A RELAX NG schema document is validated before pattern interpretation
in three layers: the section-3 grammar check (vocabulary, attributes,
arity, text, QNames, datatypeLibrary URIs, hrefs, 4.16 excepts, xmlns
prohibitions), compiler checks (4.17 combine rules, unresolved refs,
parentRef scope, startless grammars, include/externalRef cycles and
overrides, grammar-checked loaded documents, unknown datatypes,
built-in-library params), and the 4.19/7.1-7.4 restrictions over the
compiled algebra after 4.20/4.21 normalization (prohibited paths,
content types, duplicate attributes via representative-name overlap,
infinite-class attributes outside oneOrMore, interleave constraints),
with recursion detection deliberately before normalization. Incorrect
schemas: 213 compiling down to 7, all the pre-Fifth-Edition name-class
class (count asserted). Two leniency tests updated to spec behavior.
Closes#131
A value of type QName compiles to its (namespace, local) pair via the
schema's xmlns/ns scope; the derivative engine threads the instance
element's in-scope bindings to value comparison in both the tree walk
and the streaming state (frames carry their bindings), so instance
prefixes and the default namespace resolve against the instance
document and unbound prefixes match nothing. Streaming also gains the
tree walk's empty-element rule. The spec suite's instance level is
fully clean: valid 289/289, invalid 291/291; only the asserted
schema-correctness class remains.
Each grammar element opens a define scope (scope-mangled names in the
flat table) with parentRef reaching the enclosing scope; includes are
transitive and include-level defines replace the included grammar's
same-name defines (4.7 override); div wrappers flatten while keeping
ns/datatypeLibrary inheritance (4.11); value text stays untrimmed so
whitespace-preserving datatypes compare exactly (6.2.9); dataExcept
recurses through choices. Spec suite: valid 286/289, invalid 287/291;
the six remaining instance cases are all the QName datatype.
The compiler implements simplification 4.9-4.10 (ns inheritance across
ancestors and document boundaries; QName resolution against in-scope
xmlns declarations; the attribute name= shorthand stays namespace-less),
include brings in the included grammar's start with overrides (4.7),
multiple starts and defines combine with a single omitted combine
merging by the named method (4.17), data/except lands as a dataExcept
pattern in the derivative engine (4.12), an empty element matches data
whose lexical space admits the empty string, and whitespace-only
attribute values match empty-matching patterns. Spec suite: valid
274/289, invalid 279/291.
Foreign-namespace elements are stripped before pattern interpretation
(namespace-less elements count only inside fully unqualified schemas),
name/type/combine values are whitespace-trimmed, and include and
externalRef hrefs resolve against in-scope xml:base attributes and the
loaded document's URI, threaded through nested loads with visited
tracking on resolved hrefs. Spec-suite baselines tighten to valid
242/289 and invalid 278/291.
The derivation final check and Particle Valid (Restriction) move from
fail-fast throws at schema compile into composable Validation rules
(finalRespected, restrictionsAreSubsets) over per-type SchemaTypeFact
subjects, so a schema with several problems reports every finding at
once. SchemaError gains .inconsistent([String]) carrying all findings
(texts unchanged) and drops .finalViolation/.invalidRestriction.
checkRedefine, checkAllGroups, and notASchema stay throws: they examine
the raw schema source, the compilation analog of well-formedness.
A complex type derived by restriction is checked at schema compile to accept
a structural subset of its base, closing the declared XSD 1.0 spec gap.
ParticleRestriction covers element name matching, element-vs-wildcard
admission, wildcard narrowing, occurrence-range subsumption, and the group
recursions: sequence/all order-preserving with emptiable skips (Recurse),
choice mapping (RecurseLax), sequence-into-choice (MapAndSum, approximated by
per-particle checks, a documented simplification), sequence-into-all
(RecurseUnordered), and RecurseAsIfGroup for a lone element against a group.
An unfaithful restriction throws SchemaError.invalidRestriction(type:base:
reason:). All 834 pre-existing tests pass unchanged (no false positives on
the existing restriction-using schemas); 7 new tests cover the accept and
reject paths plus a conformance-harness pair.
