Added support for final classes

- This commit was originally many. Unfortunately, certain Git objects became
  corrupt shortly after my 500th commit due to HDD issues. Due to the scope, I
  was unable to recover the set of commits I needed (after an hour of trying
  every method).
  - Fortunately, vim's swap files came to the rescue. Had I been able to
    properly shut down my PC, I would have been rather frustrated.

lib/class_builder.js

@@ -200,6 +200,15 @@ exports.build = function extend()
             || { __length: 0 }
     ;
 
+    // prevent extending final classes
+    if ( base.___$$final$$ === true )
+    {
+        throw Error(
+            "Cannot extend final class " +
+                ( base.___$$meta$$.name || '(anonymous)' )
+        );
+    }
+
     // grab the name, if one was provided
     if ( cname = props.__name )
     {
@@ -252,6 +261,8 @@ exports.build = function extend()
     new_class.___$$methods$$ = members;
     new_class.___$$sinit$$   = staticInit;
 
+    attachFlags( new_class, props );
+
     // We reduce the overall cost of this definition by defining it on the
     // prototype rather than during instantiation. While this does increase the
     // amount of time it takes to access the property through the prototype
@@ -1032,3 +1043,21 @@ function attachId( ctor, id )
     util.defineSecureProp( ctor.prototype, '__cid', id );
 }
 
+
+/**
+ * Sets class flags
+ *
+ * @param  {Class}   ctor   class to flag
+ * @param  {Object}  props  class properties
+ *
+ * @return  {undefined}
+ */
+function attachFlags( ctor, props )
+{
+    ctor.___$$final$$    = !!( props.___$$final$$ );
+
+    // The properties are no longer needed. Set to undefined rather than delete
+    // (v8 performance)
+    props.___$$final$$ = undefined;
+}
+

lib/class_final.js

@@ -0,0 +1,41 @@
+/**
+ * Wrapper permitting the definition of final classes
+ *
+ *  Copyright (C) 2010 Mike Gerwitz
+ *
+ *  This file is part of ease.js.
+ *
+ *  ease.js is free software: you can redistribute it and/or modify it under the
+ *  terms of the GNU Lesser General Public License as published by the Free
+ *  Software Foundation, either version 3 of the License, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @author  Mike Gerwitz
+ * @package core
+ */
+
+var Class = require( __dirname + '/class' );
+
+module.exports = function()
+{
+    // the last argument _should_ be the definition
+    var dfn = arguments[ arguments.length - 1 ];
+
+    if ( typeof dfn === 'object' )
+    {
+        // mark it as final
+        dfn.___$$final$$ = true;
+    }
+
+    // forward everything to Class
+    return Class.apply( this, arguments );
+};
+

lib/member_builder.js

@@ -81,13 +81,24 @@ exports.buildMethod = function(
             : {}
     ;
 
-    // do not permit private abstract methods (doesn't make sense, since
+    if ( keywords[ 'abstract' ] )
-    // they cannot be inherited/overridden)
-    if ( keywords[ 'abstract' ] && keywords[ 'private' ] )
     {
-        throw TypeError(
+        // do not permit private abstract methods (doesn't make sense, since
-            "Method '" + name + "' cannot be both private and abstract"
+        // they cannot be inherited/overridden)
-        );
+        if ( keywords[ 'private' ] )
+        {
+            throw TypeError(
+                "Method '" + name + "' cannot be both private and abstract"
+            );
+        }
+
+        // abstract final also does not make sense
+        if ( keywords[ 'final' ] )
+        {
+            throw TypeError(
+                "Method '" + name + "' cannot be both abstract and final"
+            );
+        }
     }
 
     // const doesn't make sense for methods; they're always immutable

test/test-class_builder-final.js

@@ -24,7 +24,10 @@
 
 var common  = require( './common' ),
     assert  = require( 'assert' ),
-    builder = common.require( 'class_builder' )
+    builder = common.require( 'class_builder' ),
+
+    Class      = common.require( 'class' )
+    FinalClass = common.require( 'class_final' )
 ;
 
 
@@ -83,7 +86,7 @@ var common  = require( './common' ),
     {
         assert.ok(
             e.message.search( 'foo' ) !== -1,
-            "Final property error message contains name of method"
+            "Final property error message contains name of property"
         );
 
         return;
@@ -92,3 +95,65 @@ var common  = require( './common' ),
     assert.fail( "Should not be able to use final keyword with properties" );
 } )();
 
+
+/**
+ * The 'abstract' keyword's very point is to state that no definition is
+ * provided and that a subtype must provide one. Therefore, declaring something
+ * 'abstract final' is rather contradictory and should not be permitted.
+ */
+( function testFinalyKeywordCannotBeUsedWithAbstract()
+{
+    try
+    {
+        // should fail
+        builder.build( { 'abstract final foo': [] } );
+    }
+    catch ( e )
+    {
+        assert.ok(
+            e.message.search( 'foo' ) !== -1,
+            "Abstract final error message contains name of method"
+        );
+
+        return;
+    }
+
+    assert.fail( "Should not be able to use final keyword with abstract" );
+} )();
+
+
+/**
+ * Ensure that FinalClass properly forwards data to create a new Class.
+ */
+( function testFinalClassesAreValidClasses()
+{
+    assert.ok( Class.isClass( FinalClass( {} ) ),
+        "Final classes should generate valid classes"
+    );
+} )();
+
+
+/**
+ * When a class is declared as final, it should prevent it from ever being
+ * extended. Ever.
+ */
+( function testFinalClassesCannotBeExtended()
+{
+    try
+    {
+        // this should fail
+        FinalClass( 'Foo', {} ).extend( {} );
+    }
+    catch ( e )
+    {
+        assert.ok(
+            e.message.search( 'Foo' ) !== -1,
+            "Final class error message should contain name of class"
+        );
+
+        return;
+    }
+
+    assert.fail( "Should not be able to extend final classes" );
+} )();
+

tools/combine

@@ -29,7 +29,7 @@ RMTRAIL="$PATH_TOOLS/rmtrail"
 
 # order matters
 CAT_MODULES="prop_parser util propobj member_builder class_builder"
-CAT_MODULES="$CAT_MODULES class interface"
+CAT_MODULES="$CAT_MODULES class class_final interface"
 
 ##
 # Output template header