✨ Codable GeoJSON

Package.swift

@@ -137,5 +137,19 @@ let package = Package(
 			"GeodeticConversions",
 			"WGS84Conversions",
 		]),
+
+		// 📄 GeoJSON representation
+		.target(
+			name: "GeoJSON",
+			dependencies: [
+				.target(name: "GeoModels"),
+				.target(name: "Turf"),
+				.product(name: "NonEmpty", package: "swift-nonempty"),
+			]
+		),
+		.testTarget(
+			name: "GeoJSONTests",
+			dependencies: ["GeoJSON"]
+		),
 	]
 )

Sources/GeoJSON/BoundingBox.swift

@@ -0,0 +1,31 @@
+//
+//  BoundingBox.swift
+//  GeoSwift
+//
+//  Created by Rémi Bardon on 04/02/2022.
+//  Copyright © 2022 Rémi Bardon. All rights reserved.
+//
+
+import GeoModels
+
+public protocol BoundingBox: Hashable, Codable {
+
+	var asAny: AnyBoundingBox { get }
+
+}
+
+public typealias BoundingBox2D = GeoModels.BoundingBox2D
+
+extension BoundingBox2D: BoundingBox {
+
+	public var asAny: AnyBoundingBox { .twoDimensions(self) }
+
+}
+
+public enum AnyBoundingBox: BoundingBox, Hashable, Codable {
+
+	case twoDimensions(BoundingBox2D)
+
+	public var asAny: AnyBoundingBox { self }
+
+}

Sources/GeoJSON/Errors.swift

@@ -0,0 +1,15 @@
+//
+//  Errors.swift
+//  SwiftGeo
+//
+//  Created by Rémi Bardon on 07/02/2022.
+//  Copyright © 2022 Rémi Bardon. All rights reserved.
+//
+
+import Foundation
+
+/// See [RFC 7946, section 3.1.6](https://datatracker.ietf.org/doc/html/rfc7946#section-3.1.6).
+public enum LinearRingError: Error {
+	case firstAndLastPositionsShouldBeEquivalent
+	case notEnoughPoints
+}

