feat userver/universal/utils: functions SnakeCaseToCamel/ScreamingSnakeCaseToCamel

Tiket: https://nda.ya.ru/t/runvhTI57NiYa9
commit_hash:e9fcd96123e688f633b70ec0dd778fc59c8e1b98

Author: ermakoveg

universal/include/userver/utils/text_light.hpp

@@ -145,6 +145,9 @@ bool IsCString(std::string_view text) noexcept;
 /// convert CamelCase to snake_case(underscore)
 std::string CamelCaseToSnake(std::string_view camel);
 
+/// convert snake_case or SCREAMING_SNAKE_CASE to CamelCase
+std::string SnakeCaseToCamel(std::string_view snake);
+
 }  // namespace utils::text
 
 USERVER_NAMESPACE_END

universal/src/utils/text_light.cpp

@@ -343,6 +343,24 @@ std::string CamelCaseToSnake(std::string_view camel) {
     return snake;
 }
 
+std::string SnakeCaseToCamel(std::string_view snake) {
+    std::string camel;
+
+    bool next_upper = true;
+    for (const char c : snake) {
+        if (next_upper) {
+            camel += static_cast<char>(std::toupper(c));
+            next_upper = false;
+        } else if (c == '_') {
+            next_upper = true;
+        } else {
+            camel += static_cast<char>(std::tolower(c));
+        }
+    }
+
+    return camel;
+}
+
 }  // namespace utils::text
 
 USERVER_NAMESPACE_END

universal/src/utils/text_light_test.cpp

@@ -284,6 +284,20 @@ TEST(TextUtils, CamelCaseToSnake) {
     EXPECT_STREQ(" _ab_f/_bcd_e-_kq_ ", CamelCaseToSnake(" AbF/BcdE-Kq_ ").c_str());
 }
 
+TEST(TextUtils, SnakeCaseToCamel) {
+    using utils::text::SnakeCaseToCamel;
+
+    EXPECT_EQ("", SnakeCaseToCamel(""));
+    EXPECT_EQ("A", SnakeCaseToCamel("a"));
+    EXPECT_EQ("_", SnakeCaseToCamel("_"));
+    EXPECT_EQ("-", SnakeCaseToCamel("-"));
+    EXPECT_EQ("ABCD", SnakeCaseToCamel("a_b_c_d"));
+    EXPECT_EQ("FooBar", SnakeCaseToCamel("foo_bar"));
+    EXPECT_EQ("FooBar", SnakeCaseToCamel("FOO_BAR"));
+    EXPECT_EQ("_A", SnakeCaseToCamel("__A"));
+    EXPECT_EQ(" AbF/BcdE-Kq ", SnakeCaseToCamel(" _AB_F/_BCD_E-_KQ_ "));
+}
+
 TEST(CheckTextTest, Ascii) {
     using utils::text::IsPrintable;