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ruby--ruby/spec/ruby/core/array/union_spec.rb
nobu 9bc73cd81f array.c: improve operations on small arrays
[Feature #13884]

Reduce number of memory allocations for "and", "or" and "diff"
operations on small arrays

Very often, arrays are used to filter parameters and to select
interesting items from 2 collections and very often these
collections are small enough, for example:

```ruby
SAFE_COLUMNS = [:id, :title, :created_at]

def columns
  @all_columns & SAFE_COLUMNS
end
```

In this patch, I got rid of unnecessary memory allocations for
small arrays when "and", "or" and "diff" operations are performed.

name             | HEAD  | PATCH
-----------------+------:+------:
array_small_and  | 0.615 | 0.263
array_small_diff | 0.676 | 0.282
array_small_or   | 0.953 | 0.463

name             | PATCH
-----------------+------:
array_small_and  | 2.343
array_small_diff | 2.392
array_small_or   | 2.056

name             | HEAD  | PATCH
-----------------+------:+------:
array_small_and  | 1.429 | 1.005
array_small_diff | 1.493 | 0.878
array_small_or   | 1.672 | 1.152

name             | PATCH
-----------------+------:
array_small_and  | 1.422
array_small_diff | 1.700
array_small_or   | 1.452

Author:    Dmitry Bochkarev <dimabochkarev@gmail.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60057 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
2017-09-29 07:43:22 +00:00

82 lines
2.8 KiB
Ruby

require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)
describe "Array#|" do
it "returns an array of elements that appear in either array (union)" do
([] | []).should == []
([1, 2] | []).should == [1, 2]
([] | [1, 2]).should == [1, 2]
([ 1, 2, 3, 4 ] | [ 3, 4, 5 ]).should == [1, 2, 3, 4, 5]
end
it "creates an array with no duplicates" do
([ 1, 2, 3, 1, 4, 5 ] | [ 1, 3, 4, 5, 3, 6 ]).should == [1, 2, 3, 4, 5, 6]
end
it "creates an array with elements in order they are first encountered" do
([ 1, 2, 3, 1 ] | [ 1, 3, 4, 5 ]).should == [1, 2, 3, 4, 5]
end
it "properly handles recursive arrays" do
empty = ArraySpecs.empty_recursive_array
(empty | empty).should == empty
array = ArraySpecs.recursive_array
(array | []).should == [1, 'two', 3.0, array]
([] | array).should == [1, 'two', 3.0, array]
(array | array).should == [1, 'two', 3.0, array]
(array | empty).should == [1, 'two', 3.0, array, empty]
end
it "tries to convert the passed argument to an Array using #to_ary" do
obj = mock('[1,2,3]')
obj.should_receive(:to_ary).and_return([1, 2, 3])
([0] | obj).should == ([0] | [1, 2, 3])
end
# MRI follows hashing semantics here, so doesn't actually call eql?/hash for Fixnum/Symbol
it "acts as if using an intermediate hash to collect values" do
not_supported_on :opal do
([5.0, 4.0] | [5, 4]).should == [5.0, 4.0, 5, 4]
end
str = "x"
([str] | [str.dup]).should == [str]
obj1 = mock('1')
obj2 = mock('2')
obj1.stub!(:hash).and_return(0)
obj2.stub!(:hash).and_return(0)
obj2.should_receive(:eql?).at_least(1).and_return(true)
([obj1] | [obj2]).should == [obj1]
([obj1, obj1, obj2, obj2] | [obj2]).should == [obj1]
obj1 = mock('3')
obj2 = mock('4')
obj1.stub!(:hash).and_return(0)
obj2.stub!(:hash).and_return(0)
obj2.should_receive(:eql?).at_least(1).and_return(false)
([obj1] | [obj2]).should == [obj1, obj2]
([obj1, obj1, obj2, obj2] | [obj2]).should == [obj1, obj2]
end
it "does not return subclass instances for Array subclasses" do
(ArraySpecs::MyArray[1, 2, 3] | []).should be_an_instance_of(Array)
(ArraySpecs::MyArray[1, 2, 3] | ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
([] | ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
end
it "does not call to_ary on array subclasses" do
([1, 2] | ArraySpecs::ToAryArray[5, 6]).should == [1, 2, 5, 6]
end
it "properly handles an identical item even when its #eql? isn't reflexive" do
x = mock('x')
x.stub!(:hash).and_return(42)
x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
([x] | [x]).should == [x]
end
end