Closes#117
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
The whole-buffer ISO-2022-JP, GB18030, and EUC-TW decoders index the input
ArraySlice directly instead of materializing an Array first (one avoidable
O(n) allocation per decode each); declaredEncoding's subsequence scan uses
elementsEqual instead of allocating an Array per candidate offset. Document
the two analysis-flagged bounds: entity expansion is doubly bounded (the
character budget caps output; the visiting set caps recursion depth at the
number of declared entities), and the RELAX NG derivative engine carries no
memoization by design (the simplifying constructors keep real grammars
small; adversarial nested-choice grammars can grow the residual, so treat
untrusted schemas accordingly). Behavior unchanged, all suites green.
Closes#118
A selector or field XPath that fails to compile is now reported once up
front as a located error (identity constraint 'k': invalid selector/field
XPath '...'), instead of try? silently turning a schema author's typo into
a disabled constraint. The per-run query cache from #112 is the choke point:
compileErrors() probes every constraint's selector and fields in
deterministic order, the failures cache as nil, and the walk afterwards
treats those constraints as matching nothing, so the rest of the document
still validates. Tests cover a malformed field and a malformed selector.
Closes#111
XSLT: template selection resolves each match pattern once per transform via
a per-run MatchCache (the pattern's node set is computed once over the source
tree; selection becomes an identity lookup), replacing per-(node, template)
recompilation and full-tree re-walks. XSD identity validation: a per-run query
cache compiles each selector/field XPath once instead of at every visited
element. Schematron was verified to already store compiled queries. Behavior
unchanged (all suites green); a multi-template shape test over 300 nodes
guards the optimized path. MatchCache lives in its own file to keep the
transformer under the length cap.
Closes#112
An xsi:type naming an undeclared type is now a located error in both the
tree validator (validateChild) and the streaming driver, instead of a silent
fallback to the declared type. typeReference chains resolve through one
shared resolver (resolveReference, with a visited set), replacing the inline
recursion, the 64-hop cap, and the completions guard: a circular chain now
reports 'circular type reference' instead of silently truncating, and the
streaming shallow check no longer recurses without bound on a cyclic table
(a latent crash). Tests cover unknown xsi:type (tree + streaming agree),
the circular chain (tree + shallow), the resolver's three outcomes, and a
conformance-harness case pair.
Closes#110
Rule-canon audit (validation-rules.md / the OpenAPIKit idiom): the streaming
XSD validator was the one surface applying a bare method (validateShallow)
rather than a Validation<> value. Wrap it: ComplexValidator.shallowValidity is
a Validation<ResolvedElement, ComplexValidator> whose subject carries the
element with its already-resolved effective type (the contextual typing a
node-tree walk cannot express), and the streaming driver applies it via
apply(to:at:in:). Now every validation surface, DTD, XSD, RELAX NG, Schematron,
HTML, structural, conformance, and both streaming validators, routes through a
Validation value. Adds a direct unit test of the rule.
Extend an identity error's coding path past the target element to the single
field the constraint names: an attribute (list/item[2]/@id) or a child element
(.../code), resolved from the field XPath. Multi-field or complex-path
constraints stay on the target. Also add a cross-scope keyref test confirming
a keyref resolves against a key declared on an ancestor element. Updates the
identity-path tests to the more precise locations.
Closes#104
Add Schema.Document.validate(streaming:) and ComplexValidator.validateShallow:
resolve each element's type from its parent's content model (and xsi:type /
typeReference) as it opens, then check its attributes and content-model
structure shallowly as it closes, against a shallow element synthesized from
the streamed child names. A child's deeper validity is checked when it closes,
so only the open-element stack is held. A differential test asserts streaming
agrees with the tree validator across valid and invalid documents (missing
attributes, bad simple values, missing/extra/misordered children). Wildcard
processContents and substitution-group resolution in the streaming form stay
on the tree validator. The streaming methods moved to ComplexValidatorStreaming
to keep ComplexValidator under the file/type-body caps.
Closes#107
Add RelaxNG.validate(streaming:), driving the Brzozowski derivative directly
from the parse-event stream (the libxml2 xmlTextReader model). The derivative
is already incremental: the after-threaded pattern chain is the validation
stack, so only the residual pattern and a light per-element frame (for the
childrenDeriv ignorable-whitespace rule) are retained, never the tree. A
differential test asserts streaming agrees with the trusted tree engine across
valid, invalid, whitespace, and mixed-content documents. XSD streaming remains.
Part of #107, #105
Refine the identity-constraint path: rather than locating at the element
that declares the key, walk from the constraint-bearing element down to the
selected target and report the actual offender, so a duplicate key renders
"at path: list/item[2]" and a dangling keyref "at path: orders/line".
