Add examples folder and php implementation with unit tests

.gitignore

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+.idea/
+vendor
+composer.lock
+.phpunit.result.cache

examples/php/behavioral/chain_of_responsibility/Account.php

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+<?php
+
+namespace design_patterns\behavioral\chain_of_responsibility;
+
+abstract class Account
+{
+    protected ?Account $next = null;
+    protected float $balance;
+
+    public function setNext(Account $account): void
+    {
+        $this->next = $account;
+    }
+
+    public function pay(float $amountToPay): string
+    {
+        if ($this->canPay($amountToPay)) {
+            return $this->payUsing($amountToPay);
+        }
+
+        if ($this->next) {
+            return $this->cantPayUsing() . $this->next->pay($amountToPay);
+        }
+
+        return 'Cannot pay, no more accounts in the chain';
+    }
+
+    private function canPay(float $amount): bool
+    {
+        return $this->balance >= $amount;
+    }
+
+    private function payUsing(float $amountToPay): string
+    {
+        $this->balance -= $amountToPay;
+
+        return sprintf('Paid %s using %s', $amountToPay, $this->getClassName());
+    }
+
+    private function cantPayUsing(): string
+    {
+        return sprintf('Cannot pay using %s. Proceeding ..' . PHP_EOL, $this->getClassName());
+    }
+
+    private function getClassName(): string
+    {
+        $className = explode('\\', static::class);
+        return array_pop($className);
+    }
+}

examples/php/behavioral/chain_of_responsibility/Bank.php

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+<?php
+
+namespace design_patterns\behavioral\chain_of_responsibility;
+
+class Bank extends Account
+{
+    protected float $balance;
+
+    public function __construct(float $balance)
+    {
+        $this->balance = $balance;
+    }
+}

examples/php/behavioral/chain_of_responsibility/Bitcoin.php

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+<?php
+
+namespace design_patterns\behavioral\chain_of_responsibility;
+
+class Bitcoin extends Account
+{
+    protected float $balance;
+
+    public function __construct(float $balance)
+    {
+        $this->balance = $balance;
+    }
+}

examples/php/behavioral/chain_of_responsibility/ChainOfResponsibilityTest.php

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+<?php
+
+namespace design_patterns\behavioral\chain_of_responsibility;
+
+use PHPUnit\Framework\TestCase;
+
+
+/*
+// Let's prepare a chain like below
+//      $bank->$paypal->$bitcoin
+//
+// First priority bank
+//      If bank can't pay then paypal
+//      If paypal can't pay then bit coin
+
+$bank = new Bank(100);          // Bank with balance 100
+$paypal = new Paypal(200);      // Paypal with balance 200
+$bitcoin = new Bitcoin(300);    // Bitcoin with balance 300
+
+$bank->setNext($paypal);
+$paypal->setNext($bitcoin);
+
+// Let's try to pay using the first priority i.e. bank
+$bank->pay(259);
+
+// Output will be
+// ==============
+// Cannot pay using bank. Proceeding ..
+// Cannot pay using paypal. Proceeding ..:
+// Paid 259 using Bitcoin!
+*/
+
+class ChainOfResponsibilityTest extends TestCase
+{
+    public function test01(): void
+    {
+        $bank = new Bank(100);
+        $paypal = new Paypal(200);
+        $bitcoin = new Bitcoin(300);
+
+        $bank->setNext($paypal);
+        $paypal->setNext($bitcoin);
+
+        self::assertEquals("Cannot pay using Bank. Proceeding ..\nCannot pay using Paypal. Proceeding ..\nPaid 259 using Bitcoin", $bank->pay(259));
+    }
+
+    public function test02(): void
+    {
+        $bank = new Bank(100);
+        $paypal = new Paypal(200);
+        $bitcoin = new Bitcoin(100);
+
+        $bank->setNext($paypal);
+        $paypal->setNext($bitcoin);
+
+        self::assertEquals("Cannot pay using Bank. Proceeding ..\nCannot pay using Paypal. Proceeding ..\nCannot pay, no more accounts in the chain", $bank->pay(259));
+    }
+}

examples/php/behavioral/chain_of_responsibility/Paypal.php

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+<?php
+
+namespace design_patterns\behavioral\chain_of_responsibility;
+
+class Paypal extends Account
+{
+    protected float $balance;
+
+    public function __construct(float $balance)
+    {
+        $this->balance = $balance;
+    }
+}

