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[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
87 lines
2.8 KiB
Ruby
87 lines
2.8 KiB
Ruby
require File.expand_path('../../../spec_helper', __FILE__)
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require File.expand_path('../fixtures/classes', __FILE__)
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describe "Array#&" do
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it "creates an array with elements common to both arrays (intersection)" do
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([] & []).should == []
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([1, 2] & []).should == []
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([] & [1, 2]).should == []
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([ 1, 3, 5 ] & [ 1, 2, 3 ]).should == [1, 3]
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end
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it "creates an array with no duplicates" do
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([ 1, 1, 3, 5 ] & [ 1, 2, 3 ]).uniq!.should == nil
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end
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it "creates an array with elements in order they are first encountered" do
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([ 1, 2, 3, 2, 5 ] & [ 5, 2, 3, 4 ]).should == [2, 3, 5]
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end
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it "does not modify the original Array" do
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a = [1, 1, 3, 5]
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a & [1, 2, 3]
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a.should == [1, 1, 3, 5]
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end
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it "properly handles recursive arrays" do
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empty = ArraySpecs.empty_recursive_array
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(empty & empty).should == empty
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(ArraySpecs.recursive_array & []).should == []
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([] & ArraySpecs.recursive_array).should == []
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(ArraySpecs.recursive_array & ArraySpecs.recursive_array).should == [1, 'two', 3.0, ArraySpecs.recursive_array]
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end
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it "tries to convert the passed argument to an Array using #to_ary" do
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obj = mock('[1,2,3]')
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obj.should_receive(:to_ary).and_return([1, 2, 3])
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([1, 2] & obj).should == ([1, 2])
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end
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it "determines equivalence between elements in the sense of eql?" do
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not_supported_on :opal do
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([5.0, 4.0] & [5, 4]).should == []
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end
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str = "x"
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([str] & [str.dup]).should == [str]
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obj1 = mock('1')
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obj2 = mock('2')
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obj1.stub!(:hash).and_return(0)
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obj2.stub!(:hash).and_return(0)
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obj1.should_receive(:eql?).at_least(1).and_return(true)
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obj2.should_receive(:eql?).at_least(1).and_return(true)
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([obj1] & [obj2]).should == [obj1]
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([obj1, obj1, obj2, obj2] & [obj2]).should == [obj1]
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obj1 = mock('3')
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obj2 = mock('4')
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obj1.stub!(:hash).and_return(0)
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obj2.stub!(:hash).and_return(0)
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obj1.should_receive(:eql?).at_least(1).and_return(false)
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([obj1] & [obj2]).should == []
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([obj1, obj1, obj2, obj2] & [obj2]).should == [obj2]
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end
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it "does return subclass instances for Array subclasses" do
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(ArraySpecs::MyArray[1, 2, 3] & []).should be_an_instance_of(Array)
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(ArraySpecs::MyArray[1, 2, 3] & ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
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([] & ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
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end
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it "does not call to_ary on array subclasses" do
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([5, 6] & ArraySpecs::ToAryArray[1, 2, 5, 6]).should == [5, 6]
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end
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it "properly handles an identical item even when its #eql? isn't reflexive" do
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x = mock('x')
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x.stub!(:hash).and_return(42)
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x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
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([x] & [x]).should == [x]
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end
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end
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