[darwin] Simplify MGLSource initialization and pointer management

Introduce `-[MGLSource initWithPendingSource:]`, allowing the base class to track the owned `_pendingSource` pointer and implement `-addToMapView:` and `-removeFromMapView:` without any casts.

8 files changed, 67 insertions, 213 deletions

diff --git a/platform/darwin/src/MGLRasterSource.mm b/platform/darwin/src/MGLRasterSource.mm
index a3d29c7c7f..8fc18ba69d 100644
--- a/platform/darwin/src/MGLRasterSource.mm
+++ b/platform/darwin/src/MGLRasterSource.mm
@@ -15,15 +15,11 @@ static const CGFloat MGLRasterSourceRetinaTileSize = 512;
 
 @interface MGLRasterSource ()
 
-- (instancetype)initWithRawSource:(mbgl::style::RasterSource *)rawSource NS_DESIGNATED_INITIALIZER;
-
-@property (nonatomic) mbgl::style::RasterSource *rawSource;
+@property (nonatomic, readonly) mbgl::style::RasterSource *rawSource;
 
 @end
 
-@implementation MGLRasterSource {
-    std::unique_ptr<mbgl::style::RasterSource> _pendingSource;
-}
+@implementation MGLRasterSource
 
 - (instancetype)initWithIdentifier:(NSString *)identifier configurationURL:(NSURL *)configurationURL {
     // The style specification default is 512, but 256 is the expected value for
@@ -37,76 +33,32 @@ static const CGFloat MGLRasterSourceRetinaTileSize = 512;
 }
 
 - (instancetype)initWithIdentifier:(NSString *)identifier configurationURL:(NSURL *)configurationURL tileSize:(CGFloat)tileSize {
-    if (self = [super initWithIdentifier:identifier]) {
-        auto source = std::make_unique<mbgl::style::RasterSource>(identifier.UTF8String,
-                                                                  configurationURL.mgl_URLByStandardizingScheme.absoluteString.UTF8String,
-                                                                  uint16_t(round(tileSize)));
-        _pendingSource = std::move(source);
-        self.rawSource = _pendingSource.get();
-    }
-    return self;
+    auto source = std::make_unique<mbgl::style::RasterSource>(identifier.UTF8String,
+                                                              configurationURL.mgl_URLByStandardizingScheme.absoluteString.UTF8String,
+                                                              uint16_t(round(tileSize)));
+    return self = [super initWithPendingSource:std::move(source)];
 }
 
 - (instancetype)initWithIdentifier:(NSString *)identifier tileURLTemplates:(NS_ARRAY_OF(NSString *) *)tileURLTemplates options:(nullable NS_DICTIONARY_OF(MGLTileSourceOption, id) *)options {
-    if (self = [super initWithIdentifier:identifier]) {
-        mbgl::Tileset tileSet = MGLTileSetFromTileURLTemplates(tileURLTemplates, options);
-
-        uint16_t tileSize = MGLRasterSourceRetinaTileSize;
-        if (NSNumber *tileSizeNumber = options[MGLTileSourceOptionTileSize]) {
-            if (![tileSizeNumber isKindOfClass:[NSNumber class]]) {
-                [NSException raise:NSInvalidArgumentException
-                            format:@"MGLTileSourceOptionTileSize must be set to an NSNumber."];
-            }
-            tileSize = static_cast<uint16_t>(round(tileSizeNumber.doubleValue));
-        }
-
-        auto source = std::make_unique<mbgl::style::RasterSource>(identifier.UTF8String, tileSet, tileSize);
-        _pendingSource = std::move(source);
-        self.rawSource = _pendingSource.get();
-    }
-    return self;
-}
-
-- (instancetype)initWithRawSource:(mbgl::style::RasterSource *)rawSource {
-    return [super initWithRawSource:rawSource];
-}
-
-- (void)addToMapView:(MGLMapView *)mapView {
-    if (_pendingSource == nullptr) {
-        [NSException raise:@"MGLRedundantSourceException"
-                    format:@"This instance %@ was already added to %@. Adding the same source instance " \
-                           @"to the style more than once is invalid.", self, mapView.style];
-    }
-
-    mapView.mbglMap->addSource(std::move(_pendingSource));
-}
-
-- (void)removeFromMapView:(MGLMapView *)mapView {
-    if (self.rawSource != mapView.mbglMap->getSource(self.identifier.UTF8String)) {
-        return;
-    }
+    mbgl::Tileset tileSet = MGLTileSetFromTileURLTemplates(tileURLTemplates, options);
 
