Mihaela Mihaljevic
4bd23d8286
Resolve a built-in datatype named by xsi:type (xsd:int, xsd:decimal, xsd:string), which previously resolved only against schema-declared types and so reported "unknown" and wrongly rejected the element. The built-in is now resolved when it validly substitutes for the declared type per Schema-Validity Assessment: the ur-type (anyType/anySimpleType) admits any type, and a bare built-in declared type admits any built-in derived from it through the XSD Part 2 datatype lattice (new BuiltinType.derives(from:)). An invalid built-in substitution is a located error, not a silent acceptance. Resolving the override correctly exposed two pre-existing gaps, both closed so the change carries no invalid-instances-accepted regression: - A simple-typed element rejects non-schema-instance attributes. A simple type declares no attribute uses, so an element of simple type (including via an xsi:type override, and including an xsi:nil element) may carry only xsi:* and namespace attributes. Checked before the nil short-circuit. - Identity-constraint fields compare in their value space when the selected node carries an xsi:type. unique/key/keyref tuples compared lexically, so two xsi:type="xsd:decimal" fields 3.0 and 3 were treated as distinct and a unique violation was missed. Each field value now carries the type read from the node's xsi:type and compares via SimpleType.valueMatches when both share a built-in base, otherwise lexically. XSTS: valid instances rejected 248 to 233; invalid instances accepted held at 165. Identity tests corrected to spec-valid schemas (an element carrying an attribute must be a complex type, not type="xs:string").
256 lines
13 KiB
Swift
256 lines
13 KiB
Swift
/// Compiles each distinct XPath string once per validation run, so a
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/// constraint's selector and field queries are not re-parsed at every element
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/// the walk visits. A string that fails to compile caches as nil (no match).
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private final class XPathQueryCache {
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private var queries: [String: PureXML.XPath.Query?] = [:]
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func query(_ xpath: String) -> PureXML.XPath.Query? {
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if let cached = queries[xpath] { return cached }
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let compiled = try? PureXML.XPath.Query(xpath)
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queries[xpath] = compiled
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return compiled
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}
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}
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/// One field of an identity tuple: its lexical value and the simple type it
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/// compares in (from the node's `xsi:type`, if any). Two field values are equal
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/// when they denote the same value: in the value space of their type when both
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/// share a built-in base (so `3.0` equals `3` for `xsd:decimal`), otherwise by
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/// lexical form.
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private struct FieldValue: Equatable {
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let string: String
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let type: PureXML.Schema.SimpleType?
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static func == (lhs: FieldValue, rhs: FieldValue) -> Bool {
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if let lhsType = lhs.type, let rhsType = rhs.type, lhsType.base == rhsType.base {
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return lhsType.valueMatches(lhs.string, literal: rhs.string)
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}
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return lhs.string == rhs.string
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}
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}
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extension PureXML.Schema {
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/// Validates XSD identity constraints (`unique`, `key`, `keyref`) over an
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/// instance document. Each constraint is evaluated at every element whose
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/// name carries it: the selector XPath chooses target nodes relative to that
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/// element, and the field XPaths form each target's value tuple. `key` and
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/// `unique` require distinct tuples; `keyref` requires each tuple to match a
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/// key or unique of the named constraint visible in an enclosing scope.
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struct IdentityValidator {
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/// The constraints declared for each element local name.
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let constraints: [String: [IdentityConstraint]]
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/// Selector and field XPaths compiled once per run, not per element.
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private let cache = XPathQueryCache()
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init(constraints: [String: [IdentityConstraint]]) {
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self.constraints = constraints
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}
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func validate(
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_ root: PureXML.Model.TreeNode,
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at path: [PureXML.Validation.PathKey] = [],
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) -> [PureXML.Validation.ValidationError] {
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guard !constraints.isEmpty else { return [] }
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// A selector or field XPath that does not compile is a schema-author
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// error, reported once up front rather than silently disabling the
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// constraint (the broken query still evaluates as no-match below).
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var issues: [PureXML.Validation.ValidationError] = compileErrors(at: path)
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walk(root, at: path, scopes: [], into: &issues)
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return issues
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}
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/// One located error per constraint XPath that fails to compile, in a
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/// deterministic order. The failed compilations are cached, so the walk
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/// afterwards treats those constraints as matching nothing.
