1010
1111extension MassFormatter {
1212 public enum Unit : Int {
13-
1413 case gram
1514 case kilogram
1615 case ounce
@@ -21,28 +20,238 @@ extension MassFormatter {
2120
2221open class MassFormatter : Formatter {
2322
23+ public override init ( ) {
24+ numberFormatter = NumberFormatter ( )
25+ numberFormatter. numberStyle = . decimal
26+ unitStyle = . medium
27+ isForPersonMassUse = false
28+ super. init ( )
29+ }
30+
2431 public required init ? ( coder: NSCoder ) {
25- NSUnimplemented ( )
32+ numberFormatter = NumberFormatter ( )
33+ numberFormatter. numberStyle = . decimal
34+ unitStyle = . medium
35+ isForPersonMassUse = false
36+ super. init ( coder: coder)
2637 }
2738
2839 /*@NSCopying*/ open var numberFormatter : NumberFormatter ! // default is NSNumberFormatter with NSNumberFormatterDecimalStyle
2940 open var unitStyle : UnitStyle // default is NSFormattingUnitStyleMedium
41+
3042 open var isForPersonMassUse : Bool // default is NO; if it is set to YES, the number argument for -stringFromKilograms: and -unitStringFromKilograms: is considered as a person’s mass
3143
3244 // Format a combination of a number and an unit to a localized string.
33- open func string( fromValue value: Double , unit: Unit ) -> String { NSUnimplemented ( ) }
45+ open func string( fromValue value: Double , unit: Unit ) -> String {
46+ // special case: stone shows fractional values in pounds
47+ if unit == . stone {
48+ let stone = value. rounded ( . towardZero)
49+ let stoneString = singlePartString ( fromValue: stone, unit: unit) // calling `string(fromValue: stone, unit: .stone)` would infinitely recur
50+ let pounds = abs ( value. truncatingRemainder ( dividingBy: 1.0 ) ) * MassFormatter. poundsPerStone
51+
52+ // if we don't have any fractional component, don't append anything
53+ if pounds == 0 {
54+ return stoneString
55+ } else {
56+ let poundsString = string ( fromValue: pounds, unit: . pound)
57+ let separator = unitStyle == MassFormatter . UnitStyle. short ? " " : " , "
58+
59+ return ( " \( stoneString) \( separator) \( poundsString) " )
60+ }
61+ }
62+
63+ // normal case: kilograms and pounds
64+ return singlePartString ( fromValue: value, unit: unit)
65+ }
3466
3567 // Format a number in kilograms to a localized string with the locale-appropriate unit and an appropriate scale (e.g. 1.2kg = 2.64lb in the US locale).
36- open func string( fromKilograms numberInKilograms: Double ) -> String { NSUnimplemented ( ) }
68+ open func string( fromKilograms numberInKilograms: Double ) -> String {
69+ //Convert to the locale-appropriate unit
70+ let unitFromKilograms = unit ( fromKilograms: numberInKilograms)
71+
72+ //Map the unit to UnitMass type for conversion later
73+ let unitMassFromKilograms = MassFormatter . unitMass [ unitFromKilograms] !
74+
75+ //Create a measurement object based on the value in kilograms
76+ let kilogramMeasurement = Measurement < UnitMass > ( value: numberInKilograms, unit: . kilograms)
77+
78+ //Convert the object to the locale-appropriate unit determined above
79+ let unitMeasurement = kilogramMeasurement. converted ( to: unitMassFromKilograms)
80+
81+ //Extract the number from the measurement
82+ let numberInUnit = unitMeasurement. value
83+
84+ return string ( fromValue: numberInUnit, unit: unitFromKilograms)
85+ }
3786
3887 // Return a localized string of the given unit, and if the unit is singular or plural is based on the given number.
39- open func unitString( fromValue value: Double , unit: Unit ) -> String { NSUnimplemented ( ) }
88+ open func unitString( fromValue value: Double , unit: Unit ) -> String {
89+ if unitStyle == . short {
90+ return MassFormatter . shortSymbol [ unit] !
