PureXML/Sources/XSLT/XSLTFunctions.swift
Mihaela Mihaljevic b84fdd00ef fix(xslt): no fatal traps on extreme format-number and xsl:number values
format-number of a value at or beyond 2^53 ran an unguarded
Double-to-Int conversion, a fatal trap reachable from user data; a
fraction picture beyond 15 places overflowed the scale conversion the
same way; and xsl:number value= beyond 2^53 trapped identically.
Digit extraction clamps fraction places to 15 (the 2^53 exactness
bound), pads back to the picture's minimum, renders out-of-range
integers through the exponent expander, and xsl:number falls back to
plain number rendering outside [1, 2^53). Sort-key rows always carry
one key per sort. Regression tests cover all three trap paths.
2026-06-10 15:35:36 +02:00

376 lines
19 KiB
Swift

private typealias DecimalFormat = PureXML.XSLT.DecimalFormat
/// The digit-place counts, grouping, affixes, and multiplier derived from a
/// format-number subpattern. File scope and private.
private struct NumberLayout {
var prefix = ""
var suffix = ""
var minInteger = 0
var minFraction = 0
var maxFraction = 0
var groupingSize = 0
var multiplier = 1.0
}
extension PureXML.XSLT {
/// The XSLT `format-number` function. Supports `0`/`#` digit places, the
/// decimal point, grouping, and a percent suffix, honoring the symbols of the
/// chosen `xsl:decimal-format`. Pure Swift, no Foundation.
enum FormatNumber {
static func format(_ value: Double, _ picture: String, _ symbols: DecimalFormat = DecimalFormat()) -> String {
guard !value.isNaN else { return symbols.notANumber }
guard !picture.isEmpty else { return PureXML.XPath.Value.format(value) }
let subpatterns = picture.split(separator: symbols.patternSeparator, maxSplits: 1, omittingEmptySubsequences: false)
let positive = parse(String(subpatterns[0]), symbols)
// The negative subpattern contributes only its affixes; digit
// places, grouping, and multiplier come from the positive one.
// Without one the default negative prefix is the minus sign.
var layout = positive
if value < 0 {
let negative = subpatterns.count > 1 ? parse(String(subpatterns[1]), symbols) : nil
if let negative, !(negative.prefix.isEmpty && negative.suffix.isEmpty) {
layout.prefix = negative.prefix
layout.suffix = negative.suffix
} else {
// No negative subpattern, or one with no distinguishing
// affixes: the default negative prefix is the minus sign.
layout.prefix = String(symbols.minusSign) + layout.prefix
}
}
if value.isInfinite { return layout.prefix + symbols.infinity + layout.suffix }
let magnitude = Swift.abs(value) * positive.multiplier
return layout.prefix + render(magnitude, layout, symbols) + layout.suffix
}
/// Splits one subpattern into prefix, number part, and suffix, reading
/// the digit places, the grouping size (digits after the last grouping
/// separator), and the percent/per-mille multiplier from it.
private static func parse(_ subpattern: String, _ symbols: DecimalFormat) -> NumberLayout {
var layout = NumberLayout()
// When the decimal and grouping separators collide, every
// occurrence reads as grouping (the Xalan resolution).
let decimal: Character? = symbols.decimalSeparator == symbols.groupingSeparator ? nil : symbols.decimalSeparator
let numberCharacters = Set([symbols.zeroDigit, symbols.digit, symbols.groupingSeparator, symbols.decimalSeparator])
var phase = 0 // 0 prefix, 1 number, 2 suffix
var inFraction = false
var sinceGrouping: Int?
for character in subpattern {
if character == symbols.percent || character == symbols.perMille {
layout.multiplier = character == symbols.percent ? 100 : 1000
if phase == 1 { phase = 2 }
appendAffix(character, phase, &layout)
continue
}
if numberCharacters.contains(character), phase < 2 {
phase = 1
if character == decimal {
inFraction = true
} else {
countPlace(character, inFraction, symbols, &layout, &sinceGrouping)
}
continue
}
if phase == 1 { phase = 2 }
appendAffix(character, phase, &layout)
}
layout.groupingSize = sinceGrouping ?? 0
return layout
}
/// Tallies one digit-area character into the layout's place counts and
/// the running last-grouping-interval width.
