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-rw-r--r--lib/stdlib/doc/src/io.xml3
-rw-r--r--lib/stdlib/doc/src/io_lib.xml70
-rw-r--r--lib/stdlib/src/io_lib.erl42
-rw-r--r--lib/stdlib/src/io_lib_format.erl112
-rw-r--r--lib/stdlib/test/io_SUITE.erl22
5 files changed, 224 insertions, 25 deletions
diff --git a/lib/stdlib/doc/src/io.xml b/lib/stdlib/doc/src/io.xml
index a28180b42a..8ebfdb2e7f 100644
--- a/lib/stdlib/doc/src/io.xml
+++ b/lib/stdlib/doc/src/io.xml
@@ -505,7 +505,8 @@ ok
<p>Writes the data with standard syntax in the same way as
<c>~w</c>, but breaks terms whose printed representation
is longer than one line into many lines and indents each
- line sensibly. It also tries to detect lists of
+ line sensibly. Left justification is not supported.
+ It also tries to detect lists of
printable characters and to output these as strings. The
Unicode translation modifier is used for determining
what characters are printable. For example:</p>
diff --git a/lib/stdlib/doc/src/io_lib.xml b/lib/stdlib/doc/src/io_lib.xml
index 3312b08064..2117d66381 100644
--- a/lib/stdlib/doc/src/io_lib.xml
+++ b/lib/stdlib/doc/src/io_lib.xml
@@ -4,7 +4,7 @@
<erlref>
<header>
<copyright>
- <year>1996</year><year>2013</year>
+ <year>1996</year><year>2014</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -59,6 +59,35 @@
<datatype>
<name name="latin1_string"/>
</datatype>
+ <datatype>
+ <name name="format_spec"/>
+ <desc><p>Description:</p>
+ <list type="bulleted">
+ <item><p><c>control_char</c> is the type of control
+ sequence: <c>$P</c>, <c>$w</c>, and so on;</p>
+ </item>
+ <item><p><c>args</c> is a list of the arguments used by the
+ control sequence, or an empty list if the control sequence
+ does not take any arguments;</p>
+ </item>
+ <item><p><c>width</c> is the field width;</p>
+ </item>
+ <item><p><c>adjust</c> is the adjustment;</p>
+ </item>
+ <item><p><c>precision</c> is the precision of the printed
+ argument;</p>
+ </item>
+ <item><p><c>pad_char</c> is the padding character;</p>
+ </item>
+ <item><p><c>encoding</c> is set to <c>true</c> if the translation
+ modifier <c>t</c> is present;</p>
+ </item>
+ <item><p><c>strings</c> is set to <c>false</c> if the modifier
+ <c>l</c> is present.</p>
+ </item>
+ </list>
+ </desc>
+ </datatype>
</datatypes>
<funcs>
<func>
@@ -260,6 +289,45 @@
</desc>
</func>
<func>
+ <name name="scan_format" arity="2"/>
+ <fsummary>Parse all control sequences in the format string</fsummary>
+ <desc>
+ <p>Returns a list corresponding to the given format string,
+ where control sequences have been replaced with
+ corresponding tuples. This list can be passed to <seealso
+ marker="#build_text/1">io_lib:build_text/1</seealso> to have
+ the same effect as <c>io_lib:format(Format, Args)</c>, or to
+ <seealso
+ marker="#unscan_format/1">io_lib:unscan_format/1</seealso>
+ in order to get the corresponding pair of <c>Format</c> and
+ <c>Args</c> (with every <c>*</c> and corresponding argument
+ expanded to numeric values).</p>
+ <p>A typical use of this function is to replace unbounded-size
+ control sequences like <c>~w</c> and <c>~p</c> with the
+ depth-limited variants <c>~W</c> and <c>~P</c> before
+ formatting to text, e.g. in a logger.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="unscan_format" arity="1"/>
+ <fsummary>Revert a pre-parsed format list to a plain character list
+ and a list of arguments</fsummary>
+ <desc>
+ <p>See <seealso
+ marker="#scan_format/2">io_lib:scan_format/2</seealso> for
+ details.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="build_text" arity="1"/>
+ <fsummary>Build the output text for a pre-parsed format list</fsummary>
+ <desc>
+ <p>See <seealso
+ marker="#scan_format/2">io_lib:scan_format/2</seealso> for
+ details.</p>
+ </desc>
+ </func>
+ <func>
<name name="indentation" arity="2"/>
<fsummary>Indentation after printing string</fsummary>
<desc>
diff --git a/lib/stdlib/src/io_lib.erl b/lib/stdlib/src/io_lib.erl
index adc9a0cf5f..e90cda0533 100644
--- a/lib/stdlib/src/io_lib.erl
+++ b/lib/stdlib/src/io_lib.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1996-2013. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2014. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -60,6 +60,7 @@
-module(io_lib).
