* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
- * $Id: pa_bitmatch.ml,v 1.6 2008-04-02 08:05:58 rjones Exp $
+ * $Id$
*)
open Printf
*
* If this is false then no extra debugging code is emitted.
*)
-let debug = true
+let debug = false
-type m = Fields of f list (* field ; field -> ... *)
- | Bind of string option (* _ -> ... *)
-and f = {
- (* XXX fval should be a patt, not an expr *)
- fval : expr; (* field binding or value *)
+(* Work out if an expression is an integer constant.
+ *
+ * Returns [Some i] if so (where i is the integer value), else [None].
+ *
+ * Fairly simplistic algorithm: we can only detect simple constant
+ * expressions such as [k], [k+c], [k-c] etc.
+ *)
+let rec expr_is_constant = function
+ | <:expr< $int:i$ >> -> (* Literal integer constant. *)
+ Some (int_of_string i)
+ | <:expr< $a$ + $b$ >> -> (* Addition of constants. *)
+ (match expr_is_constant a, expr_is_constant b with
+ | Some a, Some b -> Some (a+b)
+ | _ -> None)
+ | <:expr< $a$ - $b$ >> -> (* Subtraction. *)
+ (match expr_is_constant a, expr_is_constant b with
+ | Some a, Some b -> Some (a-b)
+ | _ -> None)
+ | <:expr< $a$ * $b$ >> -> (* Multiplication. *)
+ (match expr_is_constant a, expr_is_constant b with
+ | Some a, Some b -> Some (a*b)
+ | _ -> None)
+ | <:expr< $a$ / $b$ >> -> (* Division. *)
+ (match expr_is_constant a, expr_is_constant b with
+ | Some a, Some b -> Some (a/b)
+ | _ -> None)
+ | <:expr< $a$ lsl $b$ >> -> (* Shift left. *)
+ (match expr_is_constant a, expr_is_constant b with
+ | Some a, Some b -> Some (a lsl b)
+ | _ -> None)
+ | <:expr< $a$ lsr $b$ >> -> (* Shift right. *)
+ (match expr_is_constant a, expr_is_constant b with
+ | Some a, Some b -> Some (a lsr b)
+ | _ -> None)
+ | _ -> None (* Anything else is not constant. *)
+
+(* Field. In bitmatch (patterns) the type is [patt field]. In
+ * BITSTRING (constructor) the type is [expr field].
+ *)
+type 'a field = {
+ field : 'a; (* field ('a is either patt or expr) *)
flen : expr; (* length in bits, may be non-const *)
- endian : endian; (* endianness *)
+ endian : Bitmatch.endian; (* endianness *)
signed : bool; (* true if signed, false if unsigned *)
t : t; (* type *)
_loc : Loc.t; (* location in source code *)
+ printer : 'a -> string; (* turn the field into a string *)
}
-and endian = BigEndian | LittleEndian | NativeEndian
-and t = Int | Bitstring
+and t = Int | String | Bitstring
(* Generate a fresh, unique symbol each time called. *)
let gensym =
incr i; let i = !i in
sprintf "__pabitmatch_%s_%d" name i
-(* Deal with the qualifiers which appear for a field. *)
-let parse_field _loc fval flen qs =
+(* Deal with the qualifiers which appear for a field of both types. *)
+let parse_field _loc field flen qs printer =
let endian, signed, t =
match qs with
| None -> (None, None, None)
if endian <> None then
Loc.raise _loc (Failure "an endian flag has been set already")
else (
- let endian = Some BigEndian in
+ let endian = Some Bitmatch.BigEndian in
(endian, signed, t)
)
| "littleendian" ->
if endian <> None then
Loc.raise _loc (Failure "an endian flag has been set already")
else (
- let endian = Some LittleEndian in
+ let endian = Some Bitmatch.LittleEndian in
(endian, signed, t)
)
| "nativeendian" ->
if endian <> None then
Loc.raise _loc (Failure "an endian flag has been set already")
else (
- let endian = Some NativeEndian in
+ let endian = Some Bitmatch.NativeEndian in
(endian, signed, t)
)
| "signed" ->
let t = Some Int in
(endian, signed, t)
)
+ | "string" ->
+ if t <> None then
+ Loc.raise _loc (Failure "a type flag has been set already")
+ else (
+ let t = Some String in
+ (endian, signed, t)
+ )
| "bitstring" ->
if t <> None then
Loc.raise _loc (Failure "a type flag has been set already")
Loc.raise _loc (Failure (s ^ ": unknown qualifier"))
) (None, None, None) qs in
- (* If type is set to bitstring then endianness and signedness
- * qualifiers are meaningless and must not be set.
