opa_parser.trx

(*
    Copyright © 2011 MLstate

    This file is part of OPA.

    OPA is free software: you can redistribute it and/or modify it under the
    terms of the GNU Affero General Public License, version 3, as published by
    the Free Software Foundation.

    OPA 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 Affero General Public License for
    more details.

    You should have received a copy of the GNU Affero General Public License
    along with OPA. If not, see <http://www.gnu.org/licenses/>.
*)
(**
   The general OPA parser, with HMX.

   @TODO: Rule [deco] should return the correct line/char number,
   which requires either advanced TRX hackery or a preliminary phase
   to associate to each file a mapping from char number to line/column number.
*)

read opa_lexer.trx
read parser_path.trx
read string_expr.trx
read action.trx
read xml.trx
read css.trx
read trx.trx
read xml_parser.trx

%%imperative-errors = true
%%opt-errors = true

{{
   open SurfaceAst
   open Parser_utils

   module SA = SurfaceAst

   (* some types for IDEs; please maintain this in particular when you add/remove/change directives *)
   (* IF YOU WANT TO CHANGE THIS UPDATE THE IDE REPO *)
   type fixed_code_for_ide = (string, parsing_directive) code
}}

(**
   General convention:

  each rule exists in two versions
   - [just_foo], which performs the actual parsing and returns the result
   - [foo], which is defined as
     [deco = deco just_foo]

   As a general guideline, you should always call rule [foo] from your other rules,
   never [just_foo].
*)


(**
   {6 Entry points}
*)
;main <- init declarations:d {{ d }}
;+main_eoi : {(SurfaceAst.nonuid, SurfaceAst.parsing_directive) SurfaceAst.code} <- init declarations:d !. {{ d }}
;+expr_eoi : {(SurfaceAst.nonuid, SurfaceAst.parsing_directive) SurfaceAst.expr} <- init expr:e spacing !. {{ e }}
;+ty_eoi : {SurfaceAst.nonuid SurfaceAst.ty} <- init typ:t spacing !. {{ t }}

(**
   {6 Initialization}
*)

init <- _succeed {{ Parser_utils.filename := _filename }}

(**
   {6 Stuff for IDEs}
*)

;+maybe_declaration : {[`failure of string * Trx_runtime.pos * Trx_runtime.pos
                       | `success of (SurfaceAst.nonuid, SurfaceAst.parsing_directive) SurfaceAst.code ]} <-
  / declaration:d {{ `success (d : (string, parsing_directive) code) }}
  / ((!declaration .)+ $_):d  {{ `failure (d, _pos_beg, _pos_end) }} ;

(**
   {6 Declarations}
   A toplevel open is rewritten into [_ = @toplevel_open(e)]
*)
;declarations <- spacing (=list0(declaration,semic?)):l semic? spacing {{ List.flatten l }}
;declaration <- (=deco(just_declaration)):p {{ let (l,label) = p in List.map (fun x -> (x, copy_label label)) l }}
;/** toplevel declaration **/
just_declaration <-
  / (_succeed {{ clear_hints () }}) _fail {{ assert false }}
  / (pos:p !(spacing "=") {{ push_hint (`declaration p) }}) _fail {{ assert false }}
  / database:d {{ d }}
  / declaration_directives:dirs Opa_lexer.REC (=list1(rec_binding_pat, and)):bindings {{
      let bindings = declaration_directive dirs bindings in
      [NewVal (bindings,true)]
    }}
  (* this case needs to come before val_binding so that css = ... is parsed by this rule *)
  / Css.css:d {{ [d] }}
  / declaration_directives:dirs deco_fun_binding:d
    {{ let ident,e = d in
       let bindings = [var_to_patvar ident, e] in
       let bindings = declaration_directive dirs bindings in
       [NewVal (bindings,false)] }}
  (* this case needs to come before pattern so that f (2) doesn't get parsed *)
  / (=deco(ml_identifier_nosp:i strict_spacing lpar)):p {{ error_fun_space (label p) }}
  / declaration_directives:dirs val_binding:b {{ [NewVal (declaration_directive dirs [b], false)] }}
  (* 'do' is a keyword, so situation like do(1,2) is not ambiguous *)
  / do_block:b {{ [NewVal ([b],false) ] }}
  / typedef_directives:dirs Opa_lexer.TYPE (=list1(type_binding,Opa_lexer.AND)):typedefs
    {{
       let ty_def_options, visibility_dirs = dirs in
       (* First, update the visibility of each individual defined type with the
          visibility directives that are global here for all types
          and-defined. *)
       let updated_typedefs =
         List.map
           (fun (ty_def, pos) ->
              (*
                merging the options between the global (before the type keyword)
                and the local options, in case of several definitions
              *)
              let ty_def_options =
                let global = ty_def_options in
                let local = ty_def.SurfaceAst.ty_def_options in
                Parser_utils.merge_type_def_options ~global ~local
              in
              let updated_visibility =
                Parser_utils.merge_type_def_visibility
                  (ty_def.SurfaceAst.ty_def_visibility :: visibility_dirs) pos
              in
              ({ ty_def with SurfaceAst.
                   ty_def_options ;
                   ty_def_visibility = updated_visibility ;
               },
               pos))
           typedefs in
       [NewType updated_typedefs]
    }}
  / (=Opa_lexer.exact_ident("package")) package_identifier:name {{ [Package (`declaration, name)] }}
  / (=Opa_lexer.exact_ident("import-plugin")) package_expr_list:s {{ [Package (`import_plugin, s)] }}
  / (=Opa_lexer.exact_ident("import")) package_expr_list:s {{ [Package (`import, s)] }}
  / (&. {{ print_hints () }}) _fail {{ assert false }}

; typedef_directives <-
  / ("@" !strict_spacing deco_ml_identifier_nosp:v spacing {{ undecorate v }})*:list
    {|
        (*
          Return in case of a syntax error,
          the production {| will return None, and trx gets a syntax error
        *)
        Return.set_checkpoint_none (
          fun label ->
            let parse_error () = Return.return label () in
            let rec fold (ty_def_options, visibility_dirs) = function
              | "abstract" ->
                  let visibility_dirs = SurfaceAst.TDV_abstract :: visibility_dirs in
                  ty_def_options, visibility_dirs
              | "private" ->
                  let visibility_dirs = SurfaceAst.TDV_private :: visibility_dirs in
                  ty_def_options, visibility_dirs
              | "opacapi" ->
                  let ty_def_options =
                    { ty_def_options with QmlAst.
                        opacapi = true ;
                    } in
                  ty_def_options, visibility_dirs
              | _ -> parse_error ()
            in
            let ty_def_options = QmlAst.ty_def_options in
            List.fold_left fold (ty_def_options, []) list
        )
     |}

