gcc/ada/s-valuti.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                      S Y S T E M . V A L _ U T I L                       --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2002, 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 2,  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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 with System.Case_Util; use System.Case_Util;
  35
  36 package body System.Val_Util is
  37
  38    ----------------------
  39    -- Normalize_String --
  40    ----------------------
  41
  42    procedure Normalize_String
  43      (S    : in out String;
  44       F, L : out Integer)
  45    is
  46    begin
  47       F := S'First;
  48       L := S'Last;
  49
  50       --  Scan for leading spaces
  51
  52       while F <= L and then S (F) = ' ' loop
  53          F := F + 1;
  54       end loop;
  55
  56       --  Check for case when the string contained no characters
  57
  58       if F > L then
  59          raise Constraint_Error;
  60       end if;
  61
  62       --  Scan for trailing spaces
  63
  64       while S (L) = ' ' loop
  65          L := L - 1;
  66       end loop;
  67
  68       --  Except in the case of a character literal, convert to upper case
  69
  70       if S (F) /= ''' then
  71          for J in F .. L loop
  72             S (J) := To_Upper (S (J));
  73          end loop;
  74       end if;
  75
  76    end Normalize_String;
  77
  78    -------------------
  79    -- Scan_Exponent --
  80    -------------------
  81
  82    function Scan_Exponent
  83      (Str  : String;
  84       Ptr  : access Integer;
  85       Max  : Integer;
  86       Real : Boolean := False)
  87       return Integer
  88    is
  89       P : Natural := Ptr.all;
  90       M : Boolean;
  91       X : Integer;
  92
  93    begin
  94       if P >= Max
  95         or else (Str (P) /= 'E' and then Str (P) /= 'e')
  96       then
  97          return 0;
  98       end if;
  99
 100       --  We have an E/e, see if sign follows
 101
 102       P := P + 1;
 103
 104       if Str (P) = '+' then
 105          P := P + 1;
 106
 107          if P > Max then
 108             return 0;
 109          else
 110             M := False;
 111          end if;
 112
 113       elsif Str (P) = '-' then
 114          P := P + 1;
 115
 116          if P > Max or else not Real then
 117             return 0;
 118          else
 119             M := True;
 120          end if;
 121
 122       else
 123          M := False;
 124       end if;
 125
 126       if Str (P) not in '0' .. '9' then
 127          return 0;
 128       end if;
 129
 130       --  Scan out the exponent value as an unsigned integer. Values larger
 131       --  than (Integer'Last / 10) are simply considered large enough here.
 132       --  This assumption is correct for all machines we know of (e.g. in
 133       --  the case of 16 bit integers it allows exponents up to 3276, which
 134       --  is large enough for the largest floating types in base 2.)
 135
 136       X := 0;
 137
 138       loop
 139          if X < (Integer'Last / 10) then
 140             X := X * 10 + (Character'Pos (Str (P)) - Character'Pos ('0'));
 141          end if;
 142
 143          P := P + 1;
 144
 145          exit when P > Max;
 146
 147          if Str (P) = '_' then
 148             Scan_Underscore (Str, P, Ptr, Max, False);
 149          else
 150             exit when Str (P) not in '0' .. '9';
 151          end if;
 152       end loop;
 153
 154       if M then
 155          X := -X;
 156       end if;
 157
 158       Ptr.all := P;
 159       return X;
 160
 161    end Scan_Exponent;
 162
 163    ---------------
 164    -- Scan_Sign --
 165    ---------------
 166
 167    procedure Scan_Sign
 168      (Str   : String;
 169       Ptr   : access Integer;
 170       Max   : Integer;
 171       Minus : out Boolean;
 172       Start : out Positive)
 173    is
 174       P : Natural := Ptr.all;
 175
 176    begin
 177       --  Deal with case of null string (all blanks!). As per spec, we
 178       --  raise constraint error, with Ptr unchanged, and thus > Max.
 179
 180       if P > Max then
 181          raise Constraint_Error;
 182       end if;
 183
 184       --  Scan past initial blanks
 185
 186       while Str (P) = ' ' loop
 187          P := P + 1;
 188
 189          if P > Max then
 190             Ptr.all := P;
 191             raise Constraint_Error;
 192          end if;
 193       end loop;
 194
 195       Start := P;
 196
 197       --  Remember an initial minus sign
 198
 199       if Str (P) = '-' then
 200          Minus := True;
 201          P := P + 1;
 202
 203          if P > Max then
 204             Ptr.all := Start;
 205             raise Constraint_Error;
 206          end if;
 207
 208       --  Skip past an initial plus sign
 209
 210       elsif Str (P) = '+' then
 211          Minus := False;
 212          P := P + 1;
 213
 214          if P > Max then
 215             Ptr.all := Start;
 216             raise Constraint_Error;
 217          end if;
 218
 219       else
 220          Minus := False;
 221       end if;
 222
 223       Ptr.all := P;
 224    end Scan_Sign;
 225
 226    --------------------------
 227    -- Scan_Trailing_Blanks --
 228    --------------------------
 229
 230    procedure Scan_Trailing_Blanks (Str : String; P : Positive) is
 231    begin
 232       for J in P .. Str'Last loop
 233          if Str (J) /= ' ' then
 234             raise Constraint_Error;
 235          end if;
 236       end loop;
 237    end Scan_Trailing_Blanks;
 238
 239    ---------------------
 240    -- Scan_Underscore --
 241    ---------------------
 242
 243    procedure Scan_Underscore
 244      (Str : String;
 245       P   : in out Natural;
 246       Ptr : access Integer;
 247       Max : Integer;
 248       Ext : Boolean)
 249    is
 250       C : Character;
 251
 252    begin
 253       P := P + 1;
 254
 255       --  If underscore is at the end of string, then this is an error and
 256       --  we raise Constraint_Error, leaving the pointer past the undescore.
 257       --  This seems a bit strange. It means e,g, that if the field is:
 258
 259       --    345_
 260
 261       --  that Constraint_Error is raised. You might think that the RM in
 262       --  this case would scan out the 345 as a valid integer, leaving the
 263       --  pointer at the underscore, but the ACVC suite clearly requires
 264       --  an error in this situation (see for example CE3704M).
 265
 266       if P > Max then
 267          Ptr.all := P;
 268          raise Constraint_Error;
 269       end if;
 270
 271       --  Similarly, if no digit follows the underscore raise an error. This
 272       --  also catches the case of double underscore which is also an error.
 273
 274       C := Str (P);
 275
 276       if C in '0' .. '9'
 277         or else
 278           (Ext and then (C in 'A' .. 'F' or else C in 'a' .. 'f'))
 279       then
 280          return;
 281       else
 282          Ptr.all := P;
 283          raise Constraint_Error;
 284       end if;
 285    end Scan_Underscore;
 286
 287 end System.Val_Util;