gcc/ada/libgnat/g-forstr.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                G N A T . F O R M A T T E D _ S T R I N G                 --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --           Copyright (C) 2014-2017, Free Software Foundation, Inc.        --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package add support for formatted string as supported by C printf()
  33
  34 --  A simple usage is:
  35 --
  36 --     Put_Line (-(+"%s" & "a string"));
  37 --
  38 --  or with a constant for the format:
  39 --
  40 --     declare
  41 --       Format : constant Formatted_String := +"%s";
  42 --     begin
  43 --       Put_Line (-(Format & "a string"));
  44 --     end;
  45 --
  46 --  Finally a more complex example:
  47 --
  48 --     declare
  49 --        F : Formatted_String := +"['%c' ; %10d]";
  50 --        C : Character := 'v';
  51 --        I : Integer := 98;
  52 --     begin
  53 --        F := F & C & I;
  54 --        Put_Line (-F);
  55 --     end;
  56
  57 --  Which will display:
  58
  59 --     ['v' ;         98]
  60
  61 --  Each format specifier is: %[flags][width][.precision][length]specifier
  62
  63 --  Specifiers:
  64 --    d or i    Signed decimal integer
  65 --    u         Unsigned decimal integer
  66 --    o         Unsigned octal
  67 --    x         Unsigned hexadecimal integer
  68 --    X         Unsigned hexadecimal integer (uppercase)
  69 --    f         Decimal floating point, lowercase
  70 --    F         Decimal floating point, uppercase
  71 --    e         Scientific notation (mantissa/exponent), lowercase
  72 --    E         Scientific notation (mantissa/exponent), uppercase
  73 --    g         Use the shortest representation: %e or %f
  74 --    G         Use the shortest representation: %E or %F
  75 --    c         Character
  76 --    s         String of characters
  77 --    p         Pointer address
  78 --    %         A % followed by another % character will write a single %
  79
  80 --  Flags:
  81
  82 --    -         Left-justify within the given field width;
  83 --              Right justification is the default.
  84
  85 --    +         Forces to preceed the result with a plus or minus sign (+ or -)
  86 --              even for positive numbers. By default, only negative numbers
  87 --              are preceded with a - sign.
  88
  89 --    (space)   If no sign is going to be written, a blank space is inserted
  90 --              before the value.
  91
  92 --    #         Used with o, x or X specifiers the value is preceeded with
  93 --              0, 0x or 0X respectively for values different than zero.
  94 --              Used with a, A, e, E, f, F, g or G it forces the written
  95 --              output to contain a decimal point even if no more digits
  96 --              follow. By default, if no digits follow, no decimal point is
  97 --              written.
  98
  99 --    ~         As above, but using Ada style based <base>#<number>#
 100
 101 --    0         Left-pads the number with zeroes (0) instead of spaces when
 102 --              padding is specified.
 103
 104 --  Width:
 105 --    number    Minimum number of characters to be printed. If the value to
 106 --              be printed is shorter than this number, the result is padded
 107 --              with blank spaces. The value is not truncated even if the
 108 --              result is larger.
 109
 110 --    *         The width is not specified in the format string, but as an
 111 --              additional integer value argument preceding the argument that
 112 --              has to be formatted.
 113 --  Precision:
 114 --    number    For integer specifiers (d, i, o, u, x, X): precision specifies
 115 --              the minimum number of digits to be written. If the value to be
 116 --              written is shorter than this number, the result is padded with
 117 --              leading zeros. The value is not truncated even if the result
 118 --              is longer. A precision of 0 means that no character is written
 119 --              for the value 0.
 120
 121 --              For e, E, f and F specifiers: this is the number of digits to
 122 --              be printed after the decimal point (by default, this is 6).
 123 --              For g and G specifiers: This is the maximum number of
 124 --              significant digits to be printed.
 125
 126 --              For s: this is the maximum number of characters to be printed.
 127 --              By default all characters are printed until the ending null
 128 --              character is encountered.
 129
 130 --              If the period is specified without an explicit value for
 131 --              precision, 0 is assumed.
 132
 133 --    .*        The precision is not specified in the format string, but as an
 134 --              additional integer value argument preceding the argument that
 135 --              has to be formatted.
 136
 137 with Ada.Text_IO;
 138 with System;
 139
 140 private with Ada.Finalization;
 141 private with Ada.Strings.Unbounded;
 142
 143 package GNAT.Formatted_String is
 144    use Ada;
 145
 146    type Formatted_String (<>) is private;
 147    --  A format string as defined for printf routine. This string is the
 148    --  actual format for all the parameters added with the "&" routines below.
 149    --  Note that a Formatted_String object can't be reused as it serves as
 150    --  recipient for the final result. That is, each use of "&" will build
 151    --  incrementally the final result string which can be retrieved with
 152    --  the "-" routine below.
 153
 154    Format_Error : exception;
 155    --  Raised for every mismatch between the parameter and the expected format
 156    --  and for malformed format.