; /** package **/
package_identifier <- spacing ([a-zA-Z0-9_.\-]+ $_):s {{ s }}
; /** package expression **/
package_expr <- spacing package_expr_no_spacing+:l {{ String.concat "" l }}
package_expr_no_spacing <-
              / [a-zA-Z0-9_.\-*]+ $_
              / "{" package_expr_list:s rbrace {{ s }}
package_expr_list <-
  (=list1(package_expr,comma)):l
    {{ Base.String.sconcat ~left:"{" ~right:"}" "," l }}

;/** file path **/
file_path <- [ a-zA-Z0-9-._~]* '/' [ a-zA-Z0-9-._/~]* $_

;/** network hostname (or IPv4 address) **/
network_hostname <- [a-zA-Z0-9-.]+ $_

;/** colon and network server port **/
network_port <- Opa_lexer.colon_nosp Opa_lexer.int:p {{ p }}

(**
  {6 Database}
*)/** database declaration **/
database <-
  (* single database, short form and full form *)
  / Opa_lexer.DATABASE spacing file_path:s {{ [Database ("database", [], [`engine (`db3 (Some s))])] }}
  / Opa_lexer.DATABASE spacing db_options:dbo {{ [Database ("database", [], dbo)] }}
  (* many-db or one, but named, db *)
  / Opa_lexer.DATABASE ml_identifier:i assign spacing db_options:dbo {{ [Database (i, [i], dbo)] }}
  (* a common error *)
  / Opa_lexer.DATABASE deco_ml_identifier:e !assign {{ error_db_file_without_slash e }}
  (* other db specifications *)
  / (=exact_ident("db")) db_pathdef:d db_virtual?:v
    {{ match v with
       | None -> d
       | Some v ->
           match d with
           | (NewDbDef(
                QmlAst.Db.Db_TypeDecl(l,_)
              | QmlAst.Db.Db_Default(l,_)
              | QmlAst.Db.Db_Alias(l,_)
              | QmlAst.Db.Db_Constraint(l,_)))::_ ->
               d@[NewDbDef(QmlAst.Db.Db_Virtual(l, v))]
           | _ -> assert false (* see db_pathdef *)
     }}

/** database path declaration **/
db_pathdef <-
  / Parser_path.pathdef_type:l colon typ:t (assign expr:e{{e}})?:o
    {{ let dec = [NewDbDef(QmlAst.Db.Db_TypeDecl(l, t))] in
         match o with
           | None -> dec
           | Some e -> NewDbDef(QmlAst.Db.Db_Default(l, e)) :: dec
     }}
  / Parser_path.pathdef:l assign expr:e
    {{ [NewDbDef(QmlAst.Db.Db_Default(l, e))] }}
  / (Parser_path.pathdef / (=exact_ident("/")) {{ [] }}):l (=exact_ident("alias")) Parser_path.pathdef:l2
    {{ [NewDbDef(QmlAst.Db.Db_Alias(l, l2))] }}
  / Parser_path.pathdef:l db_constraint:c
    {{ [NewDbDef(QmlAst.Db.Db_Constraint(l, c))] }}

/** database constraint **/
db_constraint <-
  / (=exact_ident("full")) {{ QmlAst.Db.C_Private }}

/** database virtual path **/
db_virtual <-
  / (=exact_ident(":=")) expr:e {{ e }}

/** database options **/
db_options <-
  / "@" "local" Opa_lexer.lpar_nosp spacing '"' file_path:s '"' rpar {{ [`engine (`db3 (Some s))] }}
  / "@" "local" {{ [`engine (`db3 None)] }}
  / "@" "light" Opa_lexer.lpar_nosp spacing '"' file_path:s '"' rpar {{ [`engine (`db3light (Some s))] }}
  / "@" "light" {{ [`engine (`db3light None)] }}
  / "@" "meta" {{ [`engine (`meta)] }}
  / "@" "shared" Opa_lexer.lpar_nosp spacing '"' network_hostname?:h network_port?:p '"' rpar {{ [`engine (`client (h, p))] }}
  / "@" "shared" {{ [`engine (`client (None, None))] }}

(**
   {6 Bindings}
   Bindings or assimilated (like do)
*)
(* Regrouped here so that toplevel bindings and local bindings reuse the same rules *)

may_coerce <- (colon typ:t{{t}})?
;let deco_fun_binding_gen Ident =
   Ident:ident function_parameters_nosp+:argss may_coerce:t assign expr:e
     {{ let e = List.fold_right (fun (args,label) acc -> args_expr_to_lambda ~zero_ary:label args acc) argss (may_coerce_expr e t) in
       (ident, e) }}
deco_fun_binding <- (=deco_fun_binding_gen(deco_ml_identifier_nosp))
/** function binding **/
fun_binding <- deco_fun_binding:d {{ let (i,e) = d in (undecorate i, e) }}
fun_binding_ <- deco_fun_binding:d {{ let (i,e) = d in (var_to_patvar i, e) }}
/** pattern binding **/
val_binding <- pattern:p assign expr:e {{ (p,e) }}
/** identifier binding **/
ident_binding <- fun_binding
                / ml_identifier:i may_coerce:t assign expr:e {{ (i,may_coerce_expr e t) }}

(* this rule is meant for modules only, where the fact of writing a rec doesn't matter
 * but you must write to be able to write rec val ... *)
rec_ident_binding <-
  / Opa_lexer.REC? ident_binding:b {{ b }}
  / Opa_lexer.REC (=deco((=exact_ident("val")))):o ident_binding:b {{
    let (_, label) = o in
    let (i, e) = b in
    (i, (Directive (`recval, [e], []), label))
  }}

binding_pat <- fun_binding_ / val_binding
rec_binding_pat <- (=deco((=exact_ident("val"))))?:o binding_pat:b
  {{ let _ = (b : string pat * (_,_) expr) in
     let r =
       match o with
       | None -> b
       | Some (_, label) ->
           let (p, e) = b in
           (p, (Directive (`recval, [e], []), label)) in
     r : string pat * (_,_) expr
  }}
/** long binding **/
long_ident_nosp <- deco_ml_identifier_nosp:i ('.' deco_ml_identifier_nosp:i {{i}})*:l {{ i :: l }}
long_ident <- spacing long_ident_nosp:l {{ l }}
long_binding <- (=deco_fun_binding_gen(long_ident_nosp))
              / long_ident:i may_coerce:t assign expr:e {{ (i,may_coerce_expr e t) }}


;/** do block **/
do_block <- Opa_lexer.DO expr:e {{ let e = magic_do e in
                                   let p = (PatAny, nlabel e) in
                                   (p,e)
                                }}

