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