666 lines
24 KiB
Swift
666 lines
24 KiB
Swift
// Parser.swift
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//
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// Half inspired by Reader class from John Sundell's Ink project
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// https://github.com/JohnSundell/Ink/blob/master/Sources/Ink/Internal/Reader.swift
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// with optimisation working ie removing String and doing my own UTF8 processing inspired by Fabian Fett's work in
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// https://github.com/swift-extras/swift-extras-json/blob/main/Sources/ExtrasJSON/Parsing/DocumentReader.swift
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//
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// This is a copy of the parser from Hummingbird. I am not using the version in Hummingbird to avoid the dependency
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import Foundation
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/// Reader object for parsing String buffers
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struct HBParser {
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enum Error: Swift.Error {
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case overflow
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case unexpected
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case emptyString
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case invalidUTF8
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case invalidPosition
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}
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/// Create a Parser object
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/// - Parameter string: UTF8 data to parse
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init?<Bytes: Collection>(_ utf8Data: Bytes, validateUTF8: Bool = true) where Bytes.Element == UInt8 {
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if let buffer = utf8Data as? [UInt8] {
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self.buffer = buffer
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} else {
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buffer = Array(utf8Data)
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}
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index = 0
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range = 0 ..< buffer.endIndex
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// should check that the data is valid utf8
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if validateUTF8 == true, self.validateUTF8() == false {
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return nil
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}
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}
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init(_ string: String) {
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buffer = Array(string.utf8)
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index = 0
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range = 0 ..< buffer.endIndex
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}
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/// Return contents of parser as a string
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var count: Int {
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return range.count
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}
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/// Return contents of parser as a string
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var string: String {
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return makeString(buffer[range])
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}
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private var buffer: [UInt8]
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private var index: Int
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private let range: Range<Int>
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}
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// MARK: sub-parsers
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extension HBParser {
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/// initialise a parser that parses a section of the buffer attached to another parser
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init(_ parser: HBParser, range: Range<Int>) {
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buffer = parser.buffer
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index = range.startIndex
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self.range = range
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precondition(range.startIndex >= 0 && range.endIndex <= buffer.endIndex)
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precondition(buffer[range.startIndex] & 0xC0 != 0x80) // check we arent in the middle of a UTF8 character
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}
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/// initialise a parser that parses a section of the buffer attached to this parser
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func subParser(_ range: Range<Int>) -> HBParser {
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return HBParser(self, range: range)
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}
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}
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extension HBParser {
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/// Return current character
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/// - Throws: .overflow
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/// - Returns: Current character
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mutating func character() throws -> Unicode.Scalar {
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guard !reachedEnd() else { throw Error.overflow }
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return unsafeCurrentAndAdvance()
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}
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/// Read the current character and return if it is as intended. If character test returns true then move forward 1
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/// - Parameter char: character to compare against
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/// - Throws: .overflow
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/// - Returns: If current character was the one we expected
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mutating func read(_ char: Unicode.Scalar) throws -> Bool {
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let initialIndex = index
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let c = try character()
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guard c == char else { index = initialIndex; return false }
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return true
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}
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/// Read the current character and check if it is in a set of characters If character test returns true then move forward 1
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/// - Parameter characterSet: Set of characters to compare against
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/// - Throws: .overflow
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/// - Returns: If current character is in character set
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mutating func read(_ characterSet: Set<Unicode.Scalar>) throws -> Bool {
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let initialIndex = index
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let c = try character()
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guard characterSet.contains(c) else { index = initialIndex; return false }
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return true
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}
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/// Compare characters at current position against provided string. If the characters are the same as string provided advance past string
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/// - Parameter string: String to compare against
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/// - Throws: .overflow, .emptyString
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/// - Returns: If characters at current position equal string
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mutating func read(_ string: String) throws -> Bool {
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let initialIndex = index
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guard string.count > 0 else { throw Error.emptyString }
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let subString = try read(count: string.count)
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guard subString.string == string else { index = initialIndex; return false }
