302 lines
9.5 KiB
OCaml
302 lines
9.5 KiB
OCaml
(* camlp4r q_MLast.cmo *)
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(* $Id$ *)
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value _loc = (Token.nowhere, Token.nowhere);
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type spc =
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[ SPCterm of (MLast.patt * option MLast.expr)
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| SPCnterm of MLast.patt and MLast.expr
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| SPCsterm of MLast.patt ]
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;
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exception NotImpl;
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value rec subst v e =
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match e with
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[ <:expr< $lid:x$ >> -> if x = "strm__" then <:expr< $lid:v$ >> else e
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| <:expr< $uid:_$ >> -> e
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| <:expr< $int:_$ >> -> e
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| <:expr< $chr:_$ >> -> e
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| <:expr< $str:_$ >> -> e
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| <:expr< $e1$ . $lab$ >> -> <:expr< $subst v e1$ . $lab$ >>
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| <:expr< $x$ $y$ >> -> <:expr< $subst v x$ $subst v y$ >>
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| <:expr< let $lid:s1$ = $e1$ in $e2$ >> ->
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if s1 = v then <:expr< let $lid:s1$ = $subst v e1$ in $e2$ >>
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else <:expr< let $lid:s1$ = $subst v e1$ in $subst v e2$ >>
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| <:expr< let _ = $e1$ in $e2$ >> ->
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<:expr< let _ = $subst v e1$ in $subst v e2$ >>
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| <:expr< ($list:el$) >> -> <:expr< ($list:List.map (subst v) el$) >>
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| _ -> raise NotImpl ]
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;
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value rec is_free v =
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fun
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[ <:expr< $lid:x$ >> -> x <> v
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| <:expr< $uid:_$ >> -> True
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| <:expr< $int:_$ >> -> True
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| <:expr< $chr:_$ >> -> True
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| <:expr< $str:_$ >> -> True
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| <:expr< $e$ . $_$ >> -> is_free v e
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| <:expr< $x$ $y$ >> -> is_free v x && is_free v y
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| <:expr< let $lid:s1$ = $e1$ in $e2$ >> ->
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is_free v e1 && (s1 = v || is_free v e2)
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| <:expr< let _ = $e1$ in $e2$ >> -> is_free v e1 && is_free v e2
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| <:expr< ($list:el$) >> -> List.for_all (is_free v) el
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| _ -> raise NotImpl ]
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;
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value gensym =
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let cnt = ref 0 in
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fun () ->
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do { incr cnt; "pr_rp_symb_" ^ string_of_int cnt.val }
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;
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value free_var_in_expr c e =
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let rec loop_alpha v =
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let x = String.make 1 v in
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if is_free x e then Some x
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else if v = 'z' then None
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else loop_alpha (Char.chr (Char.code v + 1))
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in
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let rec loop_count cnt =
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let x = String.make 1 c ^ string_of_int cnt in
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if is_free x e then x else loop_count (succ cnt)
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in
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try
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match loop_alpha c with
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[ Some v -> v
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| None -> loop_count 1 ]
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with
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[ NotImpl -> gensym () ]
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;
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value parserify =
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fun
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[ <:expr< $e$ strm__ >> -> e
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| e -> <:expr< fun strm__ -> $e$ >> ]
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;
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value is_raise_failure =
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fun
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[ <:expr< raise Stream.Failure >> -> True
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| _ -> False ]
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;
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value is_raise_error =
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fun
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[ <:expr< raise (Stream.Error $_$) >> -> True
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| _ -> False ]
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;
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value semantic e =
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try
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if is_free "strm__" e then e
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else
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let v = free_var_in_expr 's' e in
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<:expr< let $lid:v$ = strm__ in $subst v e$ >>
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with
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[ NotImpl -> e ]
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;
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value rewrite_parser =
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rewrite True where rec rewrite top ge =
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match ge with
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[ <:expr< let $p$ = try $e$ with [ Stream.Failure -> raise $exc$ ] in
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$sp_kont$ >> ->
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let f = parserify e in
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some $p$ -> $rewrite False sp_kont$
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| _ -> raise $exc$ ]
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>>
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| <:expr< let $p$ = Stream.count strm__ in $f$ >> ->
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try
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if is_free "strm__" f then ge
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else
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let v = free_var_in_expr 's' f in
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<:expr<
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let $lid:v$ = strm__ in
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let $p$ = Stream.count strm__ in $subst v f$
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>>
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with
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[ NotImpl -> ge ]
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| <:expr< let $p$ = strm__ in $e$ >> ->
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<:expr< let $p$ = strm__ in $rewrite False e$ >>
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| <:expr< let $p$ = $f$ strm__ in $sp_kont$ >> when top ->
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some $p$ -> $rewrite False sp_kont$
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| _ -> raise Stream.Failure ]
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>>
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| <:expr< let $p$ = $e$ in $sp_kont$ >> ->
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if match e with
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[ <:expr< match try Some $_$ with [ Stream.Failure -> None ] with
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[ $list:_$ ] >>
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| <:expr< match Stream.peek strm__ with [ $list:_$ ] >>
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| <:expr< try $_$ with [ Stream.Failure -> $_$ ] >>
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| <:expr< let $_$ = Stream.count strm__ in $_$ >> -> True
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| _ -> False ]
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then
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let f = rewrite True <:expr< fun strm__ -> $e$ >> in
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let exc =
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if top then <:expr< Stream.Failure >>
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else <:expr< Stream.Error "" >>
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in
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some $p$ -> $rewrite False sp_kont$
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| _ -> raise $exc$ ]
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>>
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else semantic ge
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| <:expr< match try Some $e$ with [ Stream.Failure -> None ] with
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[ Some $p$ -> $sp_kont$
