diff --git a/Sources/GRPCProtobufCodeGen/CamelCaser.swift b/Sources/GRPCProtobufCodeGen/CamelCaser.swift new file mode 100644 index 0000000..5e8e059 --- /dev/null +++ b/Sources/GRPCProtobufCodeGen/CamelCaser.swift @@ -0,0 +1,43 @@ +/* + * Copyright 2024, gRPC Authors All rights reserved. + * + * Licensed 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 enum CamelCaser { + /// Converts a string from upper camel case to lower camel case. + package static func toLowerCamelCase(_ input: String) -> String { + guard let indexOfFirstLowercase = input.firstIndex(where: { $0.isLowercase }) else { + return input.lowercased() + } + + if indexOfFirstLowercase == input.startIndex { + // `input` already begins with a lower case letter. As in: "importCSV". + return input + } else if indexOfFirstLowercase == input.index(after: input.startIndex) { + // The second character in `input` is lower case. As in: "ImportCSV". + // returns "importCSV" + return input[input.startIndex].lowercased() + input[indexOfFirstLowercase...] + } else { + // The first lower case character is further within `input`. Tentatively, `input` begins + // with one or more abbreviations. Therefore, the last encountered upper case character + // could be the beginning of the next word. As in: "FOOBARImportCSV". + + let leadingAbbreviation = input[..