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return true
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}
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/// Read next so many characters from buffer
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/// - Parameter count: Number of characters to read
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/// - Throws: .overflow
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/// - Returns: The string read from the buffer
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mutating func read(count: Int) throws -> HBParser {
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var count = count
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var readEndIndex = index
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while count > 0 {
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guard readEndIndex != range.endIndex else { throw Error.overflow }
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readEndIndex = skipUTF8Character(at: readEndIndex)
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count -= 1
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}
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let result = subParser(index ..< readEndIndex)
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index = readEndIndex
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return result
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}
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/// Read from buffer until we hit a character. Position after this is of the character we were checking for
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/// - Parameter until: Unicode.Scalar to read until
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/// - Throws: .overflow if we hit the end of the buffer before reading character
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/// - Returns: String read from buffer
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@discardableResult mutating func read(until: Unicode.Scalar, throwOnOverflow: Bool = true) throws -> HBParser {
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let startIndex = index
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while !reachedEnd() {
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if unsafeCurrent() == until {
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return subParser(startIndex ..< index)
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}
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unsafeAdvance()
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}
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if throwOnOverflow {
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_setPosition(startIndex)
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throw Error.overflow
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}
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return subParser(startIndex ..< index)
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}
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/// Read from buffer until we hit a character in supplied set. Position after this is of the character we were checking for
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/// - Parameter characterSet: Unicode.Scalar set to check against
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/// - Throws: .overflow
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/// - Returns: String read from buffer
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@discardableResult mutating func read(until characterSet: Set<Unicode.Scalar>, throwOnOverflow: Bool = true) throws -> HBParser {
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let startIndex = index
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while !reachedEnd() {
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if characterSet.contains(unsafeCurrent()) {
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return subParser(startIndex ..< index)
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}
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unsafeAdvance()
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}
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if throwOnOverflow {
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_setPosition(startIndex)
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throw Error.overflow
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}
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return subParser(startIndex ..< index)
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}
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/// Read from buffer until we hit a character that returns true for supplied closure. Position after this is of the character we were checking for
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/// - Parameter until: Function to test
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/// - Throws: .overflow
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/// - Returns: String read from buffer
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@discardableResult mutating func read(until: (Unicode.Scalar) -> Bool, throwOnOverflow: Bool = true) throws -> HBParser {
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let startIndex = index
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while !reachedEnd() {
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if until(unsafeCurrent()) {
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return subParser(startIndex ..< index)
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}
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unsafeAdvance()
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}
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if throwOnOverflow {
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_setPosition(startIndex)
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throw Error.overflow
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}
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return subParser(startIndex ..< index)
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}
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/// Read from buffer until we hit a character where supplied KeyPath is true. Position after this is of the character we were checking for
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/// - Parameter characterSet: Unicode.Scalar set to check against
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/// - Throws: .overflow
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/// - Returns: String read from buffer
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@discardableResult mutating func read(until keyPath: KeyPath<Unicode.Scalar, Bool>, throwOnOverflow: Bool = true) throws -> HBParser {
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let startIndex = index
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while !reachedEnd() {
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if unsafeCurrent()[keyPath: keyPath] {
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return subParser(startIndex ..< index)
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}
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unsafeAdvance()
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}
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if throwOnOverflow {
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_setPosition(startIndex)
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throw Error.overflow
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}
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return subParser(startIndex ..< index)
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}
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/// Read from buffer until we hit a string. By default the position after this is of the beginning of the string we were checking for
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/// - Parameter untilString: String to check for
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/// - Parameter throwOnOverflow: Throw errors if we hit the end of the buffer
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/// - Parameter skipToEnd: Should we set the position to after the found string
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/// - Throws: .overflow, .emptyString
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/// - Returns: String read from buffer
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@discardableResult mutating func read(untilString: String, throwOnOverflow: Bool = true, skipToEnd: Bool = false) throws -> HBParser {
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var untilString = untilString
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return try untilString.withUTF8 { utf8 in
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guard utf8.count > 0 else { throw Error.emptyString }
