Add support for else if

src/main/php/com/handlebarsjs/BlockNode.class.php

@@ -1,6 +1,7 @@
 <?php namespace com\handlebarsjs;
 
 use com\github\mustache\Node;
+use util\Objects;
 
 /**
  * A block starts with {{#sec}} (or {{^sec}} for inverted blocks)
@@ -81,8 +82,8 @@ public function toString() {
       nameof($this),
       $this->name,
       ($this->options ? ' '.implode(' ', $this->options) : ''),
-      \xp::stringOf($this->fn, '  '),
-      \xp::stringOf($this->inverse, '  ')
+      Objects::stringOf($this->fn, '  '),
+      Objects::stringOf($this->inverse, '  ')
     );
   }
 
@@ -133,7 +134,7 @@ public function equals($cmp) {
       $this->name === $cmp->name &&
       $this->start === $cmp->start &&
       $this->end === $cmp->end &&
-      \util\Objects::equal($this->options, $cmp->options) &&
+      Objects::equal($this->options, $cmp->options) &&
       $this->fn->equals($cmp->fn) &&
       $this->inverse->equals($cmp->inverse)
     );

src/main/php/com/handlebarsjs/HandlebarsParser.class.php

@@ -208,9 +208,23 @@ protected function initialize() {
         $state->target->add(new IteratorNode(true));
         return;
       } else if ('else' === $parsed[0] && $state->parents) {
-        $context= $state->parents[sizeof($state->parents) - 1];
+        $context= &$state->parents[sizeof($state->parents) - 1];
         if ($context instanceof BlockNode) {
-          $state->target= $context->inverse();
+
+          // `else if` vs. `else`
+          if (isset($parsed[1]) && 'if' === (string)$parsed[1]) {
+            $context= $context->inverse()->add(new IfBlockHelper(
+              array_slice($parsed, 2),
+              null,
+              null,
+              $state->start,
+              $state->end
+            ));
+            $state->target= $context->fn();
+          } else {
+            $state->target= $context->inverse();
+          }
+
           return;
         }
         // Fall through, "else" has no special meaning here.

src/main/php/com/handlebarsjs/IfBlockHelper.class.php

@@ -27,8 +27,7 @@ public function __construct($options= [], NodeList $fn= null, NodeList $inverse=
    * @param  io.streams.OutputStream $out
    */
   public function write($context, $out) {
-    $f= $this->options[0];
-    $target= $f($this, $context, []);
+    $target= $this->options[0]($this, $context, []);
 
     if ($target instanceof \Generator ? $target->valid() : $context->isTruthy($target)) {
       $this->fn->write($context, $out);

src/test/php/com/handlebarsjs/unittest/IfHelperTest.class.php

@@ -25,6 +25,13 @@ public function shows_for_non_empty_array() {
     ]));
   }
 
+  #[Test, Values(map: ['one' => '1', 'two' => '2', 'three' => '3', 'other' => '3'])]
+  public function chained_elses($key, $expected) {
+    Assert::equals($expected, $this->evaluate('{{#if one}}1{{else if two}}2{{else}}3{{/if}}', [
+      $key => true
+    ]));
+  }
+
   #[Test, Values(['else', '^'])]
   public function else_invoked_for_non_truthy($else) {
     Assert::equals('Default', $this->evaluate('{{#if var}}-{{var}}-{{'.$else.'}}Default{{/if}}', [