Files
mercury/compiler/field_access.m
2015-10-20 21:53:36 +11:00

337 lines
15 KiB
Mathematica

%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 1993-2006, 2008-2012 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.
%-----------------------------------------------------------------------------%
%
% File: field_access.
%
% This submodule of make_hlds handles the declarations of fields
%
%-----------------------------------------------------------------------------%
:- module hlds.make_hlds.field_access.
:- interface.
:- import_module hlds.hlds_goal.
:- import_module hlds.hlds_module.
:- import_module hlds.make_hlds.qual_info.
:- import_module hlds.make_hlds.state_var.
:- import_module mdbcomp.
:- import_module mdbcomp.sym_name.
:- import_module parse_tree.error_util.
:- import_module parse_tree.maybe_error.
:- import_module parse_tree.prog_data.
:- import_module assoc_list.
:- import_module list.
:- import_module pair.
%-----------------------------------------------------------------------------%
:- type field_list == assoc_list(sym_name, list(prog_term)).
% Expand a field update goal into a list of goals which each get or set
% one level of the structure.
%
% A field update goal:
% Term = Term0 ^ module_info ^ ctors := Ctors
% is expanded into
% V_1 = Term0 ^ module_info,
% V_3 = V_2 ^ ctors := Ctors,
% Term = Term0 ^ module_info := V_3.
%
:- pred expand_set_field_function_call(prog_context::in,
unify_main_context::in, unify_sub_contexts::in, field_list::in,
prog_var::in, prog_var::in, prog_var::in, cons_id::out,
pair(cons_id, unify_sub_contexts)::out, hlds_goal::out,
svar_state::in, svar_state::out, svar_store::in, svar_store::out,
prog_varset::in, prog_varset::out,
module_info::in, module_info::out, qual_info::in, qual_info::out,
list(error_spec)::in, list(error_spec)::out) is det.
% Expand a field extraction goal into a list of goals which each get one
% level of the structure.
%
% A field extraction goal:
% := (ModuleName, ^ module_info ^ sub_info ^ module_name,
% DCG_in, DCG_out).
% is expanded into
% DCG_out = DCG_in,
% V_1 = DCG_out ^ module_info
% V_2 = V_1 ^ sub_info,
% ModuleName = V_2 ^ module_name.
%
:- pred expand_dcg_field_extraction_goal(prog_context::in,
unify_main_context::in, unify_sub_contexts::in, field_list::in,
prog_var::in, prog_var::in, prog_var::in, cons_id::out,
pair(cons_id, unify_sub_contexts)::out, hlds_goal::out,
svar_state::in, svar_state::out, svar_store::in, svar_store::out,
prog_varset::in, prog_varset::out,
module_info::in, module_info::out, qual_info::in, qual_info::out,
list(error_spec)::in, list(error_spec)::out) is det.
% Expand a field extraction function call into a list of goals which
% each get one level of the structure.
%
% A field extraction goal:
% ModuleName = Info ^ module_info ^ sub_info ^ module_name
% is expanded into
% V_1 = Info ^ module_info,
% V_2 = V_1 ^ sub_info,
% ModuleName = V_2 ^ module_name.
%
:- pred expand_get_field_function_call(prog_context::in,
unify_main_context::in, unify_sub_contexts::in, field_list::in,
prog_var::in, prog_var::in, purity::in, cons_id::out,
pair(cons_id, unify_sub_contexts)::out, hlds_goal::out,
svar_state::in, svar_state::out, svar_store::in, svar_store::out,
prog_varset::in, prog_varset::out,
module_info::in, module_info::out, qual_info::in, qual_info::out,
list(error_spec)::in, list(error_spec)::out) is det.
:- pred maybe_parse_field_list(prog_term::in, prog_varset::in,
field_list::out) is semidet.
:- pred parse_field_list(prog_term::in, prog_varset::in,
list(format_component)::in, maybe1(field_list)::out) is det.
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module hlds.hlds_data.
:- import_module hlds.hlds_pred.
:- import_module hlds.make_hlds.superhomogeneous.
:- import_module parse_tree.parse_tree_out_term.
:- import_module parse_tree.prog_io_sym_name.
:- import_module int.
:- import_module require.
:- import_module term.
:- import_module varset.
%-----------------------------------------------------------------------------%
expand_set_field_function_call(Context, MainContext, SubContext0, FieldNames,
FieldValueVar, TermInputVar, TermOutputVar, Functor, FieldSubContext,
Goal, !SVarState, !SVarStore, !VarSet,
!ModuleInfo, !QualInfo, !Specs) :-
expand_set_field_function_call_2(Context, MainContext, SubContext0,
FieldNames, FieldValueVar, TermInputVar, TermOutputVar, Functor,
FieldSubContext, Goals,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs),
goal_info_init(Context, GoalInfo),
conj_list_to_goal(Goals, GoalInfo, Goal).