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private func compileErrors(at path: [PureXML.Validation.PathKey]) -> [PureXML.Validation.ValidationError] {
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var errors: [PureXML.Validation.ValidationError] = []
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for key in constraints.keys.sorted() {
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for constraint in constraints[key] ?? [] {
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if cache.query(constraint.selector) == nil {
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errors.append(.init(reason: "identity constraint '\(constraint.name)': invalid selector XPath '\(constraint.selector)'", at: path))
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}
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for field in constraint.fields where cache.query(field) == nil {
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errors.append(.init(reason: "identity constraint '\(constraint.name)': invalid field XPath '\(field)'", at: path))
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}
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}
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}
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return errors
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}
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private func walk(
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_ node: PureXML.Model.TreeNode,
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at path: [PureXML.Validation.PathKey],
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scopes: [[String: [[FieldValue?]]]],
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into issues: inout [PureXML.Validation.ValidationError],
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) {
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var frame: [String: [[FieldValue?]]] = [:]
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let declared = node.name.flatMap { constraints[$0.localName] } ?? []
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// Collect key and unique tuples first so a keyref on the same element
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// can resolve against them.
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for constraint in declared {
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collect(constraint, at: node, path: path, frame: &frame, into: &issues)
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}
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let visible = scopes + [frame]
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for constraint in declared {
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if case .keyref = constraint.kind {
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checkKeyref(constraint, at: node, path: path, scopes: visible, into: &issues)
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}
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}
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let elementChildren = node.children.filter { $0.kind == .element }
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for (child, step) in zip(elementChildren, childSteps(elementChildren)) {
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walk(child, at: path + [step], scopes: visible, into: &issues)
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}
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}
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/// The coding-path step for each element child: its name, with a sibling
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/// index only when more than one child shares that name. Mirrors the
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/// complex-type validator's path construction so identity-constraint
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/// errors and content errors locate consistently.
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private func childSteps(_ children: [PureXML.Model.TreeNode]) -> [PureXML.Validation.PathKey] {
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PureXML.Validation.PathKey.steps(forChildNames: children.map { $0.name?.description ?? "" })
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}
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/// The coding-path steps from the constraint-bearing `container` down to a
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/// selected `target`, so an identity error locates the actual offending
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/// element rather than the element that merely declares the constraint.
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/// Returns an empty path if `target` is not a descendant of `container`.
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private func steps(from container: PureXML.Model.TreeNode, to target: PureXML.Model.TreeNode) -> [PureXML.Validation.PathKey] {
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var chain: [PureXML.Model.TreeNode] = []
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var current = target
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while current !== container {
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guard let parent = current.parent else { return [] }
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chain.append(current)
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current = parent
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}
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var steps: [PureXML.Validation.PathKey] = []
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var parent = container
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for node in chain.reversed() {
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let name = node.name?.description ?? ""
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let siblings = parent.children.filter { $0.kind == .element && ($0.name?.description ?? "") == name }
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if siblings.count > 1, let index = siblings.firstIndex(where: { $0 === node }) {
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steps.append(.element(name, index: index + 1))
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} else {
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steps.append(.element(name))
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}
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parent = node
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}
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return steps
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}
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/// The coding-path step from a `target` down to the single field a
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/// constraint names, so an error locates the offending value (`@id`, a
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/// child element) rather than just the target. Empty for a multi-field
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/// constraint or a complex field path, in which case the error stays on the
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/// target.
