Reimplement style values atop NSExpression (#10726)

* [ios, macos] Import headers, not implementation files

* [core] Added accessors for various expression parameters

Added missing parameter accessors to various expression operator classes, as well as a method on InterpolatorBase and Step that enumerates the stops and their values.

* [ios, macos] Silenced warning in test of error condition

* [ios, macos] Made MGLSphericalPosition boxable

* [ios, macos] Implemented array enumeration during conversion

* [ios, macos] Temporarily ignore heatmap layer type

* [ios, macos] Migrated MGLSymbolStyleLayer.text to NSExpression

MGLSymbolStyleLayer.text is now of type NSExpression instead of MGLStyleValue, as a first step toward migrating the entire layer API from style values to expressions.

Implemented conversions from NSExpression to JSON arrays and vice versa. The most common NSExpression functions are now converted into style expressions, but not all of the most common style expression operators are supported yet.

* [ios, macos] Implemented string coercion

* [ios, macos] Color literals

* [ios, macos] Null constant expressions

* [ios, macos] Convert dictionary literals

* [ios, macos] Interpolation expressions

* [ios, macos] to-boolean, to-number, get from object

* [ios, macos] Variable expressions

Implemented custom expression functions for assigning and referring to variables within the context of an expression. Variables are assigned via a “context dictionary” and applied to an subexpression that is given as another argument to the same expression. Also implemented built-in variable expressions for zoom level and heatmap density.

* [ios, macos] Convert colors, offsets, padding in expressions to JSON objects

* [ios, macos] Expression-based style property getters

Implemented a conversion from mbgl::style::PropertyValues to Objective-C JSON objects, which are then converted to NSExpressions.

* [ios, macos] Consolidated property value–expression conversion in MGLStyleValueTransformer

* [ios, macos] Predicate and expression guide

Extracted documentation about predicates from a documentation comment in MGLVectorStyleLayer.h to a new jazzy guide. Added details about NSExpression support as well. Began updating the “For Style Authors” guide to reflect the transition from style values to expressions.

* [ios, macos] Updated style authoring guide

Updated the Information for Style Authors guide to discuss expressions instead of style functions. Included a table mapping style specification expression operators to NSExpression syntaxes.

* [ios, macos] Migrated codegen templates to expressions

* [ios, macos] Applied expression changes via codegen

Ran make darwin-style-code.

* [macos] Migrated macosapp to expressions

* [ios, macos] Updated style function guide

This guide needs to be thoroughly rewritten, but for now the example code has been migrated to expressions.

* [ios, macos] Eviscerated style function tests

* [ios, macos] Updated changelogs

* [ios] Migrated iosapp to expressions

* [ios, macos] Exposed JSON conversion methods publicly

* [ios, macos] Removed MGLStyleValue, MGLStyleFunction

1 files changed, 77 insertions, 126 deletions

diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 4306354030..0f617188b9 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -897,8 +897,8 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
         MGLFillExtrusionStyleLayer* layer = [[MGLFillExtrusionStyleLayer alloc] initWithIdentifier:@"extrudedBuildings" source:source];
         layer.sourceLayerIdentifier = @"building";
         layer.predicate = [NSPredicate predicateWithFormat:@"extrude == 'true' AND height > 0"];
-        layer.fillExtrusionBase = [MGLStyleValue valueWithInterpolationMode:MGLInterpolationModeIdentity sourceStops:nil attributeName:@"min_height" options:nil];
-        layer.fillExtrusionHeight = [MGLStyleValue valueWithInterpolationMode:MGLInterpolationModeIdentity sourceStops:nil attributeName:@"height" options:nil];
+        layer.fillExtrusionBase = [NSExpression expressionForKeyPath:@"min_height"];
+        layer.fillExtrusionHeight = [NSExpression expressionForKeyPath:@"height"];
 
         // Set the fill color to that of the existing building footprint layer, if it exists.
         MGLFillStyleLayer* buildingLayer = (MGLFillStyleLayer*)[self.mapView.style layerWithIdentifier:@"building"];
@@ -906,10 +906,10 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
             if (buildingLayer.fillColor) {
                 layer.fillExtrusionColor = buildingLayer.fillColor;
             } else {
-                layer.fillExtrusionColor = [MGLStyleValue valueWithRawValue:[UIColor whiteColor]];
+                layer.fillExtrusionColor = [NSExpression expressionForConstantValue:[UIColor whiteColor]];
             }
 