;/** type binding **/
type_binding = deco(just_type_binding)
;just_type_binding <-
  / type_const:s {{ error_redefinition_basic_type s }}
  / !external typedef_directives:dirs type_identifier:i (lpar (=list1(just_flatvar,comma)):l rpar {{l}})?:o assign typ:t
  {{
     let _,loc = t in
     let l = Option.default [] o in
     let ty_def_options, visibility_dirs = dirs in
     (* Record the visibility of the type definition. However, since the parser
        can't know yet which package it is processing, we delay the
        determination of the package to later. For the moment, it is just
        sufficient to know if the definition is public, private or abstract.
        Note that the visibility set in the definition is the one attached to
        the type individually defined at this point. If some directives are
        set outside for the bunch of types defined in the global type
        definition, they will be taken into account (and hence modify the
        visibility of the current type) afterwards. *)
     let visibility = Parser_utils.merge_type_def_visibility visibility_dirs loc in
     {
       SurfaceAst.ty_def_options ;
       SurfaceAst.ty_def_visibility = visibility ;
       SurfaceAst.ty_def_name = Typeident i ;
       SurfaceAst.ty_def_params = l ;
       SurfaceAst.ty_def_body = t ;
     } : string typedef_node
   }}

(**
   {6 Patterns}
*)

(**
   Function parameters, ie the [((a,b))] in [f((a,b)) = ...]
 *)
;/** function parameters **/
function_parameters_nosp <- (=careful_deco(just_function_parameters_nosp)):l {{ l }}
;just_function_parameters_nosp <- Opa_lexer.lpar_nosp (=list0(pattern,comma)):l rpar {{ l }}

(**
   {7 Tuples}
   Tuple pattern
   (a,b,c,...)
   (a,) is a 1-uple, () doesn't exists
   it may contain [...] (like (a,...) but [(...)] and [(,...)] are not valid
 *)
/** tuple pattern or parenthized pattern **/
tuple_pat <- lpar tuple_pat_inside:p rpar {{ p }}
tuple_pat_inside <- (=list1(pattern,comma)):l tuple_pat_end:e
    {{ match l,e with
         | [p], `nothing -> undecorate p
         | _ , _ -> undecorate (coerce_name_pat (tuple_pat l) (tuple_string l))
     }}
tuple_pat_end <- comma {{ `tuple1 }}
               / _succeed {{ `nothing }}

;row_pattern <- (=exact_symbol("...")) {{ () }}

(**
   {7 Record pattern}
   A record may be empty: [{}]
   A record can contain an ellipsis (even the empty record): [{...}]
 *)
tilda <- (spacing "~")?:o {{ Option.is_some o }}
/** record pattern **/
record_pat <-
  (* null case only for speed, very common: *)
  / tilda lbrace rbrace {{ PatRecord ([], `closed) }}
  / tilda:tilda lbrace record_pat_inside:ri rbrace
  {{ let (f,row) = ri in
     let l = default_value_in_pat_record tilda f in
     match row with
     | None -> undecorate (record_pat l)
     | Some () -> PatRecord (encode_record l, `open_)
   }}
;record_pat_inside <- (=list0(field_pat,(spacing semic? $))):l semic? row_pattern?:r {{ (l,r) }}
;field_pat <- tilda:tilda deco_ml_identifier:i may_coerce:t (assign pattern:p {{ p }})?:p
  {{ let ident,label = i in
     let p =
       match p,tilda with
         | None,true -> `value (var_to_patvar i)
         | None,false -> `novalue i
         | Some p,true -> `value (PatAs (p,{ident=ident;directives=[]}),label)
         | Some p,false -> `value p in
       (ident, p, t)
   }}

(**
  {7 List patterns}
*)
list_pat <-
  / lbracket (=list0(pattern,comma)):l pos:p comma? (Opa_lexer.BAR pattern:p {{p}})?:tl rbracket
  {{ undecorate (list_pat_of_pat_list ?tl l p) }}


(**
  {7 Patterns}
  A pattern is a basic pattern, with optionally a 'as' and a coerce around it
*)
;/** pattern **/
pattern = deco just_pattern_as_coerce
;just_pattern_as_coerce <- pattern_as:p (colon typ:te {{ te }})?:o
    {{ match o with
         | None -> undecorate p
         | Some te -> PatCoerce (p, te)
     }}
;pattern_as = deco just_pattern_as
;just_pattern_as <- pattern_no_as_coerce:p (Opa_lexer.AS ml_identifier:v {{ v }})?:o
    {{ match o with
         | None -> undecorate p
         | Some i -> PatAs (p,{ident=i;directives=[]})
     }}
;pattern_no_as_coerce = deco just_pattern_no_as_coerce
;just_pattern_no_as_coerce <-
    Opa_lexer.UNDERSCORE {{ PatAny }}
  / ml_identifier_nosp:i !"(" {{ PatVar {ident=i;directives=[]} }}
  / const:c {{ PatConst c }}
  / tuple_pat
  / record_pat
  / list_pat

(**
   {6 Expressions}

   Expressions are divided into differents to take care of operators priorities
   - <-
   - %
   - |
   - &
   - <
   - *
   - unary -
   - : (coercion)
   - and then expressions without operators (at the top)
*)

;/** expression **/
expr <- top_expr
;top_expr = deco just_top_expr;
;expr0 = deco just_expr0;
;expr7 = deco just_expr7;
;expr8 = deco just_expr8;
;expr9 = deco just_expr9;
;expr10 = deco just_expr10;

(**
   {7 Operators }
*)
(* no spaces are parsed around operators on purpose
 * it is because spaces matters to see if the operators is actually infix
 * the infix rule takes care of them *)
let ident_careful_deco rule = (=careful_deco(rule)):t {{let (i,label) = t in (Ident i, label)}}
;OpCont <- !"/*" [.+\-^*/<>=@|&!]
(* Operatort beginning with ('|' [&!.]) are forbidden because parser syntax *)
;OpPipe = ident_careful_deco(!"||" "|" ![&!.] OpCont+ $_ / "@" OpCont* $_)
;OpOr   = ident_careful_deco("||" OpCont* $_ / "?" OpCont* $_)
;OpAnd  = ident_careful_deco("&" OpCont* $_)
;OpComp = ident_careful_deco(  ( "=" OpCont+ $_
                    / ( ">" / "<=" / ">=" /  "!=" / (!"<-" !Xml.xhtml "<":s {{s}}) ) OpCont* $_))
;OpAdd  = ident_careful_deco(!"->" [+\-^] OpCont*  $_)
;OpMul  = ident_careful_deco("*" OpCont* $_  / !"/*" !"//" "/" OpCont* $_)
;NegOp  = ident_careful_deco( "-." !OpCont {{ Opacapi.unary_minus_dot }}
                            / "-" !OpCont  {{ Opacapi.unary_minus }})


(**
   {7 The different levels of expressions }
*)

/** db path write **/
write_expr <- (=deco(larrow)):p expr0:e2 {{ e2 }}

/** side effect expr **/
se_expr = deco just_se_expr;

just_se_expr <-
  (* on dom *)
  / pos:p Action.action:a
  {{
     let l = list_expr_of_expr_list [a] p in
     dom_transform l
   }}
  (* dbpath update *)
  / Parser_path.path_update

