PureXML/Sources/XSLT/XSLTMatchCache.swift
Mihaela Mihaljevic 40605ff6e5 feat(xslt): contextual sort keys and cross-document template matching
Sort keys evaluate once per node with the node's own position, size,
variables, and bindings, so position()-based keys work, and NaN keys
order before numbers under data-type=number. Match patterns evaluate
over the matched node's own document, so templates match nodes loaded
through document(); the match cache keys include the document
identity. Xalan baseline 204 -> 187 (sort 18 -> 11, mdocs 14 -> 6).
2026-06-10 13:54:37 +02:00

73 lines
3.4 KiB
Swift

/// What one match pattern selected: tree-node and attribute identities.
private struct PatternMatches {
var trees: Set<ObjectIdentifier> = []
var attributes: Set<PureXML.XSLT.AttributeIdentity> = []
}
extension PureXML.XSLT {
/// An attribute node's identity: its owner's identity plus its name.
struct AttributeIdentity: Hashable {
let owner: ObjectIdentifier
let name: String
}
/// Caches, per transform, the node set each match pattern selects over the
/// source tree (tree nodes and attribute nodes), so a pattern is compiled
/// and evaluated once per document rather than once per (node, template)
/// pair during template selection.
final class MatchCache {
private var matched: [String: PatternMatches] = [:]
/// The identities of the tree nodes `pattern` selects over `root`.
func nodes(
matching pattern: String,
over root: PureXML.Model.TreeNode,
functions: PureXML.XPath.FunctionTable = .init(),
namespaces: [String: String] = [:],
) -> Set<ObjectIdentifier> {
compute(pattern, root, functions, namespaces).trees
}
/// The identities of the attribute nodes `pattern` selects over `root`.
func attributes(
matching pattern: String,
over root: PureXML.Model.TreeNode,
functions: PureXML.XPath.FunctionTable = .init(),
namespaces: [String: String] = [:],
) -> Set<AttributeIdentity> {
compute(pattern, root, functions, namespaces).attributes
}
/// Computed and cached on first use; a branch that fails to compile
/// selects nothing. The function table makes `key()` and `id()`
/// patterns work; the bindings resolve prefixed name tests by URI.
private func compute(_ pattern: String, _ root: PureXML.Model.TreeNode, _ functions: PureXML.XPath.FunctionTable, _ namespaces: [String: String]) -> PatternMatches {
var key = pattern + "\u{1}" + namespaces.sorted(by: { $0.key < $1.key }).map { $0.key + "=" + $0.value }.joined(separator: ";")
key += "\u{1}\(UInt(bitPattern: ObjectIdentifier(root).hashValue))"
if let cached = matched[key] { return cached }
var result = PatternMatches()
for branch in pattern.split(separator: "|") {
let trimmed = branch.trimmingXMLWhitespace()
let path = trimmed.hasPrefix("/") || trimmed.hasPrefix("key(") || trimmed.hasPrefix("id(") ? trimmed : "//" + trimmed
guard let query = try? PureXML.XPath.Query(path),
let value = try? query.value(atNode: .tree(root), position: 1, size: 1, variables: [:], functions: functions, namespaces: namespaces),
let selected = value.nodes
else { continue }
for node in selected {
switch node {
case let .tree(tree):
result.trees.insert(ObjectIdentifier(tree))
case let .attribute(owner, attribute):
result.attributes.insert(AttributeIdentity(owner: ObjectIdentifier(owner), name: attribute.name.description))
case .namespace:
break
}
}
}
matched[key] = result
return result
}
}
}