Add generic set type (#21408)

This PR adds a generic set type to get rid of maps used as sets.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

3 files changed, 94 insertions, 14 deletions

diff --git a/modules/container/map.go b/modules/container/map.go
deleted file mode 100644
index 3519de0951..0000000000
--- a/modules/container/map.go
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2022 The Gitea Authors. All rights reserved.
-// Use of this source code is governed by a MIT-style
-// license that can be found in the LICENSE file.
-
-package container
-
-// KeysInt64 returns keys slice for a map with int64 key
-func KeysInt64(m map[int64]struct{}) []int64 {
-	keys := make([]int64, 0, len(m))
-	for k := range m {
-		keys = append(keys, k)
-	}
-	return keys
-}
diff --git a/modules/container/set.go b/modules/container/set.go
new file mode 100644
index 0000000000..4b4c74525d
--- /dev/null
+++ b/modules/container/set.go
@@ -0,0 +1,57 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package container
+
+type Set[T comparable] map[T]struct{}
+
+// SetOf creates a set and adds the specified elements to it.
+func SetOf[T comparable](values ...T) Set[T] {
+	s := make(Set[T], len(values))
+	s.AddMultiple(values...)
+	return s
+}
+
+// Add adds the specified element to a set.
+// Returns true if the element is added; false if the element is already present.
+func (s Set[T]) Add(value T) bool {
+	if _, has := s[value]; !has {
+		s[value] = struct{}{}
+		return true
+	}
+	return false
+}
+
+// AddMultiple adds the specified elements to a set.
+func (s Set[T]) AddMultiple(values ...T) {
+	for _, value := range values {
+		s.Add(value)
+	}
+}
+
+// Contains determines whether a set contains the specified element.
+// Returns true if the set contains the specified element; otherwise, false.
+func (s Set[T]) Contains(value T) bool {
+	_, has := s[value]
+	return has
+}
+
+// Remove removes the specified element.
+// Returns true if the element is successfully found and removed; otherwise, false.
+func (s Set[T]) Remove(value T) bool {
+	if _, has := s[value]; has {
+		delete(s, value)
+		return true
+	}
+	return false
+}
+
+// Values gets a list of all elements in the set.
+func (s Set[T]) Values() []T {
+	keys := make([]T, 0, len(s))
+	for k := range s {
+		keys = append(keys, k)
+	}
+	return keys
+}
diff --git a/modules/container/set_test.go b/modules/container/set_test.go
new file mode 100644
index 0000000000..6654763e56
--- /dev/null
+++ b/modules/container/set_test.go
@@ -0,0 +1,37 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package container
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSet(t *testing.T) {
+	s := make(Set[string])
+
+	assert.True(t, s.Add("key1"))
+	assert.False(t, s.Add("key1"))
+	assert.True(t, s.Add("key2"))
+
+	assert.True(t, s.Contains("key1"))
+	assert.True(t, s.Contains("key2"))
+	assert.False(t, s.Contains("key3"))
+
+	assert.True(t, s.Remove("key2"))
+	assert.False(t, s.Contains("key2"))
+
+	assert.False(t, s.Remove("key3"))
+
+	s.AddMultiple("key4", "key5")
+	assert.True(t, s.Contains("key4"))
+	assert.True(t, s.Contains("key5"))
+
+	s = SetOf("key6", "key7")
+	assert.False(t, s.Contains("key1"))
+	assert.True(t, s.Contains("key6"))
+	assert.True(t, s.Contains("key7"))
+}