/** top expr **/
just_top_expr <-
             / just_se_expr

             / expr0:e1
               {{ undecorate e1
               }}

just_expr0 <- expr1:e (=exact_symbol("%"))?:o
              {{ match o with
                   | None -> undecorate e
                   | Some _ -> undecorate (record [("percent",e)])
               }}
            / deco_underscore pos:p (=exact_symbol("%"))
              {{ undecorate (lambda_to_lambda (fun e -> record [("percent",e)]) p) }}

(* would probably be more efficient to have list1sleft and list1sright *)
/** expression `|' `@' **/
expr1 <- (=list1s(expr2,OpPipe)):v  {{ apply_operators `left  v }}
/** expression `||' `?' **/
expr2 <- (=list1s(expr3,OpOr  )):v  {{ apply_operators `right v }}
/** expression `&' **/
expr3 <- (=list1s(expr4,OpAnd )):v  {{ apply_operators `right v }}
/** expression `<' `=' **/
expr4 <- (=list1s(expr5,OpComp)):v  {{ apply_operators `left  v }}
/** expression `+' `-' **/
expr5 <- (=list1s(expr6,OpAdd )):v  {{ apply_operators `left  v }}
/** expression `*' `/' **/
expr6 <- (=list1s(expr7,OpMul )):v  {{ apply_operators `left  v }}
/** expression unary '-' **/
just_expr7 <- NegOp?:i expr8:e
                 {{ match i with
                   | None -> undecorate e
                   | Some i -> i &. [e]
                  }}
            / NegOp:i deco_underscore:p {{ undecorate (apply_f_with_holes i [`hole p]) }}
/** subsumption of sum types **/
just_expr8 <- expr9:e (ltcolon typ:t {{ t }})?:t
      {{ match t with
           | None -> undecorate e
           | Some t -> coerce (directive1 `opensums e, label e) t
       }}
/** coerced expression **/
just_expr9 <- expr10:e (colon typ:t {{ t }})?:t
      {{ match t with
           | None -> undecorate e
           | Some t -> coerce e t
       }}
/** expression without operators **/
just_expr10 <-
       / function_call_dot (* also contains directives, ids and bypasses *)
       / match
       / lambda
       / letin
       / Parser_path.path_kind:v {{ let (path,access_kind) = v in DBPath (path, access_kind)}}
       (* FIXME: useful? / paths_opa_expr / props_aux*)
       / Css.css_map:e {{ undecorate e }} (* useful when saying some_style = ... *)
       / Trx.ExpressionAsFunction:e {{ parser_ e }}
       / Xml.xhtml:v {{ undecorate v }}
       / ip
       / just_module
       / just_record
       / tuple_expr (* or parenthesized expr *)
       / __position__
       / Opa_lexer.CSS lbrace Xml.css_properties:e rbrace {{ undecorate e }}
       / list
       / Opa_lexer.BEGIN expr:e Opa_lexer.END {{ undecorate e }}
       / ml_identifier_nosp:i hint_end_of_callable {{ Ident i }}
       / const:c {{ Const c }}
       / String_expr.string_with_opa:e {{ undecorate e }} (* need to come after const so that constant strings are just parsed as constants *)
       / Css.prop_value_expr_opa:e {{ undecorate e }} (* useful when constructing colors as #123456 *)

(**
  {7 Hint utils}
*)
;hint_end_of_callable <- (=careful_deco(& " (")):p {{ push_hint (`function_call (label p)); () }}
                       / !"(" $
                       (*/ (=careful_deco("(")):p {{ error_neither_ident_nor_call (label p) }}*)

(**
   {7 Declaration directives}
   These directives are linked to the identifier (even if in the ast, they end up
   in an expression)
*)

declaration_directive_any <-
  / "specialize_strict" {{ `specialize `strict }}
  / "specialize" {{ `specialize `polymorphic }}
declaration_directive1 <-
  / "deprecated" {{ `deprecated }}
declaration_directive0 <-
  / "async" {{ `async }}
  / "opacapi" {{ `opacapi }}
  / "package" {{ `package }}
  / "public_env" {{ `public_env }}
  / "private" {{ `private_ }}
  / "public" {{ `public }}
  / "expand" {{ `expand None }} (* not allowing anymore to give an integer to expand, could be put back *)
  / slicing_directive0

declaration_directive1_typ <-
  / "stringifier" {{ `stringifier }}
  / "comparator" {{ `comparator }}
  / "serializer" {{ `serializer }}
  / "xmlizer" {{ `xmlizer }}

/** toplevel directive **/
declaration_directives <- (=deco(declaration_directive))*
declaration_directive <-
  / "@" (=exact_ident(declaration_directive1)):v Opa_lexer.lpar_nosp expr:e rpar
    {{ (v, [e], []) }}
  / "@" (=exact_ident(declaration_directive0)):v !"("
    {{ (v, [], []) }}
  / "@" (=exact_ident(declaration_directive_any)):v Opa_lexer.lpar_nosp (=list0(expr,comma)):el rpar
    {{ (v, el, []) }}
  / "@" (=exact_ident(declaration_directive1_typ)):v Opa_lexer.lpar_nosp typ:t rpar
    {{ (v, [], [t]) }}

slicing_directive0 <-
  / "both_implem" {{ `side_annotation `both_implem }}
  / "both" {{ `side_annotation `both }}
  / "client" {{ `side_annotation `client }}
  / "prefer_both" {{ `side_annotation `prefer_both }}
  / "prefer_client" {{ `side_annotation `prefer_client }}
  / "prefer_server" {{ `side_annotation `prefer_server }}
  / "publish_async" {{ `visibility_annotation (`public `async) }}
  / "publish" {{ `visibility_annotation (`public `sync) }}
  / "server_private" {{ `visibility_annotation `private_ }}
  / "server" {{ `side_annotation `server }}
  / "no_client_calls" {{ `no_client_calls }}

closure_instrumentation_directive <- "public_env" {{ `public_env }}

local_binding_directive <-  "@" (=exact_ident(slicing_directive0
                                             /closure_instrumentation_directive)):v !"("
                           {{ (v, [], [])  }}
local_binding_directives <- (=deco(local_binding_directive:v))*

