schematron-engine

Parses an ISO/IEC 19757-3 schema and evaluates it against a document the caller provides through xpath_eval::Document/Node. It parses no instance XML or HTML itself; XPath goes only through xpath-eval. Support matrix and usage: README.md.

<let> scope

A <let> is scoped to the element that declares it. ISO/IEC 19757-3:2016 defines a variable (3.26) as “scoped within the parent schema, phase, pattern or rule”, and 5.4.5 makes it an error to reference a variable “not defined in the current schema, phase, pattern, or rule”. A pattern-level <let> is therefore visible to that pattern’s rules only, not to sibling patterns. The vendored schxslt case let-pattern-global expects the opposite; that is the suite’s reading (SchXslt compiles pattern variables as global XSLT variables, which its own README lists as a scoping limitation), not the standard’s text. The case stays in the known-failure list.

SVRL output

evaluate_trace / evaluate_trace_with_phase return the evaluation as a list of Events: ActivePattern, FiredRule (one per matched node) and Check (a fired assert or report, with its test and the ids of its diagnostics). to_svrl(schema, phase, &events) writes them as an SVRL document string; to_svrl_with takes a caller-supplied function for the location of a node.

Written: schematron-output (phase), ns-prefix-in-attribute-values, active-pattern (id), fired-rule (context), failed-assert and successful-report (id, role, test, location), diagnostic-reference and text. Not written: title, schemaVersion, the document, name, flag and diagnostic attributes, and property-reference, because the schema model does not carry them. The structure follows the informative Annex D.

location_path builds an XPath 1.0 path from the Node trait, for example /a[1]/*[local-name()='b' and namespace-uri()='urn:x'][2]/@id. Names in a namespace are written with local-name()/namespace-uri() so the path needs no prefix bindings. A test evaluates every generated path and checks that it selects exactly the node it names.