PHP design pattern series specification specification mode, specification mode

Specification specification mode of PHP design pattern series, specification mode

1. Pattern definition

The specification mode is an extension of the combination mode and is often used in framework development (rarely used in project-level development). Here is a brief introduction.
Specification mode can be considered an extension of the combination mode. Sometimes certain conditions in the project determine the business logic, and these conditions can be extracted and combined in a certain relationship (AND, OR, NOT) to flexibly customize the business logic. In addition, in applications such as query and filtering, the entire implementation logic can be simplified by predefining multiple conditions and then using a combination of these conditions to process the query or filtering instead of using logical judgment statements.

Each condition here is a specification, and multiple specifications/conditions are connected in series to form a combined specification with a certain logical relationship.

2. UML class diagram

3. Sample code

Item.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;
class Item
{
protected $price;

/**
* An item must have a price
*
* @param int $price
*/
public function __construct($price)
{
$this->price = $price;
}
/**
* Get the items price
*
* @return int
*/
public function getPrice()
{
return $this->price;
}
}

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SpecificationInterface.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;
/**
* 规格接口
*/
interface SpecificationInterface
{
/**
* 判断对象是否满足规格
*
* @param Item $item
*
* @return bool
*/
public function isSatisfiedBy(Item $item);

/**
* 创建一个逻辑与规格（AND）
*
* @param SpecificationInterface $spec
*/
public function plus(SpecificationInterface $spec);
/**
* 创建一个逻辑或规格（OR）
*
* @param SpecificationInterface $spec
*/
public function either(SpecificationInterface $spec);

/**
* 创建一个逻辑非规格（NOT）
*/
public function not();
}

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AbstractSpecification.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;

/**
* 规格抽象类
*/
abstract class AbstractSpecification implements SpecificationInterface
{
/**
* 检查给定Item是否满足所有规则
*
* @param Item $item
*
* @return bool
*/
abstract public function isSatisfiedBy(Item $item);
/**
* 创建一个新的逻辑与规格（AND）
*
* @param SpecificationInterface $spec
*
* @return SpecificationInterface
*/
public function plus(SpecificationInterface $spec)
{
return new Plus($this, $spec);
}
/**
* 创建一个新的逻辑或组合规格（OR）
*
* @param SpecificationInterface $spec
*
* @return SpecificationInterface
*/
public function either(SpecificationInterface $spec)
{
return new Either($this, $spec);
}
/**
* 创建一个新的逻辑非规格（NOT）
*
* @return SpecificationInterface
*/
public function not()
{
return new Not($this);
}
}

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Plus.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;
/**
* 逻辑与规格（AND）
*/
class Plus extends AbstractSpecification
{
protected $left;
protected $right;

/**
* 在构造函数中传入两种规格
*
* @param SpecificationInterface $left
* @param SpecificationInterface $right
*/
public function __construct(SpecificationInterface $left, SpecificationInterface $right)
{
$this->left = $left;
$this->right = $right;
}
/**
* 返回两种规格的逻辑与评估
*
* @param Item $item
*
* @return bool
*/
public function isSatisfiedBy(Item $item)
{
return $this->left->isSatisfiedBy($item) && $this->right->isSatisfiedBy($item);
}
}

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Either.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;

/**
* 逻辑或规格
*/
class Either extends AbstractSpecification
{

protected $left;
protected $right;
/**
* 两种规格的组合
*
* @param SpecificationInterface $left
* @param SpecificationInterface $right
*/
public function __construct(SpecificationInterface $left, SpecificationInterface $right)
{
$this->left = $left;
$this->right = $right;
}
/**
* 返回两种规格的逻辑或评估
*
* @param Item $item
*
* @return bool
*/
public function isSatisfiedBy(Item $item)
{
return $this->left->isSatisfiedBy($item) || $this->right->isSatisfiedBy($item);
}
}

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Not.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;

/**
* 逻辑非规格
*/
class Not extends AbstractSpecification
{
protected $spec;
/**
* 在构造函数中传入指定规格
*
* @param SpecificationInterface $spec
*/
public function __construct(SpecificationInterface $spec)
{
$this->spec = $spec;
}
/**
* 返回规格的相反结果
*
* @param Item $item
*
* @return bool
*/
public function isSatisfiedBy(Item $item)
{
return !$this->spec->isSatisfiedBy($item);
}
}