Also locate the "no element declaration for the root" XSD error at the root
element, matching the namespace check beside it that already did so. Lock
both with coding-path assertions in the identity tests.
The IdentityValidator emitted every key/keyref/unique error with an empty
coding path (at: []), so each rendered "at root of document" regardless of
which element violated the constraint. Thread a [PathKey] through the walk,
the way the content-model validator already does, so the failures carry the
constraining element's path. This restores the validation framework's
path-carrying contract for the one rule that was bypassing it.
A >> follow-annotation after a pattern (a foreign element name with
optional [ ... ] content) is skipped, chaining and combining with leading
annotations; neither carries schema semantics. Namespace declarations
inside annotations were already dropped by the annotation skipper, so the
RNC compact syntax is now fully covered.
A RELAX NG attribute failure now reports an undeclared attribute
("attribute @b is not allowed on <n>") separately from a declared
attribute carrying a bad value ("attribute @count on <n>: 'abc' is not a
valid integer"), quoting the value and naming its datatype by reusing the
text detail. The declared value pattern is found by matching the
attribute name through the residual.
A RELAX NG text/datatype mismatch now reports the rich datatype reason
(quoting the value and naming the type, e.g. 'abc' is not a valid
integer) and a value mismatch quotes both the actual text and the
required literal, instead of a generic "text content is not valid". The
detail is peeled from the content pattern at the failure point through
choice, group, list, and ref.
A content-model violation is now placed at the offending child with a
recovery hint naming what was expected, instead of one opaque "content
does not match the content model" per element. The sequence/choice
automaton is walked child by child via its follow-set to flag the first
child the model rejects, or the incomplete content at the end; an xs:all
group recovers past each stray child and reports every missing required
member. Well-placed children are still validated for their own content,
so an editor sees every problem at once. Brings XSD to the same located,
recovering standard as the RELAX NG, DTD, and Schematron validators.
Adds RelaxNG.errors(in:) reporting every way a document fails the schema
as individual located errors with coding paths, recovering past each
failure so all of a faulty document's problems surface at once instead of
only the first. Errors carry recovery hints naming the element types
accepted at the failure point, and distinguish unexpected elements,
invalid or missing attributes, invalid text/datatype content, and missing
required content. RelaxNG.validation() exposes the schema as a
Validation<Node, Void>, composing with the same framework as the XSD,
DTD, and Schematron rules. The boolean derivative engine remains the
authority on validity; the diagnostic walk only places and explains the
failures, recovering each step so it never cascades. Splits the engine
and the diagnostics into separate files.
A string literal split with ~ ("a" ~ "b") is the single literal "ab",
the way long values and namespace URIs are wrapped across lines. The fold
applies wherever a string literal is read: value literals and the URIs of
namespace/datatypes/include/external declarations.
A <value> pattern now carries its datatype, so matching compares the
instance and the literal in that type's value space rather than purely
lexically. Numeric and date/time types compare by value (1 equals 01,
1.5 equals 1.50); booleans treat 1/true and 0/false as equal; string and
token compare by their whitespace-normalized lexical form, as before.
Untyped values default to the built-in token type, and a bare string
literal in the compact syntax is token-typed. Durations and binary types
fall under the lexical rule.
Adds a datatypeLibrary-aware datatype resolver to the XML-syntax parser:
the in-scope library is inherited from the nearest ancestor, the default
(empty) library defines only string and token, and the W3C XML Schema
library defines the full built-in set. A type the in-scope library does
not define is an unknown datatype, so the <data>/<value> pattern matches
nothing rather than silently validating.
Adds an nsNameExcept name-class case so nsName with an <except> child
(XML syntax) and prefix:* - name subtraction (compact syntax) narrow a
namespace wildcard. The compact lexer splits prefix:* into a trailing-
colon word plus a star symbol, which the parser now recognizes.
Existing RELAX NG facet tests declared XSD types without the library and
relied on lenient resolution; they now declare the XSD datatypeLibrary,
matching what a conformant processor requires.
The compact-syntax parser now skips [ ... ] documentation/grammar
annotations (balanced over nesting) wherever they may appear, before a
define or before a pattern, and treats div { ... } as transparent
grammar grouping that contributes its defines and start directly. A
define literally named div still parses when assigned. Splits the
name-class and token helpers into a companion file to stay within the
type and file length budget.
