Vamp Build and Test

(*

    DO NOT EDIT THIS FILE.

    This file is automatically generated from the individual

    source files in the Vext repository.

*)

(* 

    Vext

    A simple manager for third-party source code dependencies

    Copyright 2017 Chris Cannam, Particular Programs Ltd,

    and Queen Mary, University of London

    Permission is hereby granted, free of charge, to any person

    obtaining a copy of this software and associated documentation

    files (the "Software"), to deal in the Software without

    restriction, including without limitation the rights to use, copy,

    modify, merge, publish, distribute, sublicense, and/or sell copies

    of the Software, and to permit persons to whom the Software is

    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be

    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR

    ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF

    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Except as contained in this notice, the names of Chris Cannam,

    Particular Programs Ltd, and Queen Mary, University of London

    shall not be used in advertising or otherwise to promote the sale,

    use or other dealings in this Software without prior written

    authorization.

*)

val vext_version = "0.9.8"

datatype vcs =

         HG |

         GIT

datatype source =

         URL_SOURCE of string |

         SERVICE_SOURCE of {

             service : string,

             owner : string option,

             repo : string option

         }

type id_or_tag = string

datatype pin =

         UNPINNED |

         PINNED of id_or_tag

datatype libstate =

         ABSENT |

         CORRECT |

         SUPERSEDED |

         WRONG

datatype localstate =

         MODIFIED |

         LOCK_MISMATCHED |

         CLEAN

datatype branch =

         BRANCH of string |

         DEFAULT_BRANCH

(* If we can recover from an error, for example by reporting failure

   for this one thing and going on to the next thing, then the error

   should usually be returned through a result type rather than an

   exception. *)

datatype 'a result =

         OK of 'a |

         ERROR of string

type libname = string

type libspec = {

    libname : libname,

    vcs : vcs,

    source : source,

    branch : branch,

    project_pin : pin,

    lock_pin : pin

}

type lock = {

    libname : libname,

    id_or_tag : id_or_tag

}

type remote_spec = {

    anon : string option,

    auth : string option

}

type provider = {

    service : string,

    supports : vcs list,

    remote_spec : remote_spec

}

type account = {

    service : string,

    login : string

}

type context = {

    rootpath : string,

    extdir : string,

    providers : provider list,

    accounts : account list

}

type userconfig = {

    providers : provider list,

    accounts : account list

}

type project = {

    context : context,

    libs : libspec list

}

structure VextFilenames = struct

    val project_file = "vext-project.json"

    val project_lock_file = "vext-lock.json"

    val user_config_file = ".vext.json"

    val archive_dir = ".vext-archive"

end

signature VCS_CONTROL = sig

    (** Test whether the library is present locally at all *)

    val exists : context -> libname -> bool result

    (** Return the id (hash) of the current revision for the library *)

    val id_of : context -> libname -> id_or_tag result

    (** Test whether the library is at the given id *)

    val is_at : context -> libname * id_or_tag -> bool result

    (** Test whether the library is on the given branch, i.e. is at

        the branch tip or an ancestor of it *)

    val is_on_branch : context -> libname * branch -> bool result

    (** Test whether the library is at the newest revision for the

        given branch. False may indicate that the branch has advanced

        or that the library is not on the branch at all. This function

        may use the network to check for new revisions *)

    val is_newest : context -> libname * branch -> bool result

    (** Test whether the library is at the newest revision available

        locally for the given branch. False may indicate that the

        branch has advanced or that the library is not on the branch

        at all. This function must not use the network *)

    val is_newest_locally : context -> libname * branch -> bool result

    (** Test whether the library has been modified in the local

        working copy *)

    val is_modified_locally : context -> libname -> bool result

    (** Check out, i.e. clone a fresh copy of, the repo for the given

        library on the given branch *)

    val checkout : context -> libname * source * branch -> unit result

    (** Update the library to the given branch tip *)

    val update : context -> libname * branch -> id_or_tag result

    (** Update the library to the given specific id or tag *)

    val update_to : context -> libname * id_or_tag -> id_or_tag result

end

signature LIB_CONTROL = sig

    val review : context -> libspec -> (libstate * localstate) result

    val status : context -> libspec -> (libstate * localstate) result

    val update : context -> libspec -> id_or_tag result

    val id_of : context -> libspec -> id_or_tag result

end

structure FileBits :> sig

    val extpath : context -> string

    val libpath : context -> libname -> string

    val subpath : context -> libname -> string -> string

    val command_output : context -> libname -> string list -> string result

    val command : context -> libname -> string list -> unit result

    val file_contents : string -> string

    val mydir : unit -> string

    val homedir : unit -> string

    val mkpath : string -> unit result

    val rmpath : string -> unit result

    val project_spec_path : string -> string

    val project_lock_path : string -> string

    val verbose : unit -> bool

end = struct

    fun verbose () =

        case OS.Process.getEnv "VEXT_VERBOSE" of

            SOME "0" => false

          | SOME _ => true

          | NONE => false

    fun extpath ({ rootpath, extdir, ... } : context) =

        let val { isAbs, vol, arcs } = OS.Path.fromString rootpath

        in OS.Path.toString {

                isAbs = isAbs,

                vol = vol,

                arcs = arcs @ [ extdir ]

            }

        end

    fun subpath ({ rootpath, extdir, ... } : context) libname remainder =

        (* NB libname is allowed to be a path fragment, e.g. foo/bar *)

        let val { isAbs, vol, arcs } = OS.Path.fromString rootpath

            val split = String.fields (fn c => c = #"/")

        in OS.Path.toString {

                isAbs = isAbs,

                vol = vol,

                arcs = arcs @ [ extdir ] @ split libname @ split remainder

            }

        end

    fun libpath context "" =

        extpath context

      | libpath context libname =

        subpath context libname ""

    fun project_file_path rootpath filename =

        let val { isAbs, vol, arcs } = OS.Path.fromString rootpath

        in OS.Path.toString {

                isAbs = isAbs,

                vol = vol,

                arcs = arcs @ [ filename ]