:- pred expand_set_field_function_call_2(prog_context::in,
unify_main_context::in, unify_sub_contexts::in, field_list::in,
prog_var::in, prog_var::in, prog_var::in, cons_id::out,
pair(cons_id, unify_sub_contexts)::out, list(hlds_goal)::out,
svar_state::in, svar_state::out, svar_store::in, svar_store::out,
prog_varset::in, prog_varset::out,
module_info::in, module_info::out, qual_info::in, qual_info::out,
list(error_spec)::in, list(error_spec)::out) is det.
expand_set_field_function_call_2(_, _, _, [], _, _, _, _, _, _,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs) :-
unexpected($module, $pred, "empty list of field names").
expand_set_field_function_call_2(Context, MainContext, SubContext0,
[FieldName - FieldArgs | FieldNames], FieldValueVar,
TermInputVar, TermOutputVar, Functor, FieldSubContext, Goals,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs) :-
make_fresh_arg_vars_subst_svars(FieldArgs, FieldArgVars, !VarSet,
!SVarState, !Specs),
(
FieldNames = [_ | _],
varset.new_var(SubTermInputVar, !VarSet),
varset.new_var(SubTermOutputVar, !VarSet),
SetArgs = FieldArgVars ++ [TermInputVar, SubTermOutputVar],
construct_field_access_function_call(set, Context,
MainContext, SubContext0, FieldName, TermOutputVar,
SetArgs, purity_pure, Functor, UpdateGoal, !QualInfo),
% Extract the field containing the field to update.
construct_field_access_function_call(get, Context,
MainContext, SubContext0, FieldName, SubTermInputVar,
FieldArgVars ++ [TermInputVar], purity_pure, _, GetSubFieldGoal,
!QualInfo),
% Recursively update the field.
SubTermInputArgNumber = 2 + list.length(FieldArgs),
TermInputContext = unify_sub_context(Functor, SubTermInputArgNumber),
SubContext = [TermInputContext | SubContext0],
expand_set_field_function_call_2(Context, MainContext,
SubContext, FieldNames, FieldValueVar, SubTermInputVar,
SubTermOutputVar, _, FieldSubContext, Goals0,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs),
Goals1 = [GetSubFieldGoal | Goals0] ++ [UpdateGoal]
;
FieldNames = [],
SetArgs = FieldArgVars ++ [TermInputVar, FieldValueVar],
construct_field_access_function_call(set, Context,
MainContext, SubContext0, FieldName, TermOutputVar,
SetArgs, purity_pure, Functor, Goal, !QualInfo),
FieldSubContext = Functor - SubContext0,
Goals1 = [Goal]
),
ArgContext = ac_functor(Functor, MainContext, SubContext0),
goal_info_init(Context, GoalInfo),
conj_list_to_goal(Goals1, GoalInfo, Conj0),
insert_arg_unifications(FieldArgVars, FieldArgs, Context, ArgContext,
Conj0, Conj, !SVarState, !SVarStore, !VarSet,
!ModuleInfo, !QualInfo, !Specs),
svar_goal_to_conj_list(Conj, Goals, !SVarStore).
expand_dcg_field_extraction_goal(Context, MainContext, SubContext, FieldNames,
FieldValueVar, TermInputVar, TermOutputVar, Functor, FieldSubContext,
Goal, !SVarState, !SVarStore, !VarSet,
!ModuleInfo, !QualInfo, !Specs) :-
% Unify the DCG input and output variables.
make_atomic_unification(TermOutputVar, rhs_var(TermInputVar), Context,
MainContext, SubContext, UnifyDCG, !QualInfo),
% Process the access function as a get function on the output DCG variable.
expand_get_field_function_call_2(Context, MainContext, SubContext,
FieldNames, FieldValueVar, TermOutputVar, purity_pure,
Functor, FieldSubContext, Goals1,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs),
Goals = [UnifyDCG | Goals1],
goal_info_init(Context, GoalInfo),
conj_list_to_goal(Goals, GoalInfo, Goal).
expand_get_field_function_call(Context, MainContext, SubContext0, FieldNames,
FieldValueVar, TermInputVar, Purity, Functor, FieldSubContext,
Goal, !SVarState, !SVarStore, !VarSet,
!ModuleInfo, !QualInfo, !Specs) :-
expand_get_field_function_call_2(Context, MainContext, SubContext0,
FieldNames, FieldValueVar, TermInputVar, Purity, Functor,
FieldSubContext, Goals, !SVarState, !SVarStore, !VarSet,
!ModuleInfo, !QualInfo, !Specs),
goal_info_init(Context, GoalInfo),
conj_list_to_goal(Goals, GoalInfo, Goal).
