enumerator.c: Introduce Enumerator::ArithmeticSequence

This commit introduces new core class Enumerator::ArithmeticSequence.
Enumerator::ArithmeticSequence is a subclass of Enumerator, and
represents a number generator of an arithmetic sequence.

After this commit, Numeric#step and Range#step without blocks
returned an ArithmeticSequence object instead of an Enumerator.

This class introduces the following incompatibilities:

- You can create a zero-step ArithmeticSequence,
  and its size is not ArgumentError, but Infinity.
- You can create a negative-step ArithmeticSequence from a range.

[ruby-core:82816] [Feature #13904]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64205 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 7 insertions, 7 deletions

diff --git a/spec/ruby/core/numeric/shared/step.rb b/spec/ruby/core/numeric/shared/step.rb
index fa703b7554..f058c64a50 100644
--- a/spec/ruby/core/numeric/shared/step.rb
+++ b/spec/ruby/core/numeric/shared/step.rb
@@ -259,15 +259,15 @@ describe :numeric_step, :shared => true do
 
   describe "when no block is given" do
     it "returns an Enumerator when step is 0" do
-      1.send(@method, *@step_args.call(2, 0)).should be_an_instance_of(Enumerator)
+      1.send(@method, *@step_args.call(2, 0)).should be_an_instance_of(Enumerator::ArithmeticSequence)
     end
 
     it "returns an Enumerator when not passed a block and self > stop" do
-      1.send(@method, *@step_args.call(0, 2)).should be_an_instance_of(Enumerator)
+      1.send(@method, *@step_args.call(0, 2)).should be_an_instance_of(Enumerator::ArithmeticSequence)
     end
 
     it "returns an Enumerator when not passed a block and self < stop" do
-      1.send(@method, *@step_args.call(2, 3)).should be_an_instance_of(Enumerator)
+      1.send(@method, *@step_args.call(2, 3)).should be_an_instance_of(Enumerator::ArithmeticSequence)
     end
 
     it "returns an Enumerator that uses the given step" do
diff --git a/spec/ruby/core/numeric/step_spec.rb b/spec/ruby/core/numeric/step_spec.rb
index a932b4df73..54133f8810 100644
--- a/spec/ruby/core/numeric/step_spec.rb
+++ b/spec/ruby/core/numeric/step_spec.rb
@@ -23,23 +23,23 @@ describe "Numeric#step" do
 
     describe "when no block is given" do
       it "returns an Enumerator when step is 0" do
-        1.step(5, 0).should be_an_instance_of(Enumerator)
+        1.step(5, 0).should be_an_instance_of(Enumerator::ArithmeticSequence)
       end
 
       it "returns an Enumerator when step is 0.0" do
-        1.step(2, 0.0).should be_an_instance_of(Enumerator)
+        1.step(2, 0.0).should be_an_instance_of(Enumerator::ArithmeticSequence)
       end
 
       describe "returned Enumerator" do
         describe "size" do
           it "raises an ArgumentError when step is 0" do
             enum = 1.step(5, 0)
-            lambda { enum.size }.should raise_error(ArgumentError)
+            enum.size.should == Float::INFINITY
           end
 
           it "raises an ArgumentError when step is 0.0" do
             enum = 1.step(2, 0.0)
-            lambda { enum.size }.should raise_error(ArgumentError)
+            enum.size.should == Float::INFINITY
           end
         end
       end