aboutsummaryrefslogtreecommitdiffstats
path: root/lib/stdlib/src/io_lib_format.erl
diff options
context:
space:
mode:
authorRichard Carlsson <[email protected]>2014-05-06 10:34:07 +0200
committerHans Bolinder <[email protected]>2015-03-10 10:21:41 +0100
commit8e7441c27485bd416abdb0253c9c92620d671065 (patch)
tree6d722b99dd0f001346450b14903e7e6f79379ecc /lib/stdlib/src/io_lib_format.erl
parent4037296294670e7a9bb2a3c1cdbd0236cbc15807 (diff)
downloadotp-8e7441c27485bd416abdb0253c9c92620d671065.tar.gz
otp-8e7441c27485bd416abdb0253c9c92620d671065.tar.bz2
otp-8e7441c27485bd416abdb0253c9c92620d671065.zip
Make the scanned form of the io_lib format strings available for processing
This adds three new functions to io_lib - scan_format/2, unscan_format/1, and build_text/1 - which expose the parsed form of the format control sequences to make it possible to easily modify or filter the input to io_lib:format/2. This can e.g. be used in order to replace unbounded-size control sequences like ~w or ~p with corresponding depth-limited ~W and ~P before doing the actual formatting.
Diffstat (limited to 'lib/stdlib/src/io_lib_format.erl')
-rw-r--r--lib/stdlib/src/io_lib_format.erl112
1 files changed, 95 insertions, 17 deletions
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);