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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 <>.
@author1 Henri Binsztok,
@author2 Gregoire Makridis
(** {6 DATA} *)
module type DATA =
TODO: documentation
type t
val empty : t
returns a debug string (summarized)
val to_string : t -> string
returns the full contents as string
val get_string : t -> string
(** {6 Projections} *)
Mathieu Wed Mar 16 11:14:27 CET 2011
Old situation:
Projections was there for historical design. There was 2 different
representation of datas, one is for being used when we manipulate the
database in memory ([t]), the other representation is used by the IO
module, for writing and reading datas in the physical database (db-files).
We will try now to simplify this design, and to merge the 2 representations
for avoiding the cost of projections.
We will apply the following steps to the code :
The 2 fonctions [write/read] of all modules implementing this interface
will be replaced by the [identity] (module by module)
The interface will be changed, so that t = io, and the 2 fonction exported
as the identity
The rest of the code using [read/write] will be changed for removing the
call to these functions. They will become unused.
The interface will be changed, removing the function [write/read], and the type [io]
(** {6 Index} *)
Indexation. Build a dictionnary entry.
Count how many time a word appears in a data.
val index_fun : t -> int StringMap.t
module type COMMON =
A private type for representing positive int.
Used for Eid, Uid, Revision.
type t
Used to be [t -> t option], returning [None]
if [t] is max_int.
But nobody was handling the case [None] ([assert false])
so, now the assert is in this function.
val succ : t -> t
Return the previous index, or [None] if the index is [0]
val pred : t -> t option
val make : int -> t
external value : t -> int = "%identity"
val to_string : t -> string
val equal : t -> t -> bool
val compare : t -> t -> int
val max : t -> t -> t
val min : t -> t -> t
Shared implementation for :
- eid
- uid
- revision
Do not coerce there into COMMON,
it would makes eid, uid and revision unifiable.
module IntCommon =
(* if you patch this, make sure that this module doesn't
* use needlessly the SLOW polymorphic comparison
* operators *)
type t = int
About the two following functions
Nobody catches the exception:
exception CommonMake
It is replaced by an assert false.
People using succ and pred used to write stuff like:
match succ uid with
| Some uid -> uid
| _ -> assert false
So, the assert false is now there directly, and no option is allocated.
let succ i =
if i < max_int
then succ i
else assert false
let pred i =
if i > 0
then Some (pred i)
else None
let make i =
(* checking that i <= max_int seems somewhat useless *)
if i >= 0 then i
else assert false
external value : t -> int = "%identity"
let to_string = string_of_int
let equal : int -> int -> bool = (=)
let compare : int -> int -> int =
(* Pervasives.max and Pervasives.min are not specialized when coerced
* so we redefine them with a specialized type *)
let max (i:int) j = if i >= j then i else j
let min (i:int) j = if i <= j then i else j