LayerFactory>> coreFactories;
     std::map<std::string, LayerFactory*> typeToFactory;
 };
     
diff --git a/platform/darwin/src/MGLStyleLayerManager.mm b/platform/darwin/src/MGLStyleLayerManager.mm
index bdcc303de5..a05e24bd9d 100644
--- a/platform/darwin/src/MGLStyleLayerManager.mm
+++ b/platform/darwin/src/MGLStyleLayerManager.mm
@@ -38,22 +38,33 @@ MGLStyleLayer* LayerManagerDarwin::createPeer(style::Layer* layer) {
 }
 
 void LayerManagerDarwin::addLayerType(std::unique_ptr<LayerPeerFactory> factory) {
-    auto* coreFactory = factory->getCoreLayerFactory();
-    std::string type{coreFactory->getTypeInfo()->type};
+    NSCAssert(getFactory(factory->getCoreLayerFactory()->getTypeInfo()) == nullptr,
+              @"A layer factory with the given info is already added.");
+    registerCoreFactory(factory->getCoreLayerFactory());
+    peerFactories.emplace_back(std::move(factory));
+}
+
+void LayerManagerDarwin::addLayerTypeCoreOnly(std::unique_ptr<LayerFactory> factory) {
+    NSCAssert(getFactory(factory->getTypeInfo()) == nullptr,
+              @"A layer factory with the given info is already added.");
+    registerCoreFactory(factory.get());
+    coreFactories.emplace_back(std::move(factory));
+}
+
+void LayerManagerDarwin::registerCoreFactory(LayerFactory* factory) {
+    std::string type{factory->getTypeInfo()->type};
     if (!type.empty()) {
-        typeToFactory.emplace(std::make_pair(std::move(type), coreFactory));
+        NSCAssert(typeToFactory.find(type) == typeToFactory.end(), @"A layer type can be registered only once.");
+        typeToFactory.emplace(std::make_pair(std::move(type), factory));
     }
-    factories.emplace_back(std::move(factory));
 }
 
 LayerPeerFactory* LayerManagerDarwin::getPeerFactory(const mbgl::style::LayerTypeInfo* typeInfo) {
-    assert(typeInfo);
-    for (const auto& factory: factories) {
+    for (const auto& factory: peerFactories) {
         if (factory->getCoreLayerFactory()->getTypeInfo() == typeInfo) {
             return factory.get();
         }
     }
-    assert(false);
     return nullptr;
 }
 
@@ -63,8 +74,17 @@ LayerFactory* LayerManagerDarwin::getFactory(const std::string& type) noexcept {
 }
 
 LayerFactory* LayerManagerDarwin::getFactory(const mbgl::style::LayerTypeInfo* info) noexcept {
-    LayerPeerFactory* peerFactory = getPeerFactory(info);
-    return (peerFactory != nullptr) ? peerFactory->getCoreLayerFactory() : nullptr;
+    if (LayerPeerFactory* peerFactory = getPeerFactory(info)) {
+        return peerFactory->getCoreLayerFactory();
+    }
+
+    for (const auto& factory: coreFactories) {
+        if (factory->getTypeInfo() == info) {
+            return factory.get();
+        }
+    }
+
+    return nullptr;
 }
 
 // static
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