May 26, 2018
Compiles CQL strings into parse trees of Node subtypes
CQLParser provides a mechanism to parse Common Query Language CQL statements. The best description of CQL comes from the CQL homepage at the Library of Congress http//www.loc.gov/z3950/agency/zing/cql/
CQL is a formal language for representing queries to information retrieval systems such as web indexes, bibliographic catalogs and museum collection information. The CQL design objective is that queries be human readable and human writable, and that the language be intuitive while maintaining the expressiveness of more complex languages.
A CQL statement can be as simple as a single keyword, or as complicated as a set of compoenents indicating search indexes, relations, relational modifiers, proximity clauses and boolean logic. CQLParser will parse CQL statements and return the root node for a tree of nodes which describes the CQL statement. This data structure can then be used by a client application to analyze the statement, and possibly turn it into a query for a local repository.