            }

        end

    fun project_spec_path rootpath =

        project_file_path rootpath (VextFilenames.project_file)

    fun project_lock_path rootpath =

        project_file_path rootpath (VextFilenames.project_lock_file)

    fun trim str =

        hd (String.fields (fn x => x = #"\n" orelse x = #"\r") str)

    fun file_contents filename =

        let val stream = TextIO.openIn filename

            fun read_all str acc =

                case TextIO.inputLine str of

                    SOME line => read_all str (trim line :: acc)

                  | NONE => rev acc

            val contents = read_all stream []

            val _ = TextIO.closeIn stream

        in

            String.concatWith "\n" contents

        end

    fun expand_commandline cmdlist =

        (* We are quite [too] strict about what we accept here, except

           for the first element in cmdlist which is assumed to be a

           known command location rather than arbitrary user input. NB

           only ASCII accepted at this point. *)

        let open Char

            fun quote arg =

                if List.all

                       (fn c => isAlphaNum c orelse c = #"-" orelse c = #"_")

                       (explode arg)

                then arg

                else "\"" ^ arg ^ "\""

            fun check arg =

                let val valid = explode " /#:;?,._-{}@="

                in

                    app (fn c =>

                            if isAlphaNum c orelse

                               List.exists (fn v => v = c) valid

                            then ()

                            else raise Fail ("Invalid character '" ^

                                             (Char.toString c) ^

                                             "' in command list"))

                        (explode arg);

                    arg

                end

        in

            String.concatWith " "

                              (map quote

                                   (hd cmdlist :: map check (tl cmdlist)))

        end

    val tick_cycle = ref 0

    val tick_chars = Vector.fromList (map String.str (explode "|/-\\"))

    fun tick libname cmdlist =

        let val n = Vector.length tick_chars

            fun pad_to n str =

                if n <= String.size str then str

                else pad_to n (str ^ " ")

            val name = if libname <> "" then libname

                       else if cmdlist = nil then ""

                       else hd (rev cmdlist)

        in

            print ("  " ^

                   Vector.sub(tick_chars, !tick_cycle) ^ " " ^

                   pad_to 24 name ^

                   "\r");

            tick_cycle := (if !tick_cycle = n - 1 then 0 else 1 + !tick_cycle)

        end

    fun run_command context libname cmdlist redirect =

        let open OS

            val dir = libpath context libname

            val cmd = expand_commandline cmdlist

            val _ = if verbose ()

                    then print ("Running: " ^ cmd ^

                                " (in dir " ^ dir ^ ")...\n")

                    else tick libname cmdlist

            val _ = FileSys.chDir dir

            val status = case redirect of

                             NONE => Process.system cmd

                           | SOME file => Process.system (cmd ^ ">" ^ file)

        in

            if Process.isSuccess status

            then OK ()

            else ERROR ("Command failed: " ^ cmd ^ " (in dir " ^ dir ^ ")")

        end

        handle ex => ERROR ("Unable to run command: " ^ exnMessage ex)

    fun command context libname cmdlist =

        run_command context libname cmdlist NONE

    fun command_output context libname cmdlist =

        let open OS

            val tmpFile = FileSys.tmpName ()

            val result = run_command context libname cmdlist (SOME tmpFile)

            val contents = file_contents tmpFile

        in

            FileSys.remove tmpFile handle _ => ();

            case result of

                OK () => OK contents

              | ERROR e => ERROR e

        end

    fun mydir () =

        let open OS

            val { dir, file } = Path.splitDirFile (CommandLine.name ())

        in

            FileSys.realPath

                (if Path.isAbsolute dir

                 then dir

                 else Path.concat (FileSys.getDir (), dir))

        end

    fun homedir () =

        (* Failure is not routine, so we use an exception here *)

        case (OS.Process.getEnv "HOME",

              OS.Process.getEnv "HOMEPATH") of

            (SOME home, _) => home

          | (NONE, SOME home) => home

          | (NONE, NONE) =>

            raise Fail "Failed to look up home directory from environment"

    fun mkpath path =

        if OS.FileSys.isDir path handle _ => false

        then OK ()

        else case OS.Path.fromString path of

                 { arcs = nil, ... } => OK ()

               | { isAbs = false, ... } => ERROR "mkpath requires absolute path"

               | { isAbs, vol, arcs } => 

                 case mkpath (OS.Path.toString {      (* parent *)

                                   isAbs = isAbs,

                                   vol = vol,

                                   arcs = rev (tl (rev arcs)) }) of

                     ERROR e => ERROR e

                   | OK () => ((OS.FileSys.mkDir path; OK ())

                               handle OS.SysErr (e, _) =>

                                      ERROR ("Directory creation failed: " ^ e))

    fun rmpath path =

        let open OS

            fun files_from dirstream =

                case FileSys.readDir dirstream of

                    NONE => []

                  | SOME file =>

                    (* readDir is supposed to filter these, 

                       but let's be extra cautious: *)

                    if file = Path.parentArc orelse file = Path.currentArc

                    then files_from dirstream

                    else file :: files_from dirstream

            fun contents dir =

                let val stream = FileSys.openDir dir

                    val files = map (fn f => Path.joinDirFile

                                                 { dir = dir, file = f })

                                    (files_from stream)

                    val _ = FileSys.closeDir stream

                in files

                end

            fun remove path =

                if FileSys.isLink path (* dangling links bother isDir *)

                then FileSys.remove path

                else if FileSys.isDir path

                then (app remove (contents path); FileSys.rmDir path)

                else FileSys.remove path

        in

            (remove path; OK ())

            handle SysErr (e, _) => ERROR ("Path removal failed: " ^ e)

        end

end

functor LibControlFn (V: VCS_CONTROL) :> LIB_CONTROL = struct

    (* Valid states for unpinned libraries:

       - CORRECT: We are on the right branch and are up-to-date with

         it as far as we can tell. (If not using the network, this

         should be reported to user as "Present" rather than "Correct"

         as the remote repo may have advanced without us knowing.)

       - SUPERSEDED: We are on the right branch but we can see that

         there is a newer revision either locally or on the remote (in

         Git terms, we are at an ancestor of the desired branch tip).

       - WRONG: We are on the wrong branch (in Git terms, we are not

         at the desired branch tip or any ancestor of it).

       - ABSENT: Repo doesn't exist here at all.

       Valid states for pinned libraries:

       - CORRECT: We are at the pinned revision.

       - WRONG: We are at any revision other than the pinned one.

       - ABSENT: Repo doesn't exist here at all.

