%---------------------------------------------------------------------------% % vim: ft=mercury ts=4 sw=4 et %---------------------------------------------------------------------------% % Copyright (C) 1994-2006, 2009, 2011-2012 The University of Melbourne. % This file may only be copied under the terms of the GNU Library General % Public License - see the file COPYING.LIB in the Mercury distribution. %---------------------------------------------------------------------------% % % File: term_io.m. % Main author: fjh. % Stability: medium to high. % % This file encapsulates all the term I/O. % This exports predicates to read and write terms in the % nice ground representation provided in term.m. % %---------------------------------------------------------------------------% %---------------------------------------------------------------------------% :- module term_io. :- interface. :- import_module char. :- import_module io. :- import_module ops. :- import_module stream. :- import_module term. :- import_module varset. %---------------------------------------------------------------------------% :- type read_term(T) ---> eof ; error(string, int) ; term(varset(T), term(T)). :- type read_term == read_term(generic). % read_term(Result, !IO): % % Read a term from standard input. Similar to NU-Prolog read_term/2, % except that resulting term is in the ground representation. % Binds Result to either `eof', `term(VarSet, Term)', or % `error(Message, LineNumber)'. % :- pred read_term(read_term(T)::out, io::di, io::uo) is det. % As above, except uses the given operator table instead of % the standard Mercury operators. % :- pred read_term_with_op_table(Ops::in, read_term(T)::out, io::di, io::uo) is det <= op_table(Ops). % Writes a term to standard output. Uses the variable names specified % by the varset. Writes _N for all unnamed variables, with N starting at 0. % :- pred write_term(varset(T)::in, term(T)::in, io::di, io::uo) is det. % As above, except uses the given operator table instead of the % standard Mercury operators. % :- pred write_term_with_op_table(Ops::in, varset(T)::in, term(T)::in, io::di, io::uo) is det <= op_table(Ops). % As above, except it appends a period and new-line. % :- pred write_term_nl(varset(T)::in, term(T)::in, io::di, io::uo) is det. % As above, except it appends a period and new-line. % :- pred write_term_nl_with_op_table(Ops::in, varset(T)::in, term(T)::in, io::di, io::uo) is det <= op_table(Ops). % Writes a constant (integer, float, string, or atom) to stdout. % :- pred write_constant(const::in, io::di, io::uo) is det. % Like write_constant, but return the result in a string. % :- func format_constant(const) = string. % Writes a variable to stdout. % :- pred write_variable(var(T)::in, varset(T)::in, io::di, io::uo) is det. % As above, except uses the given operator table instead of the % standard Mercury operators. % :- pred write_variable_with_op_table(Ops::in, var(T)::in, varset(T)::in, io::di, io::uo) is det <= op_table(Ops). % Given a string S, write S in double-quotes, with characters % escaped if necessary, to stdout. % :- pred quote_string(string::in, io::di, io::uo) is det. :- pred quote_string(Stream::in, string::in, State::di, State::uo) is det <= (stream.writer(Stream, string, State), stream.writer(Stream, char, State)). % Like quote_string, but return the result in a string. % :- func quoted_string(string) = string. % Given an atom-name A, write A, enclosed in single-quotes if necessary, % with characters escaped if necessary, to stdout. % :- pred quote_atom(string::in, io::di, io::uo) is det. :- pred