+ (* If type is set to string or bitstring then endianness and
+ * signedness qualifiers are meaningless and must not be set.
*)
- if t = Some Bitstring && (endian <> None || signed <> None) then
- Loc.raise _loc (
- Failure "bitstring type and endian or signed qualifiers cannot be mixed"
- );
+ if (t = Some Bitstring || t = Some String)
+ && (endian <> None || signed <> None) then
+ Loc.raise _loc (
+ Failure "string types and endian or signed qualifiers cannot be mixed"
+ );
(* Default endianness, signedness, type. *)
- let endian = match endian with None -> BigEndian | Some e -> e in
+ let endian = match endian with None -> Bitmatch.BigEndian | Some e -> e in
let signed = match signed with None -> false | Some s -> s in
let t = match t with None -> Int | Some t -> t in
{
- fval = fval;
+ field = field;
flen = flen;
endian = endian;
signed = signed;
t = t;
_loc = _loc;
+ printer = printer;
}
-let string_of_endian = function
- | BigEndian -> "bigendian"
- | LittleEndian -> "littleendian"
- | NativeEndian -> "nativeendian"
-
let string_of_t = function
| Int -> "int"
+ | String -> "string"
| Bitstring -> "bitstring"
-let string_of_field { fval = fval; flen = flen;
+let patt_printer = function
+ | <:patt< $lid:id$ >> -> id
+ | _ -> "[pattern]"
+
+let expr_printer = function
+ | <:expr< $lid:id$ >> -> id
+ | _ -> "[expression]"
+
+let string_of_field { field = field; flen = flen;
endian = endian; signed = signed; t = t;
- _loc = _loc } =
- let fval =
- match fval with
- | <:expr< $lid:id$ >> -> id
- | _ -> "[expression]" in
+ _loc = _loc;
+ printer = printer} =
let flen =
- match flen with
- | <:expr< $int:i$ >> -> i
- | _ -> "[non-const-len]" in
- let endian = string_of_endian endian in
+ match expr_is_constant flen with
+ | Some i -> string_of_int i
+ | None -> "[non-const-len]" in
+ let endian = Bitmatch.string_of_endian endian in
let signed = if signed then "signed" else "unsigned" in
let t = string_of_t t in
let loc_fname = Loc.file_name _loc in
let loc_char = Loc.start_off _loc - Loc.start_bol _loc in
sprintf "%s : %s : %s, %s, %s @ (%S, %d, %d)"
- fval flen t endian signed loc_fname loc_line loc_char
+ (printer field) flen t endian signed loc_fname loc_line loc_char
(* Generate the code for a constructor, ie. 'BITSTRING ...'. *)
let output_constructor _loc fields =
(* Bitstrings are created like the 'Buffer' module (in fact, using
* the Buffer module), by appending snippets to a growing buffer.
- * This is reasonable efficient and avoids a lot of garbage.
+ * This is reasonably efficient and avoids a lot of garbage.
*)
let buffer = gensym "buffer" in
(* Convert each field to a simple bitstring-generating expression. *)
let fields = List.map (
- fun {fval=fval; flen=flen; endian=endian; signed=signed; t=t} ->
+ fun {field=fexpr; flen=flen; endian=endian; signed=signed;
+ t=t; _loc=_loc} ->
(* Is flen an integer constant? If so, what is it? This
* is very simple-minded and only detects simple constants.
