Refine signature of Numeric#step

And add type of `Enumerator::ArithmeticSequence`.

Author: ksss

core/enumerator/arithmetic_sequence.rbs

@@ -0,0 +1,70 @@
+# <!-- rdoc-file=enumerator.c -->
+# Enumerator::ArithmeticSequence is a subclass of Enumerator, that is a
+# representation of sequences of numbers with common difference. Instances of
+# this class can be generated by the Range#step and Numeric#step methods.
+#
+# The class can be used for slicing Array (see Array#slice) or custom
+# collections.
+#
+class Enumerator::ArithmeticSequence < Enumerator[Numeric]
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.begin -> num or nil
+  # -->
+  # Returns the number that defines the first element of this arithmetic sequence.
+  #
+  def begin: () -> Numeric?
+
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.end -> num or nil
+  # -->
+  # Returns the number that defines the end of this arithmetic sequence.
+  #
+  def end: () -> Numeric?
+
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.each {|i| block } -> aseq
+  #   - aseq.each              -> aseq
+  # -->
+  #
+  def each: () ?{ (Numeric) -> void } -> self
+
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.exclude_end? -> true or false
+  # -->
+  # Returns `true` if this arithmetic sequence excludes its end value.
+  #
+  def exclude_end?: () -> bool
+
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.last    -> num or nil
+  #   - aseq.last(n) -> an_array
+  # -->
+  # Returns the last number in this arithmetic sequence, or an array of the last
+  # `n` elements.
+  #
+  def last: () -> Numeric?
+          | (Integer n) -> Array[Numeric]
+
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.size -> num or nil
+  # -->
+  # Returns the number of elements in this arithmetic sequence if it is a finite
+  # sequence.  Otherwise, returns `nil`.
+  #
+  def size: () -> (Integer | Float)
+
+  # <!--
+  #   rdoc-file=enumerator.c
+  #   - aseq.step -> num
+  # -->
+  # Returns the number that defines the common difference between two adjacent
+  # elements in this arithmetic sequence.
+  #
+  def step: () -> Numeric
+end

core/float.rbs

@@ -898,11 +898,6 @@ class Float < Numeric
   def round: (?half: :up | :down | :even) -> Integer
            | (int digits, ?half: :up | :down | :even) -> (Integer | Float)
 
-  def step: (?Numeric limit, ?Numeric step) { (Float) -> void } -> self
-          | (?Numeric limit, ?Numeric step) -> Enumerator[Float, self]
-          | (?by: Numeric, ?to: Numeric) { (Float) -> void } -> self
-          | (?by: Numeric, ?to: Numeric) -> Enumerator[Float, self]
-
   def to_c: () -> Complex
 
   # <!--

core/integer.rbs

@@ -1187,17 +1187,6 @@ class Integer < Numeric
   #
   def size: () -> Integer
 
-  def step: () { (Integer) -> void } -> void
-          | (Numeric limit, ?Integer step) { (Integer) -> void } -> void
-          | (Numeric limit, ?Numeric step) { (Numeric) -> void } -> void
-          | (to: Numeric, ?by: Integer) { (Integer) -> void } -> void
-          | (by: Numeric, ?to: Numeric) { (Numeric) -> void } -> void
-          | () -> Enumerator[Integer, bot]
-          | (Numeric limit, ?Integer step) -> Enumerator[Integer]
-          | (Numeric limit, ?Numeric step) -> Enumerator[Numeric]
-          | (to: Numeric, ?by: Integer) -> Enumerator[Integer]
-          | (by: Numeric, ?to: Numeric) -> Enumerator[Numeric]
-
   # <!--
   #   rdoc-file=numeric.c
   #   - succ -> next_integer

core/numeric.rbs

@@ -749,9 +749,9 @@ class Numeric
   # where *n = (limit - self)/step*.
   #
   def step: (?Numeric limit, ?Numeric step) { (Numeric) -> void } -> self
-          | (?Numeric limit, ?Numeric step) -> Enumerator[Numeric, self]
+          | (?Numeric limit, ?Numeric step) -> Enumerator::ArithmeticSequence
           | (?by: Numeric, ?to: Numeric) { (Numeric) -> void } -> self
-          | (?by: Numeric, ?to: Numeric) -> Enumerator[Numeric, self]
+          | (?by: Numeric, ?to: Numeric) -> Enumerator::ArithmeticSequence
 