-            layer.fillExtrusionOpacity = [MGLStyleValue<NSNumber *> valueWithRawValue:@0.75];
+            layer.fillExtrusionOpacity = [NSExpression expressionForConstantValue:@0.75];
         }
 
         MGLStyleLayer* labelLayer = [self.mapView.style layerWithIdentifier:@"waterway-label"];
@@ -924,48 +924,45 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
 - (void)styleWaterLayer
 {
     MGLFillStyleLayer *waterLayer = (MGLFillStyleLayer *)[self.mapView.style layerWithIdentifier:@"water"];
-    NSDictionary *waterColorStops = @{@6.0f: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor yellowColor]],
-                                      @8.0f: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor blueColor]],
-                                      @10.0f: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]],
-                                      @12.0f: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor greenColor]],
-                                      @14.0f: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor blueColor]]};
-    MGLStyleValue *waterColorFunction = [MGLStyleValue<UIColor *> valueWithInterpolationMode:MGLInterpolationModeExponential
-                                                                                 cameraStops:waterColorStops
-                                                                                     options: nil];
-    waterLayer.fillColor = waterColorFunction;
-
-    NSDictionary *fillAntialiasedStops = @{@11: [MGLStyleValue<NSNumber *> valueWithRawValue:@YES],
-                                           @12: [MGLStyleValue<NSNumber *> valueWithRawValue:@NO],
-                                           @13: [MGLStyleValue<NSNumber *> valueWithRawValue:@YES],
-                                           @14: [MGLStyleValue<NSNumber *> valueWithRawValue:@NO],
-                                           @15: [MGLStyleValue<NSNumber *> valueWithRawValue:@YES]};
-    MGLStyleValue *fillAntialiasedFunction = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeInterval
-                                                                                       cameraStops:fillAntialiasedStops
-                                                                                           options:nil];
-    waterLayer.fillAntialiased = fillAntialiasedFunction;
+    NSDictionary *waterColorStops = @{@6.0f: [UIColor yellowColor],
+                                      @8.0f: [UIColor blueColor],
+                                      @10.0f: [UIColor redColor],
+                                      @12.0f: [UIColor greenColor],
+                                      @14.0f: [UIColor blueColor]};
+    waterLayer.fillColor = [NSExpression expressionWithFormat:
+                            @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                            waterColorStops];
+
+    NSDictionary *fillAntialiasedStops = @{@11: @YES,
+                                           @12: @NO,
+                                           @13: @YES,
+                                           @14: @NO,
+                                           @15: @YES};
+    waterLayer.fillAntialiased = [NSExpression expressionWithFormat:
+                                  @"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', false, %@)",
+                                  fillAntialiasedStops];
 }
 
 - (void)styleRoadLayer
 {
     MGLLineStyleLayer *roadLayer = (MGLLineStyleLayer *)[self.mapView.style layerWithIdentifier:@"road-primary"];
-    roadLayer.lineColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor blackColor]];
-
-    NSDictionary *lineWidthStops = @{@5: [MGLStyleValue<NSNumber *> valueWithRawValue:@5],
-                                     @10: [MGLStyleValue<NSNumber *> valueWithRawValue:@15],
-                                     @15: [MGLStyleValue<NSNumber *> valueWithRawValue:@30]};
-    MGLStyleValue *lineWidthFunction = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeExponential
-                                                                                 cameraStops:lineWidthStops
-                                                                                     options:nil];
-    roadLayer.lineWidth = lineWidthFunction;
-    roadLayer.lineGapWidth = lineWidthFunction;
-
-    NSDictionary *roadLineColorStops = @{@10: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor purpleColor]],
-                                         @13: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor yellowColor]],
-                                         @16: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor cyanColor]]};
-    MGLStyleValue *roadLineColor = [MGLStyleValue<UIColor *> valueWithInterpolationMode:MGLInterpolationModeExponential
-                                                                            cameraStops:roadLineColorStops
-                                                                                options: nil];
-    roadLayer.lineColor = roadLineColor;
+    roadLayer.lineColor = [NSExpression expressionForConstantValue:[UIColor blackColor]];
+
+    NSDictionary *lineWidthStops = @{@5: @5,
+                                     @10: @15,
+                                     @15: @30};
+    NSExpression *lineWidthExpression = [NSExpression expressionWithFormat:
+                                         @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                                         lineWidthStops];
+    roadLayer.lineWidth = lineWidthExpression;
+    roadLayer.lineGapWidth = lineWidthExpression;
+
+    NSDictionary *roadLineColorStops = @{@10: [UIColor purpleColor],
+                                         @13: [UIColor yellowColor],
+                                         @16: [UIColor cyanColor]};
+    roadLayer.lineColor = [NSExpression expressionWithFormat:
+                           @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                           roadLineColorStops];
 
