tools/SwiftSyntax/DiagnosticEngine.swift

//===------------ DiagnosticEngine.swift - Diagnostic Engine --------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// This file provides the DiagnosticEngine, the class used to register
// and output diagnostics.
//===----------------------------------------------------------------------===//

import Foundation

/// The DiagnosticEngine allows Swift tools to emit diagnostics.
public class DiagnosticEngine {
  /// Creates a new DiagnosticEngine with no diagnostics.
  public init() {
  }

  /// The list of consumers of the diagnostic passing through this engine.
  internal var consumers = [DiagnosticConsumer]()

  public private(set) var diagnostics = [Diagnostic]()

  /// Adds the provided consumer to the consumers list.
  func addConsumer(_ consumer: DiagnosticConsumer) {
    consumers.append(consumer)

    // Start the consumer with all previous diagnostics.
    for diagnostic in diagnostics {
      consumer.handle(diagnostic)
    }
  }

  /// Registers a diagnostic with the diagnostic engine.
  /// - parameters:
  ///   - message: The message for the diagnostic. This message includes
  ///              a severity and text that will be conveyed when the diagnostic
  ///              is serialized.
  public func diagnose(_ message: Diagnostic.Message,
                       location: SourceLocation? = nil,
                       actions: ((inout Diagnostic.Builder) -> Void)? = nil) {
    let diagnostic = Diagnostic(message: message, location: location, 
                                actions: actions)
    diagnostics.append(diagnostic)
    for consumer in consumers {
      consumer.handle(diagnostic)
    }
  }

  /// Tells each consumer to finalize their diagnostic output.
  deinit {
    for consumer in consumers {
      consumer.finalize()
    }
  }
}