    *)

    fun check with_network context

              ({ libname, branch, project_pin, lock_pin, ... } : libspec) =

        let fun check_unpinned () =

                let val is_newest = if with_network

                                    then V.is_newest

                                    else V.is_newest_locally

                in

                    case is_newest context (libname, branch) of

                         ERROR e => ERROR e

                       | OK true => OK CORRECT

                       | OK false =>

                         case V.is_on_branch context (libname, branch) of

                             ERROR e => ERROR e

                           | OK true => OK SUPERSEDED

                           | OK false => OK WRONG

                end

            fun check_pinned target =

                case V.is_at context (libname, target) of

                    ERROR e => ERROR e

                  | OK true => OK CORRECT

                  | OK false => OK WRONG

            fun check_remote () =

                case project_pin of

                    UNPINNED => check_unpinned ()

                  | PINNED target => check_pinned target

            fun check_local () =

                case V.is_modified_locally context libname of

                    ERROR e => ERROR e

                  | OK true  => OK MODIFIED

                  | OK false => 

                    case lock_pin of

                        UNPINNED => OK CLEAN

                      | PINNED target =>

                        case V.is_at context (libname, target) of

                            ERROR e => ERROR e

                          | OK true => OK CLEAN

                          | OK false => OK LOCK_MISMATCHED

        in

            case V.exists context libname of

                ERROR e => ERROR e

              | OK false => OK (ABSENT, CLEAN)

              | OK true =>

                case (check_remote (), check_local ()) of

                    (ERROR e, _) => ERROR e

                  | (_, ERROR e) => ERROR e

                  | (OK r, OK l) => OK (r, l)

        end

    val review = check true

    val status = check false

    fun update context

               ({ libname, source, branch,

                  project_pin, lock_pin, ... } : libspec) =

        let fun update_unpinned () =

                case V.is_newest context (libname, branch) of

                    ERROR e => ERROR e

                  | OK true => V.id_of context libname

                  | OK false => V.update context (libname, branch)

            fun update_pinned target =

                case V.is_at context (libname, target) of

                    ERROR e => ERROR e

                  | OK true => OK target

                  | OK false => V.update_to context (libname, target)

            fun update' () =

                case lock_pin of

                    PINNED target => update_pinned target

                  | UNPINNED =>

                    case project_pin of

                        PINNED target => update_pinned target

                      | UNPINNED => update_unpinned ()

        in

            case V.exists context libname of

                ERROR e => ERROR e

              | OK true => update' ()

              | OK false =>

                case V.checkout context (libname, source, branch) of

                    ERROR e => ERROR e

                  | OK () => update' ()

        end

    fun id_of context ({ libname, ... } : libspec) =

        V.id_of context libname

end

(* Simple Standard ML JSON parser

   ==============================

   https://bitbucket.org/cannam/sml-simplejson

   An RFC-compliant JSON parser in one SML file with no dependency 

   on anything outside the Basis library. Also includes a simple

   serialiser.

   Tested with MLton, Poly/ML, and SML/NJ compilers.

   Parser notes:

   * Complies with RFC 7159, The JavaScript Object Notation (JSON)

     Data Interchange Format

   * Passes all of the JSONTestSuite parser accept/reject tests that

     exist at the time of writing, as listed in "Parsing JSON is a

     Minefield" (http://seriot.ch/parsing_json.php)

   * Two-pass parser using naive exploded strings, therefore not

     particularly fast and not suitable for large input files

   * Only supports UTF-8 input, not UTF-16 or UTF-32. Doesn't check

     that JSON strings are valid UTF-8 -- the caller must do that --

     but does handle \u escapes

   * Converts all numbers to type "real". If that is a 64-bit IEEE

     float type (common but not guaranteed in SML) then we're pretty

     standard for a JSON parser

   Copyright 2017 Chris Cannam.

   Parts based on the JSON parser in the Ponyo library by Phil Eaton.

   Permission is hereby granted, free of charge, to any person

   obtaining a copy of this software and associated documentation

   files (the "Software"), to deal in the Software without

   restriction, including without limitation the rights to use, copy,

   modify, merge, publish, distribute, sublicense, and/or sell copies

   of the Software, and to permit persons to whom the Software is

   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be

   included in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR

   ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF

   CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

   Except as contained in this notice, the names of Chris Cannam and

   Particular Programs Ltd shall not be used in advertising or

   otherwise to promote the sale, use or other dealings in this

   Software without prior written authorization.

*)

signature JSON = sig

    datatype json = OBJECT of (string * json) list

                  | ARRAY of json list

                  | NUMBER of real

                  | STRING of string

                  | BOOL of bool

                  | NULL

    datatype 'a result = OK of 'a

                       | ERROR of string

    val parse : string -> json result

    val serialise : json -> string

    val serialiseIndented : json -> string

end

structure Json :> JSON = struct

    datatype json = OBJECT of (string * json) list

                  | ARRAY of json list

                  | NUMBER of real

                  | STRING of string

                  | BOOL of bool

                  | NULL

    datatype 'a result = OK of 'a

                       | ERROR of string

    structure T = struct

        datatype token = NUMBER of char list

                       | STRING of string

                       | BOOL of bool

                       | NULL

                       | CURLY_L

                       | CURLY_R

                       | SQUARE_L

                       | SQUARE_R

                       | COLON

                       | COMMA

        fun toString t =

            case t of NUMBER digits => implode digits

                    | STRING s => s

                    | BOOL b => Bool.toString b

                    | NULL => "null"

                    | CURLY_L => "{"

                    | CURLY_R => "}"

                    | SQUARE_L => "["

                    | SQUARE_R => "]"

                    | COLON => ":"

                    | COMMA => ","

    end

    fun bmpToUtf8 cp =  (* convert a codepoint in Unicode BMP to utf8 bytes *)

        let open Word

	    infix 6 orb andb >>

        in

            map (Char.chr o toInt)