     roadLayer.visible = YES;
     roadLayer.maximumZoomLevel = 15;
@@ -979,11 +976,11 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:rasterSource];
 
     MGLRasterStyleLayer *rasterLayer = [[MGLRasterStyleLayer alloc] initWithIdentifier:@"my-raster-layer" source:rasterSource];
-    MGLStyleValue *opacityFunction = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeExponential
-                                                                               cameraStops:@{@20.0f: [MGLStyleValue<NSNumber *> valueWithRawValue:@1.0f],
-                                                                                             @5.0f: [MGLStyleValue<NSNumber *> valueWithRawValue:@0.0f]}
-                                                                                   options:nil];
-    rasterLayer.rasterOpacity = opacityFunction;
+    NSDictionary *opacityStops = @{@20.0f: @1.0f,
+                                   @5.0f: @0.0f};
+    rasterLayer.rasterOpacity = [NSExpression expressionWithFormat:
+                                 @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                                 opacityStops];
     [self.mapView.style addLayer:rasterLayer];
 }
 
@@ -995,7 +992,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:source];
 
     MGLFillStyleLayer *fillLayer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"test" source:source];
-    fillLayer.fillColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor purpleColor]];
+    fillLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor purpleColor]];
     [self.mapView.style addLayer:fillLayer];
 
 }
@@ -1003,7 +1000,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
 - (void)styleSymbolLayer
 {
     MGLSymbolStyleLayer *stateLayer = (MGLSymbolStyleLayer *)[self.mapView.style layerWithIdentifier:@"state-label-lg"];
-    stateLayer.textColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]];
+    stateLayer.textColor = [NSExpression expressionForConstantValue:[UIColor redColor]];
 }
 
 - (void)styleBuildingLayer
@@ -1011,13 +1008,13 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     MGLTransition transition =  { 5,  1 };
     self.mapView.style.transition = transition;
     MGLFillStyleLayer *buildingLayer = (MGLFillStyleLayer *)[self.mapView.style layerWithIdentifier:@"building"];
-    buildingLayer.fillColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor purpleColor]];
+    buildingLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor purpleColor]];
 }
 
 - (void)styleFerryLayer
 {
     MGLLineStyleLayer *ferryLineLayer = (MGLLineStyleLayer *)[self.mapView.style layerWithIdentifier:@"ferry"];
-    ferryLineLayer.lineColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]];
+    ferryLineLayer.lineColor = [NSExpression expressionForConstantValue:[UIColor redColor]];
 }
 
 - (void)removeParkLayer
@@ -1041,8 +1038,8 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
         statesLayer.predicate = [NSPredicate predicateWithFormat:@"name == 'Texas'"];
 
         // paint properties
-        statesLayer.fillColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]];
-        statesLayer.fillOpacity = [MGLStyleValue<NSNumber *> valueWithRawValue:@0.25];
+        statesLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor redColor]];
+        statesLayer.fillOpacity = [NSExpression expressionForConstantValue:@0.25];
     });
 }
 
@@ -1061,9 +1058,9 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
         countiesLayer.predicate = [NSPredicate predicateWithFormat:@"NAME10 == 'Washington'"];
 
