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One option, --warn-non-contiguous-decls, generates warnings if the
mode declarations of a predicate or function aren't in a contiguous block
immediately following the pred or func declaration. Since this is a rare
kind of "style error", this option is enabled by default.
Two options, --warn-inconsistent-pred-order-clauses and
--warn-inconsistent-pred-order-foreign-procs, warn about inconsistencies
between (a) the order in which predicates (and functions) are declared,
and (b) the order in which they are defined. The two options differ in
their scope. The latter applies to all predicates and functions defined
in the module, while the former applies only to those whose definitions
include Mercury clauses.
Since an exported predicate or function may need nonexported auxiliary
predicates and/or functions, imposing a single order the declarations and
definitions of *all* the predicates and functions in a module is not a good
idea. Instead, both options divide the predicates and functions defined
in a module two groups, the exported and the nonexported, and expect
a consistent order only within each group.
The result is output that looks like this:
time.m:021: Warning: the order of the declarations and definitions of the
time.m:021: exported predicates is inconsistent, as shown by this diff:
time.m:021:
time.m:021: --- declaration order
time.m:021: +++ definition order
time.m:021: @@ -1,7 +1,7 @@
time.m:021: predicate `clock'/3
time.m:021: -predicate `time'/3
time.m:021: predicate `times'/4
time.m:021: function `clk_tck'/0
time.m:021: +predicate `time'/3
time.m:021: function `difftime'/2
time.m:021: predicate `localtime'/4
time.m:021: function `localtime'/1
compiler/options.m:
doc/user_guide.texi:
Add the new options.
compiler/style_checks.m:
A new module that generates the new warnings if warranted.
compiler/check_hlds.m:
compiler/notes/compiler_design.html:
Include and document the new module.
compiler/mercury_compile_front_end.m:
Invoke the new module if any of the three new options is set.
compiler/hlds_pred.m:
Record the item number of every predicate, function, and mode declaration
in the module being compiled. We need this for information for the
new warnings.
compiler/hlds_module.m:
Record the context of the module declaration. We use this context
for warnings about inconsistent order, since there isn't a better one.
compiler/hlds_clauses.m:
Add a mechanism to retrieve the item numbers of a set of clauses
even if they are contiguous.
Document some old data types.
compiler/error_util.m:
Add a new phase for style checks.
compiler/accumulator.m:
compiler/add_class.m:
compiler/add_mutable_aux_preds.m:
compiler/add_pragma_tabling.m:
compiler/add_pred.m:
compiler/add_solver.m:
compiler/add_special_pred.m:
compiler/check_typeclass.m:
compiler/clause_to_proc.m:
compiler/from_ground_term_util.m:
compiler/lambda.m:
compiler/make_hlds.m:
compiler/make_hlds_passes.m:
compiler/mercury_compile.m:
compiler/par_loop_control.m:
compiler/polymorphism.m:
compiler/stm_expand.m:
compiler/table_gen.m:
compiler/unify_proc.m:
Conform the changes to the HLDS above.
compiler/typecheck_errors.m:
Fix style of error messages.
library/array2d.m:
library/assoc_list.m:
library/benchmarking.m:
library/bit_buffer.write.m:
library/bool.m:
library/builtin.m:
library/construct.m:
library/cord.m:
library/counter.m:
library/float.m:
library/injection.m:
library/lazy.m:
library/lexer.m:
library/ops.m:
library/private_builtin.m:
library/profiling_builtin.m:
library/prolog.m:
library/queue.m:
library/rational.m:
library/require.m:
library/stack.m:
library/std_util.m:
library/store.m:
library/thread.semaphore.m:
library/tree234.m:
library/univ.m:
library/version_store.m:
Move declarations or definitions around to avoid some of the warnings
that we can now generate. (There are many more left.)
Make some minor style improvements in the process.
tests/warnings/inconsistent_pred_order.{m,exp}:
tests/warnings/non_contiguous_decls.{m,exp}:
New test cases to test the new options. They are both copies of
tests/benchmarks/queens.m, with intentionally-screwed-up style.
tests/warnings/Mmakefile:
Enable the new test cases.
tests/warnings/Mercury.options:
Specify the options being tested for the new test cases.
tests/benchmarks/queens.m:
Bring the style of this module up to date (before copying it).
tests/invalid/mode_decl_in_wrong_section.err_exp:
Expect the warnings we now generate.
111 lines
2.7 KiB
Mathematica
111 lines
2.7 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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%
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% This program solves the N-queens problem. Given an N-by-N chessboard,
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% this problem asks us to find positions for N queens on the board such
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% that they do not attack each other. This means that no two queens can be
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%
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% - in the same row
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% - in the same column
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% - on the same diagnonal.
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%
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% We print the result as a list of integers. Each integer corresponds to one
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% of the board's N columns, and it gives the number of the row occupied by
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% the queen in that column. (Given the constraints of the problem, every column
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% must be occupied by exactly one queen.)
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:- module queens.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is cc_multi.
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:- implementation.
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:- import_module int.
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:- import_module list.
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main(!IO) :-
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data(Data),
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( if queen(Data, Out) then
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print_list(Out, !IO)
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else
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io.write_string("No solution\n", !IO)
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).
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% With this data, this program solves the 8-queens problem. To solve the
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% N-queens problem for some other N, make this predicate return the first
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% N integers.
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:- pred data(list(int)::out) is det.
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data([1, 2, 3, 4, 5, 6, 7, 8]).
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:- pred queen(list(int)::in, list(int)::out) is nondet.
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queen(Data, Perm) :-
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qperm(Data, Perm),
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safe(Perm).
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:- pred qperm(list(int)::in, list(int)::out) is nondet.
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qperm([], []).
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qperm([H | T], Perm) :-
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qdelete([H | T], Element, Rest),
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qperm(Rest, RestPerm),
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Perm = [Element | RestPerm].
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:- pred qdelete(list(int)::in, int::out, list(int)::out) is nondet.
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qdelete([H | T], H, T).
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qdelete([H | T], E, [H | NT]) :-
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qdelete(T, E, NT).
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:- pred safe(list(int)::in) is semidet.
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safe([]).
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safe([H | T]) :-
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nodiag(H, 1, T),
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safe(T).
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:- pred nodiag(int::in, int::in, list(int)::in) is semidet.
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nodiag(_, _, []).
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nodiag(TestRow, !.Diff, [Row | Rows]) :-
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( if !.Diff = Row - TestRow then
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fail
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else if !.Diff = TestRow - Row then
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fail
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else
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true
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),
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!:Diff = !.Diff + 1,
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nodiag(TestRow, !.Diff, Rows).
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:- pred print_list(list(int)::in, io::di, io::uo) is det.
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print_list(Xs, !IO) :-
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(
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Xs = [],
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io.write_string("[]\n", !IO)
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;
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Xs = [H | T],
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io.write_string("[", !IO),
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print_list_elements(H, T, !IO),
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io.write_string("]\n", !IO)
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).
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:- pred print_list_elements(int::in, list(int)::in, io::di, io::uo) is det.
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print_list_elements(X, Xs, !IO) :-
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io.write_int(X, !IO),
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(
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Xs = []
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;
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Xs = [H | T],
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io.write_string(", ", !IO),
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print_list_elements(H, T, !IO)
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).
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