Add Sorted method (#127)

* Add Sorted method

This is a varient on `slices.Sorted` that makes it easy to get a sorted slice. This makes it easy to get the elements of the set into a sorted slice. Quite handy when using sets to build up unique elements but then needing a well defined iteration order.

* Move to own file that can be build tagged

* Also test go 1.21

* Fix error messages in test

.github/workflows/ci.yml

@@ -4,7 +4,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.20.1]
+        go-version: [1.20.1, 1.21.1]
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:

sorted.go

@@ -0,0 +1,42 @@
+//go:build go1.21
+// +build go1.21
+
+/*
+Open Source Initiative OSI - The MIT License (MIT):Licensing
+
+The MIT License (MIT)
+Copyright (c) 2013 - 2023 Ralph Caraveo ([email protected])
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+package mapset
+
+import (
+	"cmp"
+	"slices"
+)
+
+// Sorted returns a sorted slice of a set of any ordered type in ascending order.
+// When sorting floating-point numbers, NaNs are ordered before other values.
+func Sorted[E cmp.Ordered](set Set[E]) []E {
+	s := set.ToSlice()
+	slices.Sort(s)
+	return s
+}

sorted_test.go

@@ -0,0 +1,61 @@
+//go:build go1.21
+// +build go1.21
+
+/*
+Open Source Initiative OSI - The MIT License (MIT):Licensing
+
+The MIT License (MIT)
+Copyright (c) 2013 - 2022 Ralph Caraveo ([email protected])
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+package mapset
+
+import (
+	"testing"
+)
+
+func Test_Sorted(t *testing.T) {
+	test := func(t *testing.T, ctor func(vals ...string) Set[string]) {
+		set := ctor("apple", "banana", "pear")
+		sorted := Sorted(set)
+
+		if len(sorted) != set.Cardinality() {
+			t.Errorf("Length of slice is not the same as the set. Expected: %d. Actual: %d", set.Cardinality(), len(sorted))
+		}
+
+		if sorted[0] != "apple" {
+			t.Errorf("Element 0 was not equal to apple: %s", sorted[0])
+		}
+		if sorted[1] != "banana" {
+			t.Errorf("Element 1 was not equal to banana: %s", sorted[1])
+		}
+		if sorted[2] != "pear" {
+			t.Errorf("Element 2 was not equal to pear: %s", sorted[2])
+		}
+	}
+
+	t.Run("Safe", func(t *testing.T) {
+		test(t, NewSet[string])
+	})
+	t.Run("Unsafe", func(t *testing.T) {
+		test(t, NewThreadUnsafeSet[string])
+	})
+}