*)
- let flen_is_const =
- match flen with
- | <:expr< $int:i$ >> -> Some (int_of_string i)
- | _ -> None in
+ let flen_is_const = expr_is_constant flen in
let name_of_int_construct_const = function
(* XXX As an enhancement we should allow a 64-bit-only
| (1, _, _) -> "construct_bit"
| ((2|3|4|5|6|7|8), _, false) -> "construct_char_unsigned"
| ((2|3|4|5|6|7|8), _, true) -> "construct_char_signed"
- | (i, BigEndian, false) when i <= 31 -> "construct_int_be_unsigned"
- | (i, BigEndian, true) when i <= 31 -> "construct_int_be_signed"
- | (i, LittleEndian, false) when i <= 31 -> "construct_int_le_unsigned"
- | (i, LittleEndian, true) when i <= 31 -> "construct_int_le_signed"
- | (i, NativeEndian, false) when i <= 31 -> "construct_int_ne_unsigned"
- | (i, NativeEndian, true) when i <= 31 -> "construct_int_ne_signed"
- | (32, BigEndian, false) -> "construct_int32_be_unsigned"
- | (32, BigEndian, true) -> "construct_int32_be_signed"
- | (32, LittleEndian, false) -> "construct_int32_le_unsigned"
- | (32, LittleEndian, true) -> "construct_int32_le_signed"
- | (32, NativeEndian, false) -> "construct_int32_ne_unsigned"
- | (32, NativeEndian, true) -> "construct_int32_ne_signed"
- | (_, BigEndian, false) -> "construct_int64_be_unsigned"
- | (_, BigEndian, true) -> "construct_int64_be_signed"
- | (_, LittleEndian, false) -> "construct_int64_le_unsigned"
- | (_, LittleEndian, true) -> "construct_int64_le_signed"
- | (_, NativeEndian, false) -> "construct_int64_ne_unsigned"
- | (_, NativeEndian, true) -> "construct_int64_ne_signed"
+ | (i, Bitmatch.BigEndian, false) when i <= 31 ->
+ "construct_int_be_unsigned"
+ | (i, Bitmatch.BigEndian, true) when i <= 31 ->
+ "construct_int_be_signed"
+ | (i, Bitmatch.LittleEndian, false) when i <= 31 ->
+ "construct_int_le_unsigned"
+ | (i, Bitmatch.LittleEndian, true) when i <= 31 ->
+ "construct_int_le_signed"
+ | (i, Bitmatch.NativeEndian, false) when i <= 31 ->
+ "construct_int_ne_unsigned"
+ | (i, Bitmatch.NativeEndian, true) when i <= 31 ->
+ "construct_int_ne_signed"
+ | (32, Bitmatch.BigEndian, false) -> "construct_int32_be_unsigned"
+ | (32, Bitmatch.BigEndian, true) -> "construct_int32_be_signed"
+ | (32, Bitmatch.LittleEndian, false) -> "construct_int32_le_unsigned"
+ | (32, Bitmatch.LittleEndian, true) -> "construct_int32_le_signed"
+ | (32, Bitmatch.NativeEndian, false) -> "construct_int32_ne_unsigned"
+ | (32, Bitmatch.NativeEndian, true) -> "construct_int32_ne_signed"
+ | (_, Bitmatch.BigEndian, false) -> "construct_int64_be_unsigned"
+ | (_, Bitmatch.BigEndian, true) -> "construct_int64_be_signed"
+ | (_, Bitmatch.LittleEndian, false) -> "construct_int64_le_unsigned"
+ | (_, Bitmatch.LittleEndian, true) -> "construct_int64_le_signed"
+ | (_, Bitmatch.NativeEndian, false) -> "construct_int64_ne_unsigned"
+ | (_, Bitmatch.NativeEndian, true) -> "construct_int64_ne_signed"
in
let name_of_int_construct = function
(* XXX As an enhancement we should allow users to
* specify that a field length can fit into a char/int/int32
* (of course, this would have to be checked at runtime).
