Question

如何从任何给定字符串中找到“From：Sent：Received：”模式。如果给定模式存在于字符串中，则将子字符串取出到第一个模式并忽略其余字符串。是否有任何正则表达式来实现相同的目标？注意：From：Sent：和received：。之间可能存在文本。

Answer 1

使用partial active pattern这可能看起来像

open System.Text.RegularExpressions

let (|UpToFromSentReceived|_|) candidate =
    let pattern = Regex("(.*?)From:.*Sent:.*Received:")
    let matches = pattern.Match candidate
    if matches.Success then matches.Groups.[1].Value.Trim() |> Some else None

然后可以使用

let test = function
    | UpToFromSentReceived prefix -> printfn "%s" prefix
    | s -> printfn "No match for '%s'" s

// Arbitrary prefix
test "Arbitrary prefix From: Sent: Received:"

// No match for 'Arbitrary prefix From: Sent: sorry ;-P'
test "Arbitrary prefix From: Sent: sorry ;-P"

// Foo Bar
test "Foo Bar From: arbitrary Sent: interspersed Received: text"

// First Foo Bar
test "First Foo Bar From: arbitrary Sent: interspersed Received: text Second Foo Bar From: arbitrary Sent: interspersed Received: text"

根据您的要求，您可能希望省略.Trim()

F＃中使用正则表达式进行模式匹配

1 个答案: