86 lines
2.9 KiB
Prolog
86 lines
2.9 KiB
Prolog
:- module(charsio, [read_term_from_chars/2,
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write_term_to_chars/3]).
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:- use_module(library(iso_ext)).
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fabricate_var_name(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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atom_chars(VarName, ['_', LC])
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; number_chars(NN, NNChars),
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atom_chars(VarName, ['_', LC | NNChars])
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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(V, VarName, N, N1, VarList) :-
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fabricate_var_name(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(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(Value, VarList, NewVarList) :-
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term_variables(Value, Vars),
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extend_var_list_(Vars, 0, VarList, NewVarList).
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extend_var_list_([], N, VarList, VarList).
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extend_var_list_([V|Vs], N, VarList, NewVarList) :-
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( var_list_contains_variable(VarList, V) ->
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extend_var_list_(Vs, N, VarList, NewVarList)
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; make_new_var_name(V, VarName, N, N1, VarList),
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NewVarList = [VarName = V | NewVarList0],
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extend_var_list_(Vs, N1, VarList, NewVarList0)
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).
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read_term_from_chars(Chars, Term) :-
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( var(Chars) ->
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throw(error(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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; '$skip_max_list'(_, -1, Chars, Chars0),
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Chars0 == [],
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partial_string(Chars) ->
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true
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;
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throw(error(type_error(complete_string, Chars), read_term_from_chars/2))
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),
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'$read_term_from_chars'(Chars, Term).
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write_term_to_chars(_, Options, _) :-
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var(Options), throw(error(instantiation_error, write_term_to_chars/3)).
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write_term_to_chars(Term, Options, Chars) :-
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'$skip_max_list'(_, -1, Options, Options0),
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( var(Options0) ->
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throw(error(instantiation_error, write_term_to_chars/3))
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; nonvar(Chars) ->
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throw(error(uninstantiation_error(Chars), write_term_to_chars/3))
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; Options0 == [] ->
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true
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;
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throw(error(type_error(list, Options), write_term_to_chars/3))
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),
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builtins:inst_member_or(Options, ignore_ops(IgnoreOps), ignore_ops(false)),
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builtins:inst_member_or(Options, numbervars(NumberVars), numbervars(false)),
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builtins:inst_member_or(Options, quoted(Quoted), quoted(false)),
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builtins:inst_member_or(Options, variable_names(VarNames), variable_names([])),
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builtins:inst_member_or(Options, max_depth(MaxDepth), max_depth(0)),
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extend_var_list(Term, VarNames, NewVarNames),
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'$write_term_to_chars'(Term, IgnoreOps, NumberVars, Quoted, NewVarNames, MaxDepth, Chars).
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