         // paint properties
-        countiesLayer.lineColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]];
-        countiesLayer.lineOpacity = [MGLStyleValue<NSNumber *> valueWithRawValue:@0.75];
-        countiesLayer.lineWidth = [MGLStyleValue<NSNumber *> valueWithRawValue:@5];
+        countiesLayer.lineColor = [NSExpression expressionForConstantValue:[UIColor redColor]];
+        countiesLayer.lineOpacity = [NSExpression expressionForConstantValue:@0.75];
+        countiesLayer.lineWidth = [NSExpression expressionForConstantValue:@5];
     });
 }
 
@@ -1082,8 +1079,8 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
         regionsLayer.predicate = [NSPredicate predicateWithFormat:@"HRRNUM >= %@ AND HRRNUM < 300", @(200)];
 
         // paint properties
-        regionsLayer.fillColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor blueColor]];
-        regionsLayer.fillOpacity = [MGLStyleValue<NSNumber *> valueWithRawValue:@0.5];
+        regionsLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor blueColor]];
+        regionsLayer.fillOpacity = [NSExpression expressionForConstantValue:@0.5];
     });
 }
 
@@ -1113,8 +1110,8 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
         [self.mapView.style addSource:source];
 
         MGLFillStyleLayer *fillLayer = [[MGLFillStyleLayer alloc] initWithIdentifier:queryLayerID source:source];
-        fillLayer.fillColor = [MGLConstantStyleValue<UIColor *> valueWithRawValue:[UIColor blueColor]];
-        fillLayer.fillOpacity = [MGLConstantStyleValue<NSNumber *> valueWithRawValue:@0.5];
+        fillLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor blueColor]];
+        fillLayer.fillOpacity = [NSExpression expressionForConstantValue:@0.5];
         [self.mapView.style addLayer:fillLayer];
     });
 }
@@ -1167,8 +1164,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
 
     MGLFillStyleLayer *layer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"leaf-fill-layer" source:source];
     layer.predicate = [NSPredicate predicateWithFormat:@"color = 'red'"];
-    MGLStyleValue *fillColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]];
-    layer.fillColor = fillColor;
+    layer.fillColor = [NSExpression expressionForConstantValue:[UIColor redColor]];
     [self.mapView.style addLayer:layer];
 
     NSString *geoJSON = @"{\"type\": \"Feature\", \"properties\": {\"color\": \"green\"}, \"geometry\": { \"type\": \"Point\", \"coordinates\": [ -114.06847000122069, 51.050459433092655 ] }}";
@@ -1179,7 +1175,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:pointSource];
 
     MGLCircleStyleLayer *circleLayer = [[MGLCircleStyleLayer alloc] initWithIdentifier:@"leaf-circle-layer" source:pointSource];
-    circleLayer.circleColor = [MGLStyleValue valueWithRawValue:[UIColor greenColor]];
+    circleLayer.circleColor = [NSExpression expressionForConstantValue:[UIColor greenColor]];
     circleLayer.predicate = [NSPredicate predicateWithFormat:@"color = 'green'"];
     [self.mapView.style addLayer:circleLayer];
 
@@ -1196,7 +1192,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:plainShapeSource];
 
     MGLFillStyleLayer *plainFillLayer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"leaf-plain-fill-layer" source:plainShapeSource];
-    plainFillLayer.fillColor = [MGLStyleValue valueWithRawValue:[UIColor yellowColor]];
+    plainFillLayer.fillColor = [NSExpression expressionForConstantValue:[UIColor yellowColor]];
     [self.mapView.style addLayer:plainFillLayer];
 }
 
@@ -1273,8 +1269,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:source];
 
     MGLFillStyleLayer *layer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"mutable-data-layer-features-id" source:source];
-    MGLStyleValue *fillColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]];
-    layer.fillColor = fillColor;
+    layer.fillColor = [NSExpression expressionForConstantValue:[UIColor redColor]];
     [self.mapView.style addLayer:layer];
 
     dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
@@ -1306,16 +1301,14 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:vectorSource];
 