quote_atom(Stream::in, string::in, State::di, State::uo) is det <= (stream.writer(Stream, string, State), stream.writer(Stream, char, State)). % Like quote_atom, but return the result in a string. % :- func quoted_atom(string) = string. % Given a character C, write C in single-quotes, % escaped if necessary, to stdout. % :- pred quote_char(char::in, io::di, io::uo) is det. :- pred quote_char(Stream::in, char::in, State::di, State::uo) is det <= (stream.writer(Stream, string, State), stream.writer(Stream, char, State)). % Like quote_char, but return the result in a string. % :- func quoted_char(char) = string. % Given a character C, write C, escaped if necessary, to stdout. % The character is not enclosed in quotes. % :- pred write_escaped_char(char::in, io::di, io::uo) is det. :- pred write_escaped_char(Stream::in, char::in, State::di, State::uo) is det <= (stream.writer(Stream, string, State), stream.writer(Stream, char, State)). % Like write_escaped_char, but return the result in a string. % :- func escaped_char(char) = string. % A reversible version of escaped_char. % :- pred string_is_escaped_char(char, string). :- mode string_is_escaped_char(in, out) is det. :- mode string_is_escaped_char(out, in) is semidet. % Given a string S, write S, with characters escaped if necessary, % to stdout. The string is not enclosed in quotes. % :- pred write_escaped_string(string::in, io::di, io::uo) is det. :- pred write_escaped_string(Stream::in, string::in, State::di, State::uo) is det <= (stream.writer(Stream, string, State), stream.writer(Stream, char, State)). % Like write_escaped_char, but return the result in a string. % :- func escaped_string(string) = string. %---------------------------------------------------------------------------% %---------------------------------------------------------------------------% :- implementation. % Everything below here is not intended to be part of the public interface, % and will not be included in the Mercury library reference manual. %---------------------------------------------------------------------------% :- interface. % Convert `integer_base' constant to its numeric value. % :- func integer_base_int(integer_base) = int. % Return the prefix for integer literals of the given base. % :- func integer_base_prefix(integer_base) = string. % Convert a character to the corresponding octal escape code. % % We use ISO-Prolog style octal escapes, which are of the form '\nnn\'; % note that unlike C octal escapes, they are terminated with a backslash. % % XXX Using this predicate in the compiler may cause problems interfacing % with versions of the compiler that have been built in grades which use % different character representations. % :- func mercury_escape_char(char) = string. % Succeed if the given character is a Mercury punctuation character. % :- pred is_mercury_punctuation_char(char::in) is semidet. % encode_escaped_char(Char, Str): % % Succeed in one of two cases: % % - Char is 'x', and Str is "x", where x is a valid Mercury source % character, or % - Char is '\x' and Str is "\x", where '\x' is a valid character % escape sequence. % :- pred encode_escaped_char(char, string). :- mode encode_escaped_char(in, out) is semidet. :- mode encode_escaped_char(out, in) is semidet. % for use by io.m. :- type adjacent_to_graphic_token ---> maybe_adjacent_to_graphic_token ; not_adjacent_to_graphic_token. :- pred quote_atom_agt(string::in, adjacent_to_graphic_token::in, io::di, io::uo) is det. :- pred quote_atom_agt(Stream::in, string::in, adjacent_to_graphic_token::in, State::di, State::uo) is det <= (stream.writer(Stream, string, State), stream.writer(Stream, char, State)). :- func quoted_atom_agt(string, adjacent_to_graphic_token) = string. :- pragma type_spec(term_io.quote_string/4, (Stream = io.output_stream, State = io.state)). :- pragma type_spec(term_io.quote_atom/4, (Stream = io.output_stream, State = io.state)). :- pragma type_spec(term_io.write_escaped_string/4, (Stream = io.output_stream, State = io.state)). :- pragma type_spec(term_io.write_escaped_char/4, (Stream = io.output_stream, State = io.state)). :- pragma type_spec(term_io.quote_char/4, (Stream = io.output_stream, State = io.state)). :- pragma type_spec(term_io.quote_atom_agt/5, (Stream = io.output_stream, State = io.state)). %---------------------------------------------------------------------------% %---------------------------------------------------------------------------% :- implementation. :- import_module bool. :- import_module int. :- import_module integer. :- import_module lexer. :- import_module list. :- import_module parser. :- import_module string. :- import_module stream.string_writer. %---------------------------------------------------------------------------% term_io.read_term(Result, !IO) :- io.get_op_table(Ops, !IO), term_io.read_term_with_op_table(Ops, Result, !IO). term_io.read_term_with_op_table(Ops, Result, !IO) :- parser.read_term_with_op_table(Ops, Result, !IO). %---------------------------------------------------------------------------% %---------------------------------------------------------------------------% % write a variable to standard output. % % There are two ways we could choose to write unnamed variables % (ie `_'): % Convert the variable to an integer representation and write % `_N' where N is that integer representation. This has the % advantage that such variables get printed in a canonical % way, so rearranging terms containing such variables will % not effect the way they are numbered (this includes breaking % up a term and printing the pieces separately). % or % Number the unnamed variables from 0 and write `_N' where % N is the number in the sequence of such variables. This has % the advantage that such variables can be visually scanned % rather more easily (for example in error messages). % % An ideal solution would be to provide both, and a flag to choose % between the two. At the moment we provide only the first, though % the infrastructure for the second is present in the code. term_io.write_variable(Variable, VarSet, !IO) :- io.get_op_table(Ops, !IO), term_io.write_variable_with_op_table(Ops, Variable, VarSet, !IO). term_io.write_variable_with_op_table(Ops, Variable, VarSet, !IO) :- term_io.write_variable_2(Ops, Variable, VarSet, _, 0, _, !IO). :- pred term_io.write_variable_2(Ops::in, var(T)::in, varset(T)::in, varset(T)::out, int::in, int::out, io::di, io::uo) is det <= op_table(Ops). term_io.write_variable_2(Ops, Id, !VarSet, !N, !IO) :- ( if varset.search_var(!.VarSet, Id, Val) then term_io.write_term_2(Ops, Val, !VarSet, !N, !IO) else if varset.search_name(!.VarSet, Id, Name) then io.write_string(Name, !IO) else % XXX Problems with name clashes. term.var_to_int(Id, VarNum), string.int_to_string(VarNum, Num), string.append("_", Num, VarName), varset.name_var(Id, VarName, !VarSet), !:N = !.N + 1, io.write_string(VarName, !IO) ). %---------------------------------------------------------------------------% term_io.write_term(VarSet, Term, !IO) :- io.get_op_table(Ops, !IO), term_io.write_term_with_op_table(Ops, VarSet, Term, !IO). term_io.write_term_with_op_table(Ops, VarSet, Term, !IO) :- term_io.write_term_2(Ops, Term, VarSet, _, 