1. A system for parsing complex data, the system comprising: a memory device configured to store a set of instructions; and at least one processor configured to execute the set of instructions to perform the following operations: input one or more strings into a parsing pipeline within a parser, and execute, for each inputted string into the parsing pipeline, the following operations: generate a second string, by a first handler, based in part on a current input string to the parsing pipeline, if the current input string to the parsing pipeline matches a predetermined string of an expression specified for the first handler in a parser definition; and input the second string, regeneratively, by the first handler, to the parsing pipeline, if the current input string to the parsing pipeline matches a predetermined string of an expression specified for the first handler in the parser definition.