(**
   {7 Directives}
   Everything with @ident syntax
 *)
;
directive0 <-
  / "i18n_lang"  {{ `i18n_lang }}
  / "thread_context" {{ `thread_context }}
  / "todo" {{ `todo }}
  / "toplevel" {{ `toplevel }}

directive1 <-
  / closure_instrumentation_directive
  / "assert" {{ `assert_ }}
  / "atomic" {{ `atomic }}
  / "callcc" {{ `callcc }}
  / "i18n"   {{ `i18n }}
  / "js_ident" {{ `js_ident }}
  / "may_cps" {{ `may_cps }}
  / "nonexpansive" {{ `nonexpansive }}
  / "openrecord" {{ `openrecord }}
  / "opensums" {{ `opensums }}
  / "throw"  {{ `throw }}
  / "typeof" {{ `typeof }}
  / "unsafe_cast" {{ `unsafe_cast }}
  / "wait" {{ `wait }}

directive2 <-
  / "catch" {{ `catch }}
  / "deprecated" {{ `deprecated }}
  / "with_thread_context" {{ `with_thread_context }}

directive1str <-
  / ("static_source_content" / "static_binary_content") {{ fun x -> `static_content (x, true) }}
  / "compiletime" {{ fun x -> `compiletime x }}

directive1rec <-
  / "lazy_record" {{ `create_lazy_record }}
  / "spawn" {{ `spawn }}

directive1or2str <-
  / "static_content_directory" {{ (fun x -> `static_content_directory (x, false)) }}
  / "static_content" {{ (fun x -> `static_content (x, false)) }}
  / ("static_include_directory" / "static_resource_directory" ) {{ fun x -> `static_resource_directory x }}
  / "static_resource" {{ fun x -> `static_resource x }}

;/** directive **/
directive <-
  (* FIXME: could accept assert_message(,_e)(s)
   * instead of just assert_message(s,e) *)
  / "@xml(" spacing Xml.xmlns:xmlns rpar {{ undecorate xmlns }}
  / "@typeval(" typ:t rpar {{
      (* For convenience, directive [@typeval] is handled as thin syntactic sugar.
         Therefore [@typeval(t)] is parsed as [@typeof(@unsafe_cast("dummy_for_typeval"):t)]
      *)
      let expr_cast      = (directive1 `unsafe_cast (void (nlabel t)), nlabel t) in
      let expr_coerced   = coerce_expr expr_cast t                   in
      let just_typeof    = directive1 `typeof expr_coerced           in
      just_typeof
    }}
  / "@" (=exact_ident(directive0)):v !"("
    {{ Directive (v,[],[]) }}
  / "@" (=exact_ident(directive1)):v Opa_lexer.lpar_nosp expr:e rpar
    {{ Directive (v,[e],[]) }}
  / "@" (=exact_ident(directive1str)):v Opa_lexer.lpar_nosp string:str rpar
    {{ Directive (v str,[],[]) }}
  / "@" (=exact_ident(directive1rec)):v Opa_lexer.lpar_nosp (=deco(just_record)):e rpar
    {{ Directive (v,[e],[]) }}
  / "@" (=exact_ident(directive2)):v Opa_lexer.lpar_nosp expr:e1 comma expr:e2 rpar
    {{ Directive (v,[e1;e2],[]) }}
  / "@" (=exact_ident(directive1or2str)):v Opa_lexer.lpar_nosp string:str (comma expr:e {{ [e] }} / _succeed {{ [] }}):el rpar
    {{ Directive (v str,el,[]) }}
  / "@" !strict_spacing deco_ml_identifier_nosp:v (function_arguments_nosp / !"(" {{ [] }}):l
      {|
          (* the directives in here are the ones that inspect a little too much
           * their arguments, and so it is difficult to factorize them *)

          let s = undecorate v in
          match s with

          | "fail" ->
              (*
                Argument of directive @fail is optional.
                Add the empty string in case of no argument.
              *)
              Return.set_checkpoint_none (
                fun parse_error ->
                  let l =
                    match l with
                    | [] ->
                        let label = label v in
                        [ SA.Const (SA.CString ""), label ]
                    | [ _ ] -> l
                    | _ -> Return.return parse_error ()
                  in
                  SurfaceAst.Directive (`fail, l, [])
              )

          | "llarray" -> Some (SurfaceAst.Directive (`llarray, l, []))

          | "sliced_expr" ->
              let (client,server) =
                match l with
                | [(Record l,_)] ->
                    (match l with
                     | ["server", server; "client", client] -> (client,server)
                     | ["client", client; "server", server] -> (client,server)
                     | _ -> error_sliced_expr (snd v))
                | _ -> error_static_record v in
              Some (Directive (`sliced_expr, [client; server], []))

          | "track" -> (
              match l with
              | [(Const (CString s1), label); expr] ->
                  let pos = SurfaceAstHelper.Annot.to_string label in
                  let tracker = PassTracker.next (Printf.sprintf "%s : %s" s1 pos) in
                  Some (Directive (`tracker tracker, [ expr ],  []))
              | [expr] ->
                  let pos = SurfaceAstHelper.Annot.to_string' expr in
                  let tracker = PassTracker.next pos in
                  Some (Directive (`tracker tracker, [ expr ],  []))
              | _ -> error_directive_wrong_arguments_type v
            )

          | _ -> None
      |}

(**
  {7 Position}
*)
;__position__ <-
       / (=deco((=exact_ident("__POSITION__")))):p
          {{ let pos = label p in
               Const (CString (FilePos.to_string pos.QmlLoc.pos))
           }}

(**
  {7 Function call, field access and method call}
  Function call, field access and method call are left associative and with
  the same priority
  When taking care of holes, the whole list of application/field access/...
  is looked at: [f(_).x(_)] is transformed in [y,z -> f(z).x(z)]
  An underscore at the beginning of the series of calls is valid:
  [_(x)] means [f -> f(x)], [_.x] means [fun r -> r.x], etc.
*)
/** function calls, field access **/
function_call_dot <-
       / ident_call_dot
       / paren_expr_call_dot
       / (=careful_deco(Opa_lexer.underscore_nosp)):p function_arguments_dot_method_nosp+:params hint_end_of_callable not_assign
         {{ make_function2 letins double_dot (`hole (label p)) params }}
       / expr_before_possible_function_call:e ( function_arguments_dot_method_nosp+:params hint_end_of_callable not_assign
                                                  {{ fun e -> make_function2 letins double_dot (`expr e) params }}
                                              / _succeed
                                                  {{ fun e -> undecorate e }}):f {{ f e }}


(* Only certain kind of expression can be applied *)
let call_dot func = (=careful_deco(func)):e function_arguments_dot_method_nosp+:params hint_end_of_callable not_assign
         {{ make_function2 letins double_dot (`expr e) params }}
;expr_before_possible_function_call = careful_deco just_expr_before_possible_function_call

ident_call_dot <- (=call_dot(just_ident_before_mandatory_function_call))
paren_expr_call_dot <- (=call_dot(just_paren_expr_before_mandatory_function_call))

just_ident_before_mandatory_function_call <-
     / ml_identifier_nosp:i {{ Ident i }}

just_paren_expr_before_mandatory_function_call <-
     / lpar expr:e rpar {{ undecorate e }}



just_expr_before_possible_function_call <-
     / id
     / directive
     / bypass

