messages.ts

// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

export enum WarningTypes {
  WARNING = 'Warning',
  DEPRECATION = 'DeprecationWarning',
}

export function warn(warning: Warning) {
  // Only show a given warning once
  if (warning.warned) {
    return;
  }
  warning.warned = true;
  if (typeof process !== 'undefined' && process.emitWarning) {
    // @types/node doesn't recognize the emitWarning syntax which
    // accepts a config object, so `as any` it is
    // https://nodejs.org/docs/latest-v8.x/api/process.html#process_process_emitwarning_warning_options
    // tslint:disable-next-line no-any
    process.emitWarning(warning.message, warning as any);
  } else {
    console.warn(warning.message);
  }
}

export interface Warning {
  code: string;
  type: WarningTypes;
  message: string;
  warned?: boolean;
}