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Reorganize deconstruct.m so that each predicate that deconstructs terms has
three variants:
- One that aborts when attempting to deconstruct non-canonical terms.
- One that succeeds when attempting to deconstruct a term of a non-canonical
type, but returns a constant such as "<<noncanonical>>" for such
deconstructions. It still aborts when deconstructing a noncanonical term
of an ordinarily canonical type, which can happen with HAL if the term
is currently a variable.
- One that succeeds when attempting to deconstruct non-canonical terms of both
kinds, but whose determinism requires its caller to be in a committed choice
context.
Each of the predicates function, arg, named_arg, deconstruct and
limited_deconstruct now has an extra argument that selects one of the three
variants above. Each of these predicates now has three modes, one for each
value of this argument. The separate predicates with _cc at the ends of their
names are now superseded by one of these modes.
At the same time, I also eliminated the distinction between arg and argument.
Arg used to check if the returned argument was of the expected type, and fail
if it wasn't, while argument used to return a univ. The new arg now returns
a value of an existential type, which the caller can now typecheck or put
into a univ as it pleases.
The descriptions of the changes:
library/deconstruct.m:
Implement the changes discussed above. Work around a bug by making
the foreign_procs return a univ from which we later extract the value;
this inefficiency should be fixed later, when the typechecker has been
fixed to allow different clauses to return existentially typed values.
library/std_util.m:
Reimplement the forwarding predicates that call deconstruct.m in terms
of its new interface.
library/io.m:
Make use of the new functionality in deconstruct.m to offer versions
of io__print and io__write that allow the user to choose how to print
noncanonical terms.
library/private_builtin.m:
Export the `sorry' predicate for use in deconstruct.m and elsewhere.
runtime/mercury_deconstruct.[ch]:
runtime/mercury_ml_expand_body.h:
runtime/mercury_ml_arg_body.h:
runtime/mercury_ml_deconstruct_body.h:
runtime/mercury_ml_functor_body.h:
Implement the new functionality.
library/store.m:
extras/trailed_update/tr_store.m:
Conform to the new interfaces of some functions in the updated files
in the runtime.
tests/debugger/polymorphic_output.exp*:
Update for an updated error message.
tests/hard_coded/deconstruct_arg.{m,exp*}:
Update the test case to test the committed choice versions of the
deconstruction predicates as well as the usual versions. (The aborting
versions cannot all be tested in a single test case.)
150 lines
5.1 KiB
C
150 lines
5.1 KiB
C
/*
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** vim:ts=4 sw=4 expandtab
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*/
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/*
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** Copyright (C) 2002 The University of Melbourne.
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** This file may only be copied under the terms of the GNU Library General
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** Public License - see the file COPYING.LIB in the Mercury distribution.
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*/
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/*
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** mercury_deconstruct.h
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**
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** This file declares utility functions for deconstructing terms,
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** for use by the standard library and the debugger.
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*/
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#ifndef MERCURY_DECONSTRUCT_H
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#define MERCURY_DECONSTRUCT_H
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#include "mercury_imp.h"
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#include <stdio.h>
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typedef struct {
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int num_extra_args;
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MR_Word *arg_values;
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MR_TypeInfo *arg_type_infos;
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bool can_free_arg_type_infos;
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} MR_Expand_Args_Fields;
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typedef struct {
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int arity;
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MR_ConstString functor;
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MR_Expand_Args_Fields args;
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} MR_Expand_Functor_Args_Info;
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typedef struct {
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int arity;
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MR_ConstString functor;
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MR_Expand_Args_Fields args;
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bool limit_reached;
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} MR_Expand_Functor_Args_Limit_Info;
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typedef struct {
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int arity;
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MR_ConstString functor_only;
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} MR_Expand_Functor_Only_Info;
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typedef struct {
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int arity;
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MR_Expand_Args_Fields args_only;
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} MR_Expand_Args_Only_Info;
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typedef struct {
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int arity;
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bool chosen_index_exists;
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MR_Word *chosen_value_ptr;
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MR_TypeInfo chosen_type_info;
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} MR_Expand_Chosen_Arg_Only_Info;
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/*
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** MR_NONCANON_ABORT asks that deconstructions of noncanonical types should
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** cause a runtime abort.
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**
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** MR_NONCANON_ALLOW asks that deconstructions of noncanonical types should
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** return a constant that indicates this fact.
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**
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** MR_NONCANON_CC asks that deconstruction of noncanonical types should
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** deconstruct the term as if it were canonical. Since by definition,
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** noncanonical types may have more than one representation for the same value,
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** this requires the caller to be in a committed choice context.
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*/
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typedef enum {
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MR_NONCANON_ABORT,
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MR_NONCANON_ALLOW,
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MR_NONCANON_CC
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} MR_noncanon_handling;
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extern void MR_expand_functor_args(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_Expand_Functor_Args_Info *expand_info);
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extern void MR_expand_functor_args_limit(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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int max_arity,
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MR_Expand_Functor_Args_Limit_Info *expand_info);
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extern void MR_expand_functor_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_Expand_Functor_Only_Info *expand_info);
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extern void MR_expand_args_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_Expand_Args_Only_Info *expand_info);
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extern void MR_expand_chosen_arg_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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int chosen, MR_Expand_Chosen_Arg_Only_Info *expand_info);
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extern void MR_expand_named_arg_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_ConstString chosen_name,
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MR_Expand_Chosen_Arg_Only_Info *expand_info);
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/*
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** MR_arg() takes the address of a term, its type, and an
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** argument position (the first argument being at position 1).
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** If the given term has an argument at that position, MR_arg
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** returns TRUE and fills in the locations pointed to by the
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** argument_ptr and arg_type_info_ptr arguments with the value
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** and type of the argument at the selected position.
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** If it doesn't, it fails (i.e. returns FALSE).
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**
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** You need to wrap MR_{save/restore}_transient_hp() around
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** calls to this function.
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*/
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extern bool MR_arg(MR_TypeInfo type_info, MR_Word *term, int arg_index,
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MR_TypeInfo *arg_type_info_ptr, MR_Word **argument_ptr,
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MR_noncanon_handling noncanon);
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/*
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** MR_named_arg() is just like MR_arg, except the argument
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** is selected by name, not by position.
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**
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** You need to wrap MR_{save/restore}_transient_hp() around
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** calls to this function.
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*/
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extern bool MR_named_arg(MR_TypeInfo type_info, MR_Word *term,
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MR_ConstString arg_name, MR_TypeInfo *arg_type_info_ptr,
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MR_Word **argument_ptr, MR_noncanon_handling noncanon);
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/*
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** MR_named_arg_num() takes the address of a term, its type,
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** and an argument name. If the given term has an argument
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** with the given name, it succeeds and returns the argument
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** number (counted starting from 0) of the argument. If it
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** doesn't, it fails (i.e. returns FALSE).
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**
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** You need to wrap MR_{save/restore}_transient_hp() around
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** calls to this function.
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*/
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extern bool MR_named_arg_num(MR_TypeInfo type_info, MR_Word *term_ptr,
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const char *arg_name, int *arg_num_ptr);
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#endif /* MERCURY_DECONSTRUCT_H */
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