feat: add string manipulation functions for startswith and endswith

Author: CodeWithKyrian

src/Runtime/StringValue.php

@@ -14,6 +14,7 @@ class StringValue extends RuntimeValue
     public function __construct(string $value)
     {
         parent::__construct($value);
+
         $this->builtins = [
             "upper" => new FunctionValue(fn() => new StringValue(strtoupper($this->value))),
             "lower" => new FunctionValue(fn() => new StringValue(strtolower($this->value))),
@@ -22,6 +23,30 @@ public function __construct(string $value)
             "length" => new NumericValue(strlen($this->value)),
             "rstrip" => new FunctionValue(fn() => new StringValue(rtrim($this->value))),
             "lstrip" => new FunctionValue(fn() => new StringValue(ltrim($this->value))),
+            "startswith" => new FunctionValue(function ($args) {
+                if (count($args) === 0) {
+                    throw new \Exception("startswith() requires at least one argument");
+                }
+
+                $prefix = $args[0];
+                if (!($prefix instanceof StringValue)) {
+                    throw new \Exception("startswith() requires a string argument");
+                }
+
+                return new BooleanValue(str_starts_with($this->value, $prefix->value));
+            }),
+            "endswith" => new FunctionValue(function ($args) {
+                if (count($args) === 0) {
+                    throw new \Exception("endswith() requires at least one argument");
+                }
+
+                $suffix = $args[0];
+                if (!($suffix instanceof StringValue)) {
+                    throw new \Exception("endswith() requires a string argument");
+                }
+
+                return new BooleanValue(str_ends_with($this->value, $suffix->value));
+            }),
             "split" => new FunctionValue(fn($args) => new ArrayValue(explode($args[0] ?? ' ', $this->value, $args[1] ?? -1))),
         ];
     }