-export([fwrite/2,fread/2,fread/3,format/2]).
+-export([scan_format/2,unscan_format/1,build_text/1]).
-export([print/1,print/4,indentation/2]).
-export([write/1,write/2,write/3,nl/0,format_prompt/1,format_prompt/2]).
@@ -83,7 +84,7 @@
deep_unicode_char_list/1]).
-export_type([chars/0, latin1_string/0, continuation/0,
- fread_error/0, fread_item/0]).
+ fread_error/0, fread_item/0, format_spec/0]).
%%----------------------------------------------------------------------
@@ -108,6 +109,18 @@
-type fread_item() :: string() | atom() | integer() | float().
+-type format_spec() ::
+ #{
+ control_char => char(),
+ args => [any()],
+ width => 'none' | integer(),
+ adjust => 'left' | 'right',
+ precision => 'none' | integer(),
+ pad_char => char(),
+ encoding => 'unicode' | 'latin1',
+ strings => boolean()
+ }.
+
%%----------------------------------------------------------------------
%% Interface calls to sub-modules.
@@ -156,6 +169,31 @@ format(Format, Args) ->
Other
end.
+-spec scan_format(Format, Data) -> FormatList when
+ Format :: io:format(),
+ Data :: [term()],
+ FormatList :: [char() | format_spec()].
+
+scan_format(Format, Args) ->
+ try io_lib_format:scan(Format, Args)
+ catch
+ _:_ -> erlang:error(badarg, [Format, Args])
+ end.
+
+-spec unscan_format(FormatList) -> {Format, Data} when
+ FormatList :: [char() | format_spec()],
+ Format :: io:format(),
+ Data :: [term()].
+
+unscan_format(FormatList) ->
+ io_lib_format:unscan(FormatList).
+
+-spec build_text(FormatList) -> chars() when
+ FormatList :: [char() | format_spec()].
+
+build_text(FormatList) ->
+ io_lib_format:build(FormatList).
+
-spec print(Term) -> chars() when
Term :: term().
diff --git a/lib/stdlib/src/io_lib_format.erl b/lib/stdlib/src/io_lib_format.erl
index 89ae6fb187..015afb317a 100644
--- a/lib/stdlib/src/io_lib_format.erl
+++ b/lib/stdlib/src/io_lib_format.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1996-2013. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2014. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -20,10 +20,9 @@
%% Formatting functions of io library.
--export([fwrite/2,fwrite_g/1,indentation/2]).
+-export([fwrite/2,fwrite_g/1,indentation/2,scan/2,unscan/1,build/1]).
-%% fwrite(Format, ArgList) -> string().
-%% Format the arguments in ArgList after string Format. Just generate
+%% Format the arguments in Args after string Format. Just generate
%% an error if there is an error in the arguments.
%%
%% To do the printing command correctly we need to calculate the
@@ -37,15 +36,84 @@
%% and it also splits the handling of the control characters into two
%% parts.
-fwrite(Format, Args) when is_atom(Format) ->
- fwrite(atom_to_list(Format), Args);
-fwrite(Format, Args) when is_binary(Format) ->
- fwrite(binary_to_list(Format), Args);
+-spec fwrite(Format, Data) -> FormatList when
+ Format :: io:format(),
+ Data :: [term()],
+ FormatList :: [char() | io_lib:format_spec()].
+
fwrite(Format, Args) ->
- Cs = collect(Format, Args),
+ build(scan(Format, Args)).
+
+%% Build the output text for a pre-parsed format list.
+
+-spec build(FormatList) -> io_lib:chars() when
+ FormatList :: [char() | io_lib:format_spec()].
+
+build(Cs) ->
Pc = pcount(Cs),
build(Cs, Pc, 0).
+%% Parse all control sequences in the format string.
+
+-spec scan(Format, Data) -> FormatList when
+ Format :: io:format(),
+ Data :: [term()],
+ FormatList :: [char() | io_lib:format_spec()].