-    auto removedSource = mapView.mbglMap->removeSource(self.identifier.UTF8String);
-
-    mbgl::style::RasterSource *source = dynamic_cast<mbgl::style::RasterSource *>(removedSource.get());
-    if (!source) {
-        return;
+    uint16_t tileSize = MGLRasterSourceRetinaTileSize;
+    if (NSNumber *tileSizeNumber = options[MGLTileSourceOptionTileSize]) {
+        if (![tileSizeNumber isKindOfClass:[NSNumber class]]) {
+            [NSException raise:NSInvalidArgumentException
+                        format:@"MGLTileSourceOptionTileSize must be set to an NSNumber."];
+        }
+        tileSize = static_cast<uint16_t>(round(tileSizeNumber.doubleValue));
     }
 
-    removedSource.release();
-
-    _pendingSource = std::unique_ptr<mbgl::style::RasterSource>(source);
-    self.rawSource = _pendingSource.get();
+    auto source = std::make_unique<mbgl::style::RasterSource>(identifier.UTF8String, tileSet, tileSize);
+    return self = [super initWithPendingSource:std::move(source)];
 }
 
 - (mbgl::style::RasterSource *)rawSource {
     return (mbgl::style::RasterSource *)super.rawSource;
 }
 
-- (void)setRawSource:(mbgl::style::RasterSource *)rawSource {
-    super.rawSource = rawSource;
-}
-
 - (NSURL *)configurationURL {
     auto url = self.rawSource->getURL();
     return url ? [NSURL URLWithString:@(url->c_str())] : nil;
diff --git a/platform/darwin/src/MGLRasterSource_Private.h b/platform/darwin/src/MGLRasterSource_Private.h
index 47b1c13517..76790bd053 100644
--- a/platform/darwin/src/MGLRasterSource_Private.h
+++ b/platform/darwin/src/MGLRasterSource_Private.h
@@ -2,16 +2,7 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-namespace mbgl {
-    namespace style {
-        class RasterSource;
-    }
-}
-
 @interface MGLRasterSource (Private)
-
-- (instancetype)initWithRawSource:(mbgl::style::RasterSource *)rawSource;
-
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/platform/darwin/src/MGLShapeSource.mm b/platform/darwin/src/MGLShapeSource.mm
index 7de2d69af3..15437ebedb 100644
--- a/platform/darwin/src/MGLShapeSource.mm
+++ b/platform/darwin/src/MGLShapeSource.mm
@@ -20,38 +20,26 @@ const MGLShapeSourceOption MGLShapeSourceOptionSimplificationTolerance = @"MGLSh
 
 @interface MGLShapeSource ()
 
-- (instancetype)initWithRawSource:(mbgl::style::GeoJSONSource *)rawSource NS_DESIGNATED_INITIALIZER;
-
 @property (nonatomic, readwrite) NSDictionary *options;
-@property (nonatomic) mbgl::style::GeoJSONSource *rawSource;
+@property (nonatomic, readonly) mbgl::style::GeoJSONSource *rawSource;
 
 @end
 
-@implementation MGLShapeSource {
-    std::unique_ptr<mbgl::style::GeoJSONSource> _pendingSource;
-}
+@implementation MGLShapeSource
 
 - (instancetype)initWithIdentifier:(NSString *)identifier URL:(NSURL *)url options:(NS_DICTIONARY_OF(NSString *, id) *)options {
-    if (self = [super initWithIdentifier:identifier]) {
-        auto geoJSONOptions = MGLGeoJSONOptionsFromDictionary(options);
-        auto source = std::make_unique<mbgl::style::GeoJSONSource>(identifier.UTF8String, geoJSONOptions);
-
-        _pendingSource = std::move(source);
-        self.rawSource = _pendingSource.get();
-
+    auto geoJSONOptions = MGLGeoJSONOptionsFromDictionary(options);
+    auto source = std::make_unique<mbgl::style::GeoJSONSource>(identifier.UTF8String, geoJSONOptions);
+    if (self = [super initWithPendingSource:std::move(source)]) {
         self.URL = url;
     }
     return self;
 }
 
