feat: add stringx.ToCamelCase (#2622)

core/stringx/strings.go

@@ -2,6 +2,7 @@ package stringx
 
 import (
 	"errors"
+	"unicode"
 
 	"github.com/zeromicro/go-zero/core/lang"
 )
@@ -168,6 +169,15 @@ func TakeWithPriority(fns ...func() string) string {
 	return ""
 }
 
+// ToCamelCase returns the string that converts the first letter to lowercase.
+func ToCamelCase(s string) string {
+	for i, v := range s {
+		return string(unicode.ToLower(v)) + s[i+1:]
+	}
+
+	return ""
+}
+
 // Union merges the strings in first and second.
 func Union(first, second []string) []string {
 	set := make(map[string]lang.PlaceholderType)

core/stringx/strings_test.go

@@ -396,6 +396,61 @@ func TestTakeWithPriority(t *testing.T) {
 	}
 }
 
+func TestToCamelCase(t *testing.T) {
+	tests := []struct {
+		input  string
+		expect string
+	}{
+		{
+			input:  "",
+			expect: "",
+		},
+		{
+			input:  "A",
+			expect: "a",
+		},
+		{
+			input:  "a",
+			expect: "a",
+		},
+		{
+			input:  "hello_world",
+			expect: "hello_world",
+		},
+		{
+			input:  "Hello_world",
+			expect: "hello_world",
+		},
+		{
+			input:  "hello_World",
+			expect: "hello_World",
+		},
+		{
+			input:  "helloWorld",
+			expect: "helloWorld",
+		},
+		{
+			input:  "HelloWorld",
+			expect: "helloWorld",
+		},
+		{
+			input:  "hello World",
+			expect: "hello World",
+		},
+		{
+			input:  "Hello World",
+			expect: "hello World",
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.input, func(t *testing.T) {
+			assert.Equal(t, test.expect, ToCamelCase(test.input))
+		})
+	}
+}
+
 func TestUnion(t *testing.T) {
 	first := []string{
 		"one",