Mihaela Mihaljevic
9168f990d6
Parse the XML declaration's pseudo-attributes instead of skipping the <?xml?> processing instruction: - version, encoding, and standalone are surfaced on a new XMLDeclaration, returned from parseWithDocumentType and via PureXML.xmlDeclaration(_:). - The pseudo-attributes are validated: fixed order (version, encoding, standalone), known names only, and standalone must be yes or no. A malformed declaration is rejected. - The declared version is now readable, a prerequisite for XML 1.1. parseWithDocumentType returns a ParsedDocument struct (node, documentType, declaration) rather than a 2-tuple; the member names are unchanged so existing call sites are unaffected. Closes #95
61 lines
2.5 KiB
Swift
61 lines
2.5 KiB
Swift
public extension PureXML.Parsing {
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/// The XML declaration `<?xml version="1.0" encoding="UTF-8" standalone="yes"?>`
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/// at the very start of a document: its version, the declared encoding name (if
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/// any), and the standalone document declaration (if any).
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struct XMLDeclaration: Equatable, Sendable {
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public var version: String?
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public var encoding: String?
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public var standalone: Bool?
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public init(version: String? = nil, encoding: String? = nil, standalone: Bool? = nil) {
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self.version = version
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self.encoding = encoding
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self.standalone = standalone
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}
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/// Parses the pseudo-attributes that follow `<?xml` in an XML declaration.
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/// The grammar fixes their order (`version`, then optional `encoding`, then
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/// optional `standalone`) and `standalone` must be `yes` or `no`. Returns
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/// nil when the text violates that grammar.
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static func parse(_ data: String) -> XMLDeclaration? {
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var scanner = PseudoAttributeScanner(data)
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let pairs = scanner.scan()
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guard let pairs, !pairs.isEmpty else { return nil }
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let names = pairs.map(\.name)
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guard names.first == "version", isOrdered(names) else { return nil }
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var declaration = XMLDeclaration()
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for pair in pairs {
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switch pair.name {
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case "version": declaration.version = pair.value
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case "encoding": declaration.encoding = pair.value
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case "standalone":
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guard let flag = standaloneFlag(pair.value) else { return nil }
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declaration.standalone = flag
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default: return nil
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}
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}
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return declaration
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}
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/// Whether the pseudo-attribute names appear in the grammar's fixed order
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/// with no repeats: version, then encoding, then standalone.
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private static func isOrdered(_ names: [String]) -> Bool {
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let rank = ["version": 0, "encoding": 1, "standalone": 2]
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var last = -1
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for name in names {
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guard let position = rank[name], position > last else { return false }
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last = position
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}
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return true
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}
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private static func standaloneFlag(_ value: String) -> Bool? {
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switch value {
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case "yes": true
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case "no": false
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default: nil
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}
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}
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}
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}
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