126 lines
3.2 KiB
Swift
126 lines
3.2 KiB
Swift
import Foundation
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extension CharacterSet {
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static let hex = CharacterSet(charactersIn: "0123456789abcdef")
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static let name = alphanumerics.union(CharacterSet.init(charactersIn: "_/"))
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}
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extension Collection {
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func chunks(size: Int) -> UnfoldSequence<Self.SubSequence, Self.Index> {
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sequence(state: startIndex) { state -> SubSequence? in
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guard state != endIndex else { return nil }
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let next = index(state, offsetBy: size, limitedBy: endIndex) ?? endIndex
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defer { state = next }
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return self[state..<next]
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}
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}
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}
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extension Scanner {
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func string(_ s: String) -> Bool {
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return scanString(s) != nil
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}
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func color() -> Color? {
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if string("#"), let digits = scanCharacters(from: .hex) {
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switch digits.count {
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case 3, 4: //rgb(a)
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let digits = digits.chunks(size: 1)
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.compactMap { UInt8($0, radix: 16) }
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.map { $0 << 4 | $0 }
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return Color(digits)
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case 6, 8: //rrggbb(aa)
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let digits = digits.chunks(size: 2).compactMap { UInt8($0, radix: 16) }
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return Color(digits)
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default: return nil
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}
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}
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if string("rgba"), string("("), let components = commaSeparated(), components.count == 4, string(")") {
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return Color(components)
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}
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if string("rgb"), string("("), let components = commaSeparated(), components.count == 3, string(")") {
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return Color(components)
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}
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return nil
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}
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func colorReference() -> String? {
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guard string("@") else { return nil }
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return name()
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}
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func name() -> String? {
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guard let name = scanCharacters(from: .name), !name.isEmpty else {
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return nil
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}
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return name
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}
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func colorDef() -> ColorDef? {
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if let color = color() {
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return .color(color)
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}
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if let ref = colorReference() {
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return .reference(ref)
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}
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return nil
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}
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func colorLine() -> (String, ColorDef)? {
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guard let name = self.name(),
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let def = colorDef(),
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endOfLine() else {
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return nil
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}
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return (name, def)
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}
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func endOfLine() -> Bool {
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guard isAtEnd || string("\n") else {
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return false
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}
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_ = scanCharacters(from: .whitespacesAndNewlines)
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return true
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}
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func colorList() throws -> [String: ColorDef] {
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var result: [String: ColorDef] = [:]
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while !isAtEnd {
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guard let (name, def) = colorLine() else {
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throw Errors.syntaxError
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}
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guard !result.keys.contains(name) else {
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throw Errors.duplicateColor(name)
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}
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result[name] = def
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}
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return result
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}
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func commaSeparated() -> [UInt8]? {
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var result: [UInt8] = []
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repeat {
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guard let int = scanInt(), let component = UInt8(exactly: int) else {
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return nil
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}
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result.append(component)
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} while string(",")
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return result
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}
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}
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