*)
- | (BigEndian, false) -> "construct_int64_be_unsigned"
- | (BigEndian, true) -> "construct_int64_be_signed"
- | (LittleEndian, false) -> "construct_int64_le_unsigned"
- | (LittleEndian, true) -> "construct_int64_le_signed"
- | (NativeEndian, false) -> "construct_int64_ne_unsigned"
- | (NativeEndian, true) -> "construct_int64_ne_signed"
+ | (Bitmatch.BigEndian, false) -> "construct_int64_be_unsigned"
+ | (Bitmatch.BigEndian, true) -> "construct_int64_be_signed"
+ | (Bitmatch.LittleEndian, false) -> "construct_int64_le_unsigned"
+ | (Bitmatch.LittleEndian, true) -> "construct_int64_le_signed"
+ | (Bitmatch.NativeEndian, false) -> "construct_int64_ne_unsigned"
+ | (Bitmatch.NativeEndian, true) -> "construct_int64_ne_signed"
in
let expr =
exn_used := true;
<:expr<
- Bitmatch.$lid:construct_func$ $lid:buffer$ $fval$ $flen$
+ Bitmatch.$lid:construct_func$ $lid:buffer$ $fexpr$ $flen$
$lid:exn$
>>
<:expr<
if $flen$ >= 1 && $flen$ <= 64 then
- Bitmatch.$lid:construct_func$ $lid:buffer$ $fval$ $flen$
+ Bitmatch.$lid:construct_func$ $lid:buffer$ $fexpr$ $flen$
$lid:exn$
else
raise (Bitmatch.Construct_failure
$int:loc_line$, $int:loc_char$))
>>
+ (* String, constant length > 0, must be a multiple of 8. *)
+ | String, Some i when i > 0 && i land 7 = 0 ->
+ let bs = gensym "bs" in
+ <:expr<
+ let $lid:bs$ = $fexpr$ in
+ if String.length $lid:bs$ = ($flen$ lsr 3) then
+ Bitmatch.construct_string $lid:buffer$ $lid:bs$
+ else
+ raise (Bitmatch.Construct_failure
+ ("length of string does not match declaration",
+ $str:loc_fname$,
+ $int:loc_line$, $int:loc_char$))
+ >>
+
+ (* String, constant length -1, means variable length string
+ * with no checks.
+ *)
+ | String, Some (-1) ->
+ <:expr< Bitmatch.construct_string $lid:buffer$ $fexpr$ >>
+
+ (* String, constant length = 0 is probably an error, and so is
+ * any other value.
+ *)
+ | String, Some _ ->
+ Loc.raise _loc (Failure "length of string must be > 0 and a multiple of 8, or the special value -1")
+
+ (* String, non-constant length.
+ * We check at runtime that the length is > 0, a multiple of 8,
+ * and matches the declared length.
+ *)
+ | String, None ->
+ let bslen = gensym "bslen" in
+ let bs = gensym "bs" in
+ <:expr<
+ let $lid:bslen$ = $flen$ in
+ if $lid:bslen$ > 0 then (
+ if $lid:bslen$ land 7 = 0 then (
+ let $lid:bs$ = $fexpr$ in
+ if String.length $lid:bs$ = ($lid:bslen$ lsr 3) then
+ Bitmatch.construct_string $lid:buffer$ $lid:bs$
+ else
+ raise (Bitmatch.Construct_failure
+ ("length of string does not match declaration",
+ $str:loc_fname$,
+ $int:loc_line$, $int:loc_char$))
+ ) else
+ raise (Bitmatch.Construct_failure
+ ("length of string must be a multiple of 8",
+ $str:loc_fname$,
+ $int:loc_line$, $int:loc_char$))
+ ) else
+ raise (Bitmatch.Construct_failure
+ ("length of string must be > 0",
+ $str:loc_fname$,
+ $int:loc_line$, $int:loc_char$))
+ >>
+
(* Bitstring, constant length > 0. *)
| Bitstring, Some i when i > 0 ->
let bs = gensym "bs" in
<:expr<
- let $lid:bs$ = $fval$ in
+ let $lid:bs$ = $fexpr$ in
if Bitmatch.bitstring_length $lid:bs$ = $flen$ then
Bitmatch.construct_bitstring $lid:buffer$ $lid:bs$
else
* with no checks.
*)
| Bitstring, Some (-1) ->
- <:expr< Bitmatch.construct_bitstring $lid:buffer$ $fval$ >>
+ <:expr< Bitmatch.construct_bitstring $lid:buffer$ $fexpr$ >>
- (* Bitstring, constant length = 0 is probably an error, and so it
+ (* Bitstring, constant length = 0 is probably an error, and so is
* any other value.
