MaxKeys: NAT = 3;

KeyChar: CHAR = 'k;

-- This interface is designed to allow clients to generate a list of filenames from a template.

-- Its main purpose is to overcome the difficulty of generating filenames to meet local

-- naming conventions.

-- For example, a problem occurs with AIS separation files. Normally AIS filenames conform to

-- the template <FileStem>-<SeparationFlag>.<AISExtension>. Even so at least two different

-- SeparationFlag naming conventions exist and at least two AISExtension naming conventions.

-- Typically one client will use the flag "grn" to name the green separation, another "g" and

-- a third "green". When these options are permuted with the AISExtension naming

-- conventions ".pic", ".ais", ".image", 9 possible need to be tested.

--

-- Expand provides a simple way of specifying a template containing keys that are

-- to be replaced by ropes extracted from the user.profile.

--

-- Template format:

-- The format rope conforms to the protocol used by the formatting routine PutF in IO.

-- (See IODoc.tioga). In its simplest form expand can be used like PutFR to generate

-- a single rope which is the result of calling PutFR with the format rope and the

-- IO.Values: v1..v5. Expand actually returns a list of length 1.

-- e.g. Expand["File%g.ext", IO.real[99]] => "File99.ext"

--

-- To use the user.profile substitution feature a special format sequence introduced by %k is

-- used. The general form is: %k<c><UserProfileKey><c><Default><c> where:

--  <c>    is any character used to delimit the following sequences of characters

--  <UserProfileKey> is a user.profile key as specified by UserProfileDoc.Tioga

--  <Default> is a default sequence to be used if no corresponding key is found

--

-- So the example above would be handled as follows:

--

-- l ← Expand["%g%k|AISseparationKeys.green|red|.%k|AISExtensions|ais|", IO.rope[fileStem]];

--

-- The user profile would be searched for the keys: "AISseparationKeys.green" and

-- "AISExtensions" and every possible permutation of ropes returned.

--

-- If the user profile contained the entries:

--  AISseparationKeys.green: "-grn" "-green" "-g"

--  AISExtensions: "ais" "pic" "image"

--

-- and fileStem = "Foo", then

-- l = ("Foo-grn.ais", "Foo-grn.pic", "Foo-grn.image", "Foo-green.ais",

--  "Foo-green.pic", "Foo-green.image", "Foo-g.ais", "Foo-g.pic", "Foo-g.image")

-- Note that the first name in the list is built from the first options of each user.prfile key

--

-- If neither key had been present in the user.profile then

-- l = ("Foo-grn.ais")

format: Rope.ROPE ← NIL,

v1, v2, v3, v4, v5: IO.Value ← [null[]]

]

RETURNS [names: LIST OF Rope.ROPE ← NIL] ;

proc: EnumerateProc,

format: Rope.ROPE ← NIL,

v1, v2, v3, v4, v5: IO.Value ← [null[]]

] ;

-- Expands the format string using the values v1 .. v5 to produce a list of ropes. The client

-- procedure is then called for each rope in the sequence. If the client procedure returns

-- FALSE then Enumerate returns.

format: Rope.ROPE ← NIL,

v1, v2, v3, v4, v5: IO.Value ← [null[]],

accessOptions: FS.AccessOptions ← $read,

streamOptions: FS.StreamOptions ← FS.defaultStreamOptions,

keep: CARDINAL ← 1,

createByteCount: FS.ByteCount ← 2560,

streamBufferParms: FS.StreamBufferParms ← FS.defaultStreamBufferParms,

extendFileProc: FS.ExtendFileProc ← NIL

]

RETURNS [stream: IO.STREAM ← NIL] ;

-- Expands the format string using the values v1 .. v5. The result is expected to be a list of

-- filenames. An attempt is made to open or create each filename (depending on accessOptions)

-- until one succeeds and produces a stream. If no stream can be produced NIL is returned.

END.