pattern-matching

问题 Consider a piece of code: def foo(xs: Seq[Int]) = xs match { case Nil => "empty list" case head :: Nil => "one element list" case head :: tail => s"head is $head and tail is $tail" } val x1 = Seq(1,2,3) println(foo(x1)) val x2 = Seq() println(foo(x2)) val x3 = Seq(1) println(foo(x3)) val problem = 1 to 10 println(foo(problem)) A problem occurs, when we try to match a Range in foo(problem) . scala.MatchError: Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) (of class scala.collection.immutable.Range

问题 Consider a piece of code: def foo(xs: Seq[Int]) = xs match { case Nil => "empty list" case head :: Nil => "one element list" case head :: tail => s"head is $head and tail is $tail" } val x1 = Seq(1,2,3) println(foo(x1)) val x2 = Seq() println(foo(x2)) val x3 = Seq(1) println(foo(x3)) val problem = 1 to 10 println(foo(problem)) A problem occurs, when we try to match a Range in foo(problem) . scala.MatchError: Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) (of class scala.collection.immutable.Range

问题 I've been trying for a while to solve this problem and I checked many posts (for example here Print lines in one file matching patterns in another file or here awk search for a field in another file) without really finding what I am looking for. I need the solution with bash tools like sed, grep, awk (no python, R,...) I have two files (much bigger than those): file1: 2 891299 0.50923964E-02 1248 4.713 1349.08 3 245857 0.57915542E-02 1335 4.671 1369.65 file2: 278 2645 2334659 0.75142 0.53123

问题 Foreword: My question is mainly an algorithmic question, so even if you are not familiar with suffix and LCP arrays you can probably help me. In this paper it is described how to efficiently use suffix and LCP arrays for string pattern matching. I understood SA and LCP work and how the algorithm's runtime can be improved from O(P*log(N)) (where P is the length of the pattern and N is length of the string) to O(P+log(N)) (Thanks to Chris Eelmaa's answer here and jogojapans answer here). I was

问题 Foreword: My question is mainly an algorithmic question, so even if you are not familiar with suffix and LCP arrays you can probably help me. In this paper it is described how to efficiently use suffix and LCP arrays for string pattern matching. I understood SA and LCP work and how the algorithm's runtime can be improved from O(P*log(N)) (where P is the length of the pattern and N is length of the string) to O(P+log(N)) (Thanks to Chris Eelmaa's answer here and jogojapans answer here). I was

问题 I would like to print ONLY the line which contains "Server" in the below piece of output: Date: Sun, 16 Dec 2012 20:07:44 GMT Expires: -1 Cache-Control: private, max-age=0 Content-Type: text/html; charset=ISO-8859-1 Set-Cookie: PREF=ID=da8d52b67e5c7522:FF=0:TM=1355688464:LM=1355688464:S=CrK5vV-qb3UgWUM1; expires=Tue, 16-Dec-2014 20:07:44 GMT; path=/; domain=.google.com Set-Cookie: NID=67=nICkwXDM6H7TNQfHbo06FbvZhO61bzNmtOn4HA71ukaVDSgywlBjBkAR-gXCpMNo1TlYym

问题 I want to retrieve a strings from a global string via Matcher & Pattern using REGEX. String str = "<strong>ABC</strong>123<strong>DEF</strong>" Pattern pattern = Pattern.compile("<strong>(.*)</strong>"); Matcher matcher = pattern.matcher(str); My problem is that the matcher gives me just one match that is inside the global tag strong: ABC</strong>123<strong>DEF My objective is to get 2 matches: ABC DEF Thank you very match for you help. 回答1: You need a non greedy regex: Pattern pattern =

问题 how can I do a pattern match over a reflect.runtime.universe.Type? def test(t: reflect.runtime.universe.Type) { t match { case Int => \\ ... case Double => \\ ... case String => \\ ... case _ => \\ ... } } This dosn't work, as the interpreter complains: error: pattern type is incompatible with expected type; found : Int.type required: reflect.runtime.universe.Type Note: if you intended to match against the class, try `case _: Int` case Int => // ... ^ Trying the suggestion does not work

问题 I have the following code: type Message<'a> = | Message of 'a let handleMessage message = match box message with | :? Message<_> -> printfn "Message" | _ -> printfn "Not message" let handleMessageEx message = match box message with | :? Message<int> -> printfn "Message" | _ -> printfn "Not message" handleMessage <| Message 1 handleMessage <| Message (1 :> obj) handleMessageEx <| Message 1 The output in F# Interactive is the following: Not message Message Message Why does the first statement

问题 If you have a filename such as "Committee minutes [October 2010] - hq.doc", how do you get Powershell to replace the square brackets? The following doesn't work: ls -filter *`[*`]* | foreach -Process { Rename-Item $_ -NewName ($_.Name -replace '\[', '\(') | Rename-Item $_ -NewName ($_.Name -replace '\]', '\)')} I get the error: Rename-Item : Cannot rename because item at 'Committee minutes [October 2010] - hq.doc' does not exist. At line:1 char:53 + ls -filter *`[*`]* | foreach -Process {