The compact-syntax name class * - nameClass now parses as anyName except
the subtracted class (the model already had anyNameExcept). ns:* - name
would need an nsName-except model case and is left as a refinement.
Part of #79
The RNC datatype parameter block xsd:int { minInclusive = "5" } is now
parsed into facets (previously skipped), matching the XML-syntax <param>
support. The facet mapping is shared by both parsers through a new
RelaxNGFacets helper.
Part of #79
A <data type=> pattern now carries a SimpleType (base + facets) rather
than a bare built-in, and its <param name=>value</param> children
populate the facets (minLength, maxLength, length, pattern, min/max
inclusive/exclusive, total/fraction digits), reusing the XSD datatype
facet validation. So a constrained datatype like xsd:string with
minLength rejects too-short values.
datatypeLibrary resolution, typed <value> comparison, and the RNC
datatype parameter blocks remain.
Part of #79
The validation framework already conforms to the OpenAPIKit idiom: named
composable Validation values, a Validator with blank/validating/
withoutValidating, located errors, parameterized over both subject and
document. The DTD layer is already four named rules.
XSD content validation stays a single recursive Validation
(contentValidity) rather than a rule per constraint, because XSD is a
recursive type system: a child's type is resolved from its parent's
content model and position, then rewritten by xsi:type and the derivation
controls mid-walk, so the constraint categories are interdependent and
cannot be split into independent rules without changing semantics or
duplicating the recursion. That is the sanctioned multi-error form.
To keep each category verifiable on its own (the idiom's testability),
add XSDCategoryTests exercising ComplexValidator directly per category
(attributes, content, nillable, fixed); derivation, wildcards, and
namespaces are already isolation-tested through crafted schema strings.
Closes#101
A define repeated with combine="choice" or combine="interleave" now
merges with the existing definition (as a choice or interleave pattern)
instead of the last one silently replacing it. A plain redefinition with
no combine still replaces. Applied consistently in a grammar and across
include merges.
<param> facets under <data>, datatypeLibrary resolution, typed <value>
comparison, and the RNC-syntax gaps remain.
Part of #79
Make XSD validation namespace-aware and enforce the form defaults and
xs:all structural constraints that were previously ignored:
- targetNamespace is tracked: a schema's global elements are in its
target namespace, and an instance's root element must be in it.
- elementFormDefault / attributeFormDefault (and per-declaration form)
qualify local element and attribute declarations. The content-model
matcher already compares namespace URIs, so qualified declarations
now match only same-namespace instance nodes; attribute matching
became namespace-aware too.
- xs:all groups are checked at compile time: every member must be an
element occurring at most once, the group may occur at most once, and
nested model groups inside an all are rejected (a SchemaError).
When a schema has no target namespace the stamping is a no-op, so
unqualified schemas validate exactly as before.
Cross-namespace type references through xs:import resolve by local name
only; full multi-namespace type tables are not modeled.
Closes#78
Read and enforce the XSD 1.0 derivation controls that were previously
ignored:
- abstract elements may not appear in an instance directly, only through
a substitution member; an element of an abstract complex type must
supply an xsi:type naming a concrete derived type.
- block on a type forbids the disallowed xsi:type substitutions; block on
an element drops substitution-group members that derive by a blocked
method.
- final on a type rejects, at compile time, any type that derives from it
by a final method.
- xs:redefine requires the redefined type to derive from itself.
Track each named complex type's base and derivation method as the
backbone these checks walk. Also compose complexContent extension and
restriction content models, which were previously dropped: an extension
now inherits its base's attributes and content (base first, then the
extension, in sequence).
Complex-type restriction is not verified to be a structurally valid
subset of its base (Particle Valid (Restriction)); that limit is
documented at its sites.
Closes#76
Add xs:any and xs:anyAttribute wildcards with namespace and
processContents constraints (skip/lax/strict), and resolve the
list built-in datatypes (IDREFS, ENTITIES, NMTOKENS) to their
item types so each list item validates.
WildcardNamespace models ##any/##other/enumerated URI sets;
Wildcard.admits gates undeclared attributes and wildcard-matched
children. ContentNFA.follow exposes the follow set for completions.
