This article presents the development of a native Swift library that parses .proto files—commonly used in Protocol Buffers (Protobuf)—without relying on the external protoc tool. It addresses a critical gap in Swift’s ecosystem by enabling direct, run-time access to Protobuf schemas. Drawing on the theoretical foundations of lexical analysis, the paper outlines how the library’s lexer and parser transform raw .proto input into descriptor structures amenable to dynamic serialization and integration with SwiftProtoReflect. The proposed approach substantially reduces dependency on external code generation and simplifies tasks such as documentation generation, code formatting, linting, and IDE-based tooling. Experimental evidence and test results show that the library can reliably handle core Protobuf features, including nested messages, enums, services, and custom options, thereby laying the groundwork for a fully Swift-based workflow in gRPC and Protocol Buffers development.

Swift, Protocol Buffers, lexical analysis, parsing, dynamic serialization

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