Added method for returning immutable objects.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@14776 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,14 @@
+2002-10-14  Richard Frith-Macdonald <rfm@gnu.org>
+
+	Source/NSObject.m: Add ([-makeImmutableCopyOnFail:]) for use by methods
+	wishing to return constant string/array/dictionary etc results after
+	building them using mutable objects they created.
+	Source/GSArray.m: Implement ([makeImmutableCopyOnFail:])
+	Source/GSString.m: ditto
+	Source/GSDictionary.m: ditto
+	Source/GSSet.m: ditto
+	Source/NSFileManager.m: Use it
+
 2002-10-13  Mirko Viviani  <mirko.viviani@rccr.cremona.it>
 
 	* Source/NSBundle.m ([NSBundle +_addFrameworkFromClass:]): remove

Headers/gnustep/base/NSObject.h

@@ -285,6 +285,7 @@ GS_EXPORT NSRecursiveLock *gnustep_global_lock;
 + (void) descriptionWithLocale: (NSDictionary*)aLocale
 			indent: (unsigned)level
 			    to: (id<GNUDescriptionDestination>)output;
+- (id) makeImmutableCopyOnFail: (BOOL)force;
 - (Class) transmuteClassTo: (Class)aClassObject;
 - (id) subclassResponsibility: (SEL)aSel;
 - (id) shouldNotImplement: (SEL)aSel;

Source/GSArray.m

@@ -479,6 +479,12 @@ static SEL	eqSel;
   _contents_array[index] = RETAIN(anObject);
 }
 
+- (id) makeImmutableCopyOnFail: (BOOL)force
+{
+  isa = [GSArray class];
+  return self;
+}
+
 - (void) removeLastObject
 {
   if (_count == 0)

Source/GSDictionary.m

@@ -284,6 +284,12 @@ static SEL	objSel;
   return self;
 }
 
+- (id) makeImmutableCopyOnFail: (BOOL)force
+{
+  isa = [GSDictionary class];
+  return self;
+}
+
 - (void) setObject: (id)anObject forKey: (id)aKey
 {
   GSIMapNode	node;

Source/GSSet.m

@@ -562,6 +562,12 @@ static Class	mutableSetClass;
     }
 }
 
+- (id) makeImmutableCopyOnFail: (BOOL)force
+{
+  isa = [GSSet class];
+  return self;
+}
+
 - (void) minusSet: (NSSet*) other
 {
   if (other == self)

Source/GSString.m

@@ -2920,6 +2920,12 @@ transmute(ivars self, NSString *aString)
     return lossyCString_c((ivars)self);
 }
 
+- (id) makeImmutableCopyOnFail: (BOOL)force
+{
+  isa = [GSString class];
+  return self;
+}
+
 - (id) mutableCopy
 {
   GSMutableString	*obj;

Source/NSFileManager.m

@@ -45,9 +45,9 @@
 #include <Foundation/NSLock.h>
 #include <Foundation/NSDebug.h>
 #include <Foundation/NSProcessInfo.h>
-#include <Foundation/NSDictionary.h>
 #include <Foundation/NSEnumerator.h>
 #include <Foundation/NSSet.h>
+#include "GSPrivate.h"
 
 #include <stdio.h>
 
@@ -1428,12 +1428,12 @@ static NSFileManager* defaultManager = nil;
   
   id  values[5];
   id	keys[5] = {
-	  NSFileSystemSize,
-	  NSFileSystemFreeSize,
-	  NSFileSystemNodes,
-	  NSFileSystemFreeNodes,
-	  NSFileSystemNumber
-      };
+    NSFileSystemSize,
+    NSFileSystemFreeSize,
+    NSFileSystemNodes,
+    NSFileSystemFreeNodes,
+    NSFileSystemNumber
+  };
   
   if (stat(cpath, &statbuf) != 0)
     return nil;
@@ -1468,7 +1468,8 @@ static NSFileManager* defaultManager = nil;
  * Returns an array of the contents of the specified directory.<br />
  * The listing does <strong>not</strong> recursively list subdirectories.<br />
  * The special files '.' and '..' are not listed.<br />
- * Returns nil if path is not a directory (or it can't be read for some reason).
+ * Indicates an error by returning nil (eg. if path is not a directory or
+ * it can't be read for some reason).
  */
 - (NSArray*) directoryContentsAtPath: (NSString*)path
 {
@@ -1504,7 +1505,7 @@ static NSFileManager* defaultManager = nil;
     }
   RELEASE(direnum);
 
-  return content;
+  return [content makeImmutableCopyOnFail: NO];
 }
 
 /**
@@ -1569,7 +1570,7 @@ static NSFileManager* defaultManager = nil;
   
   RELEASE(direnum);
 
-  return content;
+  return [content makeImmutableCopyOnFail: NO];
 }
 
 /**

Source/NSObject.m

@@ -2088,18 +2088,45 @@ static BOOL double_release_check_enabled = NO;
             :class_get_class_method(GSObjCClass(self), aSel)));
 }
 
+/**
+ * Transmutes the receiver into an immutable version of the same object
+ * and returns the result.<br />
+ * If the receiver is not a mutable object or cannot be simply transmuted,
+ * then this method either returns the receiver unchanged or,
+ * if the force flag is set to YES, returns an autoreleased copy of the
+ * receiver.<br />
+ * Mutable classes should override this default implementation.<br />
+ * This method is used in methods which are declared to return immutable
+ * objects (eg. an NSArray), but which create and build mutable ones
+ * internally.
+ */
+- (id) makeImmutableCopyOnFail: (BOOL)force
+{
+  if (force == YES)
+    {
+      return AUTORELEASE([self copy]);
+    }
+  return self;
+}
+
+/**
+ * Changes the class of the receiver (the 'isa' pointer) to be aClassObject,
+ * but only if the receiver is an instance of a subclass of aClassObject
+ * which has not added extra instance variables.<br />
+ * Returns zero on failure, or the old class on success.
+ */
 - (Class) transmuteClassTo: (Class)aClassObject
 {
   if (GSObjCIsInstance(self) == YES)
     if (class_is_class(aClassObject))
       if (class_get_instance_size(aClassObject)==class_get_instance_size(isa))
-        if ([self isKindOfClass:aClassObject])
+        if ([self isKindOfClass: aClassObject])
           {
             Class old_isa = isa;
             isa = aClassObject;
             return old_isa;
           }
-  return nil;
+  return 0;
 }
 
 - (id) subclassResponsibility: (SEL)aSel