1 files changed, 280 insertions, 0 deletions
diff --git a/test/typeparam/sets.go b/test/typeparam/sets.go
new file mode 100644
index 0000000..bd08ad7
--- /dev/null
+++ b/test/typeparam/sets.go
@@ -0,0 +1,280 @@
+// run
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"sort"
+)
+
+// _Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func _SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// A _Set is a set of elements of some type.
+type _Set[Elem comparable] struct {
+	m map[Elem]struct{}
+}
+
+// _Make makes a new set.
+func _Make[Elem comparable]() _Set[Elem] {
+	return _Set[Elem]{m: make(map[Elem]struct{})}
+}
+
+// Add adds an element to a set.
+func (s _Set[Elem]) Add(v Elem) {
+	s.m[v] = struct{}{}
+}
+
+// Delete removes an element from a set. If the element is not present
+// in the set, this does nothing.
+func (s _Set[Elem]) Delete(v Elem) {
+	delete(s.m, v)
+}
+
+// Contains reports whether v is in the set.
+func (s _Set[Elem]) Contains(v Elem) bool {
+	_, ok := s.m[v]
+	return ok
+}
+
+// Len returns the number of elements in the set.
+func (s _Set[Elem]) Len() int {
+	return len(s.m)
+}
+
+// Values returns the values in the set.
+// The values will be in an indeterminate order.
+func (s _Set[Elem]) Values() []Elem {
+	r := make([]Elem, 0, len(s.m))
+	for v := range s.m {
+		r = append(r, v)
+	}
+	return r
+}
+
+// _Equal reports whether two sets contain the same elements.
+func _Equal[Elem comparable](s1, s2 _Set[Elem]) bool {
+	if len(s1.m) != len(s2.m) {
+		return false
+	}
+	for v1 := range s1.m {
+		if !s2.Contains(v1) {
+			return false
+		}
+	}
+	return true
+}
+
+// Copy returns a copy of s.
+func (s _Set[Elem]) Copy() _Set[Elem] {
+	r := _Set[Elem]{m: make(map[Elem]struct{}, len(s.m))}
+	for v := range s.m {
+		r.m[v] = struct{}{}
+	}
+	return r
+}
+
+// AddSet adds all the elements of s2 to s.
+func (s _Set[Elem]) AddSet(s2 _Set[Elem]) {
+	for v := range s2.m {
+		s.m[v] = struct{}{}
+	}
+}
+
+// SubSet removes all elements in s2 from s.
+// Values in s2 that are not in s are ignored.
+func (s _Set[Elem]) SubSet(s2 _Set[Elem]) {
+	for v := range s2.m {
+		delete(s.m, v)
+	}
+}
+
+// Intersect removes all elements from s that are not present in s2.
+// Values in s2 that are not in s are ignored.
+func (s _Set[Elem]) Intersect(s2 _Set[Elem]) {
+	for v := range s.m {
+		if !s2.Contains(v) {
+			delete(s.m, v)
+		}
+	}
+}
+
+// Iterate calls f on every element in the set.
+func (s _Set[Elem]) Iterate(f func(Elem)) {
+	for v := range s.m {
+		f(v)
+	}
+}
+
+// Filter deletes any elements from s for which f returns false.
+func (s _Set[Elem]) Filter(f func(Elem) bool) {
+	for v := range s.m {
+		if !f(v) {
+			delete(s.m, v)
+		}
+	}
+}
+
+func TestSet() {
+	s1 := _Make[int]()
+	if got := s1.Len(); got != 0 {
+		panic(fmt.Sprintf("Len of empty set = %d, want 0", got))
+	}
+	s1.Add(1)
+	s1.Add(1)
+	s1.Add(1)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	s1.Add(2)
+	s1.Add(3)
+	s1.Add(4)
+	if got := s1.Len(); got != 4 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 4", s1, got))
+	}
+	if !s1.Contains(1) {
+		panic(fmt.Sprintf("(%v).Contains(1) == false, want true", s1))
+	}
+	if s1.Contains(5) {
+		panic(fmt.Sprintf("(%v).Contains(5) == true, want false", s1))
+	}
+	vals := s1.Values()
+	sort.Ints(vals)
+	w1 := []int{1, 2, 3, 4}
+	if !_SliceEqual(vals, w1) {
+		panic(fmt.Sprintf("(%v).Values() == %v, want %v", s1, vals, w1))
+	}
+}
+
+func TestEqual() {
+	s1 := _Make[string]()
+	s2 := _Make[string]()
+	if !_Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s1.Add("hello")
+	s1.Add("world")
+	if got := s1.Len(); got != 2 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 2", s1, got))
+	}
+	if _Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
+	}
+}
+
+func TestCopy() {
+	s1 := _Make[float64]()
+	s1.Add(0)
+	s2 := s1.Copy()
+	if !_Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s1.Add(1)
+	if _Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
+	}
+}
+
+func TestAddSet() {
+	s1 := _Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := _Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.AddSet(s2)
+	if got := s1.Len(); got != 3 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 3", s1, got))
+	}
+	s2.Add(1)
+	if !_Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
+	}
+}
+
+func TestSubSet() {
+	s1 := _Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := _Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.SubSet(s2)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	if vals, want := s1.Values(), []int{1}; !_SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after SubSet got %v, want %v", vals, want))
+	}
+}
+
+func TestIntersect() {
+	s1 := _Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := _Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.Intersect(s2)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	if vals, want := s1.Values(), []int{2}; !_SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after Intersect got %v, want %v", vals, want))
+	}
+}
+
+func TestIterate() {
+	s1 := _Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s1.Add(3)
+	s1.Add(4)
+	tot := 0
+	s1.Iterate(func(i int) { tot += i })
+	if tot != 10 {
+		panic(fmt.Sprintf("total of %v == %d, want 10", s1, tot))
+	}
+}
+
+func TestFilter() {
+	s1 := _Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s1.Add(3)
+	s1.Filter(func(v int) bool { return v%2 == 0 })
+	if vals, want := s1.Values(), []int{2}; !_SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after Filter got %v, want %v", vals, want))
+	}
+
+}
+
+func main() {
+	TestSet()
+	TestEqual()
+	TestCopy()
+	TestAddSet()
+	TestSubSet()
+	TestIntersect()
+	TestIterate()
+	TestFilter()
+}