86 lines
1.6 KiB
Ruby
86 lines
1.6 KiB
Ruby
# frozen_string_literal: true
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require 'minitest/autorun'
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require 'minitest/pride'
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require_relative '../lib/mutual_recursion'
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class InventoryTest < Minitest::Test
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def test_terminal_value
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tail = terminal_value(42)
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assert_equal(42, tail.invoke)
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end
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def test_single_recursion
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tail = tail_call { terminal_value(42) }
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assert_equal(42, tail.invoke)
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end
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def test_several_recursions
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tail = tail_call { tail_call { tail_call { terminal_value(42) } } }
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assert_equal(42, tail.invoke)
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end
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def test_mutual_tail_recursion
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tail = one(50_000)
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assert_equal(50_001, tail.invoke)
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end
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def test_direct_tail_recursion
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tail = direct(50_000)
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assert_equal(50_001, tail.invoke)
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end
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def test_recursive_function_can_return_lambda
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tail = lambda_returning
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assert_kind_of(Proc, tail.invoke)
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end
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def test_recursive_function_can_return_proc
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tail = proc_returning
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assert_kind_of(Proc, tail.invoke)
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end
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def test_non_tail_call_detected
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tail = bad_return
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assert_raises(TypeError) { tail.invoke }
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end
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end
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class TailCallDecoy
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attr_reader :value, :block
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def initialize
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@value = 99
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@block = proc { 25 }
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end
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end
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def one(x, y = 0)
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return terminal_value(y) if x.negative?
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tail_call { two(x, y + 1) }
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end
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def two(x, y)
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tail_call { one(x - 1, y) }
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end
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def direct(x, y = 0)
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return terminal_value(y) if x.negative?
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tail_call { direct(x - 1, y + 1) }
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end
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def lambda_returning
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terminal_value(-> { 24 })
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end
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def proc_returning
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terminal_value(proc { 24 })
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end
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def bad_return
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tail_call { TailCallDecoy.new }
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end
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