0, _, !IO). :- pred term_io.write_term_2(Ops::in, term(T)::in, varset(T)::in, varset(T)::out, int::in, int::out, io::di, io::uo) is det <= op_table(Ops). term_io.write_term_2(Ops, Term, !VarSet, !N, !IO) :- term_io.write_term_3(Ops, Term, ops.max_priority(Ops) + 1, !VarSet, !N, !IO). :- pred term_io.write_arg_term(Ops::in, term(T)::in, varset(T)::in, varset(T)::out, int::in, int::out, io::di, io::uo) is det <= op_table(Ops). term_io.write_arg_term(Ops, Term, !VarSet, !N, !IO) :- term_io.write_term_3(Ops, Term, ops.arg_priority(Ops), !VarSet, !N, !IO). :- pred term_io.write_term_3(Ops::in, term(T)::in, ops.priority::in, varset(T)::in, varset(T)::out, int::in, int::out, io::di, io::uo) is det <= op_table(Ops). term_io.write_term_3(Ops, term.variable(Id, _), _, !VarSet, !N, !IO) :- term_io.write_variable_2(Ops, Id, !VarSet, !N, !IO). term_io.write_term_3(Ops, term.functor(Functor, Args, _), Priority, !VarSet, !N, !IO) :- ( if Functor = term.atom("[|]"), Args = [ListHead, ListTail] then io.write_char('[', !IO), term_io.write_arg_term(Ops, ListHead, !VarSet, !N, !IO), term_io.write_list_tail(Ops, ListTail, !VarSet, !N, !IO), io.write_char(']', !IO) else if Functor = term.atom("[]"), Args = [] then io.write_string("[]", !IO) else if Functor = term.atom("{}"), Args = [BracedTerm] then io.write_string("{ ", !IO), term_io.write_term_2(Ops, BracedTerm, !VarSet, !N, !IO), io.write_string(" }", !IO) else if Functor = term.atom("{}"), Args = [BracedHead | BracedTail] then io.write_char('{', !IO), term_io.write_arg_term(Ops, BracedHead, !VarSet, !N, !IO), term_io.write_term_args(Ops, BracedTail, !VarSet, !N, !IO), io.write_char('}', !IO) else if % The empty functor '' is used for higher-order syntax: Var(Arg, ...) % gets parsed as ''(Var, Arg). When writing it out, we want to use % the nice syntax. Functor = term.atom(""), Args = [term.variable(Var, _), FirstArg | OtherArgs] then term_io.write_variable_2(Ops, Var, !VarSet, !N, !IO), io.write_char('(', !IO), term_io.write_arg_term(Ops, FirstArg, !VarSet, !N, !IO), term_io.write_term_args(Ops, OtherArgs, !VarSet, !N, !IO), io.write_char(')', !IO) else if Args = [PrefixArg], Functor = term.atom(OpName), ops.lookup_prefix_op(Ops, OpName, OpPriority, OpAssoc) then io.output_stream(Stream, !IO), maybe_write_paren(Stream, '(', Priority, OpPriority, !IO), term_io.write_constant(Functor, !IO), io.write_char(' ', !IO), adjust_priority_for_assoc(OpPriority, OpAssoc, NewPriority), term_io.write_term_3(Ops, PrefixArg, NewPriority, !VarSet, !N, !IO), maybe_write_paren(Stream, ')', Priority, OpPriority, !IO) else if Args = [PostfixArg], Functor = term.atom(OpName), ops.lookup_postfix_op(Ops, OpName, OpPriority, OpAssoc) then io.output_stream(Stream, !IO), maybe_write_paren(Stream, '(', Priority, OpPriority, !IO), adjust_priority_for_assoc(OpPriority, OpAssoc, NewPriority), term_io.write_term_3(Ops, PostfixArg, NewPriority, !VarSet, !N, !IO), io.write_char(' ', !IO), term_io.write_constant(Functor, !IO), maybe_write_paren(Stream, ')', Priority, OpPriority, !IO) else if Args = [Arg1, Arg2], Functor = term.atom(OpName), ops.lookup_infix_op(Ops, OpName, OpPriority, LeftAssoc, RightAssoc) then io.output_stream(Stream, !IO), maybe_write_paren(Stream, '(', Priority, OpPriority, !IO), adjust_priority_for_assoc(OpPriority, LeftAssoc, LeftPriority), term_io.write_term_3(Ops, Arg1, LeftPriority, !VarSet, !N, !IO), ( if OpName = "," then io.write_string(", ", !IO) else if OpName = "." then % If the operator is '.'