library-ts/browser/expressions/AsyncBooleanExpression.ts

export abstract class AsyncBooleanExpression<T>
{
  abstract evaluate( t:T ):Promise<boolean>;
  
  NOT():AsyncBooleanExpression<T>
  {
    return new NotAsyncExpression<T>( this );
  }

  AND( matcher:AsyncBooleanExpression<T>):AsyncBooleanExpression<T>
  {
    return new AndAsyncExpression<T>( [ this, matcher ] );
  }

  OR( matcher:AsyncBooleanExpression<T>):AsyncBooleanExpression<T>
  {
    return new OrAsyncExpression<T>( [ this, matcher ] );
  }
}

export class NotAsyncExpression<T> extends AsyncBooleanExpression<T>
{
  private _matcher:AsyncBooleanExpression<T>;

  constructor( matcher:AsyncBooleanExpression<T> )
  {
    super();
    this._matcher = matcher;
  }

  async evaluate( t:T ):Promise<boolean>
  {
    let result = await this._matcher.evaluate( t );
    return Promise.resolve( ! result );
  } 

  NOT()
  {
    return this._matcher;
  }
}

export abstract class ListInputAsyncExpression<T> extends AsyncBooleanExpression<T>
{
  protected _matchers:AsyncBooleanExpression<T>[];
  
  constructor( matchers:AsyncBooleanExpression<T>[] )
  {
    super();
    this._matchers = matchers;
  }
}

export class AndAsyncExpression<T> extends ListInputAsyncExpression<T>
{
  async evaluate( t:T ):Promise<boolean>
  {
    for ( let matcher of this._matchers )
    {
      let result = await matcher.evaluate( t );
      
      if ( ! result )
      {
        return Promise.resolve( false );
      }
    }

    return Promise.resolve( true );
  }

  AND( matcher:AsyncBooleanExpression<T> )
  {
    this._matchers.push( matcher );
    return this;
  }
}

export class OrAsyncExpression<T> extends ListInputAsyncExpression<T>
{
  async evaluate( t:T ):Promise<boolean>
  {
    for ( let matcher of this._matchers )
    {
      let result = await matcher.evaluate( t );
      
      if ( result )
      {
        return Promise.resolve( true );
      }
    }

    return Promise.resolve( false );
  }

  OR( matcher:AsyncBooleanExpression<T> )
  {
    this._matchers.push( matcher );
    return this;
  }
}