Use [GSModelLoaderFactory modelLoaderForData:] to generically implement methods that unarchive a model purely from data since we cannot use the file extension to determine which loader to instantiate.

ChangeLog

@@ -1,3 +1,21 @@
+2021-04-24 Gregory John Casamento <greg.casamento@gmail.com>
+
+	* Headers/Additions/GNUstepGUI/GSModelLoaderFactory.h:
+        Declaration of canReadData: in the GSModelLoader class and
+        declaration of modelLoaderForData: in GSModelLoaderFactory.
+	* Source/GSGModelLoader.m: Prototype method for canReadData:
+        Implementation of modelLoaderForData:.
+	* Source/GSGormLoader.m
+	* Source/GSModelLoaderFactory.m
+	* Source/GSNibLoader.m
+	* Source/GSXibLoader.m: Implement -canReadData: method to
+        determine for each loader if that loader can handle the data
+        passed into it.
+	* Source/NSNib.m: Use of [GSModelLoaderFactory modelLoaderForData:]
+        to more generically implement methods that initialize an archive from
+        archived data since we have no file extention to rely on to identify
+        the archive contents.
+
 2021-04-23 Gregory John Casamento <greg.casamento@gmail.com>
 
 	* Source/Functions.m: QuickFix. Remove unecessary warning

Source/GSGModelLoader.m

@@ -29,6 +29,7 @@
 #import <Foundation/NSArray.h>
 #import <Foundation/NSBundle.h>
 #import <Foundation/NSDebug.h>
+#import <Foundation/NSData.h>
 #import <Foundation/NSDictionary.h>
 #import <Foundation/NSEnumerator.h>
 #import <Foundation/NSException.h>
@@ -80,6 +81,33 @@ Class gmodel_class(void)
   // register for the gmodel type.
 }
 
++ (BOOL) canReadData: (NSData *)theData
+{
+  char *header = calloc(1024, sizeof(char));
+
+  if (header != NULL)
+    {
+      NSUInteger len = [theData length];
+      NSRange r = NSMakeRange(len - 1024, len - 1);
+      NSString *hdr = nil;
+
+      [theData getBytes: header
+                  range: r];
+      hdr = [[NSString alloc] initWithBytes: header
+                                     length: 1024
+                                   encoding: NSUTF8StringEncoding];
+      AUTORELEASE(hdr);
+      if ([hdr containsString: @"GMModel"])
+        {
+          return YES;
+        }
+
+      free(header);
+    }
+
+  return NO;
+}
+
 + (NSString *) type
 {
   return @"gmodel";
@@ -119,7 +147,7 @@ Class gmodel_class(void)
   if ([ext isEqualToString: @"gmodel"])
     {
       return [gmodel_class() loadIMFile: fileName
-		      owner: [context objectForKey: NSNibOwner]];
+                                  owner: [context objectForKey: NSNibOwner]];
     } 
 
   return NO;

Source/GSGormLoader.m

@@ -81,6 +81,26 @@
     }
 }
 
++ (BOOL) canReadData: (NSData *)theData
+{
+  char *header = calloc(16, sizeof(char));
+
+  if (header != NULL)
+    {
+      [theData getBytes: header
+                 length: 16];
+
+      if (strncmp("GNUstep archive",header,15) == 0)
+        {
+          return YES;
+        }
+
+      free(header);
+    }
+
+  return NO;
+}
+
 + (NSString *)type
 {
   return @"gorm";

Source/GSNibLoader.m

@@ -49,6 +49,39 @@
   // should do something...
 }
 
++ (BOOL) canReadData: (NSData *)theData
+{
+  char *header = calloc(1024, sizeof(char));
+
+  if (header != NULL)
+    {
+      [theData getBytes: header
+                 length: 1024];
+
+      if (strncmp("bplist00",header,8) == 0)
+        {
+          free(header);
+          return YES;
+        }
+      else
+        {
+          NSString *hdr = [[NSString alloc] initWithBytes: header
+                                                   length: 1024
+                                                 encoding: NSUTF8StringEncoding];
+          AUTORELEASE(hdr);
+          if ([hdr containsString: @"NSKeyedArchiver"])
+            {
+              free(header);
+              return YES;
+            }
+        }
+
+      free(header);
+    }
+
+  return NO;
+}
+
 + (NSString *)type
 {
   return @"nib";

