A pipeline is provided for processing network packets. The pipeline includes a look-ahead stage, an operation stage, an insert/remove stage, and an interleave stage. The look-ahead stage synchronizes two or more fields of a network packet. The operation stage modifies one or more of the fields of the network packet. The operation stage may modify state data and the fields of the network packet as a function of the state data and the fields. The insert/remove stage performs data insertion and removal at one or more fields of the network packet. The interleave stage ensures that the modified network packet follows rules for interleaving network packets. The look-ahead, operation, insert/remove, and interleave stages are generated from a textual language specification of the processing of the network packets by the pipeline.