Closes#77
Slice 4 of #94 (completes the epic). Quick-fixes are derived from the structured
schema completions, never by parsing a diagnostic message:
- TreeNode gains contentRange (the span between an element's start and end tags),
captured by the ranged reader, so an inserted attribute or child is placed
exactly.
- QuickFix and TextEdit model an editor edit (a replacement over a source range;
an insertion is a zero-width range).
- QuickFixEngine turns a Completions into fixes: a required-but-absent attribute
becomes an insertion before the start tag's >, and a still-expected required
child becomes an insertion before the end tag. Schema.Document.quickFixes(at:in:)
is the entry over a ranged tree.
Tests apply a fix and re-validate: adding the required id, or inserting the
required qty, yields XML the schema then accepts; a complete element offers none.
#94 (editor integration) is complete: ranged recovering read, unified lint,
schema completions, and quick-fixes.
Slice 3 of #94. From the compiled schema, compute exactly what is allowed at an
element, for autocomplete and "what's missing".
- ContentNFA.follow(after:) returns the precise follow-set: the element-name
labels the content automaton can accept next after the children already
present, plus whether the content may legally end there.
- Schema.Completions reports the allowed next elements, the complete flag (false
means a required child is still expected), a wildcard flag, and each declared
attribute with its required and present status.
- CompletionEngine resolves an element's declared type along a coding path (the
global declaration, then each parent's content model) and computes the
completions; Schema.Document.completions(at:in:) is the entry over a ranged
tree.
Tests pin the follow-set as the children accumulate (name then qty then the
optional note, complete flipping true), the attribute required/present status,
and resolution for a nested element by its coding path.
Slice 2 of #94. One call for an editor: PureXML.lint reads the document once into
the ranged, best-effort tree (never throwing), then merges the parse diagnostics
and the validation findings into a single source-ranged, severity-tagged list in
document order.
- LintDiagnostic carries message, severity, and the SourceRange to highlight.
- lint(_:validate:) takes a node-based validate closure that runs over the
RECOVERED tree, so validation works even when the document is not well-formed:
a truncated, schema-invalid document yields both a parse diagnostic and the
validation finding, each with a range.
- Schema.Document gains validate(_ node:) so a caller validates the same tree it
is editing; validate(_ xml:) delegates to it.
Tests cover a clean lint, well-formedness-only lint, a range-located validation
finding, and the both-truncated-and-invalid editor case.
Closes#75, on the validation framework. XSD instance-level features:
- nillable elements: an xsi:nil="true" element is accepted (its content model is
not checked) only when the element is declared nillable and carries no content;
xsi:nil on a non-nillable element, or a nilled element with content, is a
located error.
- fixed value constraints: a present fixed attribute must equal its fixed value,
and a fixed element's text must match.
- default/fixed are parsed onto AttributeUse (per use) and collected per element
name (nillable set + value constraints), threaded through XSDContext to the
ComplexValidator.
All findings are located ValidationErrors. Collection and helper methods move to
same-file extensions to stay within type-body limits.
Slice 4 of #92. The XSD complex-type and identity-constraint validators move
onto the validation framework, producing located results.
- ComplexValidator threads a coding path through its (inherently recursive)
descent, so every content-model, attribute, and simple-type violation is now
a ValidationError located by path ("... at path: order/qty"). Child steps
carry a sibling index only when a name repeats.
- IdentityValidator returns ValidationError instead of Issue.
- A new XSD rules enum wraps both as Validation<Node, XSDContext> values gated to
the document root, combined by Validator<XSDContext>. XSDContext carries the
type table, the identity constraints, and the root declaration.
- Schema.Document.validate builds the context and runs the validator, returning
[ValidationError].
XSD content-model validation is recursive by nature (a child's type depends on
its position), so the rules delegate to the recursion while contributing to one
error collection. Schematron is the last validator on Issue and migrates next.
Compile RELAX NG from both syntaxes and across documents:
- A compact-syntax parser (lexer plus recursive descent) produces the same
pattern algebra the XML syntax compiles to. It covers element and attribute
declarations with name classes and namespace resolution, the , | & combinators
and ? * + cardinality, text/empty/notAllowed, list and mixed, datatypes and
value literals, grammars with start and named definitions (= |= &=), nested
grammars, and include/external references.
- The XML-syntax parser gains include (merging another grammar's definitions,
with the include's own nested definitions overriding) and externalRef
(resolving to an external schema's pattern), both through an injected loader.
