1. One or more computer-readable storage media that store executable instructions that, when executed by a computer, cause the computer to perform acts comprising: receiving a specification of a text pattern to be matched in an input stream, said specification comprising one or more data expressions and one or more code expressions, the data expressions defining one or more phrase sets, a first one of the code expressions comprising a container that comprises a first phrase set and a second phrase set; comparing words in said input stream with said container; determining that a context in said input stream matches said container; and generating a report indicating that said container matches a sequence of words in said input stream.