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yap-6.3/packages/xml/xml.lpa.pl

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/* xml.lpa.pl : Wrapper for LPA Prolog.
*
* Copyright (C) 2001-2005 Binding Time Limited
* Copyright (C) 2005-2011 John Fletcher
*
* Current Release: $Revision: 3.3 $
*
* TERMS AND CONDITIONS:
*
* This program is offered free of charge, as unsupported source code. You may
* use it, copy it, distribute it, modify it or sell it without restriction,
* but entirely at your own risk.
*
* xml is intended to be a rather modular module: it should be easy to
* build a program that can output XML, but not read it, or vice versa.
* Similarly, you may be happy to dispense with diagnosis once you are
* sure that your code will only try to make valid calls to xml_parse/2.
*
* It is intended that the code should be very portable too. Clearly,
* some small changes will be needed between platforms, but these should
* be limited to xml_utilities. xml_utilities contains most of the shared
* code and most of the potentially non-portable code.
*/
:- ensure_loaded( xml_driver ).
/* atom_codes/2, number_codes/2 and throw/1 are ISO predicates, mapped to
* the Quintus equivalent here.
*/
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/** @pred atom_codes(? _A_,? _L_) is iso
The predicate holds when at least one of the arguments is ground
(otherwise, an error message will be displayed). The argument _A_ will
be unified with an atom and _L_ with the list of the ASCII
codes for the characters of the external representation of _A_.
*/
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atom_codes( Atom, Codes ) :-
atom_chars( Atom, Codes ).
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/** @pred number_codes(? _A_,? _L_) is iso
The predicate holds when at least one of the arguments is ground
(otherwise, an error message will be displayed). The argument _A_
will be unified with a number and _L_ with the list of the ASCII
codes for the characters of the external representation of _A_.
*/
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number_codes( Number, Codes ) :-
number_chars( Number, Codes ).
/* xml_exception( +Message, +Document, +Culprit, +Path ) is a hook to
* raise an exception to be raised in respect of a fault in the XML Term:
* Document.
* - Culprit is a sub-term of Document which cannot be serialized;
* - Message is an atom naming the type of error;
* - Path is a string encoding a list of SubTerm's ancestor elements in the
* form <tag>{(id)}* where <tag> is the element tag and <id> is the value
* of any attribute _named_ id.
*/
xml_exception( Message, Document, Culprit, Path ) :-
throw( 23, xml_error([Message,Document,Culprit,Path] ) ).
/* select( ?Element, ?List0, ?List1 ) is true if List1 is equal to List0
* with Element removed.
*/
select( H, [H|T], T ).
select( Element, [H|T0], [H|T1] ):-
select( Element, T0, T1 ).
/* is_list( +List ) holds when List is a list.
*/
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/** @pred is_list(+ _List_)
True when _List_ is a proper list. That is, _List_
is bound to the empty list (nil) or a term with functor '.' and arity 2.
*/
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is_list( List ) :-
nonvar( List ),
is_list1( List ).
is_list1( [] ).
is_list1( [_|_] ).