examples/php/behavioral/command/Bulb.php

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+<?php
+
+namespace design_patterns\behavioral\command;
+
+class Bulb
+{
+    public function turnOn(): string
+    {
+        return "Bulb has been lit!";
+    }
+
+    public function turnOff(): string
+    {
+        return "Darkness!";
+    }
+}

examples/php/behavioral/command/Command.php

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+<?php
+
+namespace design_patterns\behavioral\command;
+
+interface Command
+{
+    public function execute(): string;
+    public function undo(): string;
+    public function redo(): string;
+}

examples/php/behavioral/command/CommandTest.php

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+<?php
+
+namespace design_patterns\behavioral\command;
+
+use PHPUnit\Framework\TestCase;
+
+/*
+$bulb = new Bulb();
+
+$turnOn = new TurnOn($bulb);
+$turnOff = new TurnOff($bulb);
+
+$remote = new RemoteControl();
+$remote->submit($turnOn); // Bulb has been lit!
+$remote->submit($turnOff); // Darkness!
+*/
+
+class CommandTest extends TestCase
+{
+    public function test01(): void
+    {
+        $bulb = new Bulb();
+
+        $turnOn = new TurnOn($bulb);
+        $turnOff = new TurnOff($bulb);
+
+        $remote = new RemoteControl();
+        self::assertEquals('Bulb has been lit!', $remote->submit($turnOn));
+        self::assertEquals('Darkness!', $remote->submit($turnOff));
+    }
+}

examples/php/behavioral/command/RemoteControl.php

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+<?php
+
+namespace design_patterns\behavioral\command;
+
+class RemoteControl
+{
+    public function submit(Command $command): string
+    {
+        return $command->execute();
+    }
+}

examples/php/behavioral/command/TurnOff.php

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+<?php
+
+namespace design_patterns\behavioral\command;
+
+class TurnOff implements Command
+{
+    private Bulb $bulb;
+
+    public function __construct(Bulb $bulb)
+    {
+        $this->bulb = $bulb;
+    }
+
+    public function execute(): string
+    {
+        return $this->bulb->turnOff();
+    }
+
+    public function undo(): string
+    {
+        return $this->bulb->turnOn();
+    }
+
+    public function redo(): string
+    {
+        return $this->execute();
+    }
+}

examples/php/behavioral/command/TurnOn.php

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+<?php
+
+namespace design_patterns\behavioral\command;
+
+class TurnOn implements Command
+{
+    private Bulb $bulb;
+
+    public function __construct(Bulb $bulb)
+    {
+        $this->bulb = $bulb;
+    }
+
+    public function execute(): string
+    {
+        return $this->bulb->turnOn();
+    }
+
+    public function undo(): string
+    {
+        return $this->bulb->turnOff();
+    }
+
+    public function redo(): string
+    {
+        return $this->execute();
+    }
+}

examples/php/behavioral/interpreter/Interpreter.php

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+<?php

examples/php/behavioral/iterator/IteratorTest.php

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+<?php
+
+namespace design_patterns\behavioral\iterator;
+
+use PHPUnit\Framework\TestCase;
+
+/*
+$stationList = new StationList();
+
+$stationList->addStation(new RadioStation(89));
+$stationList->addStation(new RadioStation(101));
+$stationList->addStation(new RadioStation(102));
+$stationList->addStation(new RadioStation(103.2));
+
+foreach($stationList as $station) {
+    echo $station->getFrequency() . PHP_EOL;
+}
+
+$stationList->removeStation(new RadioStation(89)); // Will remove station 89
+*/
+
+class IteratorTest extends TestCase
+{
+    public function test01(): void
+    {
+        $stationList = new StationList();
+
+        $stationList->addStation(new RadioStation(89));
+        $stationList->addStation(new RadioStation(101));
+        $stationList->addStation(new RadioStation(102));
+        $stationList->addStation(new RadioStation(103.2));
+
+        self::assertEquals(4, $stationList->count());
+
+        $expect = [89, 101, 102, 103.2];
+        foreach($stationList as $key => $station) {
+            self::assertEquals($expect[$key], $station->getFrequency());
+        }
+
+        $stationList->removeStation(new RadioStation(89));
+        self::assertEquals(3, $stationList->count());
+    }
+}

examples/php/behavioral/iterator/RadioStation.php

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+<?php
+
+namespace design_patterns\behavioral\iterator;
+
+class RadioStation
+{
+    private float $frequency;
+
+    public function __construct(float $frequency)
+    {
+        $this->frequency = $frequency;
+    }
+
+    public function getFrequency(): float
+    {
+        return $this->frequency;
+    }
+}