e8e39e597b
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@843 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
68 lines
1.8 KiB
Plaintext
68 lines
1.8 KiB
Plaintext
:- object(url).
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:- info([
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version is 1.0,
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date is 2003/7/7,
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author is 'Paulo Moura',
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comment is 'Simple example of URL parsing.']).
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:- public(parse/2).
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:- mode(parse(@list, -list), zero_or_one).
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:- info(parse/2, [
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comment is 'Parses a URL into its components.',
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argnames is ['URL', 'Components']]).
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parse(URL, [protocol(Protocol), address(Address), path(Path), file(File)]) :-
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phrase(url(Protocol, Address, Path, File), URL).
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url(Protocol, Address, Path, File) --> protocol(Protocol), "://", address(Address), path(Path), file(File).
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protocol(ftp) --> "ftp".
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protocol(http) --> "http".
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protocol(https) --> "https".
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protocol(rtsp) --> "rtsp".
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address(Address) --> ip_number(Address).
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address([Identifier| Identifiers]) --> identifier(Identifier), dot_identifiers(Identifiers).
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ip_number([N1, N2, N3, N4]) --> ip_subnumber(N1), ".", ip_subnumber(N2), ".", ip_subnumber(N3), ".", ip_subnumber(N4).
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ip_subnumber(N) --> [N1, N2, N3], {N is N3 - 0'0 + 10*(N2 - 0'0) + 100*(N1 - 0'0), N >= 0, N =< 255}.
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ip_subnumber(N) --> [N1, N2], {N is N2 - 0'0 + 10*(N1 - 0'0), N >= 0, N =< 255}.
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ip_subnumber(N) --> [N1], {N is N1 - 0'0, N >= 0, N =< 255}.
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identifier(Identifier) --> characters(Codes), {atom_codes(Identifier, Codes)}.
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characters([]) --> [].
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characters([Code| Codes]) --> [Code], {character(Code)}, characters(Codes).
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character(Code) :- Code @>= 0'a, Code @=< 0'z, !.
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character(Code) :- Code @>= 0'A, Code @=< 0'Z.
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dot_identifiers([]) --> [].
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dot_identifiers([Identifier| Identifiers]) --> ".", identifier(Identifier), dot_identifiers(Identifiers).
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path([]) --> [].
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path([Identifier| Path]) --> "/", identifier(Identifier), path(Path).
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file('') --> [].
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file(File) --> "/", identifier(Name), ".", identifier(Extension), {atom_concat(Name, '.', Aux), atom_concat(Aux, Extension, File)}.
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:- end_object.
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