François Bry, Tim Furche, Sebastian Schaffert:
Tim Furche (editor):
Initial Draft of a Language Syntax.

Complete Text [
.pdf, 3876KB]
In: (I4-D6)

This article defines an initial proposal for the syntax of the I4 query language, Xcerpt. Indeed, not only a single syntax, but rather three syntactical forms of Xcerpt are introduced: (1) the term syntax, a nonstandard syntax that allows the succinct formulation of queries and is intended mostly for human authors; (2) the XML syntax provides a fine granular language markup in XML, ideal for processing through XMLbased tools and for automated query generation or reasoning about query programs; (3) the compact XML syntax is a hybrid syntax of (1) and (2). The concepts are introduced UML. In addition to the formal syntax specification, principles of the syntax design are disucssed. Furthermore, for a number of advanced constructs the reasoning supporting the design choice, as well as alternative solutions are illustrated. An impression of how the introduced language constructs allow to write and understand complex queries is given by numerous examples interspersed among the construct specifications.



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