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(*
Copyright (c) 2000
Cambridge University Technical Services Limited
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*)
(*
Title: Parse Types.
Author: Dave Matthews, Cambridge University Computer Laboratory
Copyright Cambridge University 1985
*)
functor PARSE_TYPE (
structure SYMBOLS : SymbolsSig
structure SYMSET : SymsetSig
structure LEX : LEXSIG
structure SKIPS :
sig
type sys;
type lexan;
type symset;
type location =
{ file: string, startLine: FixedInt.int, startPosition: FixedInt.int,
endLine: FixedInt.int, endPosition: FixedInt.int }
val badsyms: sys * lexan -> unit;
val getsym: sys * lexan -> unit;
val skipon: symset * symset * string * lexan -> unit;
val getid: symset * symset * lexan -> string * location;
val getLabel: symset * lexan -> string * location;
val getList: sys * symset * lexan * (unit -> 'a * location) -> 'a list * location;
end;
structure UTILITIES :
sig
val noDuplicates: (string * 'a * 'a -> unit) ->
{ apply: (string * 'a -> unit) -> unit,
enter: string * 'a -> unit,
lookup: string -> 'a option };
end
structure TYPETREE : TYPETREESIG
(*****************************************************************************)
(* PARSETYPE sharing constraints *)
(*****************************************************************************)
sharing type
SYMBOLS.sys
= SYMSET.sys
= SKIPS.sys
= LEX.sys
sharing type
SYMSET.symset
= SKIPS.symset
sharing type
LEX.lexan
= SKIPS.lexan
) :
(*****************************************************************************)
(* PARSETYPE export signature *)
(*****************************************************************************)
sig
type symset;
type lexan;
type types;
type typeParsetree;
type typeVarForm
type location =
{ file: string, startLine: FixedInt.int, startPosition: FixedInt.int,
endLine: FixedInt.int, endPosition: FixedInt.int }
val parseType: symset * lexan * {lookupTvar:string -> typeVarForm} -> typeParsetree * location;
end =
(*****************************************************************************)
(* PARSETYPE functor body *)
(*****************************************************************************)
struct
open TYPETREE
open LEX
open SYMSET
open SKIPS
open SYMBOLS
open UTILITIES
infix 8 ++;
infix 8 inside;
val tyseqSyntax = SYMSET.comma ++ SYMSET.rightParen
val lrSyntax = SYMSET.comma ++ SYMSET.rightCurly
fun parseType (fsys, lex, env) =
let
fun tupleType fsys =
let
fun basicType fsys =
let (* First part may be a type sequence. *)
val sym = sy lex and startLocn = location lex
val (tySeq, seqLocn) =
case sym of
LeftParen => (* sequence of types *)
let
fun processList () =
let
val thisType =
if sy lex inside startTypeSys
then #1 (parseType (fsys ++ tyseqSyntax, lex, env))
else
(
badsyms (TypeIdent, lex);
ParseTypeBad (* not there *)
);
fun testfor (sym, startsys, lex) =
(* repeat if the separator or a starting sym is found *)
if sy lex = sym
then (insymbol lex; true)
else if sy lex inside startsys
then (badsyms (sym, lex); true)
else false;
in (* Check for any more *)
if testfor (SYMBOLS.Comma, startTypeSys, lex)
then thisType :: processList() (* get some more *)
else [thisType] (* that's it *)
end (* processList *);
val () = insymbol lex; (* Remove opening bracket *)
val sequence = processList(); (* read list of items *)
val endLocn = location lex (* Should be the loc. of the close paren. *)
in
getsym (SYMBOLS.RightParen, lex);
(sequence, locSpan(startLocn, endLocn))
end
| LeftCurly =>
let
val () = insymbol lex; (* Remove opening bracket *)
val posEnd = location lex
in
case sy lex of
RightCurly =>
let
val () = insymbol lex
val locs = locSpan(startLocn, posEnd)
in
([unitTree locs], locs)
end
| _ =>
let
(* The same label name should not be used more than once. *)
fun reportDup (name, newLoc, _) =
errorMessage (lex, newLoc, "Label (" ^ name ^ ") appears more than once.")
val dupCheck = noDuplicates reportDup
(* All the labels should be the same sort. *)
val (l, _) =
getList (SYMBOLS.Comma, empty, lex,
fn () =>
let
val nameAndLoc as (_, nameLoc) =
getLabel (fsys ++ SYMSET.colon, lex);
val () = #enter dupCheck nameAndLoc;
val () = getsym (SYMBOLS.Colon, lex);
val (types, typeLoc) = parseType (fsys ++ lrSyntax, lex, env)
val fullLoc = locSpan(nameLoc, typeLoc)
in
((nameAndLoc, types, fullLoc), fullLoc)
end);
val locs = locSpan(startLocn, location lex) (* Include '}' *)
in
getsym (SYMBOLS.RightCurly, lex);
([makeParseTypeLabelled(l, true, locs) (* frozen *)], locs)
end
end
| TypeIdent =>
let (* type variable *)
val ty = #lookupTvar env (id lex);
in
getsym (TypeIdent, lex);
([makeParseTypeId(ty, startLocn)], startLocn)
end
| Ident =>
(* Constructor such as `int' *)
let
val idLocn as (_, locn) = getid (SYMSET.ident, fsys, lex)
in
([makeParseTypeConstruction (idLocn, ([], locn), locn)], locn)
end
| _ =>
(
badsyms (SYMBOLS.Ident, lex);
([], startLocn)
)
in
(* Type sequence read. Can now have some type constructors. *)
case (sy lex, tySeq) of
(Ident, _) =>
let (* Returns the type made from the constructors. *)
fun constructors(args, argLoc) =
let
val idAndLoc as (_, idLoc) = (id lex, location lex)
val loc = locSpan(argLoc, idLoc)
val constructed = makeParseTypeConstruction(idAndLoc, (args, argLoc), loc);
in
insymbol lex;
if sy lex = SYMBOLS.Ident
then constructors([constructed], loc)
else (constructed, loc)
end;
in
constructors(tySeq, seqLocn)
end
(* no constructor - get the first part of the sequence
and check that that's all. *)
| (_, []) => (ParseTypeBad, seqLocn)
| (_, [t]) => (t, seqLocn)
| (_, t::_) => (badsyms (SYMBOLS.Ident, lex); (t, seqLocn))
end (* basicType *);
(* ty * .. * ty *)
fun getProduct () =
let
val fsys' = fsys ++ SYMSET.asterisk;
val (firstPart, firstLocn) = basicType fsys'
in
case sy lex of
Asterisk =>
let
val () = insymbol lex
val (rest, restLocn) = getProduct ()
in
(firstPart :: rest, locSpan(firstLocn, restLocn))
end
| _ => ([firstPart], firstLocn)
end
in
case getProduct () of
([notProduct], locn) => (notProduct, locn)
| (product, locn) => (makeParseTypeProduct(product, locn), locn)
end (* tupleType *)(* ty -> ty *)
val (firstType, firstLoc) = tupleType (fsys ++ SYMSET.arrow);
in
case sy lex of
Arrow =>
let
val () = insymbol lex
val (resType, resLocn) = parseType (fsys, lex, env)
val locs = locSpan(firstLoc, resLocn)
in
(makeParseTypeFunction (firstType, resType, locs), locs)
end
| _ =>
(
skipon (fsys, empty, "End of type", lex);
(firstType, firstLoc)
)
end
end;
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