private static func countPlace(
_ character: Character,
_ inFraction: Bool,
_ symbols: DecimalFormat,
_ layout: inout NumberLayout,
_ sinceGrouping: inout Int?,
) {
if character == symbols.groupingSeparator {
if !inFraction { sinceGrouping = 0 }
} else if inFraction {
layout.maxFraction += 1
if character == symbols.zeroDigit { layout.minFraction += 1 }
} else {
if character == symbols.zeroDigit { layout.minInteger += 1 }
sinceGrouping = sinceGrouping.map { $0 + 1 }
}
}
private static func appendAffix(_ character: Character, _ phase: Int, _ layout: inout NumberLayout) {
// The generic currency sign renders as this processor's (en-US)
// currency symbol, the JDK affix substitution.
let resolved: Character = character == "\u{A4}" ? "$" : character
if phase == 0 {
layout.prefix.append(resolved)
} else {
layout.suffix.append(resolved)
}
}
private static func render(_ value: Double, _ layout: NumberLayout, _ symbols: DecimalFormat) -> String {
// One scaled rounding, then pure integer digit extraction: repeated
// float multiplication would re-introduce representation error
// (0.4812 must render 4812, not 481199...). The scaled product must
// stay under 2^53 for exact integer extraction, so the picture's
// fraction places are clamped to 15 and padded back to the
// requested minimum.
let places = Swift.min(layout.maxFraction, 15)
var scale = 1.0
for _ in 0 ..< places {
scale *= 10
}
let (integerDigits, allFractionDigits) = digits(value, scale: scale, places: places)
var paddedInteger = integerDigits
while paddedInteger.count < Swift.max(1, layout.minInteger) {
paddedInteger = "0" + paddedInteger
}
var integerText = digitsToSymbols(paddedInteger, symbols)
if layout.groupingSize > 0 { integerText = group(integerText, symbols.groupingSeparator, layout.groupingSize) }
var fractionDigits = allFractionDigits
while fractionDigits.count > layout.minFraction, fractionDigits.hasSuffix("0") {
fractionDigits.removeLast()
}
while fractionDigits.count < layout.minFraction {
fractionDigits += "0"
}
let fractionText = digitsToSymbols(fractionDigits, symbols)
return fractionText.isEmpty ? integerText : integerText + String(symbols.decimalSeparator) + fractionText
}
/// The integer and fraction digit strings of `value` carried to
/// `places` fraction digits, via a single scaled rounding when the
/// magnitude fits an Int exactly. Beyond 2^53 a Double holds no
/// fraction anyway, so the integer digits come from the exponent
/// expander and the fraction is zeros: no Double-to-Int conversion
/// here may trap, whatever the value or the picture.
private static func digits(_ value: Double, scale: Double, places: Int) -> (String, String) {
let scaled = (value * scale).rounded()
guard scaled.isFinite, scaled < 9_007_199_254_740_992, scale < 9_007_199_254_740_992 else {
let integer = PureXML.XPath.Value.format(value.rounded(.towardZero))
return (integer, String(repeating: "0", count: places))
}
let total = Int(scaled)
let divisor = Int(scale)
var fraction = String(total % divisor)
while fraction.count < places {
fraction = "0" + fraction
}
return (String(total / divisor), places > 0 ? fraction : "")
}
/// Maps ASCII digits to the format's digit set, offset from its zero-digit.
private static func digitsToSymbols(_ digits: String, _ symbols: DecimalFormat) -> String {
guard symbols.zeroDigit != "0", let zero = symbols.zeroDigit.unicodeScalars.first else { return digits }
return String(digits.map { character in
guard let value = character.wholeNumberValue, let scalar = Unicode.Scalar(zero.value + UInt32(value)) else { return character }
return Character(scalar)
})
}
private static func group(_ digits: String, _ separator: Character, _ size: Int) -> String {
var result = ""
for (offset, character) in digits.reversed().enumerated() {
if offset > 0, offset.isMultiple(of: size) { result.append(separator) }
result.append(character)
}
return String(result.reversed())
}
}
/// The `xsl:key` index: each key name maps a key value to the nodes indexed
/// under it.
