Creational --- Abstract Factory

佚名 6年前 (2019-05-07) 随笔 653人围观抢沙发百度已收录

Creational

Creational Design Patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation.

Abstract Factory

1. Purpose:

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To create series of related or dependent objects without specifying their concrete classess. Usually the created classes all implement the same interface. The client of the abstract factory doesn't care about how these objects are created, he just knows how they go together.

Parser.php

<?php

namespace DesignPatterns\Creational\AbstractFactory;

interface Parser
{
    public function parse(string $input): array;
}

CsvPaser.php

<?php

namespace DesignPatterns\Creational\AbstractFactory;

class CsvParser implements Parser
{
    const OPTION_CONTAINS_HEADER = true;
    const OPTION_CONTAINS_NO_HEADER = false;

    /**
     * @var bool
     */
    private $skipHeaderLine;

    public function __construct(bool $skipHeaderLine)
    {
        $this->skipHeaderLine = $skipHeaderLine;
    }

    public function parse(string $input): array
    {
        $headerWasParsed = false;
        $parsedLines = [];

        foreach (explode(PHP_EOL, $input) as $line) {
            if (!$headerWasParsed && $this->skipHeaderLine === self::OPTION_CONTAINS_HEADER) {
                continue;
            }

            $parsedLines[] = str_getcsv($line);
        }

        return $parsedLines;
    }
}

JsonParser.php

<?php

namespace DesignPatterns\Creational\AbstractFactory;

class JsonParser implements Parser
{
    public function parse(string $input): array
    {
        return json_decode($input, true);
    }
}

ParserFactory.php

<?php

namespace DesignPatterns\Creational\AbstractFactory;

class ParserFactory
{
    public function createCsvParser(bool $skipHeaderLine): CsvParser
    {
        return new CsvParser($skipHeaderLine);
    }

    public function createJsonParser(): JsonParser
    {
        return new JsonParser();
    }
}

Tests/AbstractFactoryTest.php

<?php

namespace DesignPatterns\Creational\AbstractFactory\Tests;

use DesignPatterns\Creational\AbstractFactory\CsvParser;
use DesignPatterns\Creational\AbstractFactory\JsonParser;
use DesignPatterns\Creational\AbstractFactory\ParserFactory;
use PHPUnit\Framework\TestCase;

class AbstractFactoryTest extends TestCase
{
    public function testCanCreateCsvParser()
    {
        $factory = new ParserFactory();
        $parser = $factory->createCsvParser(CsvParser::OPTION_CONTAINS_HEADER);

        $this->assertInstanceOf(CsvParser::class, $parser);
    }

    public function testCanCreateJsonParser()
    {
        $factory = new ParserFactory();
        $parser = $factory->createJsonParser();

        $this->assertInstanceOf(JsonParser::class, $parser);
    }
}