useful active patterns for link2xml

ling2xml.fs

let xname s = XName.Get s

let xn s = XName.Get s
let xe n (v: obj) = new XElement(xn (msbuildns + n), v)
let xa n (v: obj) = new XAttribute(xn n, v)

let (|Head|_|) =
    Seq.tryFind (fun _ -> true)

let (|Value|) (xe: XElement) =
    xe.Value

let (|Guid|_|) s =
    match Guid.TryParse s with
    | true, g -> Some g
    | _ -> None

let (|Descendants|_|) name (xe : XElement) =
    match xe.Descendants (xn (msbuildns + name)) with
    | null -> None
    | desc when not (Seq.isEmpty desc) -> 
        Some (desc |> Seq.toList)
    | _ -> None

let (|Descendant|_|) name (xe : XElement) =
    match xe.Descendants (xn (msbuildns + name)) with
    | null -> None
    | Head h -> Some h
    | _ -> None

let (|Element|_|) name (xe : XElement) =
    match xe.Element (xn (msbuildns + name)) with
    | null -> None 
    | e -> Some e

let (|Attribute|_|) name (xe : XElement) =
    match xe.Attribute (xn name) with
    | null -> None 
    | a -> Some a