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| _ -> $p_kont$ ] >> ->
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let f = parserify e in
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if not top && is_raise_failure p_kont then semantic ge
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else
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let (p, f, sp_kont, p_kont) =
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if top || is_raise_error p_kont then
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(p, f, rewrite False sp_kont, rewrite top p_kont)
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else
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let f =
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<:expr<
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fun strm__ ->
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match
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try Some ($f$ strm__) with [ Stream.Failure -> None ]
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with
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[ Some $p$ -> $rewrite False sp_kont$
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| _ -> $rewrite top p_kont$ ]
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>>
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in
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(<:patt< a >>, f, <:expr< a >>,
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<:expr< raise (Stream.Error "") >>)
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in
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some $p$ -> $sp_kont$
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| _ -> $p_kont$ ]
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>>
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| <:expr< match Stream.peek strm__ with [ $list:pel$ ] >> ->
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let rec iter pel =
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match pel with
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[ [(<:patt< Some $p$ >>, eo,
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<:expr< do { Stream.junk strm__; $sp_kont$ } >>);
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(<:patt< _ >>, None, p_kont) :: _] ->
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<:expr<
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match Stream.peek strm__ with
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[ Some $p$ $when:eo$ ->
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do { Stream.junk strm__; $rewrite False sp_kont$ }
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| _ -> $rewrite top p_kont$ ]
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>>
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| [(<:patt< Some $p$ >>, eo,
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<:expr< do { Stream.junk strm__; $sp_kont$ } >>) :: pel] ->
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let p_kont = iter pel in
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<:expr<
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match Stream.peek strm__ with
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[ Some $p$ $when:eo$ ->
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do { Stream.junk strm__; $rewrite False sp_kont$ }
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| _ -> $p_kont$ ]
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>>
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| _ ->
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<:expr< match Stream.peek strm__ with [ $list:pel$ ] >> ]
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in
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iter pel
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| <:expr< try Some $e$ with [ Stream.Failure -> $p_kont$ ] >> ->
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let f = parserify e in
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let e =
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some a -> Some a
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| _ -> $p_kont$ ]
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>>
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in
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rewrite top e
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| <:expr< try $e$ with [ Stream.Failure -> $p_kont$ ] >> ->
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let f = parserify e in
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let e =
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some a -> a
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| _ -> $rewrite top p_kont$ ]
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>>
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in
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rewrite top e
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| <:expr< $f$ strm__ >> ->
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if top then
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<:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some a -> a
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| _ -> raise Stream.Failure ]
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>>
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else
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let v = free_var_in_expr 's' f in
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<:expr< let $lid:v$ = strm__ in $subst v f$ $lid:v$ >>
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| e -> semantic e ]
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;
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value spc_of_parser =
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let rec parser_cases e =
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match e with
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[ <:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some $p$ -> $sp_kont$
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| _ -> $p_kont$ ]
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>> ->
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let spc = (SPCnterm p f, None) in
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let (sp, epo, e) = kont sp_kont in
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[([spc :: sp], epo, e) :: parser_cases p_kont]
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| <:expr<
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match Stream.peek strm__ with
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[ Some $p$ $when:wo$ -> do { Stream.junk strm__; $sp_kont$ }
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| _ -> $p_kont$ ]
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>> ->
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let spc = (SPCterm (p, wo), None) in
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let (sp, epo, e) = kont sp_kont in
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[([spc :: sp], epo, e) :: parser_cases p_kont]
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| <:expr< let $p$ = strm__ in $sp_kont$ >> ->
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let spc = (SPCsterm p, None) in
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let (sp, epo, e) = kont sp_kont in
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[([spc :: sp], epo, e)]
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| <:expr< let $p$ = Stream.count strm__ in $e$ >> -> [([], Some p, e)]
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| <:expr< raise Stream.Failure >> -> []
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| _ -> [([], None, e)] ]
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and kont e =
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match e with
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[ <:expr<
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match try Some ($f$ strm__) with [ Stream.Failure -> None ] with
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[ Some $p$ -> $sp_kont$
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| _ -> raise (Stream.Error $err$) ]
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>> ->
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let err =
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match err with
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[ <:expr< "" >> -> None
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| _ -> Some err ]
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in
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let spc = (SPCnterm p f, err) in
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let (sp, epo, e) = kont sp_kont in
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([spc :: sp], epo, e)
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| <:expr<
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match Stream.peek strm__ with
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[ Some $p$ $when:wo$ -> do { Stream.junk strm__; $sp_kont$ }
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| _ -> raise (Stream.Error $err$) ]
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>> ->
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let err =
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match err with
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[ <:expr< "" >> -> None
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| _ -> Some err ]
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in
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let spc = (SPCterm (p, wo), err) in
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let (sp, epo, e) = kont sp_kont in
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([spc :: sp], epo, e)
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| <:expr< let $p$ = strm__ in $sp_kont$ >> ->
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let spc = (SPCsterm p, None) in
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let (sp, epo, e) = kont sp_kont in
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([spc :: sp], epo, e)
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| <:expr< let $p$ = Stream.count strm__ in $e$ >> -> ([], Some p, e)
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| _ -> ([], None, e) ]
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in
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parser_cases
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;
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value parser_of_expr e = spc_of_parser (rewrite_parser e);
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