Sources/GeoJSON/GeoJSON+Codable.swift

@@ -0,0 +1,286 @@
+//
+//  GeoJSON+Codable.swift
+//  SwiftGeo
+//
+//  Created by Rémi Bardon on 07/02/2022.
+//  Copyright © 2022 Rémi Bardon. All rights reserved.
+//
+
+import Foundation
+import GeoModels
+
+//extension BinaryFloatingPoint {
+//
+//	/// Rounds the double to decimal places value
+//	fileprivate func roundedToPlaces(_ places: Int) -> Self {
+//		let divisor = pow(10.0, Double(places))
+//		return Self((Double(self) * divisor).rounded() / divisor)
+//	}
+//
+//}
+
+extension Double {
+
+	/// Rounds the double to decimal places value
+	func roundedToPlaces(_ places: Int) -> Decimal {
+		let divisor = pow(10.0, Double(places))
+		return Decimal((self * divisor).rounded()) / Decimal(divisor)
+	}
+
+}
+
+extension Latitude: Codable {
+
+	public init(from decoder: Decoder) throws {
+		let container = try decoder.singleValueContainer()
+
+		let decimalDegrees = try container.decode(Double.self)
+
+		self.init(decimalDegrees: decimalDegrees)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		try container.encode(self.decimalDegrees.roundedToPlaces(6))
+	}
+
+}
+
+extension Longitude: Codable {
+
+	public init(from decoder: Decoder) throws {
+		let container = try decoder.singleValueContainer()
+
+		let decimalDegrees = try container.decode(Double.self)
+
+		self.init(decimalDegrees: decimalDegrees)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		try container.encode(self.decimalDegrees.roundedToPlaces(6))
+	}
+
+}
+
+extension Position2D: Codable {
+
+	public init(from decoder: Decoder) throws {
+		var container = try decoder.unkeyedContainer()
+
+		let longitude = try container.decode(Longitude.self)
+		let latitude = try container.decode(Latitude.self)
+
+		self.init(latitude: latitude, longitude: longitude)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.unkeyedContainer()
+
+		try container.encode(self.longitude)
+		try container.encode(self.latitude)
+	}
+
+}
+
+extension LinearRingCoordinates {
+
+	public init(from decoder: Decoder) throws {
+		let container = try decoder.singleValueContainer()
+
+		let coordinates = try container.decode(Self.RawValue.self)
+
+		try self.init(rawValue: coordinates)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		try container.encode(self.rawValue)
+	}
+
+}
+
+fileprivate enum SingleGeometryCodingKeys: String, CodingKey {
+	case geoJSONType = "type"
+	case coordinates
+}
+
+extension SingleGeometry {
+
+	public init(from decoder: Decoder) throws {
+		let container = try decoder.container(keyedBy: SingleGeometryCodingKeys.self)
+
+		let type = try container.decode(GeoJSON.`Type`.self, forKey: .geoJSONType)
+		guard type == Self.geoJSONType else {
+			throw DecodingError.typeMismatch(Self.self, DecodingError.Context(
+				codingPath: container.codingPath,
+				debugDescription: "Found GeoJSON type '\(type.rawValue)'"
+			))
+		}
+
+		let coordinates = try container.decode(Self.Coordinates.self, forKey: .coordinates)
+
+		self.init(coordinates: coordinates)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: SingleGeometryCodingKeys.self)
+
+		try container.encode(Self.geoJSONType, forKey: .geoJSONType)
+		try container.encode(self.coordinates, forKey: .coordinates)
+	}
+
+}
+
+fileprivate enum AnyGeometryCodingKeys: String, CodingKey {
+	case geoJSONType = "type"
+}
+
+extension AnyGeometry {
+
+	public init(from decoder: Decoder) throws {
+		let typeContainer = try decoder.container(keyedBy: SingleGeometryCodingKeys.self)
+		let type = try typeContainer.decode(GeoJSON.`Type`.Geometry.self, forKey: .geoJSONType)
+
+		let container = try decoder.singleValueContainer()
+
+		// FIXME: Fix 2D/3D performance by checking the number of values in `bbox`
+		switch type {
+		case .geometryCollection:
+			let geometryCollection = try container.decode(GeometryCollection.self)
+			self = .geometryCollection(geometryCollection)
+		case .point:
+//			do {
+//				let point3D = try container.decode(Point3D.self)
+//				self = .point3D(point3D)
+//			} catch {
+				let point2D = try container.decode(Point2D.self)
+				self = .point2D(point2D)
+//			}
+		case .multiPoint:
+			let multiPoint2D = try container.decode(MultiPoint2D.self)
+			self = .multiPoint2D(multiPoint2D)
+		case .lineString:
+			let lineString2D = try container.decode(LineString2D.self)
+			self = .lineString2D(lineString2D)
+		case .multiLineString:
+			let multiLineString2D = try container.decode(MultiLineString2D.self)
+			self = .multiLineString2D(multiLineString2D)
+		case .polygon:
+			let polygon2D = try container.decode(Polygon2D.self)
+			self = .polygon2D(polygon2D)
+		case .multiPolygon:
+			let multiPolygon2D = try container.decode(MultiPolygon2D.self)
+			self = .multiPolygon2D(multiPolygon2D)
+		}
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		switch self {
+		case .geometryCollection(let geometryCollection):
+			try container.encode(geometryCollection)
+		case .point2D(let point2D):
+			try container.encode(point2D)
+		case .multiPoint2D(let multiPoint2D):
+			try container.encode(multiPoint2D)
+		case .lineString2D(let lineString2D):
+			try container.encode(lineString2D)
+		case .multiLineString2D(let multiLineString2D):
+			try container.encode(multiLineString2D)
+		case .polygon2D(let polygon2D):
+			try container.encode(polygon2D)
+		case .multiPolygon2D(let multiPolygon2D):
+			try container.encode(multiPolygon2D)
+		}
+	}
+
+}
+
+extension BoundingBox2D {
+
+	public init(from decoder: Decoder) throws {
+		var container = try decoder.unkeyedContainer()
+
+		let westLongitude = try container.decode(Longitude.self)
+		let southLatitude = try container.decode(Latitude.self)
+		let eastLongitude = try container.decode(Longitude.self)
+		let northLatitude = try container.decode(Latitude.self)
+
+		self.init(
+			southWest: Coordinate2D(latitude: southLatitude, longitude: westLongitude),
+			northEast: Coordinate2D(latitude: northLatitude, longitude: eastLongitude)
+		)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.unkeyedContainer()
+
+		try container.encode(self.westLongitude)
+		try container.encode(self.southLatitude)
+		try container.encode(self.eastLongitude)
+		try container.encode(self.northLatitude)
+	}
+
+}
+
+extension AnyBoundingBox {
+
+	public init(from decoder: Decoder) throws {
+		let container = try decoder.singleValueContainer()
+
+		let boundingBox2D = try container.decode(BoundingBox2D.self)
+		self = .twoDimensions(boundingBox2D)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		switch self {
+		case .twoDimensions(let boundingBox2D):
+			try container.encode(boundingBox2D)
+		}
+	}
+
+}
+
+fileprivate enum FeatureCodingKeys: String, CodingKey {
+	case geoJSONType = "type"
+	case geometry, properties, bbox
+}
+
+extension Feature {
+
+	public init(from decoder: Decoder) throws {
+		let container = try decoder.container(keyedBy: FeatureCodingKeys.self)
+
+		let type = try container.decode(GeoJSON.`Type`.self, forKey: .geoJSONType)
+		guard type == Self.geoJSONType else {
+			throw DecodingError.typeMismatch(Self.self, DecodingError.Context(
+				codingPath: container.codingPath,
+				debugDescription: "Found GeoJSON type '\(type.rawValue)'"
+			))
+		}
+
+		let geometry = try container.decodeIfPresent(AnyGeometry.self, forKey: .geometry)
+		let properties = try container.decode(Properties.self, forKey: .properties)
+
+		self.init(geometry: geometry, properties: properties)
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: FeatureCodingKeys.self)
+
+		try container.encode(Self.geoJSONType, forKey: .geoJSONType)
+		try container.encodeIfPresent(self.geometry, forKey: .geometry)
+		try container.encode(self.properties, forKey: .properties)
+		// TODO: Create GeoJSONEncoder that allows setting "export bboxes" to a boolean value
+		// TODO: Memoize bboxes not to recompute them all the time (bboxes tree)
+		try container.encodeIfPresent(self.bbox, forKey: .bbox)
+	}
+
+}

Sources/GeoJSON/Geometries/GeometryCollection.swift

@@ -0,0 +1,19 @@
+//
+//  GeometryCollection.swift
+//  GeoSwift
+//
+//  Created by Rémi Bardon on 04/02/2022.
+//  Copyright © 2022 Rémi Bardon. All rights reserved.
+//
+
+public struct GeometryCollection: Geometry {
+
+	public static var geometryType: GeoJSON.`Type`.Geometry { .geometryCollection}
+
+	public var bbox: AnyBoundingBox?
+
+	public var asAnyGeometry: AnyGeometry { .geometryCollection(self) }
+
+	public var geometries: [AnyGeometry]
+
+}