(**
   {7 Id}
*)
id <-  (=careful_deco("#")):p deco_ml_identifier_nosp:s
         {{ undecorate ((Ident "$",label p) & [string2 s]) }}
     / (=careful_deco("#")):p opa_in_braces_nosp:e
         {{ undecorate ((Ident "$",label p) & [e]) }}
naked_id <-
       (=careful_deco("#")):p deco_ml_identifier_nosp:s
         {{ string2 s }}
     / (=careful_deco("#")):p opa_in_braces_nosp:e
         {{ e }}

(**
  {7 Pattern matching}
  Or if-then-else construct

  Disjunctive patterns are allowed only at the toplevel in the pattern:
  [match e with p | p -> e] is allowed, not [match o with Some (1|2) -> e]
  Disjunctive pattern are removed right away by duplicating the pattern
*)
/** pattern/if then else **/
match <- Opa_lexer.MATCH expr:e Opa_lexer.WITH?
           Opa_lexer.BAR? (=list1(rule,match_sep)):l
           match_end
         {{ Match (e, List.flatten l) }}
       / Opa_lexer.IF expr:e1 Opa_lexer.THEN expr:e2 (Opa_lexer.ELSE expr:e {{ e }})?:o
        {{ if_then_else e1 e2 o }}
       / Opa_lexer.IF pos:p1 binding_pat separator pos:p2 Opa_lexer.THEN
        {{ Parser_utils.error_bad_compare (union_annot p1 p2) }}
       / Xml_parser.xml_parser

match_sep <- !Opa_lexer.END Opa_lexer.BAR?
match_end <- (Opa_lexer.END $ / (=exact_ident("|_")) $)?

rule <- (=list1(pattern,Opa_lexer.BAR?)):l rarrow expr:e {{ match l with
                                                             | [] -> assert false
                                                                 (* avoid duplication in the usual case where there is only one pattern *)
                                                             | h :: l -> (h,e) :: List.map (fun p -> (p,SurfaceAstCons.Refresh.expr e)) l
                                                         }}
(**
  {7 Lambda}
  The syntax is either:
  [pattern,pattern,... -> e] (the equivalent of ocaml 'fun')
  [| pattern -> e
   | pattern -> e
   | ... ] (the equivalent of ocaml 'function')
  [-> e] which means [{} -> e]
*)
/** anonymous function **/
lambda <-
     rarrow expr:e
       {{ Lambda ([], e) }}
   / (=list1(pattern,comma)):l rarrow expr:e {{ Lambda (encode_args_as_record l, e) }}
     (* making the BAR optional below causes problem
      * When it is:
      * do a -> b(2)
         | c -> d
        is understood as
        do function a -> b(2)
                  | c -> d
        but
        do a -> b
         | c -> d
        is understood as
        fun a -> (function b|c -> d)
      *)
   / (=deco(Opa_lexer.BAR)):p (=list1(rule,Opa_lexer.BAR)):l match_end {{ function_ (List.flatten l) (label p)}}

(**
  {7 Letin}
  Bindings and assimilated
  Only identifiers on the left hand side of recursive values
*)
/** local binding **/
letin <- pos:pos1 local_binding_directives:dirs Opa_lexer.REC (=list1pos(rec_binding_pat, and)):l separator pos:pos_f expr:e
          {{ let l,posl = l in
             push_hint (`same_indents ((pos1::posl) @ [pos_f]));
             let l = List.concat_map pat_in_to_simple_bindings l in
             let l = declaration_directive dirs l in
             LetIn (true, l, e)
           }}
       / pos:pos1 local_binding_directives:dirs (binding_pat / do_block):b separator:pos2 expr:e
          {{ push_hint (`same_indent (pos1,pos2));
             bind_in_to_expr_in dirs b e
           }}
       / pos:pos1 Opa_lexer.OPEN (=list1(expr,Opa_lexer.comma)):l separator:pos2 expr:e
          {{ push_hint (`same_indent (pos1,pos2)); undecorate (open_ l e) }}

and <- spacing pos:p Opa_lexer.AND {{ p }}
(* the ! here is here to prevent code such as {r=123x} to parse as {r=123 x}
 * because the user then have ununderstandable type errors *)
strict_separator <- spacing semic
separator <-  (strict_separator / not_assign ![~a-zA-Z`_]) pos:p {{ p }}
not_assign <- !(spacing may_coerce assign)

(**
  {7 Ip address}
  The parsing only allows for integers between 0 and 255, so writing
  0.0.0.256 is a parse error
*)
;int3 <- Opa_lexer.int3:i {{ CInt (Big_int.big_int_of_string i) }}
;ip_item = deco just_ip_item
;just_ip_item <- int3:v {{ Const v }}
;just_ip <- ip_item:a [.] ip_item:b [.] ip_item:c [.] ip_item:d {{ Record (encode_record [("a",a);("b",b);("c",c);("d",d)]) }}
;/** ip address **/
ip <- (=deco(just_ip)):p {{ coerce_name p Opacapi.Types.ip }}

(**
 {7 Lists }
 Either ml lists or action lists
 Empty list are just treated as action lists, but it doesn't make any difference
 since an empty action will be transformed into a regular empty list
 Action lists come first or else [ a +<- b ] is going to be parsed as [`+<-`(a,b) ]
 *)
/** expression/action list **/
list <-
    / lbracket (=list0(Action.action,comma)):l pos:p comma? (Opa_lexer.BAR expr:e {{e}})?:tl rbracket
  {{ undecorate (list_expr_of_expr_list ?tl l p) }}
    / lbracket (=list0(expr,         comma)):l pos:p comma? (Opa_lexer.BAR expr:e {{e}})?:tl rbracket
  {{ undecorate (list_expr_of_expr_list ?tl l p) }}

(**
 {7 Bypasses }
 may contain any character except %% ?
*)
/** bypass **/
bypass <- Opa_lexer.BYPASS ((!Opa_lexer.BYPASS .)* $_):content Opa_lexer.BYPASS
  {{ bypass content }}

(**
 {7 Tuples, or parenthesized expression}
  [()] is not in the syntax
  [(e)] is [e] parenthesized
  [(e,)] is the 1-uple made of [e]
  [(e,...,e)] or [(e,...,e,)] is a tuple
*)
/** tuple expression / parenthesized expression **/
tuple_expr <- lpar tuple_expr_inside:t rpar {{ t }}
tuple_expr_inside <- (=list1(expr,comma)):l comma?:o
                  {{ match l,o with
                       | [], _ -> assert false
                       | [e],None -> undecorate e
                       | _,_ -> coerce_name (tuple l) (tuple_string l)
                   }}

(**
 {7 Record or module expression}
*)


module_element <- declaration_directives:dirs spacing rec_ident_binding:d
   {{ List.hd (declaration_directive dirs [d]) }}

/** module **/
just_module <-
  / spacing "{{" spacing pos:pos (=deco((=list0pos(module_element,separator)))):r separator spacing "}}"
    {{ let (r,posl),label = r in
       push_hint (`same_indents (pos :: posl));
       module_ (Record r,label) }}