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PriceSpecification.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification;

/**
* 判断给定Item的价格是否介于最小值和最大值之间的规格
*/
class PriceSpecification extends AbstractSpecification
{
protected $maxPrice;
protected $minPrice;
/**
* 设置最大值
*
* @param int $maxPrice
*/
public function setMaxPrice($maxPrice)
{
$this->maxPrice = $maxPrice;
}
/**
* 设置最小值
*
* @param int $minPrice
*/
public function setMinPrice($minPrice)
{
$this->minPrice = $minPrice;
}
/**
* 判断给定Item的定价是否在最小值和最大值之间
*
* @param Item $item
*
* @return bool
*/
public function isSatisfiedBy(Item $item)
{
if (!empty($this->maxPrice) && $item->getPrice() > $this->maxPrice) {
return false;
}
if (!empty($this->minPrice) && $item->getPrice() < $this->minPrice) {
return false;
}
return true;
}
}

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4. Test code

Tests/SpecificationTest.php

<&#63;php
namespace DesignPatterns\Behavioral\Specification\Tests;
use DesignPatterns\Behavioral\Specification\PriceSpecification;
use DesignPatterns\Behavioral\Specification\Item;
/**
* SpecificationTest 用于测试规格模式
*/
class SpecificationTest extends \PHPUnit_Framework_TestCase
{
public function testSimpleSpecification()
{
$item = new Item(100);
$spec = new PriceSpecification();
$this->assertTrue($spec->isSatisfiedBy($item));
$spec->setMaxPrice(50);
$this->assertFalse($spec->isSatisfiedBy($item));
$spec->setMaxPrice(150);
$this->assertTrue($spec->isSatisfiedBy($item));
$spec->setMinPrice(101);
$this->assertFalse($spec->isSatisfiedBy($item));
$spec->setMinPrice(100);
$this->assertTrue($spec->isSatisfiedBy($item));
}
public function testNotSpecification()
{
$item = new Item(100);
$spec = new PriceSpecification();
$not = $spec->not();
$this->assertFalse($not->isSatisfiedBy($item));
$spec->setMaxPrice(50);
$this->assertTrue($not->isSatisfiedBy($item));
$spec->setMaxPrice(150);
$this->assertFalse($not->isSatisfiedBy($item));
$spec->setMinPrice(101);
$this->assertTrue($not->isSatisfiedBy($item));
$spec->setMinPrice(100);
$this->assertFalse($not->isSatisfiedBy($item));
}
public function testPlusSpecification()
{
$spec1 = new PriceSpecification();
$spec2 = new PriceSpecification();
$plus = $spec1->plus($spec2);
$item = new Item(100);
$this->assertTrue($plus->isSatisfiedBy($item));
$spec1->setMaxPrice(150);
$spec2->setMinPrice(50);
$this->assertTrue($plus->isSatisfiedBy($item));
$spec1->setMaxPrice(150);
$spec2->setMinPrice(101);
$this->assertFalse($plus->isSatisfiedBy($item));
$spec1->setMaxPrice(99);
$spec2->setMinPrice(50);
$this->assertFalse($plus->isSatisfiedBy($item));
}
public function testEitherSpecification()
{
$spec1 = new PriceSpecification();
$spec2 = new PriceSpecification();
$either = $spec1->either($spec2);
$item = new Item(100);
$this->assertTrue($either->isSatisfiedBy($item));
$spec1->setMaxPrice(150);
$spec2->setMaxPrice(150);
$this->assertTrue($either->isSatisfiedBy($item));
$spec1->setMaxPrice(150);
$spec2->setMaxPrice(0);
$this->assertTrue($either->isSatisfiedBy($item));
$spec1->setMaxPrice(0);
$spec2->setMaxPrice(150);
$this->assertTrue($either->isSatisfiedBy($item));
$spec1->setMaxPrice(99);
$spec2->setMaxPrice(99);
$this->assertFalse($either->isSatisfiedBy($item));
}
}

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The above content is the specification pattern of the PHP design pattern series shared by the editor of Bangkejia. I hope this article can help everyone.