*)
| Bitstring, Some _ ->
<:expr<
let $lid:bslen$ = $flen$ in
if $lid:bslen$ > 0 then (
- let $lid:bs$ = $fval$ in
+ let $lid:bs$ = $fexpr$ in
if Bitmatch.bitstring_length $lid:bs$ = $lid:bslen$ then
Bitmatch.construct_bitstring $lid:buffer$ $lid:bs$
else
let rec output_field_extraction inner = function
| [] -> inner
| field :: fields ->
- let {fval=fval; flen=flen; endian=endian; signed=signed; t=t}
+ let {field=fpatt; flen=flen; endian=endian; signed=signed;
+ t=t; _loc=_loc}
= field in
- (* Is fval a binding (an ident) or an expression? If it's
- * a binding then we will generate a binding for this field.
- * If it's an expression then we will test the field against
- * the expression.
- *)
- let fval_is_ident =
- match fval with
- | <:expr< $lid:id$ >> -> Some id
- | _ -> None in
-
(* Is flen an integer constant? If so, what is it? This
* is very simple-minded and only detects simple constants.
*)
- let flen_is_const =
- match flen with
- | <:expr< $int:i$ >> -> Some (int_of_string i)
- | _ -> None in
+ let flen_is_const = expr_is_constant flen in
let name_of_int_extract_const = function
(* XXX As an enhancement we should allow a 64-bit-only
| (1, _, _) -> "extract_bit"
| ((2|3|4|5|6|7|8), _, false) -> "extract_char_unsigned"
| ((2|3|4|5|6|7|8), _, true) -> "extract_char_signed"
- | (i, BigEndian, false) when i <= 31 -> "extract_int_be_unsigned"
- | (i, BigEndian, true) when i <= 31 -> "extract_int_be_signed"
- | (i, LittleEndian, false) when i <= 31 -> "extract_int_le_unsigned"
- | (i, LittleEndian, true) when i <= 31 -> "extract_int_le_signed"
- | (i, NativeEndian, false) when i <= 31 -> "extract_int_ne_unsigned"
- | (i, NativeEndian, true) when i <= 31 -> "extract_int_ne_signed"
- | (32, BigEndian, false) -> "extract_int32_be_unsigned"
- | (32, BigEndian, true) -> "extract_int32_be_signed"
- | (32, LittleEndian, false) -> "extract_int32_le_unsigned"
- | (32, LittleEndian, true) -> "extract_int32_le_signed"
- | (32, NativeEndian, false) -> "extract_int32_ne_unsigned"
- | (32, NativeEndian, true) -> "extract_int32_ne_signed"
- | (_, BigEndian, false) -> "extract_int64_be_unsigned"
- | (_, BigEndian, true) -> "extract_int64_be_signed"
- | (_, LittleEndian, false) -> "extract_int64_le_unsigned"
- | (_, LittleEndian, true) -> "extract_int64_le_signed"
- | (_, NativeEndian, false) -> "extract_int64_ne_unsigned"
- | (_, NativeEndian, true) -> "extract_int64_ne_signed"
+ | (i, Bitmatch.BigEndian, false) when i <= 31 ->
+ "extract_int_be_unsigned"
+ | (i, Bitmatch.BigEndian, true) when i <= 31 ->
+ "extract_int_be_signed"
+ | (i, Bitmatch.LittleEndian, false) when i <= 31 ->
+ "extract_int_le_unsigned"
+ | (i, Bitmatch.LittleEndian, true) when i <= 31 ->
+ "extract_int_le_signed"
+ | (i, Bitmatch.NativeEndian, false) when i <= 31 ->
+ "extract_int_ne_unsigned"
+ | (i, Bitmatch.NativeEndian, true) when i <= 31 ->
+ "extract_int_ne_signed"
+ | (32, Bitmatch.BigEndian, false) -> "extract_int32_be_unsigned"
+ | (32, Bitmatch.BigEndian, true) -> "extract_int32_be_signed"
+ | (32, Bitmatch.LittleEndian, false) -> "extract_int32_le_unsigned"
+ | (32, Bitmatch.LittleEndian, true) -> "extract_int32_le_signed"
+ | (32, Bitmatch.NativeEndian, false) -> "extract_int32_ne_unsigned"
+ | (32, Bitmatch.NativeEndian, true) -> "extract_int32_ne_signed"
+ | (_, Bitmatch.BigEndian, false) -> "extract_int64_be_unsigned"
+ | (_, Bitmatch.BigEndian, true) -> "extract_int64_be_signed"
+ | (_, Bitmatch.LittleEndian, false) -> "extract_int64_le_unsigned"
+ | (_, Bitmatch.LittleEndian, true) -> "extract_int64_le_signed"
+ | (_, Bitmatch.NativeEndian, false) -> "extract_int64_ne_unsigned"
+ | (_, Bitmatch.NativeEndian, true) -> "extract_int64_ne_signed"
in
let name_of_int_extract = function
(* XXX As an enhancement we should allow users to
* specify that a field length can fit into a char/int/int32
* (of course, this would have to be checked at runtime).
