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|
%---------------------------------------------------------------------------%
% Copyright (C) 1996-2000 The University of Melbourne.
% This file may only be copied under the terms of the GNU General
% Public License - see the file COPYING in the Mercury distribution.
%---------------------------------------------------------------------------%
%
% This module generates representations for pseudo-type-infos.
%
% The documentation of the structures of pseudo-type-infos is in
% runtime/mercury_type_info.h; that file also contains a list of all
% the files that depend on such data structures.
%
% Authors: trd, zs.
%
%---------------------------------------------------------------------------%
:- module pseudo_type_info.
:- interface.
:- import_module prog_data, rtti.
:- import_module list.
% pseudo_type_info__construct_pseudo_type_info(Type,
% NumUnivQTvars, ExistQVars, PseudoTypeInfo)
%
% Given a Mercury type (`Type'), this predicate returns an
% representation of the pseudo type info for that type.
%
% NumUnivQTvars is either the number of universally quantified type
% variables of the enclosing type (so that all universally quantified
% variables in the type have numbers in the range [1..NumUnivQTvars],
% or is the special value -1, meaning that all variables in the type
% are universally quantified. ExistQVars is the list of existentially
% quantified type variables of the constructor in question.
:- pred pseudo_type_info__construct_pseudo_type_info((type)::in,
int::in, existq_tvars::in, pseudo_type_info::out) is det.
:- type pseudo_type_info
---> type_var(int)
% This represents a type variable.
% Type variables are numbered consecutively,
% starting from 1.
; type_ctor_info(
%
% This represents a zero-arity type,
% i.e. a type constructor with no arguments.
%
rtti_type_id
)
; type_info(
%
% This represents a type with arity > zero,
% i.e. a type constructor applied to some arguments.
% The argument list should not be empty.
%
rtti_type_id,
list(pseudo_type_info)
)
; higher_order_type_info(
%
% This represents a higher-order or tuple type.
% The rtti_type_id field will be pred/0,
% func/0 or tuple/0; the real arity is
% given in the arity field.
%
rtti_type_id,
arity,
list(pseudo_type_info)
)
.
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module prog_util, type_util.
:- import_module int, list, term, std_util, require.
%---------------------------------------------------------------------------%
pseudo_type_info__construct_pseudo_type_info(Type, NumUnivQTvars,
ExistQTvars, Pseudo) :-
(
type_to_type_id(Type, TypeId, TypeArgs0)
->
(
% The argument to typeclass_info types is not
% a type - it encodes the class constraint.
% So we replace the argument with type `void'.
mercury_private_builtin_module(PrivateBuiltin),
TypeId = qualified(PrivateBuiltin, TName) - 1,
( TName = "typeclass_info"
; TName = "base_typeclass_info"
)
->
construct_type(unqualified("void") - 0, [], ArgType),
TypeArgs = [ArgType]
;
TypeArgs = TypeArgs0
),
(
% For higher order types: they all refer to the
% defined pred_0 type_ctor_info, have an extra
% argument for their real arity, and then type
% arguments according to their types.
% Tuples are similar -- they use the tuple_0
% type_ctor_info.
% polymorphism.m has a detailed explanation.
% XXX polymorphism.m does not have a
% detailed explanation.
( type_is_higher_order(Type, _, _, _) ->
TypeName = "pred"
; type_is_tuple(Type, _) ->
TypeName = "tuple"
;
fail
)
->
TypeModule = unqualified(""),
Arity = 0,
RttiTypeId = rtti_type_id(TypeModule, TypeName, Arity),
TypeId = _QualTypeName - RealArity,
pseudo_type_info__generate_args(TypeArgs,
NumUnivQTvars, ExistQTvars, PseudoArgs),
Pseudo = higher_order_type_info(RttiTypeId, RealArity,
PseudoArgs)
;
TypeId = QualTypeName - Arity,
unqualify_name(QualTypeName, TypeName),
sym_name_get_module_name(QualTypeName, unqualified(""),
TypeModule),
RttiTypeId = rtti_type_id(TypeModule, TypeName, Arity),
pseudo_type_info__generate_args(TypeArgs,
NumUnivQTvars, ExistQTvars, PseudoArgs),
( PseudoArgs = [] ->
Pseudo = type_ctor_info(RttiTypeId)
;
Pseudo = type_info(RttiTypeId, PseudoArgs)
)
)
;
type_util__var(Type, Var)
->
% In the case of a type variable, we need to assign a
% variable number *for this constructor*, i.e. taking
% only the existentially quantified variables of
% this constructor (and not those of other functors in
% the same type) into account.
% XXX term__var_to_int doesn't guarantee anything
% about the ints returned (other than that they be
% distinct for different variables), but here we are
% relying more, specifically, on the integers being
% allocated densely (i.e. the first N vars get integers
% 1 to N).
term__var_to_int(Var, VarInt0),
(
( VarInt0 =< NumUnivQTvars
; NumUnivQTvars < 0
)
->
% This is a universally quantified variable.
VarInt = VarInt0
;
% It is existentially quantified.
(
list__nth_member_search(ExistQTvars,
Var, ExistNum0)
->
VarInt = ExistNum0 +
pseudo_type_info__pseudo_typeinfo_exist_var_base
;
error("construct_pseudo_type_info: var not in list")
)
),
require(VarInt =< pseudo_type_info__pseudo_typeinfo_max_var,
"type_ctor_layout: type variable representation exceeds limit"),
Pseudo = type_var(VarInt)
;
error("type_ctor_layout: type neither var nor non-var")
).
:- pred pseudo_type_info__generate_args(list(type)::in,
int::in, existq_tvars::in, list(pseudo_type_info)::out) is det.
pseudo_type_info__generate_args(TypeArgs, NumUnivQTvars, ExistQTvars,
PseudoArgs) :-
list__map((pred(T::in, P::out) is det :-
pseudo_type_info__construct_pseudo_type_info(
T, NumUnivQTvars, ExistQTvars, P)
), TypeArgs, PseudoArgs).
%---------------------------------------------------------------------------%
% This number corresponds to MR_PSEUDOTYPEINFO_MAX_VAR in
% runtime/mercury_type_info.h, and must be kept in sync with it.
% The documentation is located there as well.
:- func pseudo_type_info__pseudo_typeinfo_max_var = int.
pseudo_type_info__pseudo_typeinfo_max_var = 1024.
% This number corresponds to MR_PSEUDOTYPEINFO_EXIST_VAR_BASE in
% runtime/mercury_type_info.h, and must be kept in sync with it.
% The documentation is located there as well.
:- func pseudo_type_info__pseudo_typeinfo_exist_var_base = int.
pseudo_type_info__pseudo_typeinfo_exist_var_base = 512.
%---------------------------------------------------------------------------%
|