   # <!--
   #   rdoc-file=complex.c

core/rational.rbs

@@ -438,11 +438,6 @@ class Rational < Numeric
   def round: (?half: :up | :down | :even) -> Integer
            | (Integer digits, ?half: :up | :down | :even) -> (Integer | Rational)
 
-  def step: (?Numeric limit, ?Numeric step) { (Rational) -> void } -> self
-          | (?Numeric limit, ?Numeric step) -> Enumerator[Rational, self]
-          | (?by: Numeric, ?to: Numeric) { (Rational) -> void } -> self
-          | (?by: Numeric, ?to: Numeric) -> Enumerator[Rational, self]
-
   def to_c: () -> Complex
 
   # <!--

test/stdlib/Numeric_test.rb

@@ -0,0 +1,34 @@
+require_relative "test_helper"
+
+class NumericInstanceTest < Test::Unit::TestCase
+  include TestHelper
+
+  testing 'Numeric'
+
+  def test_step
+    assert_send_type '() -> Enumerator::ArithmeticSequence',
+                     1, :step
+    assert_send_type '() { (Integer) -> void } -> Integer',
+                     1, :step do |i| break_from_block i end
+    assert_send_type '(Float) -> Enumerator::ArithmeticSequence',
+                     1, :step, 1.5
+    assert_send_type '(Float) { (Float) -> void } -> Integer',
+                     1, :step, 1.5 do |i| break_from_block i end
+    assert_send_type '(Integer, Float) -> Enumerator::ArithmeticSequence',
+                     1r, :step, 2, 0.2
+    assert_send_type '(Integer, Float) { (Float) -> void } -> Rational',
+                     1r, :step, 2, 0.2 do |i| end
+    assert_send_type '(to: Rational) -> Enumerator::ArithmeticSequence',
+                     1, :step, to: 2r
+    assert_send_type '(to: Rational) { (Integer) -> void } -> Integer',
+                     1, :step, to: 2r do |i| end
+    assert_send_type '(by: Float) -> Enumerator::ArithmeticSequence',
+                     1, :step, by: 0.2
+    assert_send_type '(by: Float) { (Float) -> void } -> Rational',
+                     1, :step, by: 0.2 do |i| break_from_block i end
+    assert_send_type '(to: Rational, by: Float) -> Enumerator::ArithmeticSequence',
+                     1, :step, to: 3r, by: 0.2
+    assert_send_type '(to: Rational, by: Float) { (Float) -> void } -> Rational',
+                     1, :step, to: 3r, by: 0.2 do |i| break_from_block i end
+   end
+end

test/stdlib/enumerator/ArithmeticSequence_test.rb

@@ -0,0 +1,45 @@
+require_relative "../test_helper"
+
+class EnumeratorArithmeticSequenceInstanceTest < Test::Unit::TestCase
+  include TestHelper
+
+  testing "::Enumerator::ArithmeticSequence"
+
+  def test_begin
+    assert_send_type "() -> Integer", 1.step(2), :begin
+    assert_send_type "() -> nil", (..3).step(1), :begin
+  end
+
+  def test_end
+    assert_send_type "() -> Integer", 1.step(2), :end
+    assert_send_type "() -> nil", (1..).step(1), :end
+  end
+
+  def test_each
+    assert_send_type "() -> Enumerator::ArithmeticSequence", 1.step(2), :each
+    assert_send_type "() { (Integer) -> void } -> Enumerator::ArithmeticSequence", 1.step(2), :each do |i| end
+    assert_send_type "() { (Float) -> void } -> Enumerator::ArithmeticSequence", 1.0.step(2), :each do |i| end
+    assert_send_type "() { (Float) -> void } -> Enumerator::ArithmeticSequence", 1.step(2.0), :each do |i| end
+    assert_send_type "() { (Float) -> void } -> Enumerator::ArithmeticSequence", 1.step(2, 1.0), :each do |i| end
+  end
+
+  def test_exclude_end?
+    assert_send_type "() -> bool", 1.step(2), :exclude_end?
+  end
+
+  def test_first
+    assert_send_type "() -> Integer", 1.step(2), :first
+  end
+
+  def test_last
+    assert_send_type "() -> Integer", 1.step(2), :last
+  end
+
+  def test_size
+    assert_send_type "() -> Integer", 1.step(2), :size
+  end
+
+  def test_step
+    assert_send_type "() -> Integer", 1.step(2), :step
+  end
+end