The XTF Text Engine is responsible for parsing and executing queries against the Lucene index. The actual work of building an index is done by the textIndexer tool.

Here's a breakdown of the Texdt Engine's major functions, and the classes associated with each function:

Query Parsing

Takes care of calling the queryParser stylesheet to transform a URL query request into a strictly structured, XML-formatted query. Also accumulates a list of terms present in the query (useful later for term highlighting.)

Query Processing

These classes implement the main logic of the package, taking a structured query and applying it to the Lucene indexes. They handle stop-word (n-gram) query pre-processing, and scoring and sorting the hits

Limiting Work Performed by a Query

To help ease server load problems due to unwitting or malicious queries, XTF has added an extensive layer of work limiting on top of Lucene.

Retrieving Query Results

Once a query has been performed, the following classes provide access to the document hits, and to text snippets within each document.

Utility classes

These classes don't fit into any other category.