add FromMap constructor

errors.go

@@ -1,9 +1,15 @@
 package timedmap
 
-import "errors"
+import (
+	"errors"
+)
 
 var (
 	// ErrKeyNotFound is returned when a key was
 	// requested which is not present in the map.
 	ErrKeyNotFound = errors.New("key not found")
+
+	// ErrValueNoMap is returned when a value passed
+	// expected was of another type.
+	ErrValueNoMap = errors.New("value is not of type map")
 )

timedmap.go

@@ -1,6 +1,7 @@
 package timedmap
 
 import (
+	"reflect"
 	"sync"
 	"time"
 )
@@ -53,23 +54,39 @@ type element struct {
 // can also be used to re-define the specification of
 // the cleanup loop when already running if you want to.
 func New(cleanupTickTime time.Duration, tickerChan ...<-chan time.Time) *TimedMap {
-	tm := &TimedMap{
-		container:       make(map[keyWrap]*element),
-		cleanerStopChan: make(chan bool),
-		elementPool: &sync.Pool{
-			New: func() interface{} {
-				return new(element)
-			},
-		},
+	return newTimedMap(make(map[keyWrap]*element), cleanupTickTime, tickerChan)
+}
+
+func FromMap(
+	m interface{},
+	expiration time.Duration,
+	cleanupTickTime time.Duration,
+	tickerChan ...<-chan time.Time,
+) (*TimedMap, error) {
+	mv := reflect.ValueOf(m)
+	if mv.Kind() != reflect.Map {
+		return nil, ErrValueNoMap
 	}
 
-	if len(tickerChan) > 0 {
-		tm.StartCleanerExternal(tickerChan[0])
-	} else if cleanupTickTime > 0 {
-		tm.StartCleanerInternal(cleanupTickTime)
+	exp := time.Now().Add(expiration)
+	container := make(map[keyWrap]*element)
+
+	iter := mv.MapRange()
+	for iter.Next() {
+		key := iter.Key()
+		val := iter.Value()
+		kw := keyWrap{
+			sec: 0,
+			key: key.Interface(),
+		}
+		el := &element{
+			value:   val.Interface(),
+			expires: exp,
+		}
+		container[kw] = el
 	}
 
-	return tm
+	return newTimedMap(container, cleanupTickTime, tickerChan), nil
 }
 
 // Section returns a sectioned subset of
@@ -383,3 +400,27 @@ func (tm *TimedMap) getSnapshot(sec int) (m map[interface{}]interface{}) {
 
 	return
 }
+
+func newTimedMap(
+	container map[keyWrap]*element,
+	cleanupTickTime time.Duration,
+	tickerChan []<-chan time.Time,
+) *TimedMap {
+	tm := &TimedMap{
+		container:       container,
+		cleanerStopChan: make(chan bool),
+		elementPool: &sync.Pool{
+			New: func() interface{} {
+				return new(element)
+			},
+		},
+	}
+
+	if len(tickerChan) > 0 {
+		tm.StartCleanerExternal(tickerChan[0])
+	} else if cleanupTickTime > 0 {
+		tm.StartCleanerInternal(cleanupTickTime)
+	}
+
+	return tm
+}

timedmap_test.go

@@ -22,6 +22,65 @@ func TestNew(t *testing.T) {
 	assert.True(t, tm.cleanerRunning)
 }
 
+func TestFromMap(t *testing.T) {
+	t.Run("map-string-string", func(t *testing.T) {
+		tm, err := FromMap(
+			map[string]string{"foo": "bar", "bazz": "fuzz"},
+			200*time.Millisecond, 10*time.Millisecond)
+		assert.Nil(t, err)
+
+		assert.EqualValues(t, "bar", tm.GetValue("foo"))
+		assert.EqualValues(t, "fuzz", tm.GetValue("bazz"))
+
+		time.Sleep(500 * time.Millisecond)
+
+		assert.False(t, tm.Contains("foo"))
+		assert.False(t, tm.Contains("bazz"))
+	})
+
+	t.Run("map-int-interface", func(t *testing.T) {
+		tm, err := FromMap(
+			map[int]interface{}{1: "foo", 2: 3.456},
+			200*time.Millisecond, 10*time.Millisecond)
+		assert.Nil(t, err)
+
+		assert.EqualValues(t, "foo", tm.GetValue(1))
+		assert.EqualValues(t, 3.456, tm.GetValue(2))
+
+		time.Sleep(500 * time.Millisecond)
+
+		assert.False(t, tm.Contains(1))
+		assert.False(t, tm.Contains(2))
+	})
+
+	t.Run("map-interface-interface", func(t *testing.T) {
+		tm, err := FromMap(
+			map[interface{}]interface{}{1: "foo", "a": 3.456},
+			200*time.Millisecond, 10*time.Millisecond)
+		assert.Nil(t, err)
+
+		assert.EqualValues(t, "foo", tm.GetValue(1))
+		assert.EqualValues(t, 3.456, tm.GetValue("a"))
+
+		time.Sleep(500 * time.Millisecond)
+
+		assert.False(t, tm.Contains(1))
+		assert.False(t, tm.Contains("a"))
+	})
+
+	t.Run("non-map", func(t *testing.T) {
+		_, err := FromMap(
+			"this is not a map",
+			200*time.Millisecond, 10*time.Millisecond)
+		assert.ErrorIs(t, err, ErrValueNoMap)
+
+		_, err = FromMap(
+			nil,
+			200*time.Millisecond, 10*time.Millisecond)
+		assert.ErrorIs(t, err, ErrValueNoMap)
+	})
+}
+
 func TestFlush(t *testing.T) {
 	tm := New(dCleanupTick)