/2 then we must not put spaces around it % (or at the very least, we should not put spaces afterwards, which % would make it appear as the end-of-term token). However, we do % have to quote it if the right hand side can begin with a digit. ( if starts_with_digit(Arg2) then Dot = "'.'" else Dot = "." ), io.write_string(Dot, !IO) else io.write_char(' ', !IO), term_io.write_constant(Functor, !IO), io.write_char(' ', !IO) ), adjust_priority_for_assoc(OpPriority, RightAssoc, RightPriority), term_io.write_term_3(Ops, Arg2, RightPriority, !VarSet, !N, !IO), maybe_write_paren(Stream, ')', Priority, OpPriority, !IO) else if Args = [Arg1, Arg2], Functor = term.atom(OpName), ops.lookup_binary_prefix_op(Ops, OpName, OpPriority, FirstAssoc, SecondAssoc) then io.output_stream(Stream, !IO), maybe_write_paren(Stream, '(', Priority, OpPriority, !IO), term_io.write_constant(Functor, !IO), io.write_char(' ', !IO), adjust_priority_for_assoc(OpPriority, FirstAssoc, FirstPriority), term_io.write_term_3(Ops, Arg1, FirstPriority, !VarSet, !N, !IO), io.write_char(' ', !IO), adjust_priority_for_assoc(OpPriority, SecondAssoc, SecondPriority), term_io.write_term_3(Ops, Arg2, SecondPriority, !VarSet, !N, !IO), maybe_write_paren(Stream, ')', Priority, OpPriority, !IO) else ( if Args = [], Functor = term.atom(Op), ops.lookup_op(Ops, Op), Priority =< ops.max_priority(Ops) then io.write_char('(', !IO), term_io.write_constant(Functor, !IO), io.write_char(')', !IO) else term_io.write_constant(Functor, maybe_adjacent_to_graphic_token, !IO) ), ( Args = [X | Xs], io.write_char('(', !IO), term_io.write_arg_term(Ops, X, !VarSet, !N, !IO), term_io.write_term_args(Ops, Xs, !VarSet, !N, !IO), io.write_char(')', !IO) ; Args = [] ) ). :- pred term_io.write_list_tail(Ops::in, term(T)::in, varset(T)::in, varset(T)::out, int::in, int::out, io::di, io::uo) is det <= op_table(Ops). term_io.write_list_tail(Ops, Term, !VarSet, !N, !IO) :- ( if Term = term.variable(Id, _), varset.search_var(!.VarSet, Id, Val) then term_io.write_list_tail(Ops, Val, !VarSet, !N, !IO) else if Term = term.functor(term.atom("[|]"), [ListHead, ListTail], _) then io.write_string(", ", !IO), term_io.write_arg_term(Ops, ListHead, !VarSet, !N, !IO), term_io.write_list_tail(Ops, ListTail, !VarSet, !N, !IO) else if Term = term.functor(term.atom("[]"), [], _) then true else io.write_string(" | ", !IO), term_io.write_term_2(Ops, Term, !VarSet, !N, !IO) ). % Succeeds iff outputting the given term would start with a digit. % (This is a safe, conservative approximation and is used to decide % whether or not to quote infix '.'/2.) % :- pred starts_with_digit(term(T)::in) is semidet. starts_with_digit(functor(integer(_), _, _)). starts_with_digit(functor(float(_), _, _)). starts_with_digit(functor(atom(Op), Args, _)) :- ( Args = [Arg, _], ops.lookup_infix_op(ops.init_mercury_op_table, Op, _, _, _) ; Args = [Arg], ops.lookup_postfix_op(ops.init_mercury_op_table, Op, _, _) ), starts_with_digit(Arg). %---------------------------------------------------------------------------% :- pred term_io.write_term_args(Ops::in, list(term(T))::in, varset(T)::in, varset(T)::out, int::in, int::out, io::di, io::uo) is det <= op_table(Ops). % write the remaining arguments term_io.write_term_args(_, [], !VarSet, !N, !IO). term_io.write_term_args(Ops, [X | Xs], !VarSet, !N, !IO) :- io.write_string(", ", !IO), term_io.write_arg_term(Ops, X, !VarSet, !N, !IO), term_io.write_term_args(Ops, Xs, !VarSet, !N, !IO). %---------------------------------------------------------------------------% term_io.write_constant(Const, !IO) :- term_io.write_constant(Const, not_adjacent_to_graphic_token, !IO). :- pred term_io.write_constant(const::in, adjacent_to_graphic_token::in, io::di, io::uo) is