+
+scan(Format, Args) when is_atom(Format) ->
+ scan(atom_to_list(Format), Args);
+scan(Format, Args) when is_binary(Format) ->
+ scan(binary_to_list(Format), Args);
+scan(Format, Args) ->
+ collect(Format, Args).
+
+%% Revert a pre-parsed format list to a plain character list and a
+%% list of arguments.
+
+-spec unscan(FormatList) -> {Format, Data} when
+ FormatList :: [char() | io_lib:format_spec()],
+ Format :: io:format(),
+ Data :: [term()].
+
+unscan(Cs) ->
+ {print(Cs), args(Cs)}.
+
+args([#{args := As} | Cs]) ->
+ As ++ args(Cs);
+args([_C | Cs]) ->
+ args(Cs);
+args([]) ->
+ [].
+
+print([#{control_char := C, width := F, adjust := Ad, precision := P,
+ pad_char := Pad, encoding := Encoding, strings := Strings} | Cs]) ->
+ print(C, F, Ad, P, Pad, Encoding, Strings) ++ print(Cs);
+print([C | Cs]) ->
+ [C | print(Cs)];
+print([]) ->
+ [].
+
+print(C, F, Ad, P, Pad, Encoding, Strings) ->
+ [$~] ++ print_field_width(F, Ad) ++ print_precision(P) ++
+ print_pad_char(Pad) ++ print_encoding(Encoding) ++
+ print_strings(Strings) ++ [C].
+
+print_field_width(none, _Ad) -> "";
+print_field_width(F, left) -> integer_to_list(-F);
+print_field_width(F, right) -> integer_to_list(F).
+
+print_precision(none) -> "";
+print_precision(P) -> [$. | integer_to_list(P)].
+
+print_pad_char($\s) -> ""; % default, no need to make explicit
+print_pad_char(Pad) -> [$., Pad].
+
+print_encoding(unicode) -> "t";
+print_encoding(latin1) -> "".
+
+print_strings(false) -> "l";
+print_strings(true) -> "".
+
collect([$~|Fmt0], Args0) ->
{C,Fmt1,Args1} = collect_cseq(Fmt0, Args0),
[C|collect(Fmt1, Args1)];
@@ -60,7 +128,10 @@ collect_cseq(Fmt0, Args0) ->
{Encoding,Fmt4,Args4} = encoding(Fmt3, Args3),
{Strings,Fmt5,Args5} = strings(Fmt4, Args4),
{C,As,Fmt6,Args6} = collect_cc(Fmt5, Args5),
- {{C,As,F,Ad,P,Pad,Encoding,Strings},Fmt6,Args6}.
+ FormatSpec = #{control_char => C, args => As, width => F, adjust => Ad,
+ precision => P, pad_char => Pad, encoding => Encoding,
+ strings => Strings},
+ {FormatSpec,Fmt6,Args6}.
encoding([$t|Fmt],Args) ->
true = hd(Fmt) =/= $l,
@@ -136,17 +207,19 @@ collect_cc([$i|Fmt], [A|Args]) -> {$i,[A],Fmt,Args}.
pcount(Cs) -> pcount(Cs, 0).
-pcount([{$p,_As,_F,_Ad,_P,_Pad,_Enc,_Str}|Cs], Acc) -> pcount(Cs, Acc+1);
-pcount([{$P,_As,_F,_Ad,_P,_Pad,_Enc,_Str}|Cs], Acc) -> pcount(Cs, Acc+1);
+pcount([#{control_char := $p}|Cs], Acc) -> pcount(Cs, Acc+1);
+pcount([#{control_char := $P}|Cs], Acc) -> pcount(Cs, Acc+1);
pcount([_|Cs], Acc) -> pcount(Cs, Acc);
pcount([], Acc) -> Acc.
-%% build([Control], Pc, Indentation) -> string().
+%% build([Control], Pc, Indentation) -> io_lib:chars().
%% Interpret the control structures. Count the number of print
%% remaining and only calculate indentation when necessary. Must also
%% be smart when calculating indentation for characters in format.