/** record **/
just_record <- tilda:tilda lbrace record_fields:f rbrace {{
                   Record (default_value_in_expr_record tilda f)
                 }}
              / tilda:tilda lbrace expr:e Opa_lexer.WITH extend_record_fields:f rbrace {{
                   let long_bindings = default_value_in_expr_record tilda f in
                   undecorate (rewrite_long_extend_record long_bindings e)
                 }}
;record_fields <- (=list0(record_element,separator)):l separator {{ l }}
;extend_record_fields <- (=list0(extend_record_element,separator)):l separator {{ l }}

record_fields_separator <- separator

record_fields_assign <- assign

record_long_ident <- long_ident

extend_record_element <-
   / long_binding:b {{ `binding b }}
   / tilda:tilda (=deco(long_ident)):lp may_coerce:t not_assign
     {{ let (l,pos) = lp in
        let p = (undecorate (List.last l), pos) in
        let rhs = if tilda then `value (var_to_exprvar p) else `novalue p in
        `noassign (l, rhs, t)
     }}

record_element <-
   / ident_binding:b {{ `binding b }}
   / tilda:tilda deco_ml_identifier:p may_coerce:t not_assign
     {{ let rhs = if tilda then `value (var_to_exprvar p) else `novalue p in
        `noassign (undecorate p, rhs, t)
     }}

(**
   {7 Function arguments}
 *)

(* used for directives, where you have no holes (at least now) *)
;/** directive arguments **/
function_arguments <- function_arguments_nosp
;function_arguments_nosp <- (=careful_deco(just_function_arguments_nosp)):l {{ undecorate l }}
;just_function_arguments_nosp <- Opa_lexer.lpar_nosp (=list0(expr,comma)):l rpar {{ l }}

(* used for actual function arguments *)
;/** function arguments **/
function_arguments2 <- function_arguments_nosp2
;function_arguments_nosp2 <- (=careful_deco(just_function_arguments_nosp2)):l {{ undecorate l }}
;just_function_arguments_nosp2 <- Opa_lexer.lpar_nosp (=list0(expr_underscore,comma)):l rpar {{ l }}
;expr_underscore = expr_or_hole expr

(* the UNDERSCORE rule needs to come after so that priorities are correct:
 * [2 + _ * 3] gets parsed like [2 + (_ * 3)]
 * and [f(_ + 2)] is parsed [f(fun x -> x + 2)] and not [f; (_ + 2)]
 *)
;let expr_or_hole expr = expr:e {{ `expr e }}
                       / deco_underscore:p {{ `hole p }}

(* used for everything assimilated to a function call: field access, method call, regular function call *)
;function_arguments_dot_method_nosp = careful_deco(just_function_arguments_dot_method_nosp)
;just_function_arguments_dot_method_nosp <-
  / function_arguments_nosp2:args {{ `function_call args }}
  / lbrace_nosp (=careful_deco(lambda)):e rbrace {{ `function_call [`expr e] }}
  / "." Opa_lexer.ml_identifier_nosp:i {{ `dot i }}
  / ".." Opa_lexer.ml_identifier_nosp:i {{ `double_dot i }}

(**
  {7 Opa expression inside braces}
  Used for embedding opa in texts like string or xhtml
*)
/** embedded opa **/
opa_in_braces_nosp <- lbrace_nosp expr:e rbrace {{ e }}
/** embedded opa **/
opa_in_braces <- lbrace expr:e rbrace {{ e }}


(**
  {6 Const }
*)
;/** constant **/
const      <- float:f {{ CFloat f }}
            / int:i {{ CInt (Big_int.big_int_of_int i) }}
            / string:s {{ CString s }}

(**
   {6 Types}
*)

(**
   {7 Type constants}
*)

;/** type constant **/
type_const = deco just_type_const;
just_type_const <-  (=exact_ident("int"))    {{TypeConst TyInt}}
                  / (=exact_ident("float"))  {{TypeConst TyFloat}}
                  / (=exact_ident("string")) {{TypeConst TyString}}

(**
   {7 Type variables}
*)

;/** type variable **/
typevar = deco just_typevar;
just_typevar <- quote ml_identifier:i {{ (i:nonuid) }}
              / Opa_lexer.UNDERSCORE {{ fresh_variable () }}

(*
  Use production [implicit_row_variable] to parse variables which
  only appear as [...] in the concrete syntax.

  e.g. [ {hd:int;...} -> int] *)

;implicit_row_variable = deco just_implicit_row_variable;
just_implicit_row_variable <- (=exact_symbol("...")) {{ Rowvar (fresh_variable ()) }}
                            / just_rowvar:r {{ r }}
;rowvar = deco just_rowvar;
just_rowvar <- just_typevar:v {{ Rowvar v }}

;colvar = deco just_colvar;
just_colvar <- just_typevar:v {{ Colvar v }}

;flatvar= deco just_flatvar;
just_flatvar<- just_typevar:v {{ Flatvar v }}

(**
   {7 Record types}
   Including syntactic sugar for tuple types
   The syntax for tuple types is the same as the one for expressions and patterns
*)

;/** record type **/
type_record = deco just_type_record
just_type_record <-
     tilda:tilda lbrace just_fields:f just_final_row_variable?:rv spacing (semic spacing)? rbrace
     {{ TyRow (default_value_in_type_record tilda f, rv)}}
   / tilda lbrace just_implicit_row_variable?:rv spacing semic? rbrace {{TyRow ([],  rv)}}

;/** module type **/
just_type_module <-
     "{{" (=list0(module_field,type_separator)):l spacing (semic spacing)? "}}"
     {{ TypeModule l }}

;/** tuple type **/
type_tuple <- lpar (=list1(typ,comma)):types comma? rpar {{ TypeNamed (Typeident(tuple_string types),types) }}

(**
   {8 Regular records}
*)
/** record type fields **/
just_fields = list1(just_field,type_separator);

type_separator <- semic / !colon

module_field <- field_name:f colon typ:ty {{ (f,ty) }}
just_field <- module_field:v     {{ let (f,ty) = v in (f, `value ty) }}
            / tilda:tilda (=deco(field_name)):f  {{ let ty =
                                                      if tilda then
                                                        `value (typenamed (undecorate f) [] (label f))
                                                      else
                                                        `novalue (f) in
                                                    (undecorate f, ty) }}
field_name  <- ml_identifier


just_final_row_variable   <- semic? just_implicit_row_variable:rv {{ rv }}


(**
   {7 Database types}

   @TODO
*)

(**
   {7 Type instances}
*)
/** type arguments **/
list_types_comma <- (=list0(typ,comma))

type_arguments <- Opa_lexer.lpar_nosp list_types_comma:l rpar {{l}}
                / !"(" {{ [] }}