                (if cp < 0wx80 then

                     [cp]

                 else if cp < 0wx800 then

                     [0wxc0 orb (cp >> 0w6), 0wx80 orb (cp andb 0wx3f)]

                 else if cp < 0wx10000 then

                     [0wxe0 orb (cp >> 0w12),

                      0wx80 orb ((cp >> 0w6) andb 0wx3f),

		      0wx80 orb (cp andb 0wx3f)]

                 else raise Fail ("Invalid BMP point " ^ (Word.toString cp)))

        end

    fun error pos text = ERROR (text ^ " at character position " ^

                                Int.toString (pos - 1))

    fun token_error pos = error pos ("Unexpected token")

    fun lexNull pos acc (#"u" :: #"l" :: #"l" :: xs) =

        lex (pos + 3) (T.NULL :: acc) xs

      | lexNull pos acc _ = token_error pos

    and lexTrue pos acc (#"r" :: #"u" :: #"e" :: xs) =

        lex (pos + 3) (T.BOOL true :: acc) xs

      | lexTrue pos acc _ = token_error pos

    and lexFalse pos acc (#"a" :: #"l" :: #"s" :: #"e" :: xs) =

        lex (pos + 4) (T.BOOL false :: acc) xs

      | lexFalse pos acc _ = token_error pos

    and lexChar tok pos acc xs =

        lex pos (tok :: acc) xs

    and lexString pos acc cc =

        let datatype escaped = ESCAPED | NORMAL

            fun lexString' pos text ESCAPED [] =

                error pos "End of input during escape sequence"

              | lexString' pos text NORMAL [] = 

                error pos "End of input during string"

              | lexString' pos text ESCAPED (x :: xs) =

                let fun esc c = lexString' (pos + 1) (c :: text) NORMAL xs

                in case x of

                       #"\"" => esc x

                     | #"\\" => esc x

                     | #"/"  => esc x

                     | #"b"  => esc #"\b"

                     | #"f"  => esc #"\f"

                     | #"n"  => esc #"\n"

                     | #"r"  => esc #"\r"

                     | #"t"  => esc #"\t"

                     | _     => error pos ("Invalid escape \\" ^

                                           Char.toString x)

                end

              | lexString' pos text NORMAL (#"\\" :: #"u" ::a::b::c::d:: xs) =

                if List.all Char.isHexDigit [a,b,c,d]

                then case Word.fromString ("0wx" ^ (implode [a,b,c,d])) of

                         SOME w => (let val utf = rev (bmpToUtf8 w) in

                                        lexString' (pos + 6) (utf @ text)

                                                   NORMAL xs

                                    end

                                    handle Fail err => error pos err)

                       | NONE => error pos "Invalid Unicode BMP escape sequence"

                else error pos "Invalid Unicode BMP escape sequence"

              | lexString' pos text NORMAL (x :: xs) =

                if Char.ord x < 0x20

                then error pos "Invalid unescaped control character"

                else

                    case x of

                        #"\"" => OK (rev text, xs, pos + 1)

                      | #"\\" => lexString' (pos + 1) text ESCAPED xs

                      | _     => lexString' (pos + 1) (x :: text) NORMAL xs

        in

            case lexString' pos [] NORMAL cc of

                OK (text, rest, newpos) =>

                lex newpos (T.STRING (implode text) :: acc) rest

              | ERROR e => ERROR e

        end

    and lexNumber firstChar pos acc cc =

        let val valid = explode ".+-e"

            fun lexNumber' pos digits [] = (rev digits, [], pos)

              | lexNumber' pos digits (x :: xs) =

                if x = #"E" then lexNumber' (pos + 1) (#"e" :: digits) xs

                else if Char.isDigit x orelse List.exists (fn c => x = c) valid

                then lexNumber' (pos + 1) (x :: digits) xs

                else (rev digits, x :: xs, pos)

            val (digits, rest, newpos) =

                lexNumber' (pos - 1) [] (firstChar :: cc)

        in

            case digits of

                [] => token_error pos

              | _ => lex newpos (T.NUMBER digits :: acc) rest

        end

    and lex pos acc [] = OK (rev acc)

      | lex pos acc (x::xs) = 

        (case x of

             #" "  => lex

           | #"\t" => lex

           | #"\n" => lex

           | #"\r" => lex

           | #"{"  => lexChar T.CURLY_L

           | #"}"  => lexChar T.CURLY_R

           | #"["  => lexChar T.SQUARE_L

           | #"]"  => lexChar T.SQUARE_R

           | #":"  => lexChar T.COLON

           | #","  => lexChar T.COMMA

           | #"\"" => lexString

           | #"t"  => lexTrue

           | #"f"  => lexFalse

           | #"n"  => lexNull

           | x     => lexNumber x) (pos + 1) acc xs

    fun show [] = "end of input"

      | show (tok :: _) = T.toString tok

    fun parseNumber digits =

        (* Note lexNumber already case-insensitised the E for us *)

        let open Char

            fun okExpDigits [] = false

              | okExpDigits (c :: []) = isDigit c

              | okExpDigits (c :: cs) = isDigit c andalso okExpDigits cs

            fun okExponent [] = false

              | okExponent (#"+" :: cs) = okExpDigits cs

              | okExponent (#"-" :: cs) = okExpDigits cs

              | okExponent cc = okExpDigits cc

            fun okFracTrailing [] = true

              | okFracTrailing (c :: cs) =

                (isDigit c andalso okFracTrailing cs) orelse

                (c = #"e" andalso okExponent cs)

            fun okFraction [] = false

              | okFraction (c :: cs) =

                isDigit c andalso okFracTrailing cs

            fun okPosTrailing [] = true

              | okPosTrailing (#"." :: cs) = okFraction cs

              | okPosTrailing (#"e" :: cs) = okExponent cs

              | okPosTrailing (c :: cs) =

                isDigit c andalso okPosTrailing cs

            fun okPositive [] = false

              | okPositive (#"0" :: []) = true

              | okPositive (#"0" :: #"." :: cs) = okFraction cs

              | okPositive (#"0" :: #"e" :: cs) = okExponent cs

              | okPositive (#"0" :: cs) = false

              | okPositive (c :: cs) = isDigit c andalso okPosTrailing cs

            fun okNumber (#"-" :: cs) = okPositive cs

              | okNumber cc = okPositive cc

        in

            if okNumber digits

            then case Real.fromString (implode digits) of

                     NONE => ERROR "Number out of range"

                   | SOME r => OK r

            else ERROR ("Invalid number \"" ^ (implode digits) ^ "\"")

        end

    fun parseObject (T.CURLY_R :: xs) = OK (OBJECT [], xs)

      | parseObject tokens =

        let fun parsePair (T.STRING key :: T.COLON :: xs) =

                (case parseTokens xs of

                     ERROR e => ERROR e

                   | OK (j, xs) => OK ((key, j), xs))

              | parsePair other =

                ERROR ("Object key/value pair expected around \"" ^

                       show other ^ "\"")

            fun parseObject' acc [] = ERROR "End of input during object"

