From 8fb747a2e478c97309a475c9664ba79bb445e26d Mon Sep 17 00:00:00 2001
From: Pavel Shevaev <pacha.shevaev@gmail.com>
Date: Fri, 5 May 2023 12:12:49 +0300
Subject: [PATCH] Adding initial support for null structs (but not generic
 ones)

---
 src/codegen.inc.php | 34 +++++++++++++++++++++++-----------
 tpl/macro.twig      | 14 +++++++++-----
 2 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/src/codegen.inc.php b/src/codegen.inc.php
index bf8631d..72d00de 100644
--- a/src/codegen.inc.php
+++ b/src/codegen.inc.php
@@ -348,23 +348,30 @@ function var_reset($name, \mtgType $type, $default = null)
   else if($type instanceof \mtgMetaStruct)
   {
     $str = "";
-    $is_pod = $type->hasToken('POD');
-    if($is_pod)
-      $str .= "$name.reset(); ";
-    else 
-      $str .= "Meta.Reset(ref $name); ";
+    if(!is_null_str($default))
+    {
+      $is_pod = $type->hasToken('POD');
+      if($is_pod)
+        $str .= "$name.reset(); ";
+      else
+        $str .= "Meta.Reset(ref $name); ";
+    }
 
     if($default)
     {
       $default = is_array($default) ? $default : json_decode($default, true);
-      if(!is_array($default))
-        throw new Exception("Bad default value for struct: $default");
-
-      foreach($default as $k => $v)
+      if(is_array($default))
       {
-        $kf = $type->getField($k); 
-        $str .= var_reset("$name." . $kf->getName(), $kf->getType(), $v);
+        foreach($default as $k => $v)
+        {
+          $kf = $type->getField($k); 
+          $str .= var_reset("$name." . $kf->getName(), $kf->getType(), $v);
+        }
       }
+      else if($default === null)
+        $str .= "$name = default; ";
+      else
+        throw new Exception("Bad default value for struct: " . var_export($default, true));
     }
   }
   else
@@ -372,6 +379,11 @@ function var_reset($name, \mtgType $type, $default = null)
   return $str;
 }
 
+function is_null_str($default)
+{
+  return is_string($default) && json_decode($default, true) === null;
+}
+
 function var_sync($fname, \mtgType $type, $buf, array $tokens, $opts)
 {
   $optional = array_key_exists('optional', $tokens);
diff --git a/tpl/macro.twig b/tpl/macro.twig
index 79fc2ad..44479ec 100644
--- a/tpl/macro.twig
+++ b/tpl/macro.twig
@@ -128,14 +128,18 @@ public FieldsMask fields_mask;
 
 {%- macro decl_struct_field(o, f) -%}
 {{_self.attributes(f)}}
-public {{f.type|cs_type|obscure_type(f)}} {{f.name}} {% if not has_token(o, 'POD') -%} {{_self.decl_init_value(f.type)}} {%- endif -%};
+public {{f.type|cs_type|obscure_type(f)}} {{f.name}} {% if not has_token(o, 'POD') -%} {{_self.decl_init_value(f)}} {%- endif -%};
 {%- endmacro -%}
 
-{% macro decl_init_value(type) %}
-{%- if type is instanceof('\\mtgBuiltinType') -%}
-{%- if type.isstring -%} = ""{%- endif -%}
+{% macro decl_init_value(f) %}
+{%- if f.type is instanceof('\\mtgBuiltinType') -%}
+{%- if f.type.isstring -%} = ""{%- endif -%}
 {%- else -%}
-= new {{type|cs_type}}()
+{%- if has_token(f, 'default') and token(f, 'default') == 'null'  -%}
+/*null*/
+{%- else -%}
+= new {{f.type|cs_type}}()
+{%- endif -%}
 {%- endif -%}
 {% endmacro %}