Mihaela Mihaljevic
d83e5a88ce
Compile and evaluate full XPath 1.0 expressions, not just location paths. Add the four-type Value (node-set, boolean, number, string) with the spec's coercion rules and canonical number formatting, a recursive-descent parser for the operator grammar (or/and, equality, relational, additive, multiplicative, unary minus, union) whose grammatical position disambiguates * and the operator keywords, function calls, variable references, and filter expressions. Predicates are now arbitrary expressions (a numeric predicate is a position test). Comparison follows the node-set quantification rules. Query gains value/number/string/boolean accessors and a $variable binding map; the core functions last, position, count, not, true, false, boolean, number, and string ship with it. Closes #42
31 lines
1.5 KiB
Swift
31 lines
1.5 KiB
Swift
extension PureXML.XPath {
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/// The core XPath functions tied to the four-type model and predicates:
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/// `last`, `position`, `count`, `not`, `true`, `false`, `boolean`, `number`,
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/// and `string`. The broader library (string, node, and number functions)
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/// extends this table.
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enum CoreFunctions {
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static let table = FunctionTable([
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"last": { _, context in .number(Double(context.size)) },
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"position": { _, context in .number(Double(context.position)) },
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"count": { arguments, _ in
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guard let nodes = arguments.first?.nodes else {
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throw PureXML.XPath.QueryError.invalidArguments("count() requires a node-set")
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}
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return .number(Double(nodes.count))
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},
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"not": { arguments, _ in .boolean(!(arguments.first?.boolean ?? false)) },
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"true": { _, _ in .boolean(true) },
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"false": { _, _ in .boolean(false) },
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"boolean": { arguments, _ in .boolean(arguments.first?.boolean ?? false) },
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"number": { arguments, context in
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if let first = arguments.first { return .number(first.number) }
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return .number(PureXML.XPath.Value.parseNumber(context.node.stringValue))
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},
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"string": { arguments, context in
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if let first = arguments.first { return .string(first.string) }
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return .string(context.node.stringValue)
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},
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])
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}
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}
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