              | parseObject' acc tokens =

                case parsePair tokens of

                    ERROR e => ERROR e

                  | OK (pair, T.COMMA :: xs) =>

                    parseObject' (pair :: acc) xs

                  | OK (pair, T.CURLY_R :: xs) =>

                    OK (OBJECT (rev (pair :: acc)), xs)

                  | OK (_, _) => ERROR "Expected , or } after object element"

        in

            parseObject' [] tokens

        end

    and parseArray (T.SQUARE_R :: xs) = OK (ARRAY [], xs)

      | parseArray tokens =

        let fun parseArray' acc [] = ERROR "End of input during array"

              | parseArray' acc tokens =

                case parseTokens tokens of

                    ERROR e => ERROR e

                  | OK (j, T.COMMA :: xs) => parseArray' (j :: acc) xs

                  | OK (j, T.SQUARE_R :: xs) => OK (ARRAY (rev (j :: acc)), xs)

                  | OK (_, _) => ERROR "Expected , or ] after array element"

        in

            parseArray' [] tokens

        end

    and parseTokens [] = ERROR "Value expected"

      | parseTokens (tok :: xs) =

        (case tok of

             T.NUMBER d => (case parseNumber d of

                                OK r => OK (NUMBER r, xs)

                              | ERROR e => ERROR e)

           | T.STRING s => OK (STRING s, xs)

           | T.BOOL b   => OK (BOOL b, xs)

           | T.NULL     => OK (NULL, xs)

           | T.CURLY_L  => parseObject xs

           | T.SQUARE_L => parseArray xs

           | _ => ERROR ("Unexpected token " ^ T.toString tok ^

                         " before " ^ show xs))

    fun parse str =

        case lex 1 [] (explode str) of

           ERROR e => ERROR e

         | OK tokens => case parseTokens tokens of

                            OK (value, []) => OK value

                          | OK (_, _) => ERROR "Extra data after input"

                          | ERROR e => ERROR e

    fun stringEscape s =

        let fun esc x = [x, #"\\"]

            fun escape' acc [] = rev acc

              | escape' acc (x :: xs) =

                escape' (case x of

                             #"\"" => esc x @ acc

                           | #"\\" => esc x @ acc

                           | #"\b" => esc #"b" @ acc

                           | #"\f" => esc #"f" @ acc

                           | #"\n" => esc #"n" @ acc

                           | #"\r" => esc #"r" @ acc

                           | #"\t" => esc #"t" @ acc

                           | _ =>

                             let val c = Char.ord x

                             in

                                 if c < 0x20

                                 then let val hex = Word.toString (Word.fromInt c)

                                      in (rev o explode) (if c < 0x10

                                                          then ("\\u000" ^ hex)

                                                          else ("\\u00" ^ hex))

                                      end @ acc

                                 else 

                                     x :: acc

                             end)

                        xs

        in

            implode (escape' [] (explode s))

        end

    fun serialise json =

        case json of

            OBJECT pp => "{" ^ String.concatWith

                                   "," (map (fn (key, value) =>

                                                serialise (STRING key) ^ ":" ^

                                                serialise value) pp) ^

                         "}"

          | ARRAY arr => "[" ^ String.concatWith "," (map serialise arr) ^ "]"

          | NUMBER n => implode (map (fn #"~" => #"-" | c => c) 

                                     (explode (Real.toString n)))

          | STRING s => "\"" ^ stringEscape s ^ "\""

          | BOOL b => Bool.toString b

          | NULL => "null"

    fun serialiseIndented json =

        let fun indent 0 = ""

              | indent i = "  " ^ indent (i - 1)

            fun serialiseIndented' i json =

                let val ser = serialiseIndented' (i + 1)

                in

                    case json of

                        OBJECT [] => "{}"

                      | ARRAY [] => "[]"

                      | OBJECT pp => "{\n" ^ indent (i + 1) ^

                                     String.concatWith

                                         (",\n" ^ indent (i + 1))

                                         (map (fn (key, value) =>

                                                  ser (STRING key) ^ ": " ^

                                                  ser value) pp) ^

                                     "\n" ^ indent i ^ "}"

                      | ARRAY arr => "[\n" ^ indent (i + 1) ^

                                     String.concatWith

                                         (",\n" ^ indent (i + 1))

                                         (map ser arr) ^

                                     "\n" ^ indent i ^ "]"

                      | other => serialise other

                end

        in

            serialiseIndented' 0 json ^ "\n"

        end

end

structure JsonBits :> sig

    val load_json_from : string -> Json.json (* filename -> json *)

    val save_json_to : string -> Json.json -> unit

    val lookup_optional : Json.json -> string list -> Json.json option

    val lookup_optional_string : Json.json -> string list -> string option

    val lookup_mandatory : Json.json -> string list -> Json.json

    val lookup_mandatory_string : Json.json -> string list -> string

end = struct

    fun load_json_from filename =

        case Json.parse (FileBits.file_contents filename) of

            Json.OK json => json

          | Json.ERROR e => raise Fail ("Failed to parse file: " ^ e)

    fun save_json_to filename json =

        (* using binary I/O to avoid ever writing CR/LF line endings *)

        let val jstr = Json.serialiseIndented json

            val stream = BinIO.openOut filename

        in

            BinIO.output (stream, Byte.stringToBytes jstr);

            BinIO.closeOut stream

        end

    fun lookup_optional json kk =

        let fun lookup key =

                case json of

                    Json.OBJECT kvs =>

                    (case List.find (fn (k, v) => k = key) kvs of

                         SOME (k, v) => SOME v

                       | NONE => NONE)

                  | _ => raise Fail "Object expected"

        in

            case kk of

                [] => NONE

              | key::[] => lookup key

              | key::kk => case lookup key of

                               NONE => NONE

                             | SOME j => lookup_optional j kk

        end

    fun lookup_optional_string json kk =

        case lookup_optional json kk of

            SOME (Json.STRING s) => SOME s

          | SOME _ => raise Fail ("Value (if present) must be string: " ^

                                  (String.concatWith " -> " kk))

          | NONE => NONE

    fun lookup_mandatory json kk =

        case lookup_optional json kk of

            SOME v => v

          | NONE => raise Fail ("Value is mandatory: " ^

                                (String.concatWith " -> " kk) ^ " in json: " ^

                                (Json.serialise json))

    fun lookup_mandatory_string json kk =

        case lookup_optional json kk of

            SOME (Json.STRING s) => s

          | _ => raise Fail ("Value must be string: " ^

                             (String.concatWith " -> " kk))

end

structure Provider :> sig

    val load_providers : Json.json -> provider list

    val load_more_providers : provider list -> Json.json -> provider list

    val remote_url : context -> vcs -> source -> libname -> string

end = struct

    val known_providers : provider list =

        [ {

            service = "bitbucket",

            supports = [HG, GIT],

            remote_spec = {

                anon = SOME "https://bitbucket.org/{owner}/{repository}",

                auth = SOME "ssh://{vcs}@bitbucket.org/{owner}/{repository}"