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private func fieldStep(_ fields: [String], at target: PureXML.Model.TreeNode) -> [PureXML.Validation.PathKey] {
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guard fields.count == 1 else { return [] }
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let field = fields[0]
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if field.hasPrefix("@"), !field.dropFirst().contains(where: { $0 == "/" || $0 == "[" }) {
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return [.attribute(String(field.dropFirst()))]
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}
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let isSimpleName = !field.contains(where: { "/@[(".contains($0) })
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if isSimpleName, let child = select(field, at: target).first, child.kind == .element {
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return steps(from: target, to: child)
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}
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return []
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}
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private func isNonRef(_ constraint: IdentityConstraint) -> Bool {
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if case .keyref = constraint.kind { return false }
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return true
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}
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private func collect(
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_ constraint: IdentityConstraint,
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at node: PureXML.Model.TreeNode,
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path: [PureXML.Validation.PathKey],
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frame: inout [String: [[FieldValue?]]],
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into issues: inout [PureXML.Validation.ValidationError],
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) {
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guard isNonRef(constraint) else { return }
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var tuples: [[FieldValue?]] = []
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var seen: [[FieldValue?]] = []
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for target in select(constraint.selector, at: node) {
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let tuple = fieldTuple(constraint.fields, at: target)
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let targetPath = path + steps(from: node, to: target)
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if constraint.kind == .key, tuple.contains(where: { $0 == nil }) {
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issues.append(.init(reason: "key '\(constraint.name)': a field is missing", at: targetPath + fieldStep(constraint.fields, at: target)))
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continue
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}
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if tuple.contains(where: { $0 == nil }) { continue }
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if seen.contains(where: { $0 == tuple }) {
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issues.append(.init(reason: "\(label(constraint)) '\(constraint.name)': duplicate value", at: targetPath + fieldStep(constraint.fields, at: target)))
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} else {
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seen.append(tuple)
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}
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tuples.append(tuple)
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}
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frame[constraint.name] = tuples
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}
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private func checkKeyref(
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_ constraint: IdentityConstraint,
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at node: PureXML.Model.TreeNode,
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path: [PureXML.Validation.PathKey],
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scopes: [[String: [[FieldValue?]]]],
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into issues: inout [PureXML.Validation.ValidationError],
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) {
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guard case let .keyref(refer) = constraint.kind else { return }
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let keyTuples = scopes.reversed().compactMap { $0[refer] }.first ?? []
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for target in select(constraint.selector, at: node) {
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let tuple = fieldTuple(constraint.fields, at: target)
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if tuple.contains(where: { $0 == nil }) { continue }
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if !keyTuples.contains(where: { $0 == tuple }) {
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let targetPath = path + steps(from: node, to: target)
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issues.append(.init(reason: "keyref '\(constraint.name)': no matching key '\(refer)'", at: targetPath + fieldStep(constraint.fields, at: target)))
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}
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}
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}
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// MARK: XPath helpers
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private func select(_ xpath: String, at node: PureXML.Model.TreeNode) -> [PureXML.Model.TreeNode] {
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guard let query = cache.query(xpath) else { return [] }
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return query.nodes(over: node)
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}
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private func fieldTuple(_ fields: [String], at node: PureXML.Model.TreeNode) -> [FieldValue?] {
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fields.map { field in
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guard let query = cache.query(field), let value = try? query.value(at: node) else {
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return nil
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}
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if let nodes = value.nodes, nodes.isEmpty { return nil }
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return FieldValue(string: value.string, type: Self.effectiveType(of: value))
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}
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}
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/// The simple type a field value compares in: the built-in named by the
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/// selected node's `xsi:type`, when present. Identity-constraint values
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/// compare in their value space, so two `xsi:type="xsd:decimal"` fields
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/// `3.0` and `3` are the same value and violate a `unique`/`key`. With no
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/// `xsi:type` the comparison falls back to the lexical form (the type
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/// declared in the schema is not threaded into identity validation).
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private static func effectiveType(of value: PureXML.XPath.Value) -> SimpleType? {
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guard let nodes = value.nodes, case let .tree(treeNode)? = nodes.first,
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treeNode.kind == .element, let local = xsiTypeLocalName(of: treeNode),
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let builtin = BuiltinType(rawValue: local)
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else { return nil }
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return SimpleType(base: builtin)
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}
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/// The local name of a tree node's `xsi:type` attribute value, recognized by
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/// the schema-instance namespace or the conventional `xsi` prefix, or nil.
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private static func xsiTypeLocalName(of node: PureXML.Model.TreeNode) -> String? {
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let schemaInstance = "http://www.w3.org/2001/XMLSchema-instance"
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guard let attribute = node.attributes.first(where: {
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$0.name.localName == "type" && ($0.name.namespaceURI == schemaInstance || $0.name.prefix == "xsi")
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}) else { return nil }
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return attribute.value.split(separator: ":").last.map(String.init) ?? attribute.value
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}
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private func label(_ constraint: IdentityConstraint) -> String {
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constraint.kind == .key ? "key" : "unique"
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}
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}
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}
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