*)
- | (BigEndian, false) -> "extract_int64_be_unsigned"
- | (BigEndian, true) -> "extract_int64_be_signed"
- | (LittleEndian, false) -> "extract_int64_le_unsigned"
- | (LittleEndian, true) -> "extract_int64_le_signed"
- | (NativeEndian, false) -> "extract_int64_ne_unsigned"
- | (NativeEndian, true) -> "extract_int64_ne_signed"
+ | (Bitmatch.BigEndian, false) -> "extract_int64_be_unsigned"
+ | (Bitmatch.BigEndian, true) -> "extract_int64_be_signed"
+ | (Bitmatch.LittleEndian, false) -> "extract_int64_le_unsigned"
+ | (Bitmatch.LittleEndian, true) -> "extract_int64_le_signed"
+ | (Bitmatch.NativeEndian, false) -> "extract_int64_ne_unsigned"
+ | (Bitmatch.NativeEndian, true) -> "extract_int64_ne_signed"
in
let expr =
- match t, fval_is_ident, flen_is_const with
- (* Common case: int field, binding, constant flen *)
- | Int, Some ident, Some i when i > 0 && i <= 64 ->
- let extract_func = name_of_int_extract_const (i,endian,signed) in
- <:expr<
- if $lid:len$ >= $flen$ then (
- let $lid:ident$, $lid:off$, $lid:len$ =
- Bitmatch.$lid:extract_func$ $lid:data$ $lid:off$ $lid:len$
- $flen$ in
- $inner$
- )
- >>
-
- (* Int field, not a binding, constant flen *)
- | Int, None, Some i when i > 0 && i <= 64 ->
+ match t, flen_is_const with
+ (* Common case: int field, constant flen *)
+ | Int, Some i when i > 0 && i <= 64 ->
let extract_func = name_of_int_extract_const (i,endian,signed) in
let v = gensym "val" in
<:expr<
let $lid:v$, $lid:off$, $lid:len$ =
Bitmatch.$lid:extract_func$ $lid:data$ $lid:off$ $lid:len$
$flen$ in
- if $lid:v$ = $fval$ then (
- $inner$
- )
+ match $lid:v$ with $fpatt$ when true -> $inner$ | _ -> ()
)
>>
- | Int, _, Some _ ->
+ | Int, Some _ ->
Loc.raise _loc (Failure "length of int field must be [1..64]")
(* Int field, non-const flen. We have to test the range of
* the field at runtime. If outside the range it's a no-match
* (not an error).
*)
- | Int, Some ident, None ->
+ | Int, None ->
let extract_func = name_of_int_extract (endian,signed) in
+ let v = gensym "val" in
<:expr<
if $flen$ >= 1 && $flen$ <= 64 && $flen$ <= $lid:len$ then (
- let $lid:ident$, $lid:off$, $lid:len$ =
+ let $lid:v$, $lid:off$, $lid:len$ =
Bitmatch.$lid:extract_func$ $lid:data$ $lid:off$ $lid:len$
$flen$ in
- $inner$
+ match $lid:v$ with $fpatt$ when true -> $inner$ | _ -> ()
)
>>
- | Int, None, None ->
- let extract_func = name_of_int_extract (endian,signed) in
- let v = gensym "val" in
+ (* String, constant flen > 0. *)
+ | String, Some i when i > 0 && i land 7 = 0 ->
+ let bs = gensym "bs" in
<:expr<
- if $flen$ >= 1 && $flen$ <= 64 && $flen$ <= $lid:len$ then (
- let $lid:v$, $lid:off$, $lid:len$ =
- Bitmatch.$lid:extract_func$ $lid:data$ $lid:off$ $lid:len$
+ if $lid:len$ >= $flen$ then (
+ let $lid:bs$, $lid:off$, $lid:len$ =
+ Bitmatch.extract_bitstring $lid:data$ $lid:off$ $lid:len$
$flen$ in
- if $lid:v$ = $fval$ then (
- $inner$
- )
+ match Bitmatch.string_of_bitstring $lid:bs$ with
+ | $fpatt$ when true -> $inner$
+ | _ -> ()
)
>>
- (* Can't compare bitstrings at the moment. *)
- | Bitstring, None, _ ->
- Loc.raise _loc
- (Failure "cannot compare a bitstring to a constant")
+ (* String, constant flen = -1, means consume all the
+ * rest of the input.