            }

          },

          {

            service = "github",

            supports = [GIT],

            remote_spec = {

                anon = SOME "https://github.com/{owner}/{repository}",

                auth = SOME "ssh://{vcs}@github.com/{owner}/{repository}"

            }

          }

        ]

    fun vcs_name vcs =

        case vcs of GIT => "git" |

                    HG => "hg"

    fun vcs_from_name name =

        case name of "git" => GIT 

                   | "hg" => HG

                   | other => raise Fail ("Unknown vcs name \"" ^ name ^ "\"")

    fun load_more_providers previously_loaded json =

        let open JsonBits

            fun load pjson pname : provider =

                {

                  service = pname,

                  supports =

                  case lookup_mandatory pjson ["vcs"] of

                      Json.ARRAY vv =>

                      map (fn (Json.STRING v) => vcs_from_name v

                          | _ => raise Fail "Strings expected in vcs array")

                          vv

                    | _ => raise Fail "Array expected for vcs",

                  remote_spec = {

                      anon = lookup_optional_string pjson ["anonymous"],

                      auth = lookup_optional_string pjson ["authenticated"]

                  }

                }

            val loaded = 

                case lookup_optional json ["services"] of

                    NONE => []

                  | SOME (Json.OBJECT pl) => map (fn (k, v) => load v k) pl

                  | _ => raise Fail "Object expected for services in config"

            val newly_loaded =

                List.filter (fn p => not (List.exists (fn pp => #service p =

                                                                #service pp)

                                                      previously_loaded))

                            loaded

        in

            previously_loaded @ newly_loaded

        end

    fun load_providers json =

        load_more_providers known_providers json

    fun expand_spec spec { vcs, service, owner, repo } login =

        (* ugly *)

        let fun replace str = 

                case str of

                    "vcs" => vcs_name vcs

                  | "service" => service

                  | "owner" =>

                    (case owner of

                         SOME ostr => ostr

                       | NONE => raise Fail ("Owner not specified for service " ^

                                             service))

                  | "repository" => repo

                  | "account" =>

                    (case login of

                         SOME acc => acc

                       | NONE => raise Fail ("Account not given for service " ^

                                             service))

                  | other => raise Fail ("Unknown variable \"" ^ other ^

                                         "\" in spec for service " ^ service)

            fun expand' acc sstr =

                case Substring.splitl (fn c => c <> #"{") sstr of

                    (pfx, sfx) =>

                    if Substring.isEmpty sfx

                    then rev (pfx :: acc)

                    else 

                        case Substring.splitl (fn c => c <> #"}") sfx of

                            (tok, remainder) =>

                            if Substring.isEmpty remainder

                            then rev (tok :: pfx :: acc)

                            else let val replacement =

                                         replace

                                             (* tok begins with "{": *)

                                             (Substring.string

                                                  (Substring.triml 1 tok))

                                 in

                                     expand' (Substring.full replacement ::

                                              pfx :: acc)

                                             (* remainder begins with "}": *)

                                             (Substring.triml 1 remainder)

                                 end

        in

            Substring.concat (expand' [] (Substring.full spec))

        end

    fun provider_url req login providers =

        case providers of

            [] => raise Fail ("Unknown service \"" ^ (#service req) ^

                              "\" for vcs \"" ^ (vcs_name (#vcs req)) ^ "\"")

          | ({ service, supports, remote_spec : remote_spec } :: rest) =>

            if service <> (#service req) orelse

               not (List.exists (fn v => v = (#vcs req)) supports)

            then provider_url req login rest

            else

                case (login, #auth remote_spec, #anon remote_spec) of

                    (SOME _, SOME auth, _) => expand_spec auth req login

                  | (SOME _, _, SOME anon) => expand_spec anon req NONE

                  | (NONE,   _, SOME anon) => expand_spec anon req NONE

                  | _ => raise Fail ("No suitable anonymous or authenticated " ^

                                     "URL spec provided for service \"" ^

                                     service ^ "\"")

    fun login_for ({ accounts, ... } : context) service =

        case List.find (fn a => service = #service a) accounts of

            SOME { login, ... } => SOME login

          | NONE => NONE

    fun remote_url (context : context) vcs source libname =

        case source of

            URL_SOURCE u => u

          | SERVICE_SOURCE { service, owner, repo } =>

            provider_url { vcs = vcs,

                           service = service,

                           owner = owner,

                           repo = case repo of

                                      SOME r => r

                                    | NONE => libname }

                         (login_for context service)

                         (#providers context)

end

structure HgControl :> VCS_CONTROL = struct

    type vcsstate = { id: string, modified: bool,

                      branch: string, tags: string list }

    val hg_args = [ "--config", "ui.interactive=true" ]

    fun hg_command context libname args =

        FileBits.command context libname ("hg" :: hg_args @ args)

    fun hg_command_output context libname args =

        FileBits.command_output context libname ("hg" :: hg_args @ args)

    fun exists context libname =

        OK (OS.FileSys.isDir (FileBits.subpath context libname ".hg"))

        handle _ => OK false

    fun remote_for context (libname, source) =

        Provider.remote_url context HG source libname

    fun current_state context libname : vcsstate result =

        let fun is_branch text = text <> "" andalso #"(" = hd (explode text)

            and extract_branch b =

                if is_branch b     (* need to remove enclosing parens *)

                then (implode o rev o tl o rev o tl o explode) b

                else "default"

            and is_modified id = id <> "" andalso #"+" = hd (rev (explode id))

            and extract_id id =

                if is_modified id  (* need to remove trailing "+" *)

                then (implode o rev o tl o rev o explode) id

                else id

            and split_tags tags = String.tokens (fn c => c = #"/") tags

            and state_for (id, branch, tags) =

                OK { id = extract_id id,

                     modified = is_modified id,

                     branch = extract_branch branch,

                     tags = split_tags tags }

        in        

            case hg_command_output context libname ["id"] of

                ERROR e => ERROR e

              | OK out =>

                case String.tokens (fn x => x = #" ") out of

                    [id, branch, tags] => state_for (id, branch, tags)

                  | [id, other] => if is_branch other

                                   then state_for (id, other, "")