 - (instancetype)initWithIdentifier:(NSString *)identifier shape:(nullable MGLShape *)shape options:(NS_DICTIONARY_OF(MGLShapeSourceOption, id) *)options {
-    if (self = [super initWithIdentifier:identifier]) {
-        auto geoJSONOptions = MGLGeoJSONOptionsFromDictionary(options);
-        auto source = std::make_unique<mbgl::style::GeoJSONSource>(identifier.UTF8String, geoJSONOptions);
-
-        _pendingSource = std::move(source);
-        self.rawSource = _pendingSource.get();
-
+    auto geoJSONOptions = MGLGeoJSONOptionsFromDictionary(options);
+    auto source = std::make_unique<mbgl::style::GeoJSONSource>(identifier.UTF8String, geoJSONOptions);
+    if (self = [super initWithPendingSource:std::move(source)]) {
         self.shape = shape;
     }
     return self;
@@ -72,46 +60,10 @@ const MGLShapeSourceOption MGLShapeSourceOptionSimplificationTolerance = @"MGLSh
     return [self initWithIdentifier:identifier shape:shapeCollection options:options];
 }
 
-- (instancetype)initWithRawSource:(mbgl::style::GeoJSONSource *)rawSource {
-    return [super initWithRawSource:rawSource];
-}
-
-- (void)addToMapView:(MGLMapView *)mapView {
-    if (_pendingSource == nullptr) {
-        [NSException raise:@"MGLRedundantSourceException"
-                    format:@"This instance %@ was already added to %@. Adding the same source instance " \
-                            "to the style more than once is invalid.", self, mapView.style];
-    }
-
-    mapView.mbglMap->addSource(std::move(_pendingSource));
-}
-
-- (void)removeFromMapView:(MGLMapView *)mapView {
-    if (self.rawSource != mapView.mbglMap->getSource(self.identifier.UTF8String)) {
-        return;
-    }
-
-    auto removedSource = mapView.mbglMap->removeSource(self.identifier.UTF8String);
-
-    mbgl::style::GeoJSONSource *source = dynamic_cast<mbgl::style::GeoJSONSource *>(removedSource.get());
-    if (!source) {
-        return;
-    }
-
-    removedSource.release();
-
-    _pendingSource = std::unique_ptr<mbgl::style::GeoJSONSource>(source);
-    self.rawSource = _pendingSource.get();
-}
-
 - (mbgl::style::GeoJSONSource *)rawSource {
     return (mbgl::style::GeoJSONSource *)super.rawSource;
 }
 
-- (void)setRawSource:(mbgl::style::GeoJSONSource *)rawSource {
-    super.rawSource = rawSource;
-}
-
 - (NSURL *)URL {
     auto url = self.rawSource->getURL();
     return url ? [NSURL URLWithString:@(url->c_str())] : nil;
diff --git a/platform/darwin/src/MGLShapeSource_Private.h b/platform/darwin/src/MGLShapeSource_Private.h
index c14f4fbb59..84eb5deed4 100644
--- a/platform/darwin/src/MGLShapeSource_Private.h
+++ b/platform/darwin/src/MGLShapeSource_Private.h
@@ -6,14 +6,10 @@ NS_ASSUME_NONNULL_BEGIN
 namespace mbgl {
     namespace style {
         class GeoJSONOptions;
-        struct GeoJSONSource;
     }
 }
 
 @interface MGLShapeSource (Private)
-
-- (instancetype)initWithRawSource:(mbgl::style::GeoJSONSource *)rawSource;
-
 @end
 
 MGL_EXPORT
diff --git a/platform/darwin/src/MGLSource.mm b/platform/darwin/src/MGLSource.mm
index c96b6c41c6..1940db688c 100644
--- a/platform/darwin/src/MGLSource.mm
+++ b/platform/darwin/src/MGLSource.mm
@@ -1,16 +1,21 @@
 #import "MGLSource_Private.h"
+#import "MGLMapView_Private.h"
 