typealias KeyIndex = [String: [String: [PureXML.Model.TreeNode]]]
/// The XSLT extensions to the XPath function library: `current`, `key`,
/// `format-number`, and `document`, plus the `xsl:key` index they read.
enum Library {
/// The XSLT functions for an evaluation whose current node is `current`,
/// reading the prebuilt `keys` index and the injected `document` loader.
static func table(
current: PureXML.XPath.Node,
keys: @escaping (PureXML.Model.TreeNode) -> KeyIndex,
loader: @escaping (String) -> String?,
decimalFormats: [String: PureXML.XSLT.DecimalFormat] = [:],
documents: PureXML.XSLT.DocumentCache,
) -> PureXML.XPath.FunctionTable {
PureXML.XPath.FunctionTable()
.adding("current") { _, _ in .nodeSet([current]) }
.adding("format-number") { arguments, _ in
let name = arguments.count > 2 ? arguments[2].string : ""
return .string(FormatNumber.format(
arguments.first?.number ?? .nan,
arguments.count > 1 ? arguments[1].string : "",
decimalFormats[name] ?? PureXML.XSLT.DecimalFormat(),
))
}
.adding("key") { arguments, context in
keyLookup(arguments, context, keys)
}
.adding("document") { arguments, _ in
// A string or a node-set of URI references, each optionally with
// a `#fragment` selecting a subset of the loaded document.
let references: [String] = if let nodes = arguments.first?.nodes {
nodes.map(\.stringValue)
} else {
[arguments.first?.string ?? ""]
}
return .nodeSet(references.flatMap { documentReference($0, loader, documents) })
}
.adding("generate-id") { arguments, context in
// No argument uses the context node; an explicit empty node-set
// is the empty string, per the XSLT definition.
let node = arguments.isEmpty ? context.node.treeNode : arguments.first?.nodes?.first?.treeNode
guard let node else { return .string("") }
return .string("N\(UInt(bitPattern: ObjectIdentifier(node).hashValue))")
}
.adding("system-property") { arguments, _ in systemProperty(arguments.first?.string ?? "") }
.adding("element-available") { arguments, _ in .boolean(instructionNames.contains(localPart(arguments.first?.string ?? ""))) }
.adding("function-available") { arguments, _ in .boolean(functionNames.contains(localPart(arguments.first?.string ?? ""))) }
.adding("unparsed-entity-uri") { _, _ in .string("") }
}
/// The `key()` implementation: the index belongs to the current
/// node's document; a node-set second argument unions the matches for
/// each member's string value; results come back in document order.
private static func keyLookup(
_ arguments: [PureXML.XPath.Value],
_ context: PureXML.XPath.EvaluationContext,
_ keys: (PureXML.Model.TreeNode) -> KeyIndex,
) -> PureXML.XPath.Value {
let name = arguments.first?.string ?? ""
guard arguments.count > 1 else { return .nodeSet([]) }
let values: [String] = if let nodes = arguments[1].nodes {
nodes.map(\.stringValue)
} else {
[arguments[1].string]
}
let owner: PureXML.Model.TreeNode? = switch context.node {
case let .tree(tree): tree
case let .attribute(treeOwner, _), let .namespace(treeOwner, _, _): treeOwner
}
guard var documentRoot = owner else { return .nodeSet([]) }
while let parent = documentRoot.parent {
documentRoot = parent
}
let index = keys(documentRoot)
var matched: [PureXML.Model.TreeNode] = []
for value in values {
for node in index[name]?[value] ?? [] where !matched.contains(where: { $0 === node }) {
matched.append(node)
}
}
return .nodeSet(matched.map { PureXML.XPath.Node.tree($0) }.sorted(by: PureXML.XPath.Node.precedes))
}
/// Loads one `document()` reference: the whole document, or, when the
/// reference has a `#fragment`, the nodes its XPointer selects.
private static func documentReference(
_ reference: String,
_ loader: (String) -> String?,
_ cache: PureXML.XSLT.DocumentCache,
) -> [PureXML.XPath.Node] {
let path: String
let fragment: String?
if let hash = reference.firstIndex(of: "#") {
path = String(reference[..<hash])
fragment = String(reference[reference.index(after: hash)...])