                                   else state_for (id, "", other)

                  | [id] => state_for (id, "", "")

                  | _ => ERROR ("Unexpected output from hg id: " ^ out)

        end

    fun branch_name branch = case branch of

                                 DEFAULT_BRANCH => "default"

                               | BRANCH "" => "default"

                               | BRANCH b => b

    fun id_of context libname =

        case current_state context libname of

            ERROR e => ERROR e

          | OK { id, ... } => OK id

    fun is_at context (libname, id_or_tag) =

        case current_state context libname of

            ERROR e => ERROR e

          | OK { id, tags, ... } => 

            OK (String.isPrefix id_or_tag id orelse

                String.isPrefix id id_or_tag orelse

                List.exists (fn t => t = id_or_tag) tags)

    fun is_on_branch context (libname, b) =

        case current_state context libname of

            ERROR e => ERROR e

          | OK { branch, ... } => OK (branch = branch_name b)

    fun is_newest_locally context (libname, branch) =

        case hg_command_output context libname

                               ["log", "-l1",

                                "-b", branch_name branch,

                                "--template", "{node}"] of

            ERROR e => ERROR e

          | OK newest_in_repo => is_at context (libname, newest_in_repo)

    fun pull context libname =

        hg_command context libname

                   (if FileBits.verbose ()

                    then ["pull"]

                    else ["pull", "-q"])

    fun is_newest context (libname, branch) =

        case is_newest_locally context (libname, branch) of

            ERROR e => ERROR e

          | OK false => OK false

          | OK true =>

            case pull context libname of

                ERROR e => ERROR e

              | _ => is_newest_locally context (libname, branch)

    fun is_modified_locally context libname =

        case current_state context libname of

            ERROR e => ERROR e

          | OK { modified, ... } => OK modified

    fun checkout context (libname, source, branch) =

        let val url = remote_for context (libname, source)

        in

            case FileBits.mkpath (FileBits.extpath context) of

                ERROR e => ERROR e

              | _ => hg_command context ""

                                ["clone", "-u", branch_name branch,

                                 url, libname]

        end

    fun update context (libname, branch) =

        let val pull_result = pull context libname

        in

            case hg_command context libname ["update", branch_name branch] of

                ERROR e => ERROR e

              | _ =>

                case pull_result of

                    ERROR e => ERROR e

                  | _ => id_of context libname

        end

    fun update_to context (libname, "") =

        ERROR "Non-empty id (tag or revision id) required for update_to"

      | update_to context (libname, id) = 

        let val pull_result = pull context libname

        in

            case hg_command context libname ["update", "-r", id] of

                OK _ => id_of context libname

              | ERROR e =>

                case pull_result of

                    ERROR e' => ERROR e' (* this was the ur-error *)

                  | _ => ERROR e

        end

end

structure GitControl :> VCS_CONTROL = struct

    (* With Git repos we always operate in detached HEAD state. Even

       the master branch is checked out using the remote reference,

       origin/master. *)

    fun git_command context libname args =

        FileBits.command context libname ("git" :: args)

    fun git_command_output context libname args =

        FileBits.command_output context libname ("git" :: args)

    fun exists context libname =

        OK (OS.FileSys.isDir (FileBits.subpath context libname ".git"))

        handle _ => OK false

    fun remote_for context (libname, source) =

        Provider.remote_url context GIT source libname

    fun branch_name branch = case branch of

                                 DEFAULT_BRANCH => "master"

                               | BRANCH "" => "master"

                               | BRANCH b => b

    fun remote_branch_name branch = "origin/" ^ branch_name branch

    fun checkout context (libname, source, branch) =

        let val url = remote_for context (libname, source)

        in

            case FileBits.mkpath (FileBits.extpath context) of

                OK () => git_command context ""

                                     ["clone", "-b",

                                      branch_name branch,

                                      url, libname]

              | ERROR e => ERROR e

        end

    (* NB git rev-parse HEAD shows revision id of current checkout;

       git rev-list -1 <tag> shows revision id of revision with that tag *)

    fun id_of context libname =

        git_command_output context libname ["rev-parse", "HEAD"]

    fun is_at context (libname, id_or_tag) =

        case id_of context libname of

            ERROR e => ERROR e

          | OK id =>

            if String.isPrefix id_or_tag id orelse

               String.isPrefix id id_or_tag

            then OK true

            else 

                case git_command_output context libname

                                        ["show-ref",

                                         "refs/tags/" ^ id_or_tag] of

                    OK "" => OK false

                  | ERROR _ => OK false

                  | OK s => OK (id = hd (String.tokens (fn c => c = #" ") s))

    fun branch_tip context (libname, branch) =

        git_command_output context libname

                           ["rev-list", "-1",

                            remote_branch_name branch]

    fun is_newest_locally context (libname, branch) =

        case branch_tip context (libname, branch) of

            ERROR e => ERROR e

          | OK rev => is_at context (libname, rev)

    fun is_on_branch context (libname, branch) =

        case branch_tip context (libname, branch) of

            ERROR e => ERROR e

          | OK rev =>

            case is_at context (libname, rev) of

                ERROR e => ERROR e

              | OK true => OK true

              | OK false =>

                case git_command context libname

                                 ["merge-base", "--is-ancestor",

                                  "HEAD", remote_branch_name branch] of

                    ERROR e => OK false  (* cmd returns non-zero for no *)

                  | _ => OK true

    fun is_newest context (libname, branch) =

        case is_newest_locally context (libname, branch) of

            ERROR e => ERROR e

          | OK false => OK false

          | OK true =>

            case git_command context libname ["fetch"] of

                ERROR e => ERROR e

              | _ => is_newest_locally context (libname, branch)

    fun is_modified_locally context libname =

        case git_command_output context libname ["status", "--porcelain"] of

            ERROR e => ERROR e

          | OK "" => OK false

          | OK _ => OK true

    (* This function updates to the latest revision on a branch rather

       than to a specific id or tag. We can't just checkout the given

       branch, as that will succeed even if the branch isn't up to

       date. We could checkout the branch and then fetch and merge,

       but it's perhaps cleaner not to maintain a local branch at all,

       but instead checkout the remote branch as a detached head. *)