det. term_io.write_constant(term.integer(I), _, !IO) :- io.write_int(I, !IO). term_io.write_constant(term.big_integer(Base, I), _, !IO) :- Prefix = integer_base_prefix(Base), IntString = integer.to_base_string(I, integer_base_int(Base)), io.write_string(Prefix, !IO), io.write_string(IntString, !IO). term_io.write_constant(term.float(F), _, !IO) :- io.write_float(F, !IO). term_io.write_constant(term.atom(A), NextToGraphicToken, !IO) :- term_io.quote_atom_agt(A, NextToGraphicToken, !IO). term_io.write_constant(term.string(S), _, !IO) :- term_io.quote_string(S, !IO). term_io.write_constant(term.implementation_defined(N), _, !IO) :- io.write_char('$', !IO), io.write_string(N, !IO). term_io.format_constant(Const) = term_io.format_constant_agt(Const, not_adjacent_to_graphic_token). :- func term_io.format_constant_agt(const, adjacent_to_graphic_token) = string. term_io.format_constant_agt(term.integer(I), _) = string.int_to_string(I). term_io.format_constant_agt(term.big_integer(Base, I), _) = integer_base_prefix(Base) ++ to_base_string(I, integer_base_int(Base)). term_io.format_constant_agt(term.float(F), _) = string.float_to_string(F). term_io.format_constant_agt(term.atom(A), NextToGraphicToken) = term_io.quoted_atom_agt(A, NextToGraphicToken). term_io.format_constant_agt(term.string(S), _) = term_io.quoted_string(S). term_io.format_constant_agt(term.implementation_defined(N), _) = "$" ++ N. integer_base_int(base_2) = 2. integer_base_int(base_8) = 8. integer_base_int(base_10) = 10. integer_base_int(base_16) = 16. integer_base_prefix(base_2) = "0b". integer_base_prefix(base_8) = "0o". integer_base_prefix(base_10) = "". integer_base_prefix(base_16) = "0x". %---------------------------------------------------------------------------% term_io.quote_char(C, !IO) :- io.write_string(term_io.quoted_char(C), !IO). term_io.quote_char(Stream, C, !State) :- stream.put(Stream, term_io.quoted_char(C), !State). term_io.quoted_char(C) = string.format("'%s'", [s(term_io.escaped_char(C))]). term_io.quote_atom(S, !IO) :- term_io.quote_atom_agt(S, not_adjacent_to_graphic_token, !IO). term_io.quote_atom(Stream, S, !State) :- term_io.quote_atom_agt(Stream, S, not_adjacent_to_graphic_token, !State). term_io.quoted_atom(S) = term_io.quoted_atom_agt(S, not_adjacent_to_graphic_token). term_io.quote_atom_agt(S, NextToGraphicToken, !IO) :- io.output_stream(Stream, !IO), term_io.quote_atom_agt(Stream, S, NextToGraphicToken, !IO). term_io.quote_atom_agt(Stream, S, NextToGraphicToken, !State) :- ShouldQuote = should_atom_be_quoted(S, NextToGraphicToken), ( ShouldQuote = no, stream.put(Stream, S, !State) ; ShouldQuote = yes, stream.put(Stream, '''', !State), term_io.write_escaped_string(Stream, S, !State), stream.put(Stream, '''', !State) ). term_io.quoted_atom_agt(S, NextToGraphicToken) = String :- ShouldQuote = should_atom_be_quoted(S, NextToGraphicToken), ( ShouldQuote = no, String = S ; ShouldQuote = yes, ES = term_io.escaped_string(S), String = string.append_list(["'", ES, "'"]) ). :- func should_atom_be_quoted(string, adjacent_to_graphic_token) = bool. should_atom_be_quoted(S, NextToGraphicToken) = ShouldQuote :- ( if % I didn't make these rules up: see ISO Prolog 6.3.1.3 and 6.4.2. -fjh ( % Letter digit token (6.4.2) string.index(S, 0, FirstChar), char.is_lower(FirstChar), string.is_all_alnum_or_underscore(S) ; % Semicolon token (6.4.2) S = ";" ; % Cut token (6.4.2) S = "!" ; % Graphic token (6.4.2) string.all_match(lexer.graphic_token_char, S), S \= "", % We need to quote tokens starting with '#', because Mercury uses % '#' to start source line number indicators. not string.index(S, 0, '#'), % If the token could be the last token in a term, and the term % could be followed with ".