+ *)
+ | String, Some i when i = -1 ->
+ let bs = gensym "bs" in
+ <:expr<
+ let $lid:bs$, $lid:off$, $lid:len$ =
+ Bitmatch.extract_remainder $lid:data$ $lid:off$ $lid:len$ in
+ match Bitmatch.string_of_bitstring $lid:bs$ with
+ | $fpatt$ when true -> $inner$
+ | _ -> ()
+ >>
+
+ | String, Some _ ->
+ Loc.raise _loc (Failure "length of string must be > 0 and a multiple of 8, or the special value -1")
- (* Bitstring, constant flen >= 0. *)
- | Bitstring, Some ident, Some i when i >= 0 ->
+ (* String field, non-const flen. We check the flen is > 0
+ * and a multiple of 8 (-1 is not allowed here), at runtime.
+ *)
+ | String, None ->
+ let bs = gensym "bs" in
+ <:expr<
+ if $flen$ >= 0 && $flen$ <= $lid:len$
+ && $flen$ land 7 = 0 then (
+ let $lid:bs$, $lid:off$, $lid:len$ =
+ Bitmatch.extract_bitstring
+ $lid:data$ $lid:off$ $lid:len$ $flen$ in
+ match Bitmatch.string_of_bitstring $lid:bs$ with
+ | $fpatt$ when true -> $inner$
+ | _ -> ()
+ )
+ >>
+
+ (* Bitstring, constant flen >= 0.
+ * At the moment all we can do is assign the bitstring to an
+ * identifier.
+ *)
+ | Bitstring, Some i when i >= 0 ->
+ let ident =
+ match fpatt with
+ | <:patt< $lid:ident$ >> -> ident
+ | <:patt< _ >> -> "_"
+ | _ ->
+ Loc.raise _loc
+ (Failure "cannot compare a bitstring to a constant") in
<:expr<
if $lid:len$ >= $flen$ then (
let $lid:ident$, $lid:off$, $lid:len$ =
(* Bitstring, constant flen = -1, means consume all the
* rest of the input.
*)
- | Bitstring, Some ident, Some i when i = -1 ->
+ | Bitstring, Some i when i = -1 ->
+ let ident =
+ match fpatt with
+ | <:patt< $lid:ident$ >> -> ident
+ | <:patt< _ >> -> "_"
+ | _ ->
+ Loc.raise _loc
+ (Failure "cannot compare a bitstring to a constant") in
<:expr<
let $lid:ident$, $lid:off$, $lid:len$ =
Bitmatch.extract_remainder $lid:data$ $lid:off$ $lid:len$ in
$inner$
>>
- | Bitstring, _, Some _ ->
+ | Bitstring, Some _ ->
Loc.raise _loc (Failure "length of bitstring must be >= 0 or the special value -1")
(* Bitstring field, non-const flen. We check the flen is >= 0
* (-1 is not allowed here) at runtime.