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let startIndex = index
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var foundIndex = index
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var untilIndex = 0
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while !reachedEnd() {
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if buffer[index] == utf8[untilIndex] {
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if untilIndex == 0 {
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foundIndex = index
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}
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untilIndex += 1
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if untilIndex == utf8.endIndex {
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unsafeAdvance()
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if skipToEnd == false {
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index = foundIndex
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}
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let result = subParser(startIndex ..< foundIndex)
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return result
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}
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} else {
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untilIndex = 0
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}
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index += 1
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}
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if throwOnOverflow {
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_setPosition(startIndex)
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throw Error.overflow
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}
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return subParser(startIndex ..< index)
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}
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}
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/// Read from buffer from current position until the end of the buffer
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/// - Returns: String read from buffer
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@discardableResult mutating func readUntilTheEnd() -> HBParser {
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let startIndex = index
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index = range.endIndex
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return subParser(startIndex ..< index)
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}
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/// Read while character at current position is the one supplied
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/// - Parameter while: Unicode.Scalar to check against
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/// - Returns: String read from buffer
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@discardableResult mutating func read(while: Unicode.Scalar) -> Int {
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var count = 0
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while !reachedEnd(),
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unsafeCurrent() == `while`
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{
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unsafeAdvance()
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count += 1
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}
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return count
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}
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/// Read while character at current position is in supplied set
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/// - Parameter while: character set to check
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/// - Returns: String read from buffer
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@discardableResult mutating func read(while characterSet: Set<Unicode.Scalar>) -> HBParser {
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let startIndex = index
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while !reachedEnd(),
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characterSet.contains(unsafeCurrent())
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{
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unsafeAdvance()
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}
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if startIndex == index {
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return subParser(startIndex ..< startIndex)
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}
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return subParser(startIndex ..< index)
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}
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/// Read while character returns true for supplied closure
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/// - Parameter while: character set to check
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/// - Returns: String read from buffer
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@discardableResult mutating func read(while: (Unicode.Scalar) -> Bool) -> HBParser {
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let startIndex = index
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while !reachedEnd(),
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`while`(unsafeCurrent())
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{
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unsafeAdvance()
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}
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return subParser(startIndex ..< index)
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}
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/// Read while character returns true for supplied KeyPath
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/// - Parameter while: character set to check
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/// - Returns: String read from buffer
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@discardableResult mutating func read(while keyPath: KeyPath<Unicode.Scalar, Bool>) -> HBParser {
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let startIndex = index
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while !reachedEnd(),
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unsafeCurrent()[keyPath: keyPath]
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{
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unsafeAdvance()
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}
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return subParser(startIndex ..< index)
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}
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/// Split parser into sections separated by character
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/// - Parameter separator: Separator character
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/// - Returns: arrays of sub parsers
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mutating func split(separator: Unicode.Scalar) -> [HBParser] {
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var subParsers: [HBParser] = []
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while !reachedEnd() {
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do {
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let section = try read(until: separator)
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subParsers.append(section)
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unsafeAdvance()
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} catch {
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if !reachedEnd() {
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subParsers.append(readUntilTheEnd())
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}
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}
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}
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return subParsers
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}
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/// Return whether we have reached the end of the buffer
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/// - Returns: Have we reached the end
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func reachedEnd() -> Bool {
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return index == range.endIndex
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}
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}
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/// Public versions of internal functions which include tests for overflow
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extension HBParser {
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/// Return the character at the current position
