- Added while/endwhile and do/while syntaxes

- Fix the abstractclass requirement of parse() function

src/ControlStructure/AbstractLoop.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Picea\ControlStructure;
+
+abstract class AbstractLoop implements ControlStructure {
+
+    public function parse(\Picea\Compiler\Context &$context, ?string $arguments, string $token) {
+        switch($token) {
+            case "while":
+            case "foreach":
+                $name = "$".uniqid("{$token}_");
+                
+                $stack = array_filter($context->iterationStack ?? [], function($item) {
+                    return ! $item['or'];
+                });
+                
+                $count = count($stack);
+
+                if ( $count > 0 ) {
+                    $name .= "[" . end($stack)['uid'] . "]";
+                }
+
+                $context->iterationStack[] = [
+                    'or' => false,
+                    'uid' => $name,
+                    'token' => "end{$token}",
+                ];
+
+                return "<?php $token ($arguments): $name = ( $name ?? 0 ) + 1; ?>";
+
+            case "endwhile":
+            case "endforeach":
+                $last = end($context->iterationStack);
+
+                if ( $last['or'] === false ) {
+                    $output = "<?php $token; ?>";
+                }
+                else {
+                    $output = "<?php endif; if ( isset({$last['uid']}) ) unset({$last['uid']}); ?>";
+                }
+
+                array_pop($context->iterationStack);
+                
+                return $output;
+        }
+    }
+}