     MGLBackgroundStyleLayer *backgroundLayer = [[MGLBackgroundStyleLayer alloc] initWithIdentifier:@"style-vector-background-layer-id"];
-    backgroundLayer.backgroundColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor blackColor]];
+    backgroundLayer.backgroundColor = [NSExpression expressionForConstantValue:[UIColor blackColor]];
     [self.mapView.style addLayer:backgroundLayer];
 
     MGLLineStyleLayer *lineLayer = [[MGLLineStyleLayer alloc] initWithIdentifier:@"style-vector-line-layer-id" source:vectorSource];
     lineLayer.sourceLayerIdentifier = @"contour";
-    NSUInteger lineJoinValue = MGLLineJoinRound;
-    lineLayer.lineJoin = [MGLStyleValue<NSValue *> valueWithRawValue:[NSValue value:&lineJoinValue withObjCType:@encode(MGLLineJoin)]];
-    NSUInteger lineCapValue = MGLLineCapRound;
-    lineLayer.lineCap = [MGLStyleValue<NSValue *> valueWithRawValue:[NSValue value:&lineCapValue withObjCType:@encode(MGLLineCap)]];
-    lineLayer.lineColor = [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor greenColor]];
+    lineLayer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
+    lineLayer.lineCap = [NSExpression expressionForConstantValue:@"round"];
+    lineLayer.lineColor = [NSExpression expressionForConstantValue:[UIColor greenColor]];
 
     [self.mapView.style addLayer:lineLayer];
 }
@@ -1393,19 +1386,19 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addSource:routeSource];
 
     MGLLineStyleLayer *baseRouteLayer = [[MGLLineStyleLayer alloc] initWithIdentifier:@"style-base-route-layer" source:routeSource];
-    baseRouteLayer.lineColor = [MGLConstantStyleValue valueWithRawValue:[UIColor orangeColor]];
-    baseRouteLayer.lineWidth = [MGLConstantStyleValue valueWithRawValue:@20];
-    baseRouteLayer.lineOpacity = [MGLConstantStyleValue valueWithRawValue:@0.5];
-    baseRouteLayer.lineCap = [MGLConstantStyleValue valueWithRawValue:[NSValue valueWithMGLLineCap:MGLLineCapRound]];
-    baseRouteLayer.lineJoin = [MGLConstantStyleValue valueWithRawValue:[NSValue valueWithMGLLineJoin:MGLLineJoinRound]];
+    baseRouteLayer.lineColor = [NSExpression expressionForConstantValue:[UIColor orangeColor]];
+    baseRouteLayer.lineWidth = [NSExpression expressionForConstantValue:@20];
+    baseRouteLayer.lineOpacity = [NSExpression expressionForConstantValue:@0.5];
+    baseRouteLayer.lineCap = [NSExpression expressionForConstantValue:@"round"];
+    baseRouteLayer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
     [self.mapView.style addLayer:baseRouteLayer];
 
     MGLLineStyleLayer *routeLayer = [[MGLLineStyleLayer alloc] initWithIdentifier:@"style-route-layer" source:routeSource];
-    routeLayer.lineColor = [MGLConstantStyleValue valueWithRawValue:[UIColor whiteColor]];
-    routeLayer.lineWidth = [MGLConstantStyleValue valueWithRawValue:@15];
-    routeLayer.lineOpacity = [MGLConstantStyleValue valueWithRawValue:@0.8];
-    routeLayer.lineCap = [MGLConstantStyleValue valueWithRawValue:[NSValue valueWithMGLLineCap:MGLLineCapRound]];
-    routeLayer.lineJoin = [MGLConstantStyleValue valueWithRawValue:[NSValue valueWithMGLLineJoin:MGLLineJoinRound]];
+    routeLayer.lineColor = [NSExpression expressionForConstantValue:[UIColor whiteColor]];
+    routeLayer.lineWidth = [NSExpression expressionForConstantValue:@15];
+    routeLayer.lineOpacity = [NSExpression expressionForConstantValue:@0.8];
+    routeLayer.lineCap = [NSExpression expressionForConstantValue:@"round"];
+    routeLayer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
     [self.mapView.style addLayer:routeLayer];
 }
 