Source/GSXibLoader.m

@@ -70,6 +70,31 @@
 
 @implementation GSXibLoader
 
++ (BOOL) canReadData: (NSData *)theData
+{
+  char *header = calloc(1024, sizeof(char));
+
+  if (header != NULL)
+    {
+      [theData getBytes: header
+                 length: 1024];
+
+      NSString *hdr = [[NSString alloc] initWithBytes: header
+                                               length: 1024
+                                             encoding: NSUTF8StringEncoding];
+      AUTORELEASE(hdr);
+      if ([hdr containsString: @"Cocoa.XIB"])
+        {
+          free(header);
+          return YES;
+        }
+
+      free(header);
+    }
+
+  return NO;
+}
+
 + (NSString*) type
 {
   return @"xib";

Source/NSNib.m

@@ -150,8 +150,7 @@
     {
       ASSIGN(_bundle, bundle);
       ASSIGN(_nibData, nibData);
-      // FIXME: Hardcode the most likely loader
-      ASSIGN(_loader, [GSModelLoaderFactory modelLoaderForFileType: @"nib"]);
+      ASSIGN(_loader, [GSModelLoaderFactory modelLoaderForData: nibData]);
     }
   return self;
 }
@@ -178,7 +177,7 @@
 - (BOOL) instantiateNibWithExternalNameTable: (NSDictionary *)externalNameTable
 {
   return [self instantiateNibWithExternalNameTable: externalNameTable
-	       withZone: NSDefaultMallocZone()];
+                                          withZone: NSDefaultMallocZone()];
 }
 
 /**
@@ -198,7 +197,8 @@
   if (topLevelObjects != 0)
     {
       *topLevelObjects = [NSMutableArray array];
-      [externalNameTable setObject: *topLevelObjects forKey: NSNibTopLevelObjects];
+      [externalNameTable setObject: *topLevelObjects
+                            forKey: NSNibTopLevelObjects];
     }
 
   return [self instantiateNibWithExternalNameTable: externalNameTable];
@@ -207,32 +207,30 @@
 - (BOOL) instantiateWithOwner: (id)owner
               topLevelObjects: (NSArray **)topLevelObjects
 {
-  return [self instantiateNibWithOwner: owner topLevelObjects: topLevelObjects];
+  return [self instantiateNibWithOwner: owner
+                       topLevelObjects: topLevelObjects];
 }
 
 - (id) initWithCoder: (NSCoder *)coder
 {
   if ((self = [super init]) != nil)
     {
-      //
-      // NOTE: This is okay, since the only encodings which will ever be built into
-      //       the gui library are nib and gorm.  GModel only supports certain
-      //       objects and is going to be deprecated in the future.  There just so
-      //       happens to be a one to one correspondence here.
-      //
       if ([coder allowsKeyedCoding])
 	{
-	  // TODO_NIB: Need to verify this key...
+          // TODO_NIB: Need to verify this key...
 	  ASSIGN(_nibData, [coder decodeObjectForKey: @"NSData"]);
-	  ASSIGN(_loader, [GSModelLoaderFactory modelLoaderForFileType: @"nib"]);
 	}
       else
 	{
 	  // this is sort of a kludge...
 	  [coder decodeValueOfObjCType: @encode(id)
-		 at: &_nibData];
-	  ASSIGN(_loader, [GSModelLoaderFactory modelLoaderForFileType: @"gorm"]);
+                                    at: &_nibData];
 	}
+
+      if (_nibData != nil)
+        {
+          ASSIGN(_loader, [GSModelLoaderFactory modelLoaderForData: _nibData]);
+        }
     }
   return self;
 }