Both syntaxes reach the loader through a new schemaLoader parameter that
returns nil by default, so compilation never touches the filesystem or network
unless a loader is supplied.
Closes#68
Validate XSD identity constraints over the instance document in a pass that
walks the tree alongside type validation:
- xs:unique requires the selected nodes' field tuples to be distinct, excluding
any node that is missing a field.
- xs:key additionally requires every field to be present.
- xs:keyref requires each tuple to equal a tuple of the named key or unique
visible in an enclosing scope, resolved through a stack of scope frames so a
keyref and the key it refers to may sit on the same element.
The selector and field XPaths run on the existing XPath engine, relative to the
declaring element and each selected node. Constraints are gathered for every
element declaration at any depth, keyed by element name.
Closes#67
Compose schemas across documents and resolve types at the instance:
- xs:include, xs:import, and xs:redefine pull a transitive closure of schema
documents through an injected loader (resolved by schemaLocation), base
schemas first so the including schema wins; a redefine's nested definitions
override the schema it includes.
- substitution groups: an xs:element ref to a head also admits every element
that substitutes for it, expanded at parse time into a choice over the head
and its transitive members.
- xsi:type overrides an element's declared type with the named type at the
instance; XML Schema instance attributes are exempt from attribute checks.
The schema parser splits across XSDContext (shared tree helpers, document
collection, parsing context), XSDSimpleParser (simple types and facets), and
XSDParser (elements, complex types, model groups) to keep each within bounds.
Closes#66
Extend the schema parser toward full structural parity:
- list simple types validate each whitespace-separated item against the item
type and count items for the length facets; union simple types admit a value
valid for any member type. A restriction over a named list or union inherits
its variety.
- Named attribute groups are expanded (transitively) into every complex type
that references them.
- Named model groups are expanded at each xs:group ref, with a cycle guard;
element refs resolve to the referenced global element's declared type,
through a reserved type-table key so forward and recursive refs settle at
validation time.
Named simple types now resolve over repeated passes so they may restrict or
list one another regardless of document order. Simple-type and facet parsing
moves into a sibling XSDSimpleParser to keep each parser within bounds.
Closes#65
Use let for never-mutated bindings in DateTimeParser, HTMLEntities, and the
XSLT parser, and drop the redundant Unicode.Scalar Comparable conformance
that the standard library already provides. No behavior change.
Add the RELAX NG pattern algebra (Pattern, NameClass), a parser for the XML
syntax into a grammar of start plus named defines, and James Clark's
derivative validation algorithm. The pattern is derived through each
start-tag, attribute, text, and end-tag event with simplifying constructors;
the document is valid when the residual pattern is nullable. Supports
element, attribute, text, empty, notAllowed, group, choice, interleave,
optional, zeroOrMore, oneOrMore, mixed, list, ref/define, data, value, and
the name classes; handles interleave and recursive grammars, reusing the XSD
datatype library for data and value.
Closes#11Closes#12
Add Schema.Document compiling an xs:schema into global element declarations
and a named-type table, and validate(_:) checking instance documents end to
end. The parser supports global and local element declarations, named and
inline simple and complex types, sequence/choice/all groups with occurrence,
attribute uses, simple content (restriction/extension), the full facet set,
and recursive types via named references resolved during validation. Extends
ComplexType with a typeReference case and ComplexValidator with a type table
so recursive schemas are representable.
Closes#10
Add ComplexValidator validating an element against a ComplexType: attribute
uses (required, typed, unknown-attribute rejection) and the content model
(empty, simpleContent, elementOnly, mixed). Particles compile to a Thompson
NFA over element names honoring minOccurs/maxOccurs with sequence and choice
compositors; all groups are validated order-independently by counting. Child
elements are validated recursively against their declared types.
Closes#9
Add the PureXML.Schema namespace validating XSD Part 2 built-in datatypes
and constraining facets. Built-ins span string/boolean/decimal, the bounded
integer family with intrinsic bounds, float/double, duration, the eight
date/time types, hexBinary, base64Binary, anyURI, QName, and the
Name/NCName/NMTOKEN/language family. Facets: length/minLength/maxLength,
pattern (via the regex engine), enumeration (value-space comparison),
whiteSpace, min/maxInclusive/Exclusive, totalDigits, fractionDigits.
Decimals compare exactly with no floating-point loss; date/time fields are
range-validated with leap years, 24:00:00, and timezone bounds.
Closes#8