+#include <mbgl/map/map.hpp>
 #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;
+@property (nonatomic, readonly) mbgl::style::Source *rawSource;
 
 @end
 
-@implementation MGLSource
+@implementation MGLSource {
+    std::unique_ptr<mbgl::style::Source> _pendingSource;
+}
+
 
 - (instancetype)initWithIdentifier:(NSString *)identifier
 {
@@ -28,18 +33,27 @@
     return self;
 }
 
+- (instancetype)initWithPendingSource:(std::unique_ptr<mbgl::style::Source>)pendingSource {
+    if (self = [self initWithRawSource:pendingSource.get()]) {
+        _pendingSource = std::move(pendingSource);
+    }
+    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];
+    if (_pendingSource == nullptr) {
+        [NSException raise:@"MGLRedundantSourceException"
+                    format:@"This instance %@ was already added to %@. Adding the same source instance " \
+                            "to the style more than once is invalid.", self, mapView.style];
+    }
+
+    mapView.mbglMap->addSource(std::move(_pendingSource));
 }
 
 - (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];
+    if (self.rawSource == mapView.mbglMap->getSource(self.identifier.UTF8String)) {
+        _pendingSource = mapView.mbglMap->removeSource(self.identifier.UTF8String);
+    }
 }
 
 - (NSString *)description {
diff --git a/platform/darwin/src/MGLSource_Private.h b/platform/darwin/src/MGLSource_Private.h
index acb325e2f3..2fc170b86b 100644
--- a/platform/darwin/src/MGLSource_Private.h
+++ b/platform/darwin/src/MGLSource_Private.h
@@ -1,5 +1,7 @@
 #import "MGLSource.h"
 
+#include <memory>
+
 NS_ASSUME_NONNULL_BEGIN
 
 namespace mbgl {
@@ -13,18 +15,25 @@ namespace mbgl {
 @interface MGLSource (Private)
 
 /**
- Initializes and returns a source with a raw pointer to the backing store.
+ Initializes and returns a source with a raw pointer to the backing store,
+ associated with a style.
  */
 - (instancetype)initWithRawSource:(mbgl::style::Source *)rawSource;
 
 /**
+ Initializes and returns a source with an owning pointer to the backing store,
+ unassociated from a style.
+ */
+- (instancetype)initWithPendingSource:(std::unique_ptr<mbgl::style::Source>)pendingSource;
+
+/**
  A raw pointer to the mbgl object, which is always initialized, either to the
  value returned by `mbgl::Map getSource`, or for independently created objects,
  to the pointer value held in `pendingSource`. In the latter case, this raw
  pointer value stays even after ownership of the object is transferred via
  `mbgl::Map addSource`.
  */
-@property (nonatomic) mbgl::style::Source *rawSource;
+@property (nonatomic, readonly) mbgl::style::Source *rawSource;
 
 /**
  Adds the mbgl source that this object represents to the mbgl map.
diff --git a/platform/darwin/src/MGLVectorSource.mm b/platform/darwin/src/MGLVectorSource.mm
index 5404f170e9..afce3bad46 100644
--- a/platform/darwin/src/MGLVectorSource.mm
+++ b/platform/darwin/src/MGLVectorSource.mm
@@ -1,88 +1,37 @@
 #import "MGLVectorSource_Private.h"
 
-#import "MGLMapView_Private.h"
 #import "MGLFeature_Private.h"
 #import "MGLSource_Private.h"
 #import "MGLTileSource_Private.h"
 #import "NSPredicate+MGLAdditions.h"
 #import "NSURL+MGLAdditions.h"
 
-#include <mbgl/map/map.hpp>
 #include <mbgl/style/sources/vector_source.hpp>
 
 @interface MGLVectorSource ()
 
-- (instancetype)initWithRawSource:(mbgl::style::VectorSource *)rawSource NS_DESIGNATED_INITIALIZER;
-
-@property (nonatomic) mbgl::style::VectorSource *rawSource;
+@property (nonatomic, readonly) mbgl::style::VectorSource *rawSource;
 
