Disclosed herein are systems and methods for converting physical input signals into bitstreams using syntax trees regardless of the physical input signal's protocol. Using declarative language definitions within a protocol declaration, a test and measurement system can compile a syntax tree that automatically translates the input data into a proper bitstream output. The declarative language definitions within the protocol declaration allow custom or standard protocol rules to be written for multiple or arbitrary input protocols without writing unsafe functions, having to access memory, or debugging more complex language codes.