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/// - Throws: .overflow
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/// - Returns: Unicode.Scalar
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func current() -> Unicode.Scalar {
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guard !reachedEnd() else { return Unicode.Scalar(0) }
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return unsafeCurrent()
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}
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/// Move forward one character
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/// - Throws: .overflow
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mutating func advance() throws {
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guard !reachedEnd() else { throw Error.overflow }
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return unsafeAdvance()
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}
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/// Move forward so many character
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/// - Parameter amount: number of characters to move forward
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/// - Throws: .overflow
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mutating func advance(by amount: Int) throws {
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var amount = amount
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while amount > 0 {
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guard !reachedEnd() else { throw Error.overflow }
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index = skipUTF8Character(at: index)
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amount -= 1
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}
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}
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/// Move backwards one character
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/// - Throws: .overflow
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mutating func retreat() throws {
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guard index > range.startIndex else { throw Error.overflow }
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index = backOneUTF8Character(at: index)
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}
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/// Move back so many characters
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/// - Parameter amount: number of characters to move back
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/// - Throws: .overflow
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mutating func retreat(by amount: Int) throws {
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var amount = amount
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while amount > 0 {
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guard index > range.startIndex else { throw Error.overflow }
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index = backOneUTF8Character(at: index)
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amount -= 1
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}
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}
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mutating func unsafeAdvance() {
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index = skipUTF8Character(at: index)
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}
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mutating func unsafeAdvance(by amount: Int) {
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var amount = amount
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while amount > 0 {
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index = skipUTF8Character(at: index)
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amount -= 1
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}
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}
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func getPosition() -> Int {
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return index
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}
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mutating func setPosition(_ index: Int) throws {
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guard range.contains(index) else { throw Error.invalidPosition }
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guard validateUTF8Character(at: index).0 != nil else { throw Error.invalidPosition }
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_setPosition(index)
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}
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}
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/// extend Parser to conform to Sequence
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extension HBParser: Sequence {
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typealias Element = Unicode.Scalar
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__consuming func makeIterator() -> Iterator {
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return Iterator(self)
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}
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struct Iterator: IteratorProtocol {
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typealias Element = Unicode.Scalar
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var parser: HBParser
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init(_ parser: HBParser) {
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self.parser = parser
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}
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mutating func next() -> Unicode.Scalar? {
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guard !parser.reachedEnd() else { return nil }
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return parser.unsafeCurrentAndAdvance()
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}
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}
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}
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// internal versions without checks
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private extension HBParser {
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func unsafeCurrent() -> Unicode.Scalar {
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return decodeUTF8Character(at: index).0
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}
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mutating func unsafeCurrentAndAdvance() -> Unicode.Scalar {
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let (unicodeScalar, index) = decodeUTF8Character(at: self.index)
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self.index = index
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return unicodeScalar
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}
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mutating func _setPosition(_ index: Int) {
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self.index = index
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}
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func makeString<Bytes: Collection>(_ bytes: Bytes) -> String where Bytes.Element == UInt8, Bytes.Index == Int {
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if let string = bytes.withContiguousStorageIfAvailable({ String(decoding: $0, as: Unicode.UTF8.self) }) {
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return string
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} else {
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return String(decoding: bytes, as: Unicode.UTF8.self)
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}
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}
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}
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// UTF8 parsing
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extension HBParser {
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func decodeUTF8Character(at index: Int) -> (Unicode.Scalar, Int) {
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var index = index
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let byte1 = UInt32(buffer[index])
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var value: UInt32
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if byte1 & 0xC0 == 0xC0 {
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index += 1
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let byte2 = UInt32(buffer[index] & 0x3F)
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if byte1 & 0xE0 == 0xE0 {
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index += 1
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let byte3 = UInt32(buffer[index] & 0x3F)
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if byte1 & 0xF0 == 0xF0 {
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index += 1
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let byte4 = UInt32(buffer[index] & 0x3F)
