lib/extensions/enumerable.rb in extensions-0.5.0 vs lib/extensions/enumerable.rb in extensions-0.6.0

@@ -165,9 +165,76 @@
   end
 end
 
 
 #
+# * Enumerable#none?
+#
+ExtensionsProject.implement(Enumerable, :none?) do
+  module Enumerable
+    #
+    # Enumerable#none? is the logical opposite of the builtin method Enumerable#any?.  It
+    # returns +true+ if and only if _none_ of the elements in the collection satisfy the
+    # predicate.
+    #
+    # If no predicate is provided, Enumerable#none? returns +true+ if and only if _none_ of the
+    # elements have a true value (i.e. not +nil+ or +false+).
+    #
+    #   [].none?                      # true
+    #   [nil].none?                   # true
+    #   [5,8,9].none?                 # false
+    #   (1...10).none? { |n| n < 0 }  # true
+    #   (1...10).none? { |n| n > 0 }  # false
+    #
+    def none?  # :yield: e
+      if block_given?
+        not self.any? { |e| yield e }
+      else
+        not self.any?
+      end
+    end
+  end
+end
+
+
+#
+# * Enumerable#one?
+#
+ExtensionsProject.implement(Enumerable, :one?) do
+  module Enumerable
+    #
+    # Enumerable#one? returns +true+ if and only if <em>exactly one</em> element in the
+    # collection satisfies the given predicate.
+    #
+    # If no predicate is provided, Enumerable#one? returns +true+ if and only if <em>exactly
+    # one</em> element has a true value (i.e. not +nil+ or +false+).
+    #
+    #   [].one?                      # false
+    #   [nil].one?                   # false
+    #   [5].one?                     # true
+    #   [5,8,9].one?                 # false
+    #   (1...10).one? { |n| n == 5 } # true
+    #   (1...10).one? { |n| n < 5 }  # false
+    #
+    def one?  # :yield: e
+      matches = 0
+      if block_given?
+        self.each do |e|
+          if yield(e)
+            matches += 1
+            return false if matches > 1
+          end
+        end
+        return (matches == 1)
+      else
+        one? { |e| e }
+      end
+    end
+  end
+end
+
+
+#
 # * Object.in?
 # This has special treatment: it's included here and in object.rb, so we don't
 # want a warning if it's alredy defined.
 #
 unless Object.method_defined?(:in?)