正则表达式 – F#使用活动模式映射正则表达式匹配

我发现使用正则表达式使用Active Patterns的这篇有用的文章：
http://www.markhneedham.com/blog/2009/05/10/f-regular-expressionsactive-patterns/

文章中使用的原始代码段是：

open System.Text.RegularExpressions

let (|Match|_|) pattern input =
    let m = Regex.Match(input,pattern) in
    if m.Success then Some (List.tl [ for g in m.Groups -> g.Value ]) else None

let ContainsUrl value = 
    match value with
        | Match "(http://S+)" result -> Some(result.Head)
        | _ -> None

如果至少找到一个网址和该网址是什么(如果我正确地理解了该片段),那会让你知道

然后在评论部分Joel建议这个修改：

Alternative,since a given group may
or may not be a successful match:

06001

Or maybe you give labels to your
groups and you want to access them by
name:

06002

试图结合所有这一切后,我想出了以下代码：

let testString = "http://www.bob.com http://www.b.com http://www.bob.com http://www.bill.com"

let (|Match|_|) pattern input =
    let re = new Regex(pattern)
    let m = re.Match(input) in
    if m.Success then Some ((re.GetGroupNames()
                                |> Seq.map (fun n -> (n,m.Groups.[n]))
                                |> Seq.filter (fun (n,g) -> g.Success)
                                |> Seq.map (fun (n,g) -> (n,g.Value))
                                |> Map.ofSeq)) else None

let GroupMatches stringToSearch = 
    match stringToSearch with
        | Match "(http://S+)" result -> printfn "%A" result
        | _ -> ()


GroupMatches testString;;

当我在交互式会话中运行我的代码时,这是什么输出：

06004

我试图实现的结果将如下所示：

06005

基本上是发现每个唯一匹配的映射,后跟在文本中找到特定匹配字符串的次数的计数.

如果你认为我要走错路,请随时提出一个完全不同的做法.我对Active Patterns和Regular Expression都有些新意,所以我不知道在哪里开始尝试解决这个问题.

我也想出了这个,基本上我将在C#中翻译成F#.

let testString = "http://www.bob.com http://www.b.com http://www.bob.com http://www.bill.com"

let matches =
    let matchDictionary = new Dictionary<string,int>()
    for mtch in (Regex.Matches(testString,"(http://S+)")) do
        for m in mtch.Captures do
            if(matchDictionary.ContainsKey(m.Value)) then
                matchDictionary.Item(m.Value) <- matchDictionary.Item(m.Value) + 1
            else
                matchDictionary.Add(m.Value,1)
    matchDictionary

运行时返回这个：

06007

这基本上是我正在寻找的结果,但是我正在尝试学习这样做的功能方式,我认为应该包括活动模式.如果它比我的第一次尝试更有意义,可以尝试“功能化”这一点.

提前致谢,

短发

let testString = "http://www.bob.com http://www.b.com http://www.bob.com http://www.bill.com"

let matches input =
    Regex.Matches(input,"(http://S+)") 
    |> Seq.cast<Match>
    |> Seq.groupBy (fun m -> m.Value)
    |> Seq.map (fun (value,groups) -> value,(groups |> Seq.length))

//FSI output:
> matches testString;;
val it : seq<string * int> =
  seq
    [("http://www.bob.com",2); ("http://www.b.com",1);
     ("http://www.bill.com",1)]

let (|InterpretedMatch|_|) pattern input =
    if input = null then None
    else
        let m = Regex.Match(input,pattern)
        if m.Success then Some [for x in m.Groups -> x]
        else None

///Match the pattern using a cached compiled Regex
let (|CompiledMatch|_|) pattern input =
    if input = null then None
    else
        let m = Regex.Match(input,pattern,RegexOptions.Compiled)
        if m.Success then Some [for x in m.Groups -> x]
        else None

type Name = {First:string; Middle:option<string>; Last:string}

let parseName name =
    match name with
    | CompiledMatch @"^(w+) (w+) (w+)$" [_; first; middle; last] ->
        Some({First=first.Value; Middle=Some(middle.Value); Last=last.Value})
    | CompiledMatch @"^(w+) (w+)$" [_; first; last] ->
        Some({First=first.Value; Middle=None; Last=last.Value})
    | _ -> 
        None