Mihaela Mihaljevic
634270d529
Add the PureXML.Catalog namespace: parse an OASIS XML catalog (public, system, uri, rewriteSystem, rewriteURI, group/catalog by local name) into a Resolver mapping public/system identifiers and URI names to URIs, with longest-prefix rewriting and system-over-public precedence. entityResolver (loadingURI:) builds a Parsing.EntityResolver that resolves an external identifier through the catalog and loads the URI via an injected closure, so a catalog plus loader wires entities and DTDs in while the default keeps XXE closed. Closes #57 Closes #58 Closes #27
85 lines
3.0 KiB
Swift
85 lines
3.0 KiB
Swift
/// Accumulates catalog entries as the tree is walked. File-scope and private: an
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/// internal detail of ``PureXML/Catalog/CatalogParser``.
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private struct CatalogBuilder {
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typealias RewriteRule = PureXML.Catalog.RewriteRule
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var systemMap: [String: String] = [:]
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var publicMap: [String: String] = [:]
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var uriMap: [String: String] = [:]
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var rewriteSystem: [RewriteRule] = []
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var rewriteURI: [RewriteRule] = []
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mutating func add(_ node: PureXML.Model.TreeNode) {
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switch node.name?.localName {
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case "system":
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insert(node, key: "systemId", value: "uri", into: &systemMap)
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case "public":
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insert(node, key: "publicId", value: "uri", into: &publicMap)
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case "uri":
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insert(node, key: "name", value: "uri", into: &uriMap)
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case "rewriteSystem":
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appendRewrite(node, start: "systemIdStartString", into: &rewriteSystem)
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case "rewriteURI":
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appendRewrite(node, start: "uriStartString", into: &rewriteURI)
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default:
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break
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}
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}
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private func insert(
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_ node: PureXML.Model.TreeNode,
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key: String,
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value: String,
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into map: inout [String: String],
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) {
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guard let identifier = attribute(node, key), let uri = attribute(node, value) else { return }
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map[identifier] = uri
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}
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private func appendRewrite(
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_ node: PureXML.Model.TreeNode,
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start: String,
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into rules: inout [RewriteRule],
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) {
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guard let startString = attribute(node, start), let rewrite = attribute(node, "rewritePrefix") else { return }
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rules.append(RewriteRule(startString: startString, rewritePrefix: rewrite))
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}
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private 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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func resolver() -> PureXML.Catalog.Resolver {
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PureXML.Catalog.Resolver(
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systemMap: systemMap,
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publicMap: publicMap,
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uriMap: uriMap,
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rewriteSystem: rewriteSystem,
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rewriteURI: rewriteURI,
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)
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}
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}
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extension PureXML.Catalog {
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/// Parses an OASIS XML catalog document into a ``Resolver``. Entries are
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/// matched by local name, so the catalog namespace is not required; `group`
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/// and `catalog` elements are recursed into.
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enum CatalogParser {
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static func parse(_ xml: String) throws -> Resolver {
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let root = try PureXML.parseTree(xml)
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var builder = CatalogBuilder()
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collect(root, into: &builder)
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return builder.resolver()
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}
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private static func collect(_ node: PureXML.Model.TreeNode, into builder: inout CatalogBuilder) {
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for child in node.children where child.kind == .element {
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builder.add(child)
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if child.name?.localName == "group" || child.name?.localName == "catalog" {
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collect(child, into: &builder)
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}
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}
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}
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}
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}
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