add pattern Interpreter

Behavioral/Interpreter/AbstractExp.php

@@ -0,0 +1,8 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Interpreter;
+
+abstract class AbstractExp
+{
+    abstract public function interpret(Context $context): bool;
+}

Behavioral/Interpreter/AndExp.php

@@ -0,0 +1,20 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Interpreter;
+
+class AndExp extends AbstractExp
+{
+    private AbstractExp $first;
+    private AbstractExp $second;
+
+    public function __construct(AbstractExp $first, AbstractExp $second)
+    {
+        $this->first = $first;
+        $this->second = $second;
+    }
+
+    public function interpret(Context $context): bool
+    {
+        return (bool) $this->first->interpret($context) && $this->second->interpret($context);
+    }
+}

Behavioral/Interpreter/Context.php

@@ -0,0 +1,24 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Interpreter;
+
+use Exception;
+
+class Context
+{
+    private array $poolVariable;
+
+    public function lookUp(string $name): bool
+    {
+        if (!key_exists($name, $this->poolVariable)) {
+            throw new Exception("no exist variable: $name");
+        }
+
+        return $this->poolVariable[$name];
+    }
+
+    public function assign(VariableExp $variable, bool $val)
+    {
+        $this->poolVariable[$variable->getName()] = $val;
+    }
+}

Behavioral/Interpreter/OrExp.php

@@ -0,0 +1,20 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Interpreter;
+
+class OrExp extends AbstractExp
+{
+    private AbstractExp $first;
+    private AbstractExp $second;
+
+    public function __construct(AbstractExp $first, AbstractExp $second)
+    {
+        $this->first = $first;
+        $this->second = $second;
+    }
+
+    public function interpret(Context $context): bool
+    {
+        return $this->first->interpret($context) || $this->second->interpret($context);
+    }
+}

Behavioral/Interpreter/Tests/InterpreterTest.php

@@ -0,0 +1,63 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Interpreter\Tests;
+
+use DesignPatterns\Behavioral\Interpreter\AndExp;
+use DesignPatterns\Behavioral\Interpreter\Context;
+use DesignPatterns\Behavioral\Interpreter\OrExp;
+use DesignPatterns\Behavioral\Interpreter\VariableExp;
+use PHPUnit\Framework\TestCase;
+
+class InterpreterTest extends TestCase
+{
+    private Context $context;
+    private VariableExp $a;
+    private VariableExp $b;
+    private VariableExp $c;
+
+    public function setUp(): void
+    {
+        $this->context = new Context();
+        $this->a = new VariableExp('A');
+        $this->b = new VariableExp('B');
+        $this->c = new VariableExp('C');
+    }
+
+    public function testOr()
+    {
+        $this->context->assign($this->a, false);
+        $this->context->assign($this->b, false);
+        $this->context->assign($this->c, true);
+
+        // A ∨ B
+        $exp1 = new OrExp($this->a, $this->b);
+        $result1 = $exp1->interpret($this->context);
+
+        $this->assertFalse($result1, 'A ∨ B must false');
+
+        // $exp1 ∨ C
+        $exp2 = new OrExp($exp1, $this->c);
+        $result2 = $exp2->interpret($this->context);
+
+        $this->assertTrue($result2, '(A ∨ B) ∨ C must true');
+    }
+
+    public function testAnd()
+    {
+        $this->context->assign($this->a, true);
+        $this->context->assign($this->b, true);
+        $this->context->assign($this->c, false);
+
+        // A ∧ B
+        $exp1 = new AndExp($this->a, $this->b);
+        $result1 = $exp1->interpret($this->context);
+
+        $this->assertTrue($result1, 'A ∧ B must true');
+
+        // $exp1 ∧ C
+        $exp2 = new AndExp($exp1, $this->c);
+        $result2 = $exp2->interpret($this->context);
+
+        $this->assertFalse($result2, '(A ∧ B) ∧ C must false');
+    }
+}

Behavioral/Interpreter/VariableExp.php

@@ -0,0 +1,23 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Interpreter;
+
+class VariableExp extends AbstractExp
+{
+    private string $name;
+
+    public function __construct(string $name)
+    {
+        $this->name = $name;
+    }
+
+    public function interpret(Context $context): bool
+    {
+        return $context->lookUp($this->name);
+    }
+
+    public function getName(): string
+    {
+        return $this->name;
+    }
+}