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structure Stream :> STREAM = struct
type fileId = int
type fileOffset = int
datatype pos = Pos of string * int * int
type t = {
id: fileOffset,
fname: string,
off: fileOffset,
contents: string,
(* offset * line * col *)
cache: fileOffset * int * int
}
exception EOF
exception UngetcError
val updateStream = fn z =>
let
fun from id fname off contents cache =
{ id, fname, off, contents, cache }
fun to f { id, fname, off, contents, cache } =
f id fname off contents cache
in
FRU.makeUpdate5 (from, from, to)
end
z
fun pos2str (Pos (pos, line, col)) =
let
val % = Int.toString
in
pos ^ ":" ^ %line ^ ":" ^ %col
end
fun getcharSure (S as { contents, off, ... }: t) =
(String.sub (contents, off), updateStream S s#off (off + 1) %)
fun getchar stream =
(fn (c, s) => (SOME c, s)) $ getcharSure stream handle
Subscript => (NONE, stream)
fun getcharEx stream = getcharSure stream handle Subscript => raise EOF
fun ungetc ({ off = 0, ... }: t) =
raise UngetcError
| ungetc stream = updateStream stream u#off (fn off => off - 1) %
fun getSubstr startOff endOff ({ contents, ... }: t) =
String.substring (contents, startOff, endOff - startOff)
fun getFname ({ fname, ... }: t) = fname
fun createFromInstream fname instream =
let
open TextIO
val contents = inputAll instream
val () = closeIn instream
in
{ id = 0, fname, off = 0, contents, cache = (0, 1, 1) }
end
fun create fname = createFromInstream fname (TextIO.openIn fname)
fun getOffset ({ off, ... }: t) = off
fun getPosRaw off (S as { cache = (prevOff, line, col), fname,
contents, ... }: t) =
let
fun calcPos curOff (line, col) =
if curOff = off then
(line, col)
else
calcPos (curOff + 1)
(if String.sub (contents,curOff) = #"\n" then (line + 1, 1)
else (line, col + 1))
val (line, col) = calcPos prevOff (line, col)
in
assert $ off >= prevOff;
(Pos (fname, line, col), updateStream S s#cache (off, line, col) %)
end
fun getPos (S as { off, ... }: t) =
getPosRaw off S
fun EOFpos (S as { contents, ... }: t) =
getPosRaw (String.size contents) S
fun getPosAfterChar stream =
getPosRaw (getOffset stream -1) stream
end
|
