From 191458111a02407e5841b4247d85a120d33ca46c Mon Sep 17 00:00:00 2001
From: "David P. Chassin" <dchassin@slac.stanford.edu>
Date: Wed, 11 Nov 2020 07:11:50 -0800
Subject: [PATCH] Add support for parent class definition in loader

---
 gldcore/class.cpp |  7 +++++-
 gldcore/load.cpp  | 57 +++++++++++++++++++++++++++++++++++++++++++++++
 gldcore/load.h    |  1 +
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/gldcore/class.cpp b/gldcore/class.cpp
index 3034aaedd..9e198c062 100644
--- a/gldcore/class.cpp
+++ b/gldcore/class.cpp
@@ -351,7 +351,12 @@ PROPERTY *class_add_extended_property(CLASS *oclass,      /**< the class to whic
 	prop->width = property_type[ptype].size;
 	prop->access = PA_PUBLIC;
 	prop->unit = pUnit;
-	prop->addr = (void*)(int64)oclass->size;
+	int64 offset = (int64)oclass->size;
+	for ( CLASS *parent = oclass->parent ; parent != NULL ; parent = parent->parent )
+	{
+		offset += parent->size;
+	}
+	prop->addr = (void*)offset;
 	prop->delegation = NULL;
 	prop->keywords = NULL;
 	prop->description = NULL;
diff --git a/gldcore/load.cpp b/gldcore/load.cpp
index 1553fa440..a062cff1d 100755
--- a/gldcore/load.cpp
+++ b/gldcore/load.cpp
@@ -340,6 +340,12 @@ std::string GldLoader::setup_class(CLASS *oclass)
 	snprintf(buffer,sizeof(buffer),"\toclass->size = sizeof(%s);\n", oclass->name);
 	result.append(buffer);
 
+	if ( oclass->parent != NULL )
+	{
+		snprintf(buffer,sizeof(buffer),"\toclass->parent = (*(callback->class_getname(\"%s\")));",oclass->parent->name);
+		result.append(buffer);
+	}
+
 	PROPERTY *prop;
 	for (prop=oclass->pmap; prop!=NULL; prop=prop->next)
 	{
@@ -3296,6 +3302,53 @@ int GldLoader::class_event_handler(PARSER, CLASS *oclass)
 	DONE;
 }
 
+int GldLoader::class_parent_definition(PARSER, CLASS *oclass)
+{
+	char classname[1024];
+	START;
+	if WHITE ACCEPT;
+	if ( LITERAL("parent") )
+	{
+		if WHITE ACCEPT;
+		if ( TERM(name(HERE,classname,sizeof(classname))) ) 
+		{
+			if ( oclass->module != NULL )
+			{
+				syntax_error(filename,linenum,"cannot set parent of class defined in module");
+				REJECT;
+			}
+			else
+			{
+				oclass->parent = class_get_class_from_classname(classname);
+				if ( oclass->parent == NULL )
+				{
+					syntax_error(filename,linenum,"parent class '%s' not found", classname);
+					REJECT;
+				}
+				else if ( WHITE,LITERAL(";") )
+				{
+					ACCEPT;
+				}
+				else
+				{
+					syntax_error(filename,linenum,"missing semicolon after parent class name");
+					REJECT;
+				}
+			}
+		}
+		else
+		{
+			syntax_error(filename,linenum,"missing or invalid parent class name");
+			REJECT;
+		}
+	}
+	else
+	{
+		REJECT;
+	}
+	DONE;
+}
+
 int GldLoader::class_properties(PARSER, CLASS *oclass, int64 *functions, char *initcode, int initsize)
 {
 	static char code[65536];
@@ -3336,6 +3389,10 @@ int GldLoader::class_properties(PARSER, CLASS *oclass, int64 *functions, char *i
 		*functions |= FN_EXPORT;
 		ACCEPT;
 	}
+	else if TERM(class_parent_definition(HERE,oclass) )
+	{
+		ACCEPT;
+	}
 	else if (TERM(property_type(HERE,&type,&keys)) && (WHITE,(TERM(nameunit(HERE,propname,sizeof(propname),&pUnit))||TERM(name(HERE,propname,sizeof(propname))))) && (WHITE,LITERAL(";")) )
 	{
 		PROPERTY *prop = class_find_property(oclass,propname);
diff --git a/gldcore/load.h b/gldcore/load.h
index e8c6ed36f..c8f7253bf 100644
--- a/gldcore/load.h
+++ b/gldcore/load.h
@@ -300,6 +300,7 @@ class GldLoader
 	int class_explicit_definition(PARSER, CLASS *oclass);
 	int class_external_function(PARSER, CLASS *oclass, CLASS **eclass,char *fname, int fsize);
 	int class_event_handler(PARSER, CLASS *oclass);
+	int class_parent_definition(PARSER, CLASS *oclass);
 	int class_properties(PARSER, CLASS *oclass, int64 *functions, char *initcode, int initsize);
 	int class_block(PARSER);
 	int set_flags(OBJECT *obj, char *propval);