-build([{C,As,F,Ad,P,Pad,Enc,Str}|Cs], Pc0, I) ->
+build([#{control_char := C, args := As, width := F, adjust := Ad,
+ precision := P, pad_char := Pad, encoding := Enc,
+ strings := Str} | Cs], Pc0, I) ->
S = control(C, As, F, Ad, P, Pad, Enc, Str, I),
Pc1 = decr_pc(C, Pc0),
if
@@ -162,10 +235,14 @@ decr_pc($p, Pc) -> Pc - 1;
decr_pc($P, Pc) -> Pc - 1;
decr_pc(_, Pc) -> Pc.
-%% indentation(String, Indentation) -> Indentation.
+
%% Calculate the indentation of the end of a string given its start
%% indentation. We assume tabs at 8 cols.
+-spec indentation(String, StartIndent) -> integer() when
+ String :: io_lib:chars(),
+ StartIndent :: integer().
+
indentation([$\n|Cs], _I) -> indentation(Cs, 0);
indentation([$\t|Cs], I) -> indentation(Cs, ((I + 8) div 8) * 8);
indentation([C|Cs], I) when is_integer(C) ->
@@ -366,7 +443,6 @@ float_data([D|Cs], Ds) when D >= $0, D =< $9 ->
float_data([_|Cs], Ds) ->
float_data(Cs, Ds).
-%% fwrite_g(Float)
%% Writes the shortest, correctly rounded string that converts
%% to Float when read back with list_to_float/1.
%%
@@ -374,6 +450,8 @@ float_data([_|Cs], Ds) ->
%% in Proceedings of the SIGPLAN '96 Conference on Programming
%% Language Design and Implementation.
+-spec fwrite_g(float()) -> string().
+
fwrite_g(0.0) ->
"0.0";
fwrite_g(Float) when is_float(Float) ->
@@ -642,7 +720,7 @@ prefixed_integer(Int, F, Adj, Base, Pad, Prefix, Lowercase)
term([Prefix|S], F, Adj, none, Pad)
end.
-%% char(Char, Field, Adjust, Precision, PadChar) -> string().
+%% char(Char, Field, Adjust, Precision, PadChar) -> chars().
char(C, none, _Adj, none, _Pad) -> [C];
char(C, F, _Adj, none, _Pad) -> chars(C, F);
diff --git a/lib/stdlib/test/io_SUITE.erl b/lib/stdlib/test/io_SUITE.erl
index 2203dd8f51..8d53949c40 100644
--- a/lib/stdlib/test/io_SUITE.erl
+++ b/lib/stdlib/test/io_SUITE.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1999-2013. All Rights Reserved.
+%% Copyright Ericsson AB 1999-2014. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -31,7 +31,7 @@
printable_range/1,
io_lib_print_binary_depth_one/1, otp_10302/1, otp_10755/1,
otp_10836/1, io_lib_width_too_small/1,
- io_with_huge_message_queue/1]).
+ io_with_huge_message_queue/1, format_string/1]).
-export([pretty/2]).
@@ -71,7 +71,8 @@ all() ->
io_fread_newlines, otp_8989, io_lib_fread_literal,
printable_range,
io_lib_print_binary_depth_one, otp_10302, otp_10755, otp_10836,
- io_lib_width_too_small, io_with_huge_message_queue].
+ io_lib_width_too_small, io_with_huge_message_queue,
+ format_string].
groups() ->
[].
@@ -1035,7 +1036,14 @@ rp(Term, Col, Ll, D, M, RF) ->
lists:flatten(io_lib:format("~s", [R])).
fmt(Fmt, Args) ->
- lists:flatten(io_lib:format(Fmt, Args)).
+ FormatList = io_lib:scan_format(Fmt, Args),
+ {Fmt2, Args2} = io_lib:unscan_format(FormatList),
+ Chars1 = lists:flatten(io_lib:build_text(FormatList)),
+ Chars2 = lists:flatten(io_lib:format(Fmt2, Args2)),
+ Chars3 = lists:flatten(io_lib:format(Fmt, Args)),
+ Chars1 = Chars2,
+ Chars2 = Chars3,
+ Chars3.
rfd(a, 0) ->
[];
@@ -2261,3 +2269,9 @@ writes(0, _) -> ok;
writes(N, F1) ->
file:write(F1, "hello\n"),
writes(N - 1, F1).
+
+format_string(Config) ->
+ %% All but padding is tested by fmt/2.
+ "xxxxxxsssx" = fmt("~10.4.xs", ["sss"]),
+ "xxxxxxsssx" = fmt("~10.4.*s", [$x, "sss"]),
+ ok.
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-26 21:33:06 +0000