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135 lines
4.1 KiB
Mathematica
135 lines
4.1 KiB
Mathematica
%-----------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et wm=0 tw=0
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%-----------------------------------------------------------------------------%
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% Copyright (C) 1993-1999, 2003, 2005-2006 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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% File: require.m.
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% Main author: fjh.
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% Stability: medium to high.
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%
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% This module provides features similar to <assert.h> in C.
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%
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- module require.
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:- interface.
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:- type software_error ---> software_error(string).
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% error(Message):
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%
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% Throw a `software_error(Message)' exception.
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% This will normally cause execution to abort with an error message.
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%
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:- pred error(string::in) is erroneous.
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% func_error(Message):
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%
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% An expression that results in a `software_error(Message)'
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% exception being thrown.
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%
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:- func func_error(string) = _ is erroneous.
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% require(Goal, Message):
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%
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% Call goal, and call error(Message) if Goal fails.
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% This is not as useful as you might imagine, since it requires
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% that the goal not produce any output variables. In
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% most circumstances you should use an explicit if-then-else
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% with a call to error/1 in the "else".
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%
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:- pred require((pred)::((pred) is semidet), string::in) is det.
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% report_lookup_error(Message, Key, Value):
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%
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% Call error/1 with an error message that is appropriate for
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% the failure of a lookup operation involving the specified
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% Key and Value. The error message will include Message
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% and information about Key and Value.
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%
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:- pred report_lookup_error(string::in, K::in, V::unused) is erroneous.
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% report_lookup_error(Message, Key):
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%
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% Call error/1 with an error message that is appropriate for
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% the failure of a lookup operation involving the specified
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% Key. The error message will include Message
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% and information about Key.
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%
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:- pred report_lookup_error(string::in, K::in) is erroneous.
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- implementation.
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:- import_module exception.
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:- import_module list.
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:- import_module string.
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:- import_module type_desc.
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%-----------------------------------------------------------------------------%
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require(Goal, Message) :-
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( call(Goal) ->
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true
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;
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error(Message),
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fail
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).
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%-----------------------------------------------------------------------------%
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report_lookup_error(Msg, K, V) :-
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KeyType = type_name(type_of(K)),
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ValueType = type_name(type_of(V)),
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string.append_list(
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[Msg,
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"\n\tKey Type: ",
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KeyType,
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"\n\tKey Value: ",
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string(K),
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"\n\tValue Type: ",
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ValueType
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],
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ErrorString),
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error(ErrorString).
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report_lookup_error(Msg, K) :-
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KeyType = type_name(type_of(K)),
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string.append_list(
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[Msg,
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"\n\tKey Type: ",
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KeyType,
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"\n\tKey Value: ",
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string(K)
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],
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ErrorString),
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error(ErrorString).
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%-----------------------------------------------------------------------------%
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% Hopefully error/1 won't be called often (!), so no point inlining it.
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:- pragma no_inline(error/1).
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% We declare error/1 to be terminating so that all of the standard library
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% will treat it as terminating.
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:- pragma terminates(error/1).
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error(Message) :-
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throw(software_error(Message)).
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% Hopefully func_error/1 won't be called often (!), so no point inlining it.
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:- pragma no_inline(func_error/1).
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func_error(Message) = _ :-
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error(Message).
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%-----------------------------------------------------------------------------%
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:- end_module require.
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%-----------------------------------------------------------------------------%
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