RELAX NG parsing for Emacs' nxml-mode
Emacs' nxml-mode only allows grammars to be specified using RELAX NG's compact syntax (see RELAX NG Compact Syntax). Rng-xml will, one day, allow nxml-mode to also use the standard, XML, RELAX NG syntax (see RELAX NG).
Fortunately, Emacs comes with a compact syntax schema for the RELAX NG syntax meaning that, by the time we get the parsed XML, we know that it is structurally valid. All that is needed is to simplify it and convert it to a pattern (as defined in rng-pttrn.el).
The test suite is adapted from examples in the RELAX NG Tutorial. The RNC equivalents were generated using trang.