Extract PathKey.steps(forChildNames:) as the single path construction behind
the validator walk, the XSD content validator, and the identity validator,
replacing three identical implementations, so located errors can never
disagree on a path. Add two differentials locking the duplicated engines
together: equivalent DTD and XSD content models (sequence, choice, *, +, ?,
nested choice) must agree on every child sequence across the positional
matcher and the Thompson NFA; and the pull (EventReader) and push
(PushScanner) tokenizers must yield the same event stream for the same
document, even with the push side fed one character at a time (adjacent text
events coalesced, since chunk boundaries legitimately split text). Both
pairs agree on everything today; the differentials guard them.
Closes#115
Slice 5 of #92. The last validator moves onto the framework and the legacy
Issue type is removed, so all validation now flows through one error model.
- ValidationError gains a severity (error by default, warning for advisory
findings), chosen so Schematron's assert/report distinction survives in the
unified type.
- Schematron is a Validation<Node, Void> over the document root; a failed assert
is an error finding, a matched report a warning. Each finding is located at the
context node its rule fired on (built from the element chain, with a sibling
index only when a name repeats), not the document root.
- Schematron.validate returns [ValidationError] and runs through a Validator.
- Validation.Issue and its Severity-based result are deleted; Severity now backs
ValidationError.
Every validation layer (structural, DTD, XSD content and identity, Schematron)
now produces located ValidationError values through the shared framework.
Slice 1 of #92. Introduce the OpenAPIKit-idiom validation framework, replacing
the imperative if-tree structural validator:
- ValidationError (reason + coding path) renders "<reason> at path: root/row/cell";
ValidationErrorCollection gathers every failure and is thrown once.
- Validation<Subject, Document> is the atomic, composable rule value, with the
multi-error and single-error Bool inits (the latter auto-forms "Failed to
satisfy: <description>"). Predicate-gated, type-directed via an erased
AnyValidation that guards an optional from matching a non-optional rule.
- The framework is parameterized over both Subject and Document so the structural,
DTD, XSD, and Schematron layers share one machinery (Document = Void for rules
that need only their subject).
- Validator<Document> walks the node tree, building the coding path, with blank /
default factories and fluent validating / withoutValidating.
- The combinator algebra (&&, ||, comparison lifts, take, lift, unwrap, all) as
free functions returning closures.
The structural duplicate-attribute rule is reborn as Validation<Element, Void>.
Combinators and the erased wrapper are unit-tested as pure functions per the rule.
The legacy Validation.Issue stays only for the not-yet-migrated schema validators
and is retired in a later slice.
