bundles/menhirLib/menhir-20120123/src/keyword.ml

   1 (**************************************************************************)
   2 (*                                                                        *)
   3 (*  Menhir                                                                *)
   4 (*                                                                        *)
   5 (*  François Pottier, INRIA Rocquencourt                                  *)
   6 (*  Yann Régis-Gianas, PPS, Université Paris Diderot                      *)
   7 (*                                                                        *)
   8 (*  Copyright 2005-2008 Institut National de Recherche en Informatique    *)
   9 (*  et en Automatique. All rights reserved. This file is distributed      *)
  10 (*  under the terms of the Q Public License version 1.0, with the change  *)
  11 (*  described in file LICENSE.                                            *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  14
  15 (* This module provides some type and function definitions
  16    that help deal with the keywords that we recognize within
  17    semantic actions. *)
  18
  19 (* ------------------------------------------------------------------------- *)
  20 (* Types. *)
  21
  22 (* The user can request position information either at type
  23    [int] (a simple offset) or at type [Lexing.position]. *)
  24
  25 type flavor =
  26   | FlavorOffset
  27   | FlavorPosition
  28
  29 (* The user can request position information about the
  30    start or end of a symbol. *)
  31
  32 type where =
  33   | WhereStart
  34   | WhereEnd
  35
  36 (* The user can request position information about a production's
  37    left-hand side or about one of the symbols in its right-hand
  38    side, which he can refer to by position or by name. *)
  39
  40 type subject =
  41   | Left
  42   | RightDollar of int
  43   | RightNamed of string
  44
  45 (* Keywords inside semantic actions. They allow access to semantic
  46    values or to position information. *)
  47
  48 type keyword =
  49   | Dollar of int
  50   | Position of subject * where * flavor
  51   | PreviousError
  52   | SyntaxError
  53
  54 (* ------------------------------------------------------------------------- *)
  55 (* These auxiliary functions help map a [Position] keyword to the
  56    name of the variable that the keyword is replaced with. *)
  57
  58 let where = function
  59   | WhereStart ->
  60       "start"
  61   | WhereEnd ->
  62       "end"
  63
  64 let subject = function
  65   | Left ->
  66       ""
  67   | RightDollar i ->
  68       Printf.sprintf "__%d_" i
  69   | RightNamed id ->
  70       Printf.sprintf "_%s_" id
  71
  72 let flavor = function
  73   | FlavorPosition ->
  74       "pos"
  75   | FlavorOffset ->
  76       "ofs"
  77
  78 let posvar s w f =
  79   Printf.sprintf "_%s%s%s" (where w) (flavor f) (subject s)
  80
  81 (* ------------------------------------------------------------------------- *)
  82 (* Sets of keywords. *)
  83
  84 module KeywordSet =
  85   struct
  86     include Set.Make (struct
  87                         type t = keyword
  88                         let compare = compare
  89                       end)
  90
  91     (* This converts a list of keywords with positions into a set of keywords. *)
  92     let from_list keywords =
  93       List.fold_right add keywords empty
  94
  95   end
  96