Mihaela Mihaljevic
80fffd8127
Add PureXML.Validation.Schematron: compile a Schematron schema (matching schema/pattern/rule/assert/report by local name, so the ISO and legacy namespaces both work) and validate a document. A rule's context XPath selects the nodes it fires on; each assert/report test is evaluated relative to the node via the XPath context-node API. A failed assert is an error, a matched report a warning; within a pattern a node fires the first matching rule. Adds XPath.Query.nodes(over:) returning matched tree nodes so one tree can be queried repeatedly. Closes #52 Closes #53 Closes #25
63 lines
3.0 KiB
Swift
63 lines
3.0 KiB
Swift
extension PureXML.Validation {
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/// Parses a Schematron schema document into patterns. Namespace-agnostic: it
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/// matches the `schema`, `pattern`, `rule`, `assert`, and `report` elements by
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/// local name, so both the ISO and the legacy Schematron namespaces work.
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enum SchematronParser {
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static func parse(_ xml: String) throws -> [SchematronPattern] {
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let root = try PureXML.parseTree(xml)
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return try descendants(root, localName: "pattern").map(pattern)
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}
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private static func pattern(_ node: PureXML.Model.TreeNode) throws -> SchematronPattern {
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try SchematronPattern(rules: children(node, localName: "rule").compactMap(rule))
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}
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private static func rule(_ node: PureXML.Model.TreeNode) throws -> SchematronRule? {
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guard let context = attribute(node, "context") else { return nil }
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let assertions = try node.children
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.filter { $0.kind == .element && isAssertion($0) }
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.compactMap(assertion)
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return try SchematronRule(context: PureXML.XPath.Query(contextExpression(context)), assertions: assertions)
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}
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private static func assertion(_ node: PureXML.Model.TreeNode) throws -> SchematronAssertion? {
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guard let test = attribute(node, "test") else { return nil }
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let isReport = node.name?.localName == "report"
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return try SchematronAssertion(
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isReport: isReport,
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test: PureXML.XPath.Query(test),
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message: node.stringValue.trimmingXMLWhitespace(),
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)
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}
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private static func isAssertion(_ node: PureXML.Model.TreeNode) -> Bool {
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node.name?.localName == "assert" || node.name?.localName == "report"
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}
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/// A relative context selects matching nodes anywhere, so it is searched
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/// from the document via `//`; an absolute context is used as written.
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private static func contextExpression(_ context: String) -> String {
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context.hasPrefix("/") ? context : "//" + context
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}
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private static func attribute(_ node: PureXML.Model.TreeNode, _ name: String) -> String? {
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node.attributes.first { $0.name.localName == name || $0.name.description == name }?.value
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}
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private static func children(_ node: PureXML.Model.TreeNode, localName: String) -> [PureXML.Model.TreeNode] {
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node.children.filter { $0.kind == .element && $0.name?.localName == localName }
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}
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private static func descendants(_ node: PureXML.Model.TreeNode, localName: String) -> [PureXML.Model.TreeNode] {
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var result: [PureXML.Model.TreeNode] = []
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for child in node.children {
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if child.kind == .element, child.name?.localName == localName {
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result.append(child)
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}
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result.append(contentsOf: descendants(child, localName: localName))
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}
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return result
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}
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}
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}
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