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|
fun trim (s: substring): substring =
Substring.dropr
(fn c => c = #" " orelse c = #"\n" orelse c = #"\r")
(Substring.dropl (fn c => c = #" " orelse c = #"\n" orelse c = #"\r") s)
structure FromJson = struct
fun get (s: string) (l: Json.json): Json.json =
let
fun getJsonObjectValue (s: string) (l: (string * Json.json) list): Json.json option =
case List.find (fn tup => #1 tup = s ) l of
NONE => NONE
| SOME tup => SOME (#2 tup)
in
case l of
Json.Obj l =>
(case getJsonObjectValue s l of
NONE => raise Fail ("Failed to find JSON object key " ^ s)
| SOME v => v)
| a => raise Fail ("Expected JSON object, got: " ^ Json.print a)
end
fun asInt (j: Json.json): int =
case j of
Json.Int i => i
| _ => raise Fail ("Expected JSON int, got: " ^ Json.print j)
fun asString (j: Json.json): string =
case j of
Json.String s => s
| _ => raise Fail ("Expected JSON string, got: " ^ Json.print j)
end
(* signature LSPSPEC = sig *)
(* type textDocumentIdentifier = *)
(* { scheme: string *)
(* , authority: string *)
(* , path: string *)
(* , query: string *)
(* , fragment: string *)
(* } *)
(* type position = { line: int *)
(* , character: int *)
(* } *)
(* val readRequestFromStdIO: () -> {id: Json.json, method: string, params: Json.json} *)
(* val parseRequest: {id: Json.json, method: string, params: Json.json} -> request *)
(* datatype request = *)
(* end *)
structure LspSpec (* :> LSPSPEC *) = struct
fun readHeader (): (string * string) option =
let
val line = TextIO.inputLine TextIO.stdIn
in
case line of
NONE => OS.Process.exit OS.Process.success
| SOME str =>
let
val (key, value) = Substring.splitl (fn c => c <> #":") (Substring.full str)
in
if Substring.isEmpty (trim value)
then NONE
else SOME ( Substring.string (trim key)
, Substring.string (trim (Substring.dropl (fn c => c = #":") (trim value))))
end
end
fun readAllHeaders (): (string * string) list =
let
fun doReadAllHeaders (l: (string * string) list): (string * string) list =
case readHeader () of
NONE => l
| SOME tup => tup :: doReadAllHeaders l
in
doReadAllHeaders []
end
fun parseBasicRequest (j: Json.json): {id: Json.json, method: string, params: Json.json} =
let
val id = FromJson.get "id" j
val method = FromJson.asString (FromJson.get "method" j)
val params = FromJson.get "params" j
in
{id = id, method = method, params = params}
end
type textDocumentIdentifier =
{ scheme: string
, authority: string
, path: string
, query: string
, fragment: string
}
fun parseTextDocumentIdentifier (j: Json.json): textDocumentIdentifier =
let
val str = Substring.full (FromJson.asString (FromJson.get "uri" j))
val (scheme, rest) = Substring.splitl (fn c => c <> #":") str
val (authority, rest) = Substring.splitl (fn c => c <> #"/") (Substring.triml 3 rest (* :// *))
val (path, rest) = Substring.splitl (fn c => c <> #"?" orelse c <> #"#") (Substring.triml 1 rest (* / *))
val (query, rest) = if Substring.first rest = SOME #"?"
then Substring.splitl (fn c => c <> #"#") (Substring.triml 1 rest (* ? *))
else (Substring.full "", rest)
val fragment = if Substring.first rest = SOME #"#"
then (Substring.triml 1 rest (* # *))
else Substring.full ""
in
{ scheme = Substring.string scheme
, authority = Substring.string authority
, path = Substring.string path
, query = Substring.string query
, fragment = Substring.string fragment
}
end
type position = { line: int
, character: int
}
fun parsePosition (j: Json.json) =
{ line = FromJson.asInt (FromJson.get "line" j)
, character = FromJson.asInt (FromJson.get "character" j)
}
fun readRequestFromStdIO (): {id: Json.json, method: string, params: Json.json} =
let
val headers = readAllHeaders ()
val lengthO = List.find (fn (k,v) => k = "Content-Length") headers
val request = case lengthO of
NONE => raise Fail "No header with Content-Length found"
| SOME (k, v) =>
case Int.fromString v of
NONE => raise Fail ("Couldn't parse content-length from string: " ^ v)
| SOME i => TextIO.inputN (TextIO.stdIn, i)
val parsed = Json.parse request
in
parseBasicRequest parsed
end
fun parseHoverReq (params: Json.json): { textDocument: textDocumentIdentifier , position: position } =
{ textDocument = parseTextDocumentIdentifier (FromJson.get "textDocument" params)
, position = parsePosition (FromJson.get "position" params)
}
fun printHoverResponse (resp: {contents: string}): Json.json =
Json.Obj (("contents", Json.String (#contents resp)) :: [])
datatype 'a result =
Success of 'a
| Error of (int * string)
fun mapResult (f: 'a -> 'b) (a: 'a result): 'b result =
case a of
Success contents => Success (f contents)
| Error e => Error e
type handlers =
{ initialize: unit -> { capabilities: {hoverProvider: bool}} result
, shutdown: unit -> unit result
, textDocument_hover: { textDocument: textDocumentIdentifier
, position: position }
-> {contents: string} result
}
fun handleRequest
(requestMessage: {id: Json.json, method: string, params: Json.json})
(handlers: handlers)
: unit =
let
val result: Json.json result =
case #method requestMessage of
"initialize" =>
mapResult
(fn res => Json.Obj (("capabilities", Json.Obj (("hoverProvider", Json.Bool (#hoverProvider (#capabilities res)))
:: []))
:: []))
((#initialize handlers) ())
| "textDocument/hover" =>
mapResult
printHoverResponse
((#textDocument_hover handlers)
(parseHoverReq (#params requestMessage)))
| "shutdown" =>
mapResult
(fn () => Json.Null)
((#shutdown handlers) ())
| "exit" =>
OS.Process.exit OS.Process.success
| method => Error (~32601, "Method not supported: " ^ method)
in
case result of
Success j => TextIO.output (TextIO.stdOut,
Json.print (Json.Obj (("id", #id requestMessage)
:: ("result", j)
:: [])))
| Error (i, err) =>
TextIO.output (TextIO.stdOut,
Json.print (Json.Obj (("id", #id requestMessage)
:: ("error", Json.Obj (("code", Json.Int i)
:: ("message", Json.String err)
:: []))
:: []
)))
end
end
structure Lsp :> LSP = struct
fun serverLoop () =
let
val requestMessage = LspSpec.readRequestFromStdIO ()
in
LspSpec.handleRequest
requestMessage
{ initialize = fn () => LspSpec.Success {capabilities = {hoverProvider = true}}
, shutdown = fn () => LspSpec.Success ()
, textDocument_hover = fn _ => LspSpec.Success {contents = ""}
}
end
fun startServer () = while true do serverLoop ()
end
|