;type_instance = deco just_type_instance;
just_type_instance <- !forall !external !just_type_const type_identifier_nosp:i type_arguments:t {{(Typeident i,t)}}

(**
   {7 General types}

   By order of decreasing priority, we have
   - arrow
   - sums
*)

;/** type **/
typ = deco just_typ;
just_typ <-
  / (=deco((=list0(type_without_arrow,comma)))):p rarrow type_without_arrow:last (=deco(rarrow))?:o
    {{ match o with
       | Some (_,label) ->
           error_consecutive_arrow label
       | None ->
           let l,pos = p in
           arrow l last pos }}
  / type_without_arrow:t {{ undecorate t }}

;type_without_arrow = deco(just_type_without_arrow)
;just_type_without_arrow <- type_sum
                          / just_type_without_sum

type_sum <- (=infix(Opa_lexer.slash))? (=list1(type_sum_element,(=infix(Opa_lexer.slash)))):l end_of_type_sum?:o
            {{ match l,o with
                 | [h], None ->
                     ( match undecorate h with
                         | SumRecord r -> TypeRecord r
                         | SumName t -> TypeNamed t
                         | _ -> assert false
                     )
                 | _,_ -> TypeSumSugar (l @ Option.to_list o)
             }}
/** sum type element **/
type_sum_element = deco just_type_sum_element;
just_type_sum_element <- just_type_record:r {{ SumRecord r }}
                       / just_type_instance:t  {{ SumName t }}
end_of_type_sum <- slash end_of_type_sum_var:f {{ f }}
end_of_type_sum_var <- typevar:f {{ unc2 colvar f }}
                     / implicit_col_variable:f {{ unc2 colvar f }}
implicit_col_variable = deco just_implicit_col_variable;
just_implicit_col_variable <- (=exact_symbol("...")) {{ fresh_variable () }}

;type_without_sum = deco just_type_without_sum;
just_type_without_sum <- just_type_const:t {{ t }}
                       / just_flatvar:t {{ TypeVar t }}
                       / external {{ TypeExternal }}
                       / lpar just_typ:t rpar {{ t }}
                       / type_tuple
                       / forall (lpar (=list1(just_flatvar,comma)):l rpar {{l}}):typevars (=exact_symbol(".")) typ:t {{ TypeForall(typevars, t) }}
                       / just_type_module

external <- (=exact_ident("external"))
forall <- (=exact_ident("forall"))

(**
    Some decorations
 *)
;deco_ml_identifier_nosp = careful_deco ml_identifier_nosp
;deco_ml_identifier = deco ml_identifier
;deco_underscore <- (=deco(Opa_lexer.UNDERSCORE)):p {{ label p }}
;deco_underscore_nosp <- (=careful_deco(Opa_lexer.UNDERSCORE)):p {{ label p }}
;let deco_option rule = (=deco(rule ?))
;let exact_symbol rule = (=Opa_lexer.exact_symbol(rule))
;let exact_ident rule = (=Opa_lexer.exact_ident(rule))
(* WARNING: _succeed always succeeds but careful_deco and deco fail if they start
 * at the end of the file. So don't use pos at a place where it might be the last rule
 * applied *)
;pos <- (=careful_deco(_succeed)):p {{ label p }}
;offset <- Opa_lexer.offset

(**
   {6 Convenience functions}
 *)

(** Always succeed

    @TODO Patch Teerex to make this a primitive.
*)
(* adds some "expects ... or any character" in error messages that are not nice *)
_succeed <- (&. $/ !. $)
_fail <- &. &(!.) . $

(**
   {7 Importing the lexer}
*)
string <- Opa_lexer.string
char   <- Opa_lexer.char
int <- Opa_lexer.int
float  <- Opa_lexer.float
spacing<- Opa_lexer.spacing
strict_spacing<- Opa_lexer.strict_spacing
ml_identifier <- spacing Opa_lexer.ml_identifier {{ __2 }}
ml_identifier_nosp <- spacing Opa_lexer.ml_identifier_nosp {{ __2 }}
type_identifier <- spacing Opa_lexer.type_identifier {{ __2 }}
type_identifier_nosp <- spacing Opa_lexer.type_identifier_nosp {{ __2 }}


larrow   <- Opa_lexer.larrow $
rarrow   <- Opa_lexer.rarrow  $
lbrace   <- Opa_lexer.lbrace  $
lbrace_nosp <- Opa_lexer.lbrace_nosp $
rbrace   <- Opa_lexer.rbrace  $
lbracket <- Opa_lexer.lbracket$
rbracket <- Opa_lexer.rbracket$
colon    <- Opa_lexer.colon   $
ltcolon  <- Opa_lexer.ltcolon $
comma    <- Opa_lexer.comma   $
semic    <- Opa_lexer.semic   $
slash    <- Opa_lexer.slash   $
lpar     <- Opa_lexer.lpar    $
rpar     <- Opa_lexer.rpar    $
bquote   <- Opa_lexer.bquote  $
quote    <- Opa_lexer.quote   $
ampersand <- Opa_lexer.ampersand $
underscore <- Opa_lexer.underscore $
alias <- Opa_lexer.alias $
dots <- Opa_lexer.dots $
assign <- Opa_lexer.assign $

(**
   {6 Meta-rules}
*)

(**
   {7 Separated lists}
*)

(** list where a the separator must occur *)
let list2 element separator = element:e (separator element:e {{e}})+:l
  {{ e :: l }}

(**Non-empty lists*)
let list1 element separator = element:e (separator element {{__2}})*:l
  {{ e :: l }};

(**Possibly empty lists*)
let list0 element separator = (=list1(element,separator))?:o
  {{ match o with
       | None -> []
       | Some l -> l
   }}

(** Non-empty lists where you get the separator and maybe holes instead of expressions
  * but it avoids parsing [_] as a list of one element *)
let list1s element operator =
  / element:e ((=infix(operator)):s (=expr_or_hole(element)):e {{ (s,e) }})*:l {{ (`expr e,l) }}
  / deco_underscore:p ((=infix(operator)):s (=expr_or_hole(element)):e {{ (s,e) }})+:l {{ (`hole p,l) }}


let list1pos element separator = element:e (separator:s element:e {{ (s,e) }})*:l {{ let sl,el = List.split l in e::el,sl }}
let list0pos element separator = (=list1pos(element,separator))?:o {{ Option.default ([],[]) o }}

(**
   {7 Rules for operators}
*)
;let infix operator = spacing offset:o1 operator:s offset:o2
   {| let c1 = _get_char (o1 - 1) in
      let c2 = _get_char o2 in
      (*Printf.printf "%d %d %C %C\n%!" (o1 - 1) o2 c1 c2;*)
      if Char.is_space c1 = Char.is_space c2 then Some s else None |}

(**
   {7 Labelling stuff with positions}
*)

let careful_deco rule = (=Opa_lexer.careful_deco(rule));
let deco rule = (=Opa_lexer.deco(rule));