Mihaela Mihaljevic
39a91c258e
Identity-constraint selector and field XPath prefixes were resolved against the instance document's namespace bindings, so a constraint declared with xmlns:v="..." and a selector like .//v:vehicle matched nothing when the instance used a default namespace instead of the v prefix. The selector then selected no nodes, no key tuples were collected, and duplicate-key and keyref violations went undetected. Prefixes now resolve against the namespace bindings in scope where the constraint is declared in the schema (XSD Part 1, Identity-constraint Definition), captured at parse time onto IdentityConstraint. A QName field value still compares using the instance's bindings, so QName keys are unaffected. XSTS invalid-instances-accepted 143 to 133: the idc004/5/6 namespaced key/keyref cluster and namespace-resolution cases (idZ010 and kin), no other bucket moved.
380 lines
19 KiB
Swift
380 lines
19 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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let namespaceBindings: [String: String]
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init(string: String, type: PureXML.Schema.SimpleType?, namespaceBindings: [String: String] = [:]) {
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self.string = string
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self.type = type
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self.namespaceBindings = namespaceBindings
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}
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static func == (lhs: FieldValue, rhs: FieldValue) -> Bool {
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if let left = lhs.qnameValue, let right = rhs.qnameValue, left.uri == right.uri, left.local == right.local {
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return true
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}
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if let lhsType = lhs.type, let rhsType = rhs.type {
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if 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 false
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}
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return lhs.string == rhs.string
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}
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private var qnameValue: (uri: String?, local: String)? {
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let trimmed = string.trimmingXMLWhitespace()
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guard trimmed.contains(":") else { return nil }
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let parts = trimmed.split(separator: ":", maxSplits: 1).map(String.init)
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guard parts.count == 2 else { return nil }
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let uri = namespaceBindings[parts[0]] ?? (parts[0].isEmpty ? namespaceBindings[""] : nil)
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return (uri, parts[1])
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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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/// Simple types for identity-constraint fields keyed by
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/// ``XSDParser/identityFieldKey(selector:field:)``.
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let fieldTypes: [String: SimpleType]
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/// Global element and type declarations for runtime field typing.
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let types: [String: ElementType]
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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(
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constraints: [String: [IdentityConstraint]],
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fieldTypes: [String: SimpleType] = [:],
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types: [String: ElementType] = [:],
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) {
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self.constraints = constraints
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self.fieldTypes = fieldTypes
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self.types = types
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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 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, namespaces: [String: String]) -> [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, namespaces: namespaces).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, namespaces: constraint.namespaceBindings) {
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let targetPath = path + steps(from: node, to: target)
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if let error = fieldCardinalityError(constraint, at: target, path: targetPath) {
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issues.append(error)
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continue
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}
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let tuple = fieldTuple(constraint.fields, at: target, constraint: constraint)
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if constraint.kind == .key, tuple.contains(where: { $0 == nil }) {
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issues.append(.init(
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reason: "key '\(constraint.name)': a field is missing",
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at: targetPath + fieldStep(constraint.fields, at: target, namespaces: constraint.namespaceBindings),
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))
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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(
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reason: "\(label(constraint)) '\(constraint.name)': duplicate value",
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at: targetPath + fieldStep(constraint.fields, at: target, namespaces: constraint.namespaceBindings),
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))
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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, namespaces: constraint.namespaceBindings) {
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let targetPath = path + steps(from: node, to: target)
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if let error = fieldCardinalityError(constraint, at: target, path: targetPath) {
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issues.append(error)
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continue
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}
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let tuple = fieldTuple(constraint.fields, at: target, constraint: constraint)
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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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issues.append(.init(
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reason: "keyref '\(constraint.name)': no matching key '\(refer)'",
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at: targetPath + fieldStep(constraint.fields, at: target, namespaces: constraint.namespaceBindings),
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))
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}
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}
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}
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/// The error when a field of `constraint` selects more than one node at
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/// `target`. A field must evaluate to a node-set with at most one member
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/// (Identity-constraint Definition; cvc-identity-constraint.3); selecting
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/// several is a violation, not a multi-valued key.
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private func fieldCardinalityError(
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_ constraint: IdentityConstraint,
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at target: PureXML.Model.TreeNode,
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path targetPath: [PureXML.Validation.PathKey],
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) -> PureXML.Validation.ValidationError? {
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for field in constraint.fields where select(field, at: target, namespaces: constraint.namespaceBindings).count > 1 {
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return .init(
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reason: "\(label(constraint)) '\(constraint.name)': field '\(field)' must select at most one node",
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at: targetPath + fieldStep(constraint.fields, at: target, namespaces: constraint.namespaceBindings),
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)
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}
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return nil
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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, namespaces: [String: String]) -> [PureXML.Model.TreeNode] {
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guard let query = cache.query(xpath) else { return [] }
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return query.nodes(over: node, namespaces: namespaces)
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}
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private func fieldTuple(_ fields: [String], at node: PureXML.Model.TreeNode, constraint: IdentityConstraint) -> [FieldValue?] {
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// The field XPath's prefixes resolve against the schema (where the
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// constraint is declared); a QName field VALUE resolves against the
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// instance, so the FieldValue keeps the instance bindings.
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let instanceNamespaces = namespaceBindings(at: node)
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return fields.map { field in
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guard let query = cache.query(field),
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let value = try? query.value(at: node, namespaces: constraint.namespaceBindings)
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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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let type = resolveFieldType(field, constraint: constraint, at: node)
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?? Self.effectiveType(of: value)
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return FieldValue(string: value.string, type: type, namespaceBindings: instanceNamespaces)
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}
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}
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/// Prefix bindings in scope at `node`, gathered from ancestor elements.
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private func namespaceBindings(at node: PureXML.Model.TreeNode) -> [String: String] {
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var chain: [PureXML.Model.TreeNode] = []
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var current: PureXML.Model.TreeNode? = node
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while let element = current, element.kind == .element {
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chain.append(element)
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current = element.parent
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}
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var bindings: [String: String] = [:]
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for element in chain.reversed() {
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for attribute in element.attributes {
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if attribute.name.prefix == "xmlns" {
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bindings[attribute.name.localName] = attribute.value
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} else if attribute.name.prefix == nil, attribute.name.localName == "xmlns" {
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bindings[""] = attribute.value
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}
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}
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}
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return bindings
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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 func resolveFieldType(_ field: String, constraint: IdentityConstraint, at target: PureXML.Model.TreeNode) -> SimpleType? {
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if field == ".", let local = target.name?.localName {
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if let type = fieldTypes[PureXML.Schema.XSDParser.identityFieldKey(constraint: constraint, field: field, targetLocal: local)] {
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return type
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}
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guard let name = target.name else { return nil }
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if let declaration = types[PureXML.Schema.XSDParser.elementDeclarationKey(name)] {
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return simpleType(of: declaration)
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}
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if let declaration = types[PureXML.Schema.XSDParser.elementKey(name.localName)] {
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return simpleType(of: declaration)
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}
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}
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return fieldTypes[PureXML.Schema.XSDParser.identityFieldKey(constraint: constraint, field: field)]
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}
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private func simpleType(of declaration: ElementType) -> SimpleType? {
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switch declaration {
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case let .simple(simple): simple
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case let .complex(complex):
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if case let .simpleContent(simple) = complex.content { simple } else { nil }
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case .typeReference: nil
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}
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}
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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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extension PureXML.Schema.IdentityValidator {
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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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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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}
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