:- pred expand_get_field_function_call_2(prog_context::in,
unify_main_context::in, unify_sub_contexts::in, field_list::in,
prog_var::in, prog_var::in, purity::in, cons_id::out,
pair(cons_id, unify_sub_contexts)::out, list(hlds_goal)::out,
svar_state::in, svar_state::out, svar_store::in, svar_store::out,
prog_varset::in, prog_varset::out,
module_info::in, module_info::out, qual_info::in, qual_info::out,
list(error_spec)::in, list(error_spec)::out) is det.
expand_get_field_function_call_2(_, _, _, [], _, _, _, _, _, _,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs) :-
unexpected($module, $pred, "empty list of field names").
expand_get_field_function_call_2(Context, MainContext, SubContext0,
[FieldName - FieldArgs | FieldNames], FieldValueVar, TermInputVar,
Purity, Functor, FieldSubContext, Goals,
!SVarState, !SVarStore, !VarSet, !ModuleInfo, !QualInfo, !Specs) :-
make_fresh_arg_vars_subst_svars(FieldArgs, FieldArgVars, !VarSet,
!SVarState, !Specs),
GetArgVars = FieldArgVars ++ [TermInputVar],
(
FieldNames = [_ | _],
varset.new_var(SubTermInputVar, !VarSet),
construct_field_access_function_call(get, Context, MainContext,
SubContext0, FieldName, SubTermInputVar, GetArgVars, Purity,
Functor, Goal, !QualInfo),
% Recursively extract until we run out of field names.
TermInputArgNumber = 1 + list.length(FieldArgVars),
TermInputContext = unify_sub_context(Functor, TermInputArgNumber),
SubContext = [TermInputContext | SubContext0],
expand_get_field_function_call_2(Context, MainContext,
SubContext, FieldNames, FieldValueVar, SubTermInputVar, Purity,
_, FieldSubContext, Goals1, !SVarState, !SVarStore,
!VarSet, !ModuleInfo, !QualInfo, !Specs),
Goals2 = [Goal | Goals1]
;
FieldNames = [],
FieldSubContext = Functor - SubContext0,
construct_field_access_function_call(get, Context,
MainContext, SubContext0, FieldName, FieldValueVar,
GetArgVars, Purity, Functor, Goal, !QualInfo),
Goals2 = [Goal]
),
ArgContext = ac_functor(Functor, MainContext, SubContext0),
goal_info_init(Context, GoalInfo),
conj_list_to_goal(Goals2, GoalInfo, Conj0),
insert_arg_unifications(FieldArgVars, FieldArgs, Context, ArgContext,
Conj0, Conj, !SVarState, !SVarStore, !VarSet,
!ModuleInfo, !QualInfo, !Specs),
svar_goal_to_conj_list(Conj, Goals, !SVarStore).
:- pred construct_field_access_function_call(field_access_type::in,
prog_context::in, unify_main_context::in, unify_sub_contexts::in,
sym_name::in, prog_var::in, list(prog_var)::in, purity::in,
cons_id::out, hlds_goal::out, qual_info::in, qual_info::out) is det.
construct_field_access_function_call(AccessType, Context,
MainContext, SubContext, FieldName, RetArg, Args, Purity, Functor,
Goal, !QualInfo) :-
field_access_function_name(AccessType, FieldName, FuncName),
list.length(Args, Arity),
Functor = cons(FuncName, Arity, cons_id_dummy_type_ctor),
make_atomic_unification(RetArg,
rhs_functor(Functor, is_not_exist_constr, Args),
Context, MainContext, SubContext, Purity, Goal, !QualInfo).
maybe_parse_field_list(Term, VarSet, FieldNames) :-
% The value of ContextPieces does not matter, since we succeed
% only if it is not used.
%
% We could construct a dummy VarSet as well, if needed.
ContextPieces = [],
parse_field_list(Term, VarSet, ContextPieces, MaybeFieldNames),
MaybeFieldNames = ok1(FieldNames).
parse_field_list(Term, VarSet, ContextPieces, MaybeFieldNames) :-
( if
Term = term.functor(term.atom("^"),
[FieldNameTerm, OtherFieldNamesTerm], _)
then
( if try_parse_sym_name_and_args(FieldNameTerm, FieldName, Args) then
parse_field_list(OtherFieldNamesTerm, VarSet, ContextPieces,
MaybeFieldNamesTail),
(
MaybeFieldNamesTail = error1(_),
MaybeFieldNames = MaybeFieldNamesTail
;
MaybeFieldNamesTail = ok1(FieldNamesTail),
MaybeFieldNames = ok1([FieldName - Args | FieldNamesTail])
)
else
Spec = make_field_list_error(VarSet,
get_term_context(FieldNameTerm), Term, ContextPieces),
MaybeFieldNames = error1([Spec])
)
else
( if try_parse_sym_name_and_args(Term, FieldName, Args) then
MaybeFieldNames = ok1([FieldName - Args])
else
Spec = make_field_list_error(VarSet, get_term_context(Term), Term,
ContextPieces),
MaybeFieldNames = error1([Spec])
)
).
:- func make_field_list_error(prog_varset, term.context, prog_term,
list(format_component)) = error_spec.
make_field_list_error(VarSet, Context, Term, ContextPieces) = Spec :-
TermStr = mercury_term_to_string(VarSet, print_name_only, Term),
Pieces = ContextPieces ++ [lower_case_next_if_not_first,
words("Error: expected field name at term"),
quote(TermStr), suffix("."), nl],
Spec = error_spec(severity_error, phase_term_to_parse_tree,
[simple_msg(Context, [always(Pieces)])]).
%-----------------------------------------------------------------------------%
:- end_module hlds.make_hlds.field_access.
%-----------------------------------------------------------------------------%