Mihaela Mihaljevic
1ae6680d94
Add PureXML.XPath: a compiled location-path query engine reimplemented from the XPath 1.0 specification; no upstream code copied. - Compiler parses a path into steps; Evaluator walks the tree returning a Selection node-set (node or attribute) in document order. - Forward axes only (child, descendant //, self ., attribute @), since the value model has no parent pointers. Node tests: name, *, text(), node(), comment(). Predicates: [n], [@a], [@a='v'], [child], [child='v']. - Public surface: XPath.Query (init compiles, evaluate/elements/strings), the Selection enum (element / stringValue), QueryError, and the one-shot PureXML.xpath(_:over:). Upward/sibling axes and the full expression language are explicitly out of scope. - 12 XPath tests; 61 total.
36 lines
1.6 KiB
Swift
36 lines
1.6 KiB
Swift
public extension PureXML.XPath {
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/// A compiled XPath location-path query over the supported subset: the
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/// forward axes (child, descendant `//`, self `.`, attribute `@`), the node
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/// tests (name, `*`, `text()`, `node()`, `comment()`), and the predicates
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/// `[n]`, `[@a]`, `[@a='v']`, `[child]`, `[child='v']`.
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///
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/// Upward and sibling axes, functions, and the full expression language are
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/// intentionally out of scope. Reimplemented from the XPath 1.0 specification.
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struct Query: Sendable {
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let absolute: Bool
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let steps: [Step]
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/// Compiles an XPath location path, throwing ``QueryError`` on a path
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/// outside the supported subset.
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public init(_ path: String) throws {
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(absolute, steps) = try Compiler.compile(path)
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}
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/// Evaluates the query over a node, returning the selected node-set in
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/// document order. The node is the starting context.
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public func evaluate(over node: PureXML.Model.Node) throws -> [Selection] {
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try Evaluator.evaluate(steps: steps, over: node)
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}
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/// Evaluates the query and returns the selected elements only.
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public func elements(over node: PureXML.Model.Node) throws -> [PureXML.Model.Element] {
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try evaluate(over: node).compactMap(\.element)
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}
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/// Evaluates the query and returns the string-value of each selection.
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public func strings(over node: PureXML.Model.Node) throws -> [String] {
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try evaluate(over: node).map(\.stringValue)
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}
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}
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}
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