243 lines
7.5 KiB
Prolog
243 lines
7.5 KiB
Prolog
:- module(charsio, [char_type/2,
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chars_utf8bytes/2,
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get_single_char/1,
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read_line_to_chars/3,
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read_term_from_chars/2,
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write_term_to_chars/3,
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chars_base64/3]).
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:- use_module(library(dcgs)).
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:- use_module(library(iso_ext)).
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:- use_module(library(error)).
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:- use_module(library(lists)).
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fabricate_var_name(VarType, VarName, N) :-
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char_code('A', AC),
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LN is N mod 26 + AC,
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char_code(LC, LN),
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NN is N // 26,
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( NN =:= 0 ->
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( VarType == fabricated ->
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atom_chars(VarName, ['_', LC])
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; VarType == numbervars ->
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atom_chars(VarName, [LC])
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)
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; number_chars(NN, NNChars),
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( VarType == fabricated ->
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atom_chars(VarName, ['_', LC | NNChars])
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; VarType == numbervars ->
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atom_chars(VarName, [LC | NNChars])
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)
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).
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var_list_contains_name([VarName = _ | VarList], VarName0) :-
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( VarName == VarName0 -> true
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; var_list_contains_name(VarList, VarName0)
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).
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var_list_contains_variable([_ = Var | VarList], Var0) :-
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( Var == Var0 -> true
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; var_list_contains_variable(VarList, Var0)
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).
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make_new_var_name(VarType, V, VarName, N, N1, VarList) :-
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fabricate_var_name(VarType, VarName0, N),
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( var_list_contains_name(VarList, VarName0) ->
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N0 is N + 1,
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make_new_var_name(VarType, V, VarName, N0, N1, VarList)
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; VarName = VarName0,
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N1 is N + 1
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).
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extend_var_list(Vars, VarList, NewVarList, VarType) :-
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extend_var_list_(Vars, 0, VarList, NewVarList0, VarType),
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append(VarList, NewVarList0, NewVarList).
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extend_var_list_([], _, VarList, [], _).
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extend_var_list_([V|Vs], N, VarList, NewVarList, VarType) :-
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( var_list_contains_variable(VarList, V) ->
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extend_var_list_(Vs, N, VarList, NewVarList, VarType)
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; make_new_var_name(VarType, V, VarName, N, N1, VarList),
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NewVarList = [VarName = V | NewVarList0],
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extend_var_list_(Vs, N1, VarList, NewVarList0, VarType)
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).
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char_type(Char, Type) :-
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( var(Char) -> instantiation_error(char_type/2)
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; atom_length(Char, 1) ->
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( ground(Type) ->
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( ctype(Type) ->
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'$char_type'(Char, Type)
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; domain_error(char_type, Type, char_type/2)
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)
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; ctype(Type),
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'$char_type'(Char, Type)
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)
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; type_error(in_character, Char, char_type/2)
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).
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ctype(alnum).
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ctype(alpha).
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ctype(alphabetic).
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ctype(ascii).
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ctype(ascii_graphic).
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ctype(ascii_punctuation).
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ctype(binary_digit).
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ctype(control).
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ctype(decimal_digit).
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ctype(exponent).
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ctype(graphic).
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ctype(hexadecimal_digit).
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ctype(layout).
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ctype(lower).
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ctype(meta).
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ctype(numeric).
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ctype(octal_digit).
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ctype(prolog).
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ctype(sign).
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ctype(solo).
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ctype(symbolic_control).
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ctype(symbolic_hexadecimal).
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ctype(upper).
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ctype(whitespace).
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get_single_char(C) :-
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( var(C) -> '$get_single_char'(C)
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; atom_length(C, 1) -> '$get_single_char'(C)
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; type_error(in_character, C, get_single_char/1)
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).
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read_term_from_chars(Chars, Term) :-
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( var(Chars) ->
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instantiation_error(read_term_from_chars/2)
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; nonvar(Term) ->
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throw(error(uninstantiation_error(Term), read_term_from_chars/2))
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; '$skip_max_list'(_, -1, Chars, Chars0),
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Chars0 == [],
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partial_string(Chars) ->
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true
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;
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type_error(complete_string, Chars, read_term_from_chars/2)
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),
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'$read_term_from_chars'(Chars, Term).
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write_term_to_chars(_, Options, _) :-
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var(Options), instantiation_error(write_term_to_chars/3).
