refactor: func Close should be idempotent

kiwi.go

@@ -110,10 +110,15 @@ func (k *Kiwi) Analyze(text string, topN int, options AnalyzeOption) ([]TokenRes
 
 // Close frees the resource allocated for Kiwi and returns the exit status.
 // This must be called after New.
-//
 // Returns 0 if successful.
+// Safe to call multiple times.
 func (k *Kiwi) Close() int {
-	return int(C.kiwi_close(k.handler))
+	if k.handler != nil {
+		out := int(C.kiwi_close(k.handler))
+		k.handler = nil
+		return out
+	}
+	return 0
 }
 
 // KiwiBuilder is a wrapper for the kiwi C library.
@@ -130,28 +135,33 @@ func NewBuilder(modelPath string, numThread int, options BuildOption) *KiwiBuild
 }
 
 // AddWord set custom word with word, pos, score.
-func (k *KiwiBuilder) AddWord(word string, pos POSType, score float32) int {
-	return int(C.kiwi_builder_add_word(k.handler, C.CString(word), C.CString(string(pos)), C.float(score)))
+func (kb *KiwiBuilder) AddWord(word string, pos POSType, score float32) int {
+	return int(C.kiwi_builder_add_word(kb.handler, C.CString(word), C.CString(string(pos)), C.float(score)))
 }
 
 // LoadDict loads user dict with dict file path.
-func (k *KiwiBuilder) LoadDict(dictPath string) int {
-	return int(C.kiwi_builder_load_dict(k.handler, C.CString(dictPath)))
+func (kb *KiwiBuilder) LoadDict(dictPath string) int {
+	return int(C.kiwi_builder_load_dict(kb.handler, C.CString(dictPath)))
 }
 
 // Build creates kiwi instance with user word etc.
 func (kb *KiwiBuilder) Build() *Kiwi {
 	h := C.kiwi_builder_build(kb.handler)
-	defer C.kiwi_builder_close(kb.handler)
+	defer kb.Close()
 	return &Kiwi{
 		handler: h,
 	}
 }
 
 // Close frees the resource allocated for KiwiBuilder and returns the exit status.
 // This must be called after New but not need to called after Build.
-//
 // Returns 0 if successful.
-func (k *KiwiBuilder) Close() int {
-	return int(C.kiwi_builder_close(k.handler))
+// Safe to call multiple times.
+func (kb *KiwiBuilder) Close() int {
+	if kb.handler != nil {
+		out := int(C.kiwi_builder_close(kb.handler))
+		kb.handler = nil
+		return out
+	}
+	return 0
 }

kiwi_test.go

@@ -77,6 +77,9 @@ func TestAddWord(t *testing.T) {
 	kiwi := kb.Build()
 	res, _ := kiwi.Analyze("아버지가 방에 들어가신다", 1, KIWI_MATCH_ALL)
 
+	// kb should have been closed.
+	assert.Equal(t, 0, kb.Close())
+
 	expected := []TokenResult{
 		{
 			Tokens: []TokenInfo{
@@ -130,6 +133,10 @@ func TestLoadDict(t *testing.T) {
 	assert.Equal(t, "", err)
 
 	kiwi := kb.Build()
+
+	// kb should have been closed already.
+	assert.Equal(t, 0, kb.Close())
+
 	res, _ := kiwi.Analyze("아버지가 방에 들어가신다", 1, KIWI_MATCH_ALL)
 
 	expected := []TokenResult{