1. A method comprising: accessing a data structure stored on a computer memory device, the data structure storing data representing a plurality of keyword-condition pairs and, for each keyword-condition pair, an associated action; receiving a sequence of characters captured by a capture device; determining that the received sequence of characters includes a keyword that matches a first keyword of a first keyword-condition pair in the data structure, the first keyword-condition pair comprising the first keyword and a first condition, and determining that the first condition is satisfied; and performing a first action associated with the first keyword-condition pair in the data structure.