JS style function call argument slicing/filling + fn.length fix to be always >= 0

lib/rhino/ruby.rb

@@ -162,7 +162,8 @@ module Rhino
       
       # override int BaseFunction#getLength()
       def getLength
-        @callable.arity
+        arity = @callable.arity
+        arity < 0 ? 0 : arity  # -1 for `lambda { 42 }`
       end
 
       # #deprecated int BaseFunction#getArity()
@@ -187,7 +188,16 @@ module Rhino
       # override Object BaseFunction#call(Context context, Scriptable scope, 
       #                                   Scriptable thisObj, Object[] args)
       def call(context, scope, this, args)
-        rb_args = Rhino.args_to_ruby(args.to_a)
+        args = args.to_a # java.lang.Object[] -> Array
+        # JS function style :
+        if (arity = @callable.arity) >= 0
+          if args.size > arity # omit 'redundant' arguments
+            args = args.slice(0, arity)
+          elsif arity > args.size # fill 'missing' arguments
+            (arity - args.size).times { args.push(nil) }
+          end
+        end
+        rb_args = Rhino.args_to_ruby(args)
         begin
           result = @callable.call(*rb_args)
         rescue => e
@@ -218,7 +228,8 @@ module Rhino
 
       # override int BaseFunction#getLength()
       def getLength
-        @klass.instance_method(:initialize).arity
+        arity = @klass.instance_method(:initialize).arity
+        arity < 0 ? 0 : arity  # -1 for `initialize(*args)`
       end
       
       # override boolean Scriptable#hasInstance(Scriptable instance);
@@ -231,7 +242,7 @@ module Rhino
     end
 
     def self.cache(key)
-      fetch(key) || write(key, yield)
+      fetch(key) || store(key, yield)
     end
     
     private
@@ -245,7 +256,7 @@ module Rhino
         ref ? ref.get : nil
       end
 
-      def self.write(key, value)
+      def self.store(key, value)
         @@cache.put(key, java.lang.ref.WeakReference.new(value)) if @@cache
         value
       end

spec/rhino/ruby_spec.rb

@@ -256,6 +256,38 @@ describe Rhino::Ruby::Function do
     rb_function.call(context, scope, this, args).should be_a(Rhino::JS::NativeArray)
   end
 
+  it "slices redundant args when delegating call" do
+    klass = Class.new(Object) do
+      def foo(a1)
+        a1
+      end
+    end
+    rb_function = Rhino::Ruby::Function.wrap method = klass.new.method(:foo)
+    context = nil; scope = nil; this = nil
+    
+    args = [ 1.to_java, 2.to_java, 3.to_java ].to_java; js_return = nil
+    lambda { js_return = rb_function.call(context, scope, this, args) }.should_not raise_error
+    js_return.should == 1
+  end
+  
+  it "fills missing args when delegating call" do
+    klass = Class.new(Object) do
+      def foo(a1, a2)
+        [ a1, a2 ]
+      end
+    end
+    rb_function = Rhino::Ruby::Function.wrap method = klass.new.method(:foo)
+    context = nil; scope = nil; this = nil
+    
+    args = [ 1.to_java ].to_java; js_return = nil
+    lambda { js_return = rb_function.call(context, scope, this, args) }.should_not raise_error
+    js_return.toArray.to_a.should == [ 1, nil ]
+
+    args = [ ].to_java; js_return = nil
+    lambda { js_return = rb_function.call(context, scope, this, args) }.should_not raise_error
+    js_return.toArray.to_a.should == [ nil, nil ]
+  end
+  
   it "returns correct arity and length" do
     klass = Class.new(Object) do
       def foo(a1, a2)
@@ -267,6 +299,15 @@ describe Rhino::Ruby::Function do
     rb_function.getLength.should == 2
   end
 
+  it "reports arity and length of 0 for varargs" do
+    klass = Class.new(Object) do
+      def foo(*args); args; end
+    end
+    rb_function = Rhino::Ruby::Function.wrap klass.new.method(:foo)
+    rb_function.getArity.should == 0
+    rb_function.getLength.should == 0
+  end
+  
   describe 'with scope' do
     
     before do
@@ -326,6 +367,15 @@ describe Rhino::Ruby::Constructor do
     rb_new.getLength.should == 0
   end
 
+  it "reports arity and length of 0 for varargs" do
+    klass = Class.new do
+      def initialize(*args); args; end
+    end
+    rb_new = Rhino::Ruby::Constructor.wrap klass
+    rb_new.getArity.should == 0
+    rb_new.getLength.should == 0
+  end
+  
   describe 'with scope' do
     
     before do