Mihaela Mihaljevic
6b7853f2d5
Rebuild the XPath engine on the parent-aware tree. Add an XPath node abstraction (tree, attribute, namespace) with document order, and navigate all thirteen axes: child, descendant, parent, ancestor, following-sibling, preceding-sibling, following, preceding, attribute, namespace, self, descendant-or-self, ancestor-or-self. Support the ./../@/// abbreviations and processing-instruction() node tests. Reverse axes number nearest-first for positional predicates; results return de-duplicated in document order. The attribute axis excludes xmlns declarations; the namespace axis surfaces in-scope namespace nodes. Closes #40
49 lines
1.4 KiB
Swift
49 lines
1.4 KiB
Swift
extension PureXML.XPath {
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/// The thirteen XPath 1.0 axes. Every axis is reachable now that the tree is
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/// parent-aware, so upward and sibling navigation are first-class.
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enum Axis: Equatable {
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case child
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case descendant
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case parent
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case ancestor
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case followingSibling
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case precedingSibling
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case following
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case preceding
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case attribute
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case namespace
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case selfAxis
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case descendantOrSelf
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case ancestorOrSelf
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/// Whether the axis is a reverse axis (its nodes are numbered in reverse
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/// document order for positional predicates).
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var isReverse: Bool {
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switch self {
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case .parent, .ancestor, .precedingSibling, .preceding, .ancestorOrSelf:
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true
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default:
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false
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}
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}
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/// The principal node kind of the axis: attributes for the attribute axis,
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/// namespaces for the namespace axis, elements otherwise. Governs what a
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/// name test or `*` selects.
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var principalKind: PrincipalKind {
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switch self {
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case .attribute: .attribute
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case .namespace: .namespace
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default: .element
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}
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}
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}
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/// The principal node kind selected by name tests on an axis.
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enum PrincipalKind: Equatable {
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case element
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case attribute
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case namespace
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}
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}
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