91+ } else if unitStyle == . medium {
92+ return MassFormatter . mediumSymbol [ unit] !
93+ } else if unit == . stone { // special case, see `unitStringDisplayedAdjacent(toValue:, unit:)`
94+ return MassFormatter . largeSingularSymbol [ unit] !
95+ } else if value == 1.0 {
96+ return MassFormatter . largeSingularSymbol [ unit] !
97+ } else {
98+ return MassFormatter . largePluralSymbol [ unit] !
99+ }
100+ }
40101
41102 // Return the locale-appropriate unit, the same unit used by -stringFromKilograms:.
42- open func unitString( fromKilograms numberInKilograms: Double , usedUnit unitp: UnsafeMutablePointer < Unit > ? ) -> String { NSUnimplemented ( ) }
103+ open func unitString( fromKilograms numberInKilograms: Double , usedUnit unitp: UnsafeMutablePointer < Unit > ? ) -> String {
104+ //Convert to the locale-appropriate unit
105+ let unitFromKilograms = unit ( fromKilograms: numberInKilograms)
106+ unitp? . pointee = unitFromKilograms
107+
108+ //Map the unit to UnitMass type for conversion later
109+ let unitMassFromKilograms = MassFormatter . unitMass [ unitFromKilograms] !
110+
111+ //Create a measurement object based on the value in kilograms
112+ let kilogramMeasurement = Measurement < UnitMass > ( value: numberInKilograms, unit: . kilograms)
113+
114+ //Convert the object to the locale-appropriate unit determined above
115+ let unitMeasurement = kilogramMeasurement. converted ( to: unitMassFromKilograms)
116+
117+ //Extract the number from the measurement
118+ let numberInUnit = unitMeasurement. value
119+
120+ //Return the appropriate representation of the unit based on the selected unit style
121+ return unitString ( fromValue: numberInUnit, unit: unitFromKilograms)
122+ }
43123
44124 /// - Experiment: This is a draft API currently under consideration for official import into Foundation as a suitable alternative
45125 /// - Note: Since this API is under consideration it may be either removed or revised in the near future
46126 open override func objectValue( _ string: String ) throws -> Any ? { return nil }
127+
128+
129+ // MARK: - Private
130+
131+ /// This method selects the appropriate unit based on the formatter’s locale,
132+ /// the magnitude of the value, and isForPersonMassUse property.
133+ ///
134+ /// - Parameter numberInKilograms: the magnitude in terms of kilograms
135+ /// - Returns: Returns the appropriate unit
136+ private func unit( fromKilograms numberInKilograms: Double ) -> Unit {
137+ if numberFormatter. locale. sr3202_fix_isMetricSystemLocale ( ) {
138+ if numberInKilograms > 1.0 || numberInKilograms <= 0.0 {
139+ return . kilogram
140+ } else {
141+ return . gram
142+ }
143+ } else {
144+ let metricMeasurement = Measurement < UnitMass > ( value: numberInKilograms, unit: . kilograms)
145+ let imperialMeasurement = metricMeasurement. converted ( to: . pounds)
146+ let numberInPounds = imperialMeasurement. value
147+
148+ if numberInPounds >= 1.0 || numberInPounds <= 0.0 {
149+ return . pound
150+ } else {
151+ return . ounce
152+ }
153+ }
154+ }
155+
156+ /// Formats the given value and unit into a string containing one logical
157+ /// value. This is intended for units like kilogram and pound where
158+ /// fractional values are represented as a decimal instead of converted
159+ /// values in another unit.
160+ ///
161+ /// - Parameter value: The mass's value in the given unit.
162+ /// - Parameter unit: The unit used in the resulting mass string.
163+ /// - Returns: A properly formatted mass string for the given value and unit.
