/* -----------------------------------------------------------------------------
Copyright 2019-2021 Kevin P. Barry

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.
----------------------------------------------------------------------------- */

// Author: Kevin P. Barry [ta0kira@gmail.com]

// A map that stores values of arbitrary types.
concrete TypeMap {
  // Create a new map.
  @type new () -> (TypeMap)

  // Set or replace the value associated with the key.
  //
  // Params:
  // - #x: The value type being stored.
  @value set<#x> (TypeKey<#x>,#x) -> (TypeMap)

  // Remove the value associated with the key if present and return self.
  @value remove (TypeKey<any>) -> (TypeMap)

  // Return the value associated with the key if present.
  //
  // Params:
  // - #x: The value type being returned.
  //
  // Notes:
  // - #x does not need to be the same type as the original value, since TypeKey
  //   has a covariant parameter.
  // - The value will only be returned if it can be converted to #x. For
  //   example, if the value is actually a String but it was added as Formatted
  //   (a parent of String), then the value cannot be retrieved as a String.
  @value get<#x> (TypeKey<#x>) -> (optional #x)
}

// A typed key for use with TypeMap.
concrete TypeKey<|#x> {
  refines Formatted
  defines LessThan<TypeKey<any>>
  defines Equals<TypeKey<any>>

  // Create a new key.
  @type new () -> (TypeKey<#x>)
}