New Expression initializer (#2362)

Apps/Examples/Examples/All Examples/BuildingExtrusionsExample.swift

@@ -153,18 +153,17 @@ final class BuildingExtrusionsExample: UIViewController, ExampleProtocol {
     // See https://docs.mapbox.com/mapbox-gl-js/example/3d-buildings/ for equivalent gl-js example
     internal func addBuildingExtrusions() throws {
         let wallOnlyThreshold = 20
-        let extrudeFilter = Exp(.eq) {
-            Exp(.get) { "extrude" }
-            "true"
-        }
+        let extrudeFilter = Exp(.eq, Exp(.get, "extrude"), "true")
         var layer = FillExtrusionLayer(id: "3d-buildings", source: "composite")
             .minZoom(15)
             .sourceLayer("building")
             .fillExtrusionColor(.lightGray)
             .fillExtrusionOpacity(0.8)
             .fillExtrusionAmbientOcclusionIntensity(0.3)
             .fillExtrusionAmbientOcclusionRadius(3.0)
-
+            .fillExtrusionHeight(Exp(.get, "height"))
+            .fillExtrusionBase(Exp(.get, "min_height"))
+            .fillExtrusionVerticalScale(Exp(.interpolate, Exp(.linear), Exp(.zoom), 15, 0, 15.05, 1))
 
         layer.filter = Exp(.all) {
             extrudeFilter
@@ -174,29 +173,6 @@ final class BuildingExtrusionsExample: UIViewController, ExampleProtocol {
             }
         }
 
-        layer.fillExtrusionHeight = .expression(
-            Exp(.get) {
-                "height"
-            }
-        )
-
-        layer.fillExtrusionBase = .expression(
-            Exp(.get) {
-                "min_height"
-            }
-        )
-
-        layer.fillExtrusionVerticalScale = .expression(
-            Exp(.interpolate) {
-                Exp(.linear)
-                Exp(.zoom)
-                15
-                0
-                15.05
-                1
-            }
-        )
-
         try mapView.mapboxMap.addLayer(layer)
 
         var wallsOnlyExtrusionLayer = layer

CHANGELOG.md

@@ -9,6 +9,8 @@ Mapbox welcomes participation and contributions from everyone.
 * Add support for `zOffset` in FillLayer, PolygonAnnotation[Manager] and PolygonAnnotationGroup.
 * Add a property emphasisCircleGlowRange to LocationIndicatorLayer to control the glow effect of the emphasis circle – from the solid start to the fully transparent end.
 * Fix a crash on calling `LocationIndicatorLayer/location(coordinate:) function` due to missing 0 altitude value.
+* Add a new Expression initializer `init(_ operator: Operator, _ arguments: ExpressionArgumentConvertible...)` to simplify the creation of expressions with multiple arguments.
+That initializer doesn't require to wrap arguments in `Argument` cases. For example, `Exp(.eq, Exp(.get, "extrude"), "true")`.
 
 ## 11.8.0 - 11 November, 2024
 

Sources/MapboxMaps/Style/Types/Expression.swift

@@ -55,6 +55,11 @@ public struct Exp: Codable, CustomStringConvertible, Equatable, Sendable {
         self.init(operator: op, arguments: [])
     }
 
+    /// Initialize an expression with an operator and basic Swift types like Double, String, or even UIColor
+    public init(_ operator: Operator, _ arguments: ExpressionArgumentConvertible...) {
+        self.elements = [.operator(`operator`)] + arguments.flatMap { $0.expressionArguments }.map(Element.argument)
+    }
+
     /// Initialize an expression with an operator and arguments
     public init(operator op: Operator, arguments: [Argument]) {
         self.elements = [.operator(op)] + arguments.map { Element.argument($0) }

Tests/MapboxMapsTests/Style/ExpressionTests/ExpressionTests.swift

@@ -291,4 +291,39 @@ final class ExpressionTests: XCTestCase {
         XCTAssertNoThrow(sumExpression.operator)
         XCTAssertEqual(expectedExpressionOperator, sumExpressionOperator)
     }
+
+    func testExpressionConstructorWithTrivialConvertibleArgument() throws {
+        let shortFormExpression = Exp(.get, "name")
+        let builderBasedExpression = Exp(.get) { "name" }
+
+        XCTAssertEqual(shortFormExpression, builderBasedExpression)
+    }
+
+    func testExpressionConstructorWithComplexConvertibleArgument() throws {
+        let shortFormExpression = Exp(.interpolate, Exp(.linear), Exp(.zoom), 15, 0, 15.05, 1)
+        let longFormExpression = Exp(.interpolate) {
+            Exp(.linear)
+            Exp(.zoom)
+            15
+            0
+            15.05
+            1
+        }
+
+        XCTAssertEqual(shortFormExpression, longFormExpression)
+    }
+
+    func testExpressionConstructorWithComplexNotEqualConvertibleArgument() throws {
+        let shortFormExpression = Exp(.interpolate, Exp(.linear, Exp(.zoom), 15, 0, 15.05, 1))
+        let longFormExpression = Exp(.interpolate) {
+            Exp(.linear)
+            Exp(.zoom)
+            15
+            0
+            15.05
+            1
+        }
+
+        XCTAssertNotEqual(shortFormExpression, longFormExpression)
+    }
 }