swift2 - How do you enumerate OptionSetType in Swift? -

-

i have custom optionsettype struct in swift. how can enumerate values of instance?

this optionsettype:

struct weekdayset: optionsettype {     let rawvalue: uint8      init(rawvalue: uint8) {         self.rawvalue = rawvalue     }      static let sunday        = weekdayset(rawvalue: 1 << 0)     static let monday        = weekdayset(rawvalue: 1 << 1)     static let tuesday       = weekdayset(rawvalue: 1 << 2)     static let wednesday     = weekdayset(rawvalue: 1 << 3)     static let thursday      = weekdayset(rawvalue: 1 << 4)     static let friday        = weekdayset(rawvalue: 1 << 5)     static let saturday      = weekdayset(rawvalue: 1 << 6) }

i this:

let weekdays: weekdayset = [.monday, .tuesday] weekday in weekdays {     // weekday }

as of swift 4, there no methods in standard library enumerate elements of optionsettype (swift 2) resp. optionset (swift 3, 4).

here possible implementation checks each bit of underlying raw value, , each bit set, corresponding element returned. "overflow multiplication" &* 2 used left-shift because << defined concrete integer types, not integertype protocol.

swift 2.2:

public extension optionsettype rawvalue : integertype {      func elements() -> anysequence<self> {         var remainingbits = self.rawvalue         var bitmask: rawvalue = 1         return anysequence {             return anygenerator {                 while remainingbits != 0 {                     defer { bitmask = bitmask &* 2 }                     if remainingbits & bitmask != 0 {                         remainingbits = remainingbits & ~bitmask                         return self(rawvalue: bitmask)                     }                 }                 return nil             }         }     } }

example usage:

let weekdays: weekdayset = [.monday, .tuesday] weekday in weekdays.elements() {     print(weekday) }  // output: // weekdayset(rawvalue: 2) // weekdayset(rawvalue: 4)

swift 3:

public extension optionset rawvalue : integer {      func elements() -> anysequence<self> {         var remainingbits = rawvalue         var bitmask: rawvalue = 1         return anysequence {             return anyiterator {                 while remainingbits != 0 {                     defer { bitmask = bitmask &* 2 }                     if remainingbits & bitmask != 0 {                         remainingbits = remainingbits & ~bitmask                         return self(rawvalue: bitmask)                     }                 }                 return nil             }         }     } }

swift 4:

public extension optionset rawvalue: fixedwidthinteger {      func elements() -> anysequence<self> {         var remainingbits = rawvalue         var bitmask: rawvalue = 1         return anysequence {             return anyiterator {                 while remainingbits != 0 {                     defer { bitmask = bitmask &* 2 }                     if remainingbits & bitmask != 0 {                         remainingbits = remainingbits & ~bitmask                         return self(rawvalue: bitmask)                     }                 }                 return nil             }         }     } }

Comments

Post a Comment

Popular posts from this blog

html - Firefox flex bug applied to buttons? -

-
i'm trying apply flex button on firefox i'm having problem on chrome doesn't happens. this css: .button { display: inline-flex; align-items: center; } as can see in fiddle, "caret" word moved new line, happens if element <button> tag, <div> works expected. http://codepen.io/anon/pen/xblmgx is firefox bug or there css i'm missing? nevermind, looks "mr firefox" doesn't idea... <button> not implementable (by browsers) in pure css, bit of black box, perspective of css. means don't react in same way e.g. <div> would. this isn't specific flexbox -- e.g. don't render scrollbars if put "overflow:scroll" on button, , don't render table if put "display:table" on it. stepping further, isn't specific <button> . consider <fieldset> , <table> have special rendering behavior: data:text/html,<fieldset style="d
Read more

html - Missing border-right in select on Firefox -

-
Image
when put select div width , padding-left, options have no border on right. more, happend if select have width 118px , parent have 15px of padding left! have idea, going on? my code: <!doctype html> <html> <head lang="en"> </head> <body> <div style="width: 1000px; padding-left: 15px;"> <select style="width: 118px;"> <option>a</option> <option>b</option> <option>c</option> </select> </div> </body> </html> and result: here plunker: click it happend on firefox on windows. tested on 40.0.2 version -webkit-box-sizing: border-box; -moz-box-sizing: border-box; -ms-box-sizing: border-box; box-sizing: border-box; source: https://stackoverflow.com/a/11390432/4431269 source of problem: https://bugzilla.mozilla.org/show_bug.cgi?id=924068 and use of google ! edit: (source of problem, explained) after rea
Read more

c# - two queries in same method -

-
i trying execute 2 queries in same method gives me exception. can red of exception declaring new command there way use same command? string id="hi"; connection.open(); oledbcommand command1 = new oledbcommand(); command1.connection = connection; string query1 = "select * products category='" + combobox1.text + "' , subcategory = '" + combobox2.text + "' , sizes='" + combobox3.text + "'"; command1.commandtext = query1; oledbdatareader reader = command1.executereader(); while (reader.read()) { id = reader[0].tostring(); } textbox1.text = id; string query = "insert category_in (category_id,amount,amount_in) values ('"+ id+"' ,500,300)"; command1.commandtext = query; command1.executenonquery(); messagebox.show("saved"); connection.close();
Read more