*)
- | Bitstring, Some ident, None ->
+ | Bitstring, None ->
+ let ident =
+ match fpatt with
+ | <:patt< $lid:ident$ >> -> ident
+ | <:patt< _ >> -> "_"
+ | _ ->
+ Loc.raise _loc
+ (Failure "cannot compare a bitstring to a constant") in
<:expr<
if $flen$ >= 0 && $flen$ <= $lid:len$ then (
let $lid:ident$, $lid:off$, $lid:len$ =
(* Convert each case in the match. *)
let cases = List.map (
- function
- (* field : len ; field : len when .. -> ..*)
- | (Fields fields, Some whenclause, code) ->
- let inner =
- <:expr<
- if $whenclause$ then (
- $lid:result$ := Some ($code$);
- raise Exit
- )
- >> in
- output_field_extraction inner (List.rev fields)
-
- (* field : len ; field : len -> ... *)
- | (Fields fields, None, code) ->
- let inner =
- <:expr<
- $lid:result$ := Some ($code$);
- raise Exit
- >> in
- output_field_extraction inner (List.rev fields)
-
- (* _ as name when ... -> ... *)
- | (Bind (Some name), Some whenclause, code) ->
- <:expr<
- let $lid:name$ = ($lid:data$, $lid:off$, $lid:len$) in
- if $whenclause$ then (
- $lid:result$ := Some ($code$);
- raise Exit
- )
- >>
-
- (* _ as name -> ... *)
- | (Bind (Some name), None, code) ->
- <:expr<
- let $lid:name$ = ($lid:data$, $lid:off$, $lid:len$) in
- $lid:result$ := Some ($code$);
- raise Exit
- >>
-
- (* _ when ... -> ... *)
- | (Bind None, Some whenclause, code) ->
- <:expr<
- if $whenclause$ then (
- $lid:result$ := Some ($code$);
- raise Exit
- )
- >>
-
- (* _ -> ... *)
- | (Bind None, None, code) ->
- <:expr<
- $lid:result$ := Some ($code$);
- raise Exit
- >>
-
+ fun (fields, bind, whenclause, code) ->
+ let inner = <:expr< $lid:result$ := Some ($code$); raise Exit >> in
+ let inner =
+ match whenclause with
+ | Some whenclause ->
+ <:expr< if $whenclause$ then $inner$ >>
+ | None -> inner in
+ let inner =
+ match bind with
+ | Some name ->
+ <:expr<
+ let $lid:name$ = ($lid:data$, $lid:off$, $lid:len$) in
+ $inner$
+ >>
+ | None -> inner in
+ output_field_extraction inner (List.rev fields)
) cases in
(* Join them into a single expression.
[ LIST0 [ q = LIDENT -> q ] SEP "," ]
];
- field: [
- [ fval = expr LEVEL "top"; ":"; len = expr LEVEL "top";
+ (* Field used in the bitmatch operator (a pattern). *)
+ patt_field: [
+ [ fpatt = patt; ":"; len = expr LEVEL "top";
qs = OPT [ ":"; qs = qualifiers -> qs ] ->
- parse_field _loc fval len qs
+ parse_field _loc fpatt len qs patt_printer
]
];
+ (* Case inside bitmatch operator. *)
match_case: [
- [ "_";
+ [ "{";
+ fields = LIST0 patt_field SEP ";";
+ "}";
bind = OPT [ "as"; name = LIDENT -> name ];
- w = OPT [ "when"; e = expr -> e ]; "->";
+ whenclause = OPT [ "when"; e = expr -> e ]; "->";
code = expr ->
- (Bind bind, w, code)
+ (fields, bind, whenclause, code)
]
- | [ fields = LIST0 field SEP ";";
- w = OPT [ "when"; e = expr -> e ]; "->";
- code = expr ->
- (Fields fields, w, code)
+ ];
+
+ (* Field used in the BITSTRING constructor (an expression). *)
+ constr_field: [
+ [ fexpr = expr LEVEL "top"; ":"; len = expr LEVEL "top";
+ qs = OPT [ ":"; qs = qualifiers -> qs ] ->
+ parse_field _loc fexpr len qs expr_printer
]
];
(* 'bitmatch' expressions. *)
expr: LEVEL ";" [
- [ "bitmatch"; bs = expr; "with"; OPT "|";
+ [ "bitmatch";
+ bs = expr; "with"; OPT "|";
cases = LIST1 match_case SEP "|" ->
output_bitmatch _loc bs cases
]
(* Constructor. *)
- | [ "BITSTRING";
- fields = LIST0 field SEP ";" ->
+ | [ "BITSTRING"; "{";
+ fields = LIST0 constr_field SEP ";";
+ "}" ->
output_constructor _loc fields
]
];
git.annexia.org / ocaml-bitstring.git / blobdiff