 157
 158    function "+" (Format : String) return Formatted_String;
 159    --  Create the format string
 160
 161    function "-" (Format : Formatted_String) return String;
 162    --  Get the result of the formatted string corresponding to the current
 163    --  rendering (up to the last parameter formated).
 164
 165    function "&"
 166      (Format : Formatted_String;
 167       Var    : Character) return Formatted_String;
 168    --  A character, expect a %c
 169
 170    function "&"
 171      (Format : Formatted_String;
 172       Var    : String) return Formatted_String;
 173    --  A string, expect a %s
 174
 175    function "&"
 176      (Format : Formatted_String;
 177       Var    : Boolean) return Formatted_String;
 178    --  A boolean image, expect a %s
 179
 180    function "&"
 181      (Format : Formatted_String;
 182       Var    : Integer) return Formatted_String;
 183    --  An integer, expect a %d, %o, %x, %X
 184
 185    function "&"
 186      (Format : Formatted_String;
 187       Var    : Long_Integer) return Formatted_String;
 188    --  As above
 189
 190    function "&"
 191      (Format : Formatted_String;
 192       Var    : System.Address) return Formatted_String;
 193    --  An address, expect a %p
 194
 195    function "&"
 196      (Format : Formatted_String;
 197       Var    : Float) return Formatted_String;
 198    --  A float, expect %f, %e, %F, %E, %g, %G
 199
 200    function "&"
 201      (Format : Formatted_String;
 202       Var    : Long_Float) return Formatted_String;
 203    --  As above
 204
 205    function "&"
 206      (Format : Formatted_String;
 207       Var    : Duration) return Formatted_String;
 208    --  As above
 209
 210    --  Some generics
 211
 212    generic
 213       type Int is range <>;
 214
 215       with procedure Put
 216         (To   : out String;
 217          Item : Int;
 218          Base : Text_IO.Number_Base);
 219    function Int_Format
 220      (Format : Formatted_String;
 221       Var    : Int) return Formatted_String;
 222    --  As for Integer above
 223
 224    generic
 225       type Int is mod <>;
 226
 227       with procedure Put
 228         (To   : out String;
 229          Item : Int;
 230          Base : Text_IO.Number_Base);
 231    function Mod_Format
 232      (Format : Formatted_String;
 233       Var    : Int) return Formatted_String;
 234    --  As for Integer above
 235
 236    generic
 237       type Flt is digits <>;
 238
 239       with procedure Put
 240         (To   : out String;
 241          Item : Flt;
 242          Aft  : Text_IO.Field;
 243          Exp  : Text_IO.Field);
 244    function Flt_Format
 245      (Format : Formatted_String;
 246       Var    : Flt) return Formatted_String;
 247    --  As for Float above
 248
 249    generic
 250       type Flt is delta <>;
 251
 252       with procedure Put
 253         (To   : out String;
 254          Item : Flt;
 255          Aft  : Text_IO.Field;
 256          Exp  : Text_IO.Field);
 257    function Fixed_Format
 258      (Format : Formatted_String;
 259       Var    : Flt) return Formatted_String;
 260    --  As for Float above
 261
 262    generic
 263       type Flt is delta <> digits <>;
 264
 265       with procedure Put
 266         (To   : out String;
 267          Item : Flt;
 268          Aft  : Text_IO.Field;
 269          Exp  : Text_IO.Field);
 270    function Decimal_Format
 271      (Format : Formatted_String;
 272       Var    : Flt) return Formatted_String;
 273    --  As for Float above
 274
 275    generic
 276       type Enum is (<>);
 277    function Enum_Format
 278      (Format : Formatted_String;
 279       Var    : Enum) return Formatted_String;
 280    --  As for String above, output the string representation of the enumeration
 281
 282 private
 283    use Ada.Strings.Unbounded;
 284
 285    type I_Vars is array (Positive range 1 .. 2) of Integer;
 286    --  Used to keep 2 numbers for the possible * for the width and precision
 287
 288    type Data (Size : Natural) is record
 289       Ref_Count    : Natural := 1;
 290       Index        : Positive := 1;      -- format index for next value
 291       Result       : Unbounded_String;   -- current value
 292       Current      : Natural;            -- the current format number
 293       Stored_Value : Natural := 0;       -- number of stored values in Stack
 294       Stack        : I_Vars;
 295       Format       : String (1 .. Size); -- the format string
 296    end record;
 297
 298    type Data_Access is access Data;
 299
 300    --  The formatted string record is controlled and do not need an initialize
 301    --  as it requires an explit initial value. This is given with "+" and
 302    --  properly initialize the record at this point.
 303
 304    type Formatted_String is new Finalization.Controlled with record
 305       D : Data_Access;
 306    end record;
 307
 308    overriding procedure Adjust   (F : in out Formatted_String);
 309    overriding procedure Finalize (F : in out Formatted_String);
 310
 311 end GNAT.Formatted_String;