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write_term_to_chars(Term, Options, Chars) :-
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builtins:parse_write_options(Options,
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[IgnoreOps, MaxDepth, NumberVars, Quoted, VNNames],
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write_term_to_chars/3),
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( nonvar(Chars) ->
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throw(error(uninstantiation_error(Chars), write_term_to_chars/3))
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;
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true
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),
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term_variables(Term, Vars),
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extend_var_list(Vars, VNNames, NewVarNames, numbervars),
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'$write_term_to_chars'(Chars, Term, IgnoreOps, NumberVars, Quoted, NewVarNames, MaxDepth).
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% Encodes Ch character to list of Bytes.
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char_utf8bytes(Ch, Bytes) :-
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char_code(Ch, Code),
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phrase(code_to_utf8(Code), Bytes).
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code_to_utf8(Code) --> {Code @< 0x80}, [Code], !.
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code_to_utf8(Code) --> {Code @< 0x800}, encode(Code, 0xC0, 2), !.
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code_to_utf8(Code) --> {Code @< 0x10000}, encode(Code, 0xE0, 3), !.
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code_to_utf8(Code) --> {Code @< 0x110000}, encode(Code, 0xF0, 4), !.
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encode(_, _, 0) --> !.
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encode(Code, Prefix, Nb) -->
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{ Nb1 is Nb - 1, Byte is Prefix \/ ((Code >> (6 * Nb1)) /\ 0x3F) },
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[Byte], encode(Code, 0x80, Nb1).
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% Maps characters and UTF-8 bytes.
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% If Cs is a variable, parses Bs as a list of UTF-8 bytes.
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% Otherwise, transform the list of characters Cs to UTF-8 bytes.
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chars_utf8bytes(Cs, Bs) :-
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var(Cs), must_be(list, Bs) ->
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once(phrase(decode_utf8(Cs), Bs))
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; (must_be(list, Cs),
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maplist(must_be(atom), Cs),
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maplist(char_utf8bytes, Cs, Bss),
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append(Bss, Bs)).
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decode_utf8([]) --> [].
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decode_utf8(Chars) --> leading(Nb, Code), continuation(Code, Chars, Nb).
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leading(1, Byte) --> [Byte], {Byte /\ 0x80 =:= 0}.
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leading(2, Code) --> [Byte], {Byte /\ 0xE0 =:= 0xC0, Code is Byte - 0xC0}.
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leading(3, Code) --> [Byte], {Byte /\ 0xF0 =:= 0xE0, Code is Byte - 0xE0}.
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leading(4, Code) --> [Byte], {Byte /\ 0xF8 =:= 0xF0, Code is Byte - 0xF0}.
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leading(1, 0xFFFD) --> [_]. % invalid first byte
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continuation(Code, [H|T], 1) --> {char_code(H, Code)}, decode_utf8(T).
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continuation(Code, Chars, Nb) --> [Byte],
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{Nb1 is Nb - 1, Byte /\ 0xC0 =:= 0x80, NextCode is (Code << 6) \/ (Byte - 0x80)},
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continuation(NextCode, Chars, Nb1).
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% invalid continuation byte
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% each remaining continuation byte (if any) will raise 0xFFFD too
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continuation(_, ['\xFFFD\'|T], _) --> [_], decode_utf8(T).
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read_line_to_chars(Stream, Cs0, Cs) :-
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'$get_n_chars'(Stream, 1, Char), % this also works for binary streams
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( Char == [] -> Cs0 = Cs
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; Char = [C],
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Cs0 = [C|Rest],
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( C == '\n' -> Rest = Cs
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; read_line_to_chars(Stream, Rest, Cs)
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)
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).
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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Relation between a list of characters Cs and its Base64 encoding Bs,
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also a list of characters.
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At least one of the arguments must be instantiated.
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Options are:
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- padding(Boolean)
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Whether to use padding: true (the default) or false.
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- charset(C)
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Either 'standard' (RFC 4648 §4, the default) or 'url' (RFC 4648 §5).
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Example:
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?- chars_base64("hello", Bs, []).
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Bs = "aGVsbG8="
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; false.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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chars_base64(Cs, Bs, Options) :-
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must_be(list, Options),
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( member(O, Options), var(O) ->
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instantiation_error(chars_base64/3)
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; ( member(padding(Padding), Options) -> true
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; Padding = true
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),
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( member(charset(Charset), Options) -> true
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; Charset = standard
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)
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),
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must_be(boolean, Padding),
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must_be(atom, Charset),
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( member(Charset, [standard,url]) -> true
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; domain_error(charset, Charset, chars_base64/3)
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),
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( var(Cs) ->
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must_be(list, Bs),
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maplist(must_be(character), Bs),
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'$chars_base64'(Cs, Bs, Padding, Charset)
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; must_be(list, Cs),
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maplist(must_be(character), Cs),
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'$chars_base64'(Cs, Bs, Padding, Charset)
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).
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