} else {
path = reference
fragment = nil
}
if cache.trees[path] == nil {
guard let text = loader(path), let parsed = try? PureXML.parse(text, limits: .init(allowDoctype: true)) else { return [] }
cache.sources[path] = parsed
cache.trees[path] = PureXML.Model.TreeNode(parsed)
}
guard let tree = cache.trees[path], let parsed = cache.sources[path] else { return [] }
guard let fragment, !fragment.isEmpty else { return [.tree(tree)] }
let selections = (try? PureXML.XPointer.evaluate(fragment, over: parsed)) ?? []
return selections.compactMap { selection in
guard case let .node(node) = selection else { return nil }
return .tree(PureXML.Model.TreeNode(node))
}
}
private static func localPart(_ name: String) -> String {
name.split(separator: ":").last.map(String.init) ?? name
}
/// The XSLT system properties: the version is the number 1.0; the vendor
/// strings identify this processor. Any other property is the empty string.
private static func systemProperty(_ name: String) -> PureXML.XPath.Value {
switch localPart(name) {
case "version": .number(1.0)
case "vendor": .string("PureXML")
case "vendor-url": .string("https://github.com/mihaelamj/PureXML")
default: .string("")
}
}
/// The XSLT instruction elements this processor implements, for
/// `element-available`.
static let instructionNames: Set<String> = [
"value-of", "apply-templates", "apply-imports", "call-template", "for-each", "if", "choose",
"when", "otherwise", "element", "attribute", "copy", "copy-of", "text", "number", "comment",
"processing-instruction", "variable", "param", "with-param", "sort", "message", "fallback",
]
/// The XPath and XSLT functions this processor implements, for
/// `function-available`.
static let functionNames: Set<String> = [
"last", "position", "count", "id", "local-name", "namespace-uri", "name", "string", "concat",
"starts-with", "contains", "substring-before", "substring-after", "substring", "string-length",
"normalize-space", "translate", "boolean", "not", "true", "false", "lang", "number", "sum",
"floor", "ceiling", "round", "current", "document", "key", "format-number", "generate-id",
"system-property", "element-available", "function-available", "unparsed-entity-uri",
]
/// Builds the `xsl:key` index: each declared key maps every node matching
/// its pattern to its `use` value.
static func buildKeyIndex(stylesheet: Stylesheet, root: PureXML.Model.TreeNode) -> KeyIndex {
var index: KeyIndex = [:]
for key in stylesheet.keys {
let path = key.match.hasPrefix("/") ? key.match : "//" + key.match
guard let matchQuery = try? PureXML.XPath.Query(path),
let useQuery = try? PureXML.XPath.Query(key.use) else { continue }
for node in matchQuery.nodes(over: root) {
// A node-set use expression indexes the node under every
// member's string value.
let used = try? useQuery.value(at: node)
let values: [String] = if let nodes = used?.nodes {
nodes.map(\.stringValue)
} else {
[used?.string ?? ""]
}
for value in values {
index[key.name, default: [:]][value, default: []].append(node)
}
}
}
return index
}
}
}
extension PureXML.Emitting.Options {
/// These options with an `xsl:output`'s settings layered over them. Only an
/// explicit setting overrides; unspecified `xsl:output` attributes leave the
/// caller's corresponding option untouched.
func applying(_ output: PureXML.XSLT.Output) -> Self {
var copy = self
if let indent = output.indent {
copy.prettyPrint = indent
// Xalan-style indentation: children on their own lines with no
// leading spaces (indent-amount 0), the conformance golds' form.
copy.indent = ""
}
if let omit = output.omitXMLDeclaration { copy.includeXMLDeclaration = !omit }
if let encoding = output.encoding { copy.encodingName = encoding }
if let version = output.version { copy.xmlVersion = version }
if let standalone = output.standalone { copy.standalone = standalone }
return copy
}
}