164+ private func singlePartString( fromValue value: Double , unit: Unit ) -> String {
165+ guard let formattedValue = numberFormatter. string ( from: NSNumber ( value: value) ) else {
166+ fatalError ( " Cannot format \( value) as string " )
167+ }
168+
169+ let separator = unitStyle == MassFormatter . UnitStyle. short ? " " : " "
170+
171+ return " \( formattedValue) \( separator) \( unitStringDisplayedAdjacent ( toValue: value, unit: unit) ) "
172+ }
173+
174+ /// Return the locale-appropriate unit to be shown adjacent to the given
175+ /// value. In most cases this will match `unitStringDisplayedAdjacent(toValue:, unit:)`
176+ /// however there are a few special cases:
177+ /// - Imperial pounds with a short representation use "lb" in the
178+ /// abstract and "#" only when shown with a numeral.
179+ /// - Stones are are singular in the abstract and only plural when
180+ /// shown with a numeral.
181+ ///
182+ /// - Parameter value: The mass's value in the given unit.
183+ /// - Parameter unit: The unit used in the resulting mass string.
184+ /// - Returns: The locale-appropriate unit
185+ open func unitStringDisplayedAdjacent( toValue value: Double , unit: Unit ) -> String {
186+ if unit == . pound && unitStyle == . short {
187+ return " # "
188+ } else if unit == . stone && unitStyle == . long {
189+ if value == 1.0 {
190+ return MassFormatter . largeSingularSymbol [ unit] !
191+ } else {
192+ return MassFormatter . largePluralSymbol [ unit] !
193+ }
194+ } else {
195+ return unitString ( fromValue: value, unit: unit)
196+ }
197+ }
198+
199+
200+
201+ /// The number of pounds in 1 stone
202+ private static let poundsPerStone = 14.0
203+
204+ /// Maps MassFormatter.Unit enum to UnitMass class. Used for measurement conversion.
205+ private static let unitMass : [ Unit : UnitMass ] = [ . gram: . grams,
206+ . kilogram: . kilograms,
207+ . ounce: . ounces,
208+ . pound: . pounds,
209+ . stone: . stones]
210+
211+ /// Maps a unit to its short symbol. Reuses strings from UnitMass.
212+ private static let shortSymbol : [ Unit : String ] = [ . gram: UnitMass . grams. symbol,
213+ . kilogram: UnitMass . kilograms. symbol,
214+ . ounce: UnitMass . ounces. symbol,
215+ . pound: UnitMass . pounds. symbol, // see `unitStringDisplayedAdjacent(toValue:, unit:)`
216+ . stone: UnitMass . stones. symbol]
217+
218+ /// Maps a unit to its medium symbol. Reuses strings from UnitMass.
219+ private static let mediumSymbol : [ Unit : String ] = [ . gram: UnitMass . grams. symbol,
220+ . kilogram: UnitMass . kilograms. symbol,
221+ . ounce: UnitMass . ounces. symbol,
222+ . pound: UnitMass . pounds. symbol,
223+ . stone: UnitMass . stones. symbol]
224+
225+ /// Maps a unit to its large, singular symbol.
226+ private static let largeSingularSymbol : [ Unit : String ] = [ . gram: " gram " ,
227+ . kilogram: " kilogram " ,
228+ . ounce: " ounce " ,
229+ . pound: " pound " ,
230+ . stone: " stone " ]
231+
232+ /// Maps a unit to its large, plural symbol.
233+ private static let largePluralSymbol : [ Unit : String ] = [ . gram: " grams " ,
234+ . kilogram: " kilograms " ,
235+ . ounce: " ounces " ,
236+ . pound: " pounds " ,
237+ . stone: " stones " ]
47238}
48239
240+ internal extension Locale {
241+ /// TODO: Replace calls to the below function to use Locale.usesMetricSystem
242+ /// Temporary workaround due to unpopulated Locale attributes
243+ /// See https://bugs.swift.org/browse/SR-3202
244+ internal func sr3202_fix_isMetricSystemLocale( ) -> Bool {
245+ switch self . identifier {
246+ case " en_US " : return false
247+ case " en_US_POSIX " : return false
248+ case " haw_US " : return false
249+ case " es_US " : return false
250+ case " chr_US " : return false
251+ case " my_MM " : return false
252+ case " en_LR " : return false
253+ case " vai_LR " : return false
254+ default : return true
255+ }
256+ }
257+ }
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