    fun update context (libname, branch) =

        case git_command context libname ["fetch"] of

            ERROR e => ERROR e

          | _ =>

            case git_command context libname ["checkout", "--detach",

                                              remote_branch_name branch] of

                ERROR e => ERROR e

              | _ => id_of context libname

    (* This function is dealing with a specific id or tag, so if we

       can successfully check it out (detached) then that's all we

       need to do, regardless of whether fetch succeeded or not. We do

       attempt the fetch first, though, purely in order to avoid ugly

       error messages in the common case where we're being asked to

       update to a new pin (from the lock file) that hasn't been

       fetched yet. *)

    fun update_to context (libname, "") = 

        ERROR "Non-empty id (tag or revision id) required for update_to"

      | update_to context (libname, id) =

        let val fetch_result = git_command context libname ["fetch"]

        in

            case git_command context libname ["checkout", "--detach", id] of

                OK _ => id_of context libname

              | ERROR e =>

                case fetch_result of

                    ERROR e' => ERROR e' (* this was the ur-error *)

                  | _ => ERROR e

        end

end

structure AnyLibControl :> LIB_CONTROL = struct

    structure H = LibControlFn(HgControl)

    structure G = LibControlFn(GitControl)

    fun review context (spec as { vcs, ... } : libspec) =

        (fn HG => H.review | GIT => G.review) vcs context spec

    fun status context (spec as { vcs, ... } : libspec) =

        (fn HG => H.status | GIT => G.status) vcs context spec

    fun update context (spec as { vcs, ... } : libspec) =

        (fn HG => H.update | GIT => G.update) vcs context spec

    fun id_of context (spec as { vcs, ... } : libspec) =

        (fn HG => H.id_of | GIT => G.id_of) vcs context spec

end

type exclusions = string list

structure Archive :> sig

    val archive : string * exclusions -> project -> OS.Process.status

end = struct

    (* The idea of "archive" is to replace hg/git archive, which won't

       include files, like the Vext-introduced external libraries,

       that are not under version control with the main repo.

       The process goes like this:

       - Make sure we have a target filename from the user, and take

         its basename as our archive directory name

       - Make an "archive root" subdir of the project repo, named

         typically .vext-archive

       - Identify the VCS used for the project repo. Note that any

         explicit references to VCS type in this structure are to

         the VCS used for the project (something Vext doesn't 

         otherwise care about), not for an individual library

       - Synthesise a Vext project with the archive root as its

         root path, "." as its extdir, with one library whose

         name is the user-supplied basename and whose explicit

         source URL is the original project root; update that

         project -- thus cloning the original project to a subdir

         of the archive root

       - Synthesise a Vext project identical to the original one for

         this project, but with the newly-cloned copy as its root

         path; update that project -- thus checking out clean copies

         of the external library dirs

       - Call out to an archive program to archive up the new copy,

         running e.g.

         tar cvzf project-release.tar.gz \

             --exclude=.hg --exclude=.git project-release

         in the archive root dir

       - (We also omit the vext-project.json file and any trace of

         Vext. It can't properly be run in a directory where the

         external project folders already exist but their repo history

         does not. End users shouldn't get to see Vext)

       - Clean up by deleting the new copy

    *)

    fun project_vcs_and_id dir =

        let val context = {

                rootpath = dir,

                extdir = ".",

                providers = [],

                accounts = []

            }

            val vcs_maybe = 

                case [HgControl.exists context ".",

                      GitControl.exists context "."] of

                    [OK true, OK false] => OK HG

                  | [OK false, OK true] => OK GIT

                  | _ => ERROR ("Unable to identify VCS for directory " ^ dir)

        in

            case vcs_maybe of

                ERROR e => ERROR e

              | OK vcs =>

                case (fn HG => HgControl.id_of | GIT => GitControl.id_of)

                         vcs context "." of

                    ERROR e => ERROR ("Unable to obtain id of project repo: "

                                      ^ e)

                  | OK id => OK (vcs, id)

        end

    fun make_archive_root (context : context) =

        let val path = OS.Path.joinDirFile {

                    dir = #rootpath context,

                    file = VextFilenames.archive_dir

                }

        in

            case FileBits.mkpath path of

                ERROR e => raise Fail ("Failed to create archive directory \""

                                       ^ path ^ "\": " ^ e)

              | OK () => path

        end

    fun archive_path archive_dir target_name =

        OS.Path.joinDirFile {

            dir = archive_dir,

            file = target_name

        }

    fun check_nonexistent path =

        case SOME (OS.FileSys.fileSize path) handle OS.SysErr _ => NONE of

            NONE => ()

          | _ => raise Fail ("Path " ^ path ^ " exists, not overwriting")

    fun file_url path =

        let val forward_path = 

                String.translate (fn #"\\" => "/" |

                                     c => Char.toString c) path

        in

            (* Path is expected to be absolute already, but if it

                starts with a drive letter, we'll need an extra slash *)

            case explode forward_path of

                #"/"::rest => "file:///" ^ implode rest

              | _ => "file:///" ^ forward_path

        end

    fun make_archive_copy target_name (vcs, project_id)

                          ({ context, ... } : project) =

        let val archive_root = make_archive_root context

            val synthetic_context = {

                rootpath = archive_root,

                extdir = ".",

                providers = [],

                accounts = []

            }

            val synthetic_library = {

                libname = target_name,

                vcs = vcs,

                source = URL_SOURCE (file_url (#rootpath context)),

                branch = DEFAULT_BRANCH, (* overridden by pinned id below *)

                project_pin = PINNED project_id,

                lock_pin = PINNED project_id

            }

            val path = archive_path archive_root target_name

            val _ = print ("Cloning original project to " ^ path

                           ^ " at revision " ^ project_id ^ "...\n");

            val _ = check_nonexistent path

        in

            case AnyLibControl.update synthetic_context synthetic_library of

                ERROR e => ERROR ("Failed to clone original project to "

                                  ^ path ^ ": " ^ e)

              | OK _ => OK archive_root

        end

    fun update_archive archive_root target_name

                       (project as { context, ... } : project) =

        let val synthetic_context = {

                rootpath = archive_path archive_root target_name,

                extdir = #extdir context,

                providers = #providers context,

                accounts = #accounts context