feat: added RangeOf type

Author: joelmoss

README.md

@@ -92,6 +92,15 @@ sig name: T.RespondTo(:to_s)
 def create(name:); end
 ```
 
+#### `RangeOf`
+
+Value **MUST** be a Range of the given type
+
+```ruby
+sig name: T.RangeOf(Integer)
+def create(name: 1...2); end
+```
+
 #### `Any`
 
 Value **MUST** be any of the given list of values, that is, the value must be one of the given list.

lib/delivered/types.rb

@@ -13,6 +13,21 @@ def ===(value)
     end
   end
 
+  class RangeOfType
+    def initialize(type)
+      @type = type
+    end
+
+    def inspect = "Range(#{@type&.inspect})"
+
+    def ===(value)
+      Range === value && (
+        (@type === value.begin && (nil === value.end || @type === value.end)) ||
+        (@type === value.end && nil === value.begin)
+      )
+    end
+  end
+
   class RespondToType
     def initialize(*methods)
       @methods = methods
@@ -53,6 +68,7 @@ module Types
     module_function
 
     def Nilable(type = nil) = NilableType.new(type)
+    def RangeOf(type = nil) = RangeOfType.new(type)
     def RespondTo(*methods) = RespondToType.new(*methods)
     def Any(*types) = AnyType.new(*types)
     def Boolean = BooleanType.new

test/delivered/types.rb

@@ -43,6 +43,24 @@
     end
   end
 
+  describe 'RangeOf' do
+    it 'should be a Range of given type' do
+      assert T.RangeOf(Integer) === (1..2)
+      assert T.RangeOf(Integer) === (..2)
+      assert T.RangeOf(Integer) === (1..)
+    end
+
+    it 'raises when not a Range' do
+      expect { 1 => ^(T.RangeOf(Integer)) }.to raise_exception NoMatchingPatternError
+    end
+
+    it 'raises when not a Range of given type' do
+      expect { 1..2 => ^(T.RangeOf(String)) }.to raise_exception NoMatchingPatternError
+      expect { 1.. => ^(T.RangeOf(String)) }.to raise_exception NoMatchingPatternError
+      expect { ..2 => ^(T.RangeOf(String)) }.to raise_exception NoMatchingPatternError
+    end
+  end
+
   describe 'Boolean' do
     it 'should be true or false' do
       assert T.Boolean === true