// Sources/SwiftProtobuf/ExtensibleMessage.swift - Extension support
//
// Copyright (c) 2014 - 2016 Apple Inc. and the project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See LICENSE.txt for license information:
// https://github.com/apple/swift-protobuf/blob/master/LICENSE.txt
//
// -----------------------------------------------------------------------------
///
/// Additional capabilities needed by messages that allow extensions.
///
// -----------------------------------------------------------------------------

// Messages that support extensions implement this protocol
public protocol ExtensibleMessage: Message {
    var _protobuf_extensionFieldValues: ExtensionFieldValueSet { get set }
}

extension ExtensibleMessage {
    public mutating func setExtensionValue<F>(ext: MessageExtension<F, Self>, value: F.ValueType) {
        _protobuf_extensionFieldValues[ext.fieldNumber] = F(protobufExtension: ext, value: value)
    }

    public func getExtensionValue<F>(ext: MessageExtension<F, Self>) -> F.ValueType? {
        if let fieldValue = _protobuf_extensionFieldValues[ext.fieldNumber] as? F {
          return fieldValue.value
        }
        return nil
    }

    public func hasExtensionValue<F>(ext: MessageExtension<F, Self>) -> Bool {
        return _protobuf_extensionFieldValues[ext.fieldNumber] is F
    }

    public mutating func clearExtensionValue<F>(ext: MessageExtension<F, Self>) {
        _protobuf_extensionFieldValues[ext.fieldNumber] = nil
    }
}