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value = (byte1 & 0x7) << 18 + byte2 << 12 + byte3 << 6 + byte4
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} else {
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value = (byte1 & 0xF) << 12 + byte2 << 6 + byte3
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}
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} else {
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value = (byte1 & 0x1F) << 6 + byte2
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}
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} else {
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value = byte1 & 0x7F
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}
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let unicodeScalar = Unicode.Scalar(value)!
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return (unicodeScalar, index + 1)
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}
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func skipUTF8Character(at index: Int) -> Int {
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if buffer[index] & 0x80 != 0x80 { return index + 1 }
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if buffer[index + 1] & 0xC0 == 0x80 { return index + 2 }
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if buffer[index + 2] & 0xC0 == 0x80 { return index + 3 }
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return index + 4
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}
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func backOneUTF8Character(at index: Int) -> Int {
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if buffer[index - 1] & 0xC0 != 0x80 { return index - 1 }
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if buffer[index - 2] & 0xC0 != 0x80 { return index - 2 }
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if buffer[index - 3] & 0xC0 != 0x80 { return index - 3 }
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return index - 4
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}
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/// same as `decodeUTF8Character` but adds extra validation, so we can make assumptions later on in decode and skip
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func validateUTF8Character(at index: Int) -> (Unicode.Scalar?, Int) {
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var index = index
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let byte1 = UInt32(buffer[index])
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var value: UInt32
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if byte1 & 0xC0 == 0xC0 {
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index += 1
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let byte = UInt32(buffer[index])
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guard byte & 0xC0 == 0x80 else { return (nil, index) }
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let byte2 = UInt32(byte & 0x3F)
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if byte1 & 0xE0 == 0xE0 {
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index += 1
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let byte = UInt32(buffer[index])
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guard byte & 0xC0 == 0x80 else { return (nil, index) }
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let byte3 = UInt32(byte & 0x3F)
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if byte1 & 0xF0 == 0xF0 {
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index += 1
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let byte = UInt32(buffer[index])
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guard byte & 0xC0 == 0x80 else { return (nil, index) }
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let byte4 = UInt32(byte & 0x3F)
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value = (byte1 & 0x7) << 18 + byte2 << 12 + byte3 << 6 + byte4
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} else {
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value = (byte1 & 0xF) << 12 + byte2 << 6 + byte3
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}
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} else {
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value = (byte1 & 0x1F) << 6 + byte2
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}
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} else {
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value = byte1 & 0x7F
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}
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|
let unicodeScalar = Unicode.Scalar(value)
|
|
return (unicodeScalar, index + 1)
|
|
}
|
|
|
|
/// return if the buffer is valid UTF8
|
|
func validateUTF8() -> Bool {
|
|
var index = range.startIndex
|
|
while index < range.endIndex {
|
|
let (scalar, newIndex) = validateUTF8Character(at: index)
|
|
guard scalar != nil else { return false }
|
|
index = newIndex
|
|
}
|
|
return true
|
|
}
|
|
|
|
private static let asciiHexValues: [UInt8] = [
|
|
/* 00 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 08 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 10 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 18 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 20 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 28 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 30 */ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
|
|
/* 38 */ 0x08, 0x09, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 40 */ 0x80, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x80,
|
|
/* 48 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 50 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 58 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 60 */ 0x80, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x80,
|
|
/* 68 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 70 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 78 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
|
|
/* 80 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 88 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 90 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* 98 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* A0 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* A8 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* B0 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* B8 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* C0 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* C8 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* D0 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* D8 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* E0 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* E8 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* F0 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
/* F8 */ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
|
|
]
|
|
|
|
/// percent decode UTF8
|
|
func percentDecode() -> String? {
|
|
struct DecodeError: Swift.Error {}
|
|
func _percentDecode(_ original: ArraySlice<UInt8>, _ bytes: UnsafeMutableBufferPointer<UInt8>) throws -> Int {
|
|
var newIndex = 0
|
|
var index = original.startIndex
|
|
|
|
while index < original.endIndex {
|
|
// if we have found a percent sign
|
|
if original[index] == 0x25 {
|
|
let high = Self.asciiHexValues[Int(original[index + 1])]
|
|
let low = Self.asciiHexValues[Int(original[index + 2])]
|
|
index += 3
|
|
if ((high | low) & 0x80) != 0 {
|
|
throw DecodeError()
|
|
}
|
|
bytes[newIndex] = (high << 4) | low
|
|
newIndex += 1
|
|
} else {
|
|
bytes[newIndex] = original[index]
|
|
newIndex += 1
|
|
index += 1
|
|
}
|
|
}
|
|
return newIndex
|
|
}
|
|
|
|
guard index != range.endIndex else { return "" }
|
|
do {
|
|
if #available(macOS 11, *) {
|
|
return try String(unsafeUninitializedCapacity: range.endIndex - index) { bytes -> Int in
|
|
try _percentDecode(self.buffer[self.index ..< range.endIndex], bytes)
|
|
}
|
|
} else {
|
|
let newBuffer = try [UInt8].init(unsafeUninitializedCapacity: range.endIndex - index) { bytes, count in
|
|
try count = _percentDecode(self.buffer[self.index ..< range.endIndex], bytes)
|
|
}
|
|
return makeString(newBuffer)
|
|
}
|
|
} catch {
|
|
return nil
|
|
}
|
|
}
|
|
}
|
|
|
|
extension Unicode.Scalar {
|
|
var isWhitespace: Bool {
|
|
return properties.isWhitespace
|
|
}
|
|
|
|
var isNewline: Bool {
|
|
switch value {
|
|
case 0x000A ... 0x000D /* LF ... CR */: return true
|
|
case 0x0085 /* NEXT LINE (NEL) */: return true
|
|
case 0x2028 /* LINE SEPARATOR */: return true
|
|
case 0x2029 /* PARAGRAPH SEPARATOR */: return true
|
|
default: return false
|
|
}
|
|
}
|
|
|
|
var isNumber: Bool {
|
|
return properties.numericType != nil
|
|
}
|
|
|
|
var isLetter: Bool {
|
|
return properties.isAlphabetic
|
|
}
|
|
|
|
var isLetterOrNumber: Bool {
|
|
return isLetter || isNumber
|
|
}
|
|
}
|
|
|
|
extension Set where Element == Unicode.Scalar {
|
|
init(_ string: String) {
|
|
self = Set(string.unicodeScalars)
|
|
}
|
|
}
|