 @end
 
-@implementation MGLVectorSource {
-    std::unique_ptr<mbgl::style::VectorSource> _pendingSource;
-}
+@implementation MGLVectorSource
 
 - (instancetype)initWithIdentifier:(NSString *)identifier configurationURL:(NSURL *)configurationURL {
-    if (self = [super initWithIdentifier:identifier]) {
-        auto source = std::make_unique<mbgl::style::VectorSource>(identifier.UTF8String,
-                                                                  configurationURL.mgl_URLByStandardizingScheme.absoluteString.UTF8String);
-        _pendingSource = std::move(source);
-        self.rawSource = _pendingSource.get();
-    }
-    return self;
+    auto source = std::make_unique<mbgl::style::VectorSource>(identifier.UTF8String,
+                                                              configurationURL.mgl_URLByStandardizingScheme.absoluteString.UTF8String);
+    return self = [super initWithPendingSource:std::move(source)];
 }
 
 - (instancetype)initWithIdentifier:(NSString *)identifier tileURLTemplates:(NS_ARRAY_OF(NSString *) *)tileURLTemplates options:(nullable NS_DICTIONARY_OF(MGLTileSourceOption, id) *)options {
-    if (self = [super initWithIdentifier:identifier]) {
-        mbgl::Tileset tileSet = MGLTileSetFromTileURLTemplates(tileURLTemplates, options);
-
-        auto source = std::make_unique<mbgl::style::VectorSource>(identifier.UTF8String, tileSet);
-        _pendingSource = std::move(source);
-        self.rawSource = _pendingSource.get();
-    }
-    return self;
-}
-
-- (instancetype)initWithRawSource:(mbgl::style::VectorSource *)rawSource {
-    return [super initWithRawSource:rawSource];
-}
-
-- (void)addToMapView:(MGLMapView *)mapView {
-    if (_pendingSource == nullptr) {
-        [NSException raise:@"MGLRedundantSourceException"
-                    format:@"This instance %@ was already added to %@. Adding the same source instance " \
-                            "to the style more than once is invalid.", self, mapView.style];
-    }
-
-    mapView.mbglMap->addSource(std::move(_pendingSource));
-}
-
-- (void)removeFromMapView:(MGLMapView *)mapView {
-    if (self.rawSource != mapView.mbglMap->getSource(self.identifier.UTF8String)) {
-        return;
-    }
-
-    auto removedSource = mapView.mbglMap->removeSource(self.identifier.UTF8String);
-
-    mbgl::style::VectorSource *source = dynamic_cast<mbgl::style::VectorSource *>(removedSource.get());
-    if (!source) {
-        return;
-    }
-
-    removedSource.release();
-
-    _pendingSource = std::unique_ptr<mbgl::style::VectorSource>(source);
-    self.rawSource = _pendingSource.get();
+    mbgl::Tileset tileSet = MGLTileSetFromTileURLTemplates(tileURLTemplates, options);
+    auto source = std::make_unique<mbgl::style::VectorSource>(identifier.UTF8String, tileSet);
+    return self = [super initWithPendingSource:std::move(source)];
 }
 
 - (mbgl::style::VectorSource *)rawSource {
     return (mbgl::style::VectorSource *)super.rawSource;
 }
 
-- (void)setRawSource:(mbgl::style::VectorSource *)rawSource {
-    super.rawSource = rawSource;
-}
-
 - (NSURL *)configurationURL {
     auto url = self.rawSource->getURL();
     return url ? [NSURL URLWithString:@(url->c_str())] : nil;
diff --git a/platform/darwin/src/MGLVectorSource_Private.h b/platform/darwin/src/MGLVectorSource_Private.h
index 12fcd82012..335743173e 100644
--- a/platform/darwin/src/MGLVectorSource_Private.h
+++ b/platform/darwin/src/MGLVectorSource_Private.h
@@ -2,16 +2,7 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-namespace mbgl {
-    namespace style {
-        class VectorSource;
-    }
-}
-
 @interface MGLVectorSource (Private)
-
-- (instancetype)initWithRawSource:(mbgl::style::VectorSource *)rawSource;
-
 @end
 
 NS_ASSUME_NONNULL_END