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Add some helper methods for implementing JSONCodable
Will use these in an upcoming commit.
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-2
lines changed

2 files changed

+191
-2
lines changed

‎Sources/AblyChat/DefaultMessages.swift

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -77,12 +77,12 @@ internal final class DefaultMessages: Messages, EmitsDiscontinuities {
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throw ARTErrorInfo.create(withCode: 50000, status: 500, message: "Received incoming message without clientId")
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}
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let metadata: Metadata? = if let metadataJSONObject = data["metadata"]?.objectValue {
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let metadata: Metadata? = if let metadataJSONObject = try data.optionalObjectValueForKey("metadata") {
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try metadataJSONObject.mapValues { try MetadataValue(jsonValue: $0) }
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} else {
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nil
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}
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let headers: Headers? = if let headersJSONObject = extras["headers"]?.objectValue {
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let headers: Headers? = if let headersJSONObject = try extras.optionalObjectValueForKey("headers") {
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try headersJSONObject.mapValues { try HeadersValue(jsonValue: $0) }
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} else {
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nil

‎Sources/AblyChat/JSONCodable.swift

Lines changed: 189 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -25,6 +25,8 @@ internal protocol JSONObjectDecodable: JSONDecodable {
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internal enum JSONValueDecodingError: Error {
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case valueIsNotObject
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case noValueForKey(String)
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case wrongTypeForKey(String, actualValue: JSONValue)
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}
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// Default implementation of `JSONDecodable` conformance for `JSONObjectDecodable`
@@ -39,3 +41,190 @@ internal extension JSONObjectDecodable {
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}
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internal typealias JSONObjectCodable = JSONObjectDecodable & JSONObjectEncodable
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// MARK: - Extracting values from a dictionary
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/// This extension adds some helper methods for extracting values from a dictionary of `JSONValue` values; you may find them helpful when implementing `JSONCodable`.
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internal extension [String: JSONValue] {
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/// If this dictionary contains a value for `key`, and this value has case `object`, this returns the associated value.
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///
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/// - Throws:
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/// - `JSONValueDecodingError.noValueForKey` if the key is absent
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/// - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `object`
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func objectValueForKey(_ key: String) throws -> [String: JSONValue] {
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guard let value = self[key] else {
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throw JSONValueDecodingError.noValueForKey(key)
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}
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guard case let .object(objectValue) = value else {
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throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return objectValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `object`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
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///
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/// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `object` or `null`
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func optionalObjectValueForKey(_ key: String) throws -> [String: JSONValue]? {
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guard let value = self[key] else {
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return nil
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}
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if case .null = value {
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return nil
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}
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guard case let .object(objectValue) = value else {
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throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return objectValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `array`, this returns the associated value.
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///
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/// - Throws:
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/// - `JSONValueDecodingError.noValueForKey` if the key is absent
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/// - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `array`
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func arrayValueForKey(_ key: String) throws -> [JSONValue] {
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guard let value = self[key] else {
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throw JSONValueDecodingError.noValueForKey(key)
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}
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guard case let .array(arrayValue) = value else {
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throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return arrayValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `array`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
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///
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/// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `array` or `null`
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func optionalArrayValueForKey(_ key: String) throws -> [JSONValue]? {
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guard let value = self[key] else {
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return nil
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}
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if case .null = value {
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return nil
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}
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guard case let .array(arrayValue) = value else {
115+
throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return arrayValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `string`, this returns the associated value.
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///
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/// - Throws:
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/// - `JSONValueDecodingError.noValueForKey` if the key is absent
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/// - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `string`
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func stringValueForKey(_ key: String) throws -> String {
127+
guard let value = self[key] else {
128+
throw JSONValueDecodingError.noValueForKey(key)
129+
}
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131+
guard case let .string(stringValue) = value else {
132+
throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return stringValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `string`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
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///
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/// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `string` or `null`
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func optionalStringValueForKey(_ key: String) throws -> String? {
142+
guard let value = self[key] else {
143+
return nil
144+
}
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if case .null = value {
147+
return nil
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}
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guard case let .string(stringValue) = value else {
151+
throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return stringValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `number`, this returns the associated value.
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///
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/// - Throws:
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/// - `JSONValueDecodingError.noValueForKey` if the key is absent
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/// - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `number`
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func numberValueForKey(_ key: String) throws -> Double {
163+
guard let value = self[key] else {
164+
throw JSONValueDecodingError.noValueForKey(key)
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}
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guard case let .number(numberValue) = value else {
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throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return numberValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `number`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
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///
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/// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `number` or `null`
177+
func optionalNumberValueForKey(_ key: String) throws -> Double? {
178+
guard let value = self[key] else {
179+
return nil
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}
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if case .null = value {
183+
return nil
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}
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guard case let .number(numberValue) = value else {
187+
throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return numberValue
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}
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/// If this dictionary contains a value for `key`, and this value has case `bool`, this returns the associated value.
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///
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/// - Throws:
196+
/// - `JSONValueDecodingError.noValueForKey` if the key is absent
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/// - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `bool`
198+
func boolValueForKey(_ key: String) throws -> Bool {
199+
guard let value = self[key] else {
200+
throw JSONValueDecodingError.noValueForKey(key)
201+
}
202+
203+
guard case let .bool(boolValue) = value else {
204+
throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
205+
}
206+
207+
return boolValue
208+
}
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/// If this dictionary contains a value for `key`, and this value has case `bool`, this returns the associated value.
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///
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/// - Throws:
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/// - `JSONValueDecodingError.noValueForKey` if the key is absent
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/// - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `bool`
215+
func optionalBoolValueForKey(_ key: String) throws -> Bool? {
216+
guard let value = self[key] else {
217+
return nil
218+
}
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220+
if case .null = value {
221+
return nil
222+
}
223+
224+
guard case let .bool(boolValue) = value else {
225+
throw JSONValueDecodingError.wrongTypeForKey(key, actualValue: value)
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}
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return boolValue
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}
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}

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