add: snakecese converter

pkg/metrics/stats/snake_case_converter.go

@@ -52,12 +52,10 @@ var snakeConverters = []struct {
 	re   *regexp.Regexp
 	repl string
 }{
-	// example: LC -> L_C (e.g. CamelCase -> Camel_Case).
-	{regexp.MustCompile("([a-z])([A-Z])"), "${1}_${2}"},
-	// example: CCa -> C_Ca (e.g. CCamel -> C_Camel).
-	{regexp.MustCompile("([A-Z])([A-Z][a-z])"), "${1}_${2}"},
-	{regexp.MustCompile("\\."), "_"},
-	{regexp.MustCompile("-"), "_"},
+	{regexp.MustCompile(`([a-z])([A-Z])`), "${1}_${2}"},
+	{regexp.MustCompile(`([A-Z])([A-Z][a-z])`), "${1}_${2}"},
+	{regexp.MustCompile(`\.`), "_"},
+	{regexp.MustCompile(`-`), "_"},
 }
 
 var snakeMemoizer = memoizerType{

pkg/metrics/stats/snake_case_converter_test.go

@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package stats
+
+import "testing"
+
+func TestToSnakeCase(t *testing.T) {
+	var snakeCaseTest = []struct{ input, output string }{
+		{"Camel", "camel"},
+		{"Camel", "camel"},
+		{"CamelCase", "camel_case"},
+		{"CamelCaseAgain", "camel_case_again"},
+		{"CCamel", "c_camel"},
+		{"CCCamel", "cc_camel"},
+		{"CAMEL_CASE", "camel_case"},
+		{"camel-case", "camel_case"},
+		{"0", "0"},
+		{"0.0", "0_0"},
+		{"JSON", "json"},
+	}
+
+	for _, tt := range snakeCaseTest {
+		if got, want := toSnakeCase(tt.input), tt.output; got != want {
+			t.Errorf("want '%s', got '%s'", want, got)
+		}
+	}
+}
+
+func TestSnakeMemoize(t *testing.T) {
+	key := "Test"
+	if snakeMemoizer.memo[key] != "" {
+		t.Errorf("want '', got '%s'", snakeMemoizer.memo[key])
+	}
+	toSnakeCase(key)
+	if snakeMemoizer.memo[key] != "test" {
+		t.Errorf("want 'test', got '%s'", snakeMemoizer.memo[key])
+	}
+}