multiname.sml

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(* The Multiname Algorithm *)

structure Multiname = struct

(* Local tracing machinery *)

val doTrace = ref false
fun trace ss = if (!doTrace) then LogErr.log ("[multiname] " :: ss) else ()
fun error ss = LogErr.nameError ss
fun fmtName n = if (!doTrace) then LogErr.name n else ""
fun fmtFname n = if (!doTrace) then LogErr.fname n else ""
fun fmtMultiname n = if (!doTrace) then LogErr.multiname n else ""

fun resolve (mname:Ast.MULTINAME)
		    (curr:'a)
            (matchNamespaces:('a -> Ast.IDENT -> (Ast.NAMESPACE list) -> Ast.NAME list))
		    (getParent:('a -> ('a option)))
    : ('a * Ast.NAME) option =
    let
        val _ = trace ["resolving multiname ", fmtMultiname mname]
        val _ = if (#nss mname) = [] 
                then error ["empty namespace set in multiname: ", LogErr.multiname mname]
                else ()
        val id = (#id mname)

        (*
	     * Try each of the nested namespace sets in turn to see
         * if there is a match. Raise an exception if there is
         * more than one match. Continue up to "parent"
         * if there are none
	     *)

        fun tryMultiname [] = NONE
          | tryMultiname (x::xs:Ast.NAMESPACE list list) : Ast.NAME option =
            let
                val matches = matchNamespaces curr id x
            in case matches of
                   n :: [] => (trace ["resolved to specific name: ", fmtName n];
                               SOME n)
                 | [] => tryMultiname xs
                 | matches  => (List.app (fn m => trace ["matched:", fmtName m]) matches;
                                error ["ambiguous reference ",
					                   LogErr.multiname mname])
            end
    in
        case tryMultiname (#nss mname) of
            SOME n => SOME (curr, n)
          | NONE =>
	        (case getParent curr of
		         NONE => (trace ["exhausted search for ", fmtMultiname mname];
                          NONE)
	           | SOME parent => (trace ["moving to parent"];
                                 resolve mname parent matchNamespaces getParent))
    end


fun matchFixtures  (rib:Ast.RIB)
                   (searchId:Ast.IDENT)
                   (nss:Ast.NAMESPACE list)
    : Ast.NAME list =
    let
        fun matchFixture (fxn:Ast.FIXTURE_NAME,_) : Ast.NAME option =
            case fxn of
                Ast.TempName _ => NONE
              | Ast.PropName n =>
                let
                    val {id,ns} = n
                    fun matchNS candidateNS =
                        case candidateNS of
                            Ast.LimitedNamespace (ident,limNS) =>
                            if id = ident
                            then ns = limNS
                            else false
                          | _ => ns = candidateNS
                in
                    if searchId = id andalso (List.exists matchNS nss)
                    then SOME n
                    else NONE
                end
    in
        List.mapPartial matchFixture rib
    end

fun resolveInRibs (mname:Ast.MULTINAME)
                  (env:Ast.RIBS)
    : (Ast.RIBS * Ast.NAME) option =
    let
        fun f env ident nss = 
            case env of 
                rib::ribs => matchFixtures rib ident nss
              | _ => []

        fun tl [] = NONE
          | tl (x::xs) = SOME xs
    in
        resolve mname env f tl
    end

end