\n", then we need to quote the token, % otherwise the "." would be considered part of the same graphic % token. We can only leave it unquoted if we're sure it won't be % adjacent to any graphic token. NextToGraphicToken = not_adjacent_to_graphic_token ; % 6.3.1.3: atom = open list, close list ; S = "[]" ; % 6.3.1.3: atom = open curly, close curly ; S = "{}" ) then ShouldQuote = no else % Anything else must be output as a quoted token (6.4.2). ShouldQuote = yes ). % Note: the code here is similar to code in compiler/mercury_to_mercury.m; % any changes here may require similar changes there. term_io.quote_string(S, !IO) :- io.output_stream(Stream, !IO), term_io.quote_string(Stream, S, !IO). term_io.quote_string(Stream, S, !State) :- stream.put(Stream, '"', !State), term_io.write_escaped_string(Stream, S, !State), stream.put(Stream, '"', !State). term_io.quoted_string(S) = string.append_list(["""", term_io.escaped_string(S), """"]). term_io.write_escaped_string(String, !IO) :- io.output_stream(Stream, !IO), term_io.write_escaped_string(Stream, String, !IO). term_io.write_escaped_string(Stream, String, !State) :- string.foldl(term_io.write_escaped_char(Stream), String, !State). term_io.escaped_string(String) = string.append_list( reverse(string.foldl(term_io.add_escaped_char, String, []))). :- func term_io.add_escaped_char(char, list(string)) = list(string). term_io.add_escaped_char(Char, Strings0) = Strings :- ( if mercury_escape_special_char(Char, QuoteChar) then Strings = [from_char_list(['\\', QuoteChar]) | Strings0] else if is_mercury_source_char(Char) then Strings = [string.char_to_string(Char) | Strings0] else Strings = [mercury_escape_char(Char) | Strings0] ). % Note: the code of add_escaped_char and write_escaped_char should be % kept in sync. The code of both is similar to code in % compiler/mercury_to_mercury.m; any changes here may require % similar changes there. term_io.write_escaped_char(Char, !IO) :- io.output_stream(Stream, !IO), term_io.write_escaped_char(Stream, Char, !IO). term_io.write_escaped_char(Stream, Char, !State) :- ( if mercury_escape_special_char(Char, QuoteChar) then stream.put(Stream, ('\\'), !State), stream.put(Stream, QuoteChar, !State) else if is_mercury_source_char(Char) then stream.put(Stream, Char, !State) else stream.put(Stream, mercury_escape_char(Char), !State) ). term_io.escaped_char(Char) = String :- string_is_escaped_char(Char, String). :- pragma promise_equivalent_clauses(string_is_escaped_char/2). string_is_escaped_char(Char::in, String::out) :- ( if mercury_escape_special_char(Char, QuoteChar) then String = string.append("\\", string.char_to_string(QuoteChar)) else if is_mercury_source_char(Char) then String = string.char_to_string(Char) else String = mercury_escape_char(Char) ). string_is_escaped_char(Char::out, String::in) :- string.to_char_list(String, Chars), ( Chars = [Char], ( is_mercury_source_char(Char) ; mercury_escape_special_char(Char, _QuoteChar) ) ; Chars = ['\\', QuoteChar], mercury_escape_special_char(Char, QuoteChar) ; Chars = ['\\', Char1, Char2, Char3], NumChars = [Char1, Char2, Char3], string.from_char_list(NumChars, NumString), string.base_string_to_int(8, NumString, Int), char.to_int(Char, Int) ). mercury_escape_char(Char) = EscapeCode :- char.to_int(Char, Int), string.int_to_base_string(Int, 8, OctalString0), string.pad_left(OctalString0, '0', 3, OctalString), EscapeCode = "\\" ++ OctalString ++ "\\". % Succeed if Char is a character which is allowed in Mercury