@@ -1435,19 +1428,10 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
 
     // source, categorical function that sets any feature with a "fill" attribute value of true to red color and anything without to green
     MGLFillStyleLayer *fillStyleLayer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"fill-layer" source:shapeSource];
-    NSDictionary *stops = @{@(YES): [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor greenColor]]};
-    NSDictionary *fillColorOptions = @{MGLStyleFunctionOptionDefaultValue: [MGLStyleValue<UIColor *> valueWithRawValue:[UIColor redColor]]};
-    fillStyleLayer.fillColor = [MGLStyleValue<UIColor *> valueWithInterpolationMode:MGLInterpolationModeCategorical
-                                                                        sourceStops:stops
-                                                                      attributeName:@"fill"
-                                                                            options:fillColorOptions];
+    fillStyleLayer.fillColor = [NSExpression expressionWithFormat:@"TERNARY(fill, %@, %@)", [UIColor greenColor], [UIColor redColor]];
 
     // source, identity function that sets any feature with an "opacity" attribute to use that value and anything without to 1.0
-    NSDictionary *fillOpacityOptions = @{MGLStyleFunctionOptionDefaultValue: [MGLStyleValue<NSNumber *> valueWithRawValue:@(1.0)]};
-    fillStyleLayer.fillOpacity = [MGLStyleValue<NSNumber *> valueWithInterpolationMode:MGLInterpolationModeIdentity
-                                                                           sourceStops:nil
-                                                                         attributeName:@"opacity"
-                                                                               options:fillOpacityOptions];
+    fillStyleLayer.fillOpacity = [NSExpression expressionWithFormat:@"TERNARY(opacity != nil, opacity, 1.0)"];
     [self.mapView.style addLayer:fillStyleLayer];
 }
 
@@ -1462,43 +1446,10 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     [self.mapView.style addLayer:lineLayer];
     MGLSymbolStyleLayer *labelLayer = [[MGLSymbolStyleLayer alloc] initWithIdentifier:@"latlonlabels"
                                                                                source:source];
-    labelLayer.text = [MGLStyleValue valueWithRawValue:@"{value}"];
+    labelLayer.text = [NSExpression expressionForKeyPath:@"value"];
     [self.mapView.style addLayer:labelLayer];
 }
 
-- (void)styleLabelLanguageForLayersNamed:(NSArray<NSString *> *)layers
-{
-    _usingLocaleBasedCountryLabels = !_usingLocaleBasedCountryLabels;
-    NSString *bestLanguageForUser = [NSString stringWithFormat:@"{name_%@}", [self bestLanguageForUser]];
-    NSString *language = _usingLocaleBasedCountryLabels ? bestLanguageForUser : @"{name}";
-
-    for (NSString *layerName in layers) {
-        MGLSymbolStyleLayer *layer = (MGLSymbolStyleLayer *)[self.mapView.style layerWithIdentifier:layerName];
-
-        if ([layer isKindOfClass:[MGLSymbolStyleLayer class]]) {
-            if ([layer.text isKindOfClass:[MGLStyleConstantValue class]]) {
-                MGLStyleConstantValue *label = (MGLStyleConstantValue<NSString *> *)layer.text;
-                if ([label.rawValue hasPrefix:@"{name"]) {
-                    layer.text = [MGLStyleValue valueWithRawValue:language];
-                }
-            }
-            else if ([layer.text isKindOfClass:[MGLCameraStyleFunction class]]) {
-                MGLCameraStyleFunction *function = (MGLCameraStyleFunction<NSString *> *)layer.text;
-                NSMutableDictionary *stops = function.stops.mutableCopy;
-                [stops enumerateKeysAndObjectsUsingBlock:^(NSNumber *zoomLevel, MGLStyleConstantValue<NSString *> *stop, BOOL *done) {
-                    if ([stop.rawValue hasPrefix:@"{name"]) {
-                        stops[zoomLevel] = [MGLStyleValue<NSString *> valueWithRawValue:language];
-                    }
-                }];
-                function.stops = stops;
-                layer.text = function;
-            }
-        } else {
-            NSLog(@"%@ is not a symbol style layer", layerName);
-        }
-    }
-}
-
 - (NSString *)bestLanguageForUser
 {
     // https://www.mapbox.com/vector-tiles/mapbox-streets-v7/#overview