<?php

declare(strict_types=1);

/**
 * Hoa
 *
 *
 * @license
 *
 * New BSD License
 *
 * Copyright © 2007-2017, Hoa community. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Hoa nor the names of its contributors may be
 *       used to endorse or promote products derived from this software without
 *       specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS AND CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

namespace Kitab\Compiler\IntermediateRepresentation;

/**
 * A type intermediate representation.
 *
 * A type has a name. It can represent a value passed by copy or by
 * reference. It can be nullable, i.e. null value can be considered as valid.
 *
 * Because values in PHP are represented by union types (many types), the type
 * of a value can be undeclared (and decided at runtime). Thus, a type can
 * have no name in this intermediate representation.
 *
 * # Examples
 *
 * The following example builds a nullable reference type `T`.
 *
 * ```php
 * $type = new Kitab\Compiler\IntermediateRepresentation\Type();
 * $type->name      = 'T';
 * $type->reference = true;
 * $type->nullable  = true;
 *
 * assert('?T &' === (string) $type);
 * ```
 */
class Type
{
    /**
     * If `true`, the type will represent a value passed by reference, else
     * —`false`—, a value passed by copy.
     */
    public $reference = false;

    /**
     * A nullable type accepts the `null` value as valid. For instance the
     * type `string` does not accept the `null` value, but `?string` will
     * accept both strings and the `null` value.
     */
    public $nullable  = false;

    /**
     * Name of the type.
     */
    public $name      = null;

    /**
     * Transform this intermediate representation into its PHP representation.
     *
     * The original formatting is not kept. The applied formatting is designed for Kitab.
     *
     * # Examples
     *
     * ```php
     * $type = new Kitab\Compiler\IntermediateRepresentation\Type();
     * $type->name = 'T';
     *
     * assert('T ' === (string) $type);
     * ```
     */
    public function __toString(): string
    {
        return sprintf(
            '%s%s%s',
            $this->nullable ? '?' : '',
            $this->name,
            $this->reference ? ' &' : ($this->name ? ' ' : '')
        );
    }
}