string % and character literals. % % Note: the code here is similar to code in compiler/mercury_to_mercury.m; % any changes here may require similar changes there. % :- pred is_mercury_source_char(char::in) is semidet. is_mercury_source_char(Char) :- ( char.is_alnum(Char) ; is_mercury_punctuation_char(Char) ; char.to_int(Char) >= 0x80 ). % Currently we only allow the following characters. % XXX should we just use is_printable(Char) instead? % % Note: the code here is similar to code in runtime/mercury_trace_base.c; % any changes here may require similar changes there. is_mercury_punctuation_char(' '). is_mercury_punctuation_char('!'). is_mercury_punctuation_char('@'). is_mercury_punctuation_char('#'). is_mercury_punctuation_char('$'). is_mercury_punctuation_char('%'). is_mercury_punctuation_char('^'). is_mercury_punctuation_char('&'). is_mercury_punctuation_char('*'). is_mercury_punctuation_char('('). is_mercury_punctuation_char(')'). is_mercury_punctuation_char('-'). is_mercury_punctuation_char('_'). is_mercury_punctuation_char('+'). is_mercury_punctuation_char('='). is_mercury_punctuation_char('`'). is_mercury_punctuation_char('~'). is_mercury_punctuation_char('{'). is_mercury_punctuation_char('}'). is_mercury_punctuation_char('['). is_mercury_punctuation_char(']'). is_mercury_punctuation_char(';'). is_mercury_punctuation_char(':'). is_mercury_punctuation_char(''''). is_mercury_punctuation_char('"'). is_mercury_punctuation_char('<'). is_mercury_punctuation_char('>'). is_mercury_punctuation_char('.'). is_mercury_punctuation_char(','). is_mercury_punctuation_char('/'). is_mercury_punctuation_char('?'). is_mercury_punctuation_char('\\'). is_mercury_punctuation_char('|'). %---------------------------------------------------------------------------% :- pragma promise_equivalent_clauses(encode_escaped_char/2). encode_escaped_char(Char::in, Str::out) :- ( if mercury_escape_special_char(Char, EscapeChar) then string.from_char_list(['\\', EscapeChar], Str) else if is_mercury_source_char(Char) then string.from_char_list([Char], Str) else fail ). encode_escaped_char(Char::out, Str::in) :- string.to_char_list(Str, Chars), ( Chars = [Char] ; Chars = ['\\', EscapedChar], mercury_escape_special_char(Char, EscapedChar) ). % mercury_escape_special_char(Char, EscapeChar) is true iff Char % is character for which there is a special backslash-escape character % EscapeChar that can be used after a backslash in string literals or % atoms to represent Char. % % Note: the code here is similar to code in compiler/mercury_to_mercury.m; % any changes here may require similar changes there. % :- pred mercury_escape_special_char(char, char). :- mode mercury_escape_special_char(in, out) is semidet. :- mode mercury_escape_special_char(out, in) is semidet. mercury_escape_special_char('''', ''''). mercury_escape_special_char('"', '"'). mercury_escape_special_char('\\', '\\'). mercury_escape_special_char('\n', 'n'). mercury_escape_special_char('\t', 't'). mercury_escape_special_char('\b', 'b'). %---------------------------------------------------------------------------% %---------------------------------------------------------------------------% term_io.write_term_nl(VarSet, Term, !IO) :- io.get_op_table(Ops, !IO), term_io.write_term_nl_with_op_table(Ops, VarSet, Term, !IO). term_io.write_term_nl_with_op_table(Ops, VarSet, Term, !IO) :- term_io.write_term_with_op_table(Ops, VarSet, Term, !IO), io.write_string(".\n", !IO). %---------------------------------------------------------------------------% %---------------------------------------------------------------------------%