gcc/ada/g-spitbo.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --                         G N A T . S P I T B O L                          --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                     Copyright (C) 1997-2016, AdaCore                     --
  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 --  SPITBOL-like interface facilities
  33
  34 --  This package provides a set of interfaces to semantic operations copied
  35 --  from SPITBOL, including a complete implementation of SPITBOL pattern
  36 --  matching. The code is derived from the original SPITBOL MINIMAL sources,
  37 --  created by Robert Dewar. The translation is not exact, but the
  38 --  algorithmic approaches are similar.
  39
  40 with Ada.Finalization;      use Ada.Finalization;
  41 with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
  42 with Interfaces;            use Interfaces;
  43
  44 package GNAT.Spitbol is
  45    pragma Preelaborate;
  46
  47    --  The Spitbol package relies heavily on the Unbounded_String package,
  48    --  using the synonym VString for variable length string. The following
  49    --  declarations define this type and other useful abbreviations.
  50
  51    subtype VString is Ada.Strings.Unbounded.Unbounded_String;
  52
  53    function V (Source : String) return VString
  54      renames Ada.Strings.Unbounded.To_Unbounded_String;
  55
  56    function S (Source : VString) return String
  57      renames Ada.Strings.Unbounded.To_String;
  58
  59    Nul : VString renames Ada.Strings.Unbounded.Null_Unbounded_String;
  60
  61    -------------------------
  62    -- Facilities Provided --
  63    -------------------------
  64
  65    --  The SPITBOL support in GNAT consists of this package together with
  66    --  several child packages. In this package, we have first a set of
  67    --  useful string functions, copied exactly from the corresponding
  68    --  SPITBOL functions, except that we had to rename REVERSE because
  69    --  reverse is a reserved word (it is now Reverse_String).
  70
  71    --  The second element of the parent package is a generic implementation
  72    --  of a table facility. In SPITBOL, the TABLE function allows general
  73    --  mappings from any datatype to any other datatype, and of course, as
  74    --  always, we can freely mix multiple types in the same table.
  75
  76    --  The Ada version of tables is strongly typed, so the indexing type and
  77    --  the range type are always of a consistent type. In this implementation
  78    --  we only provide VString as an indexing type, since this is by far the
  79    --  most common case. The generic instantiation specifies the range type
  80    --  to be used.
  81
  82    --  Three child packages provide standard instantiations of this table
  83    --  package for three common datatypes:
  84
  85    --    GNAT.Spitbol.Table_Boolean     (file g-sptabo.ads)
  86
  87    --      The range type is Boolean. The default value is False. This
  88    --      means that this table is essentially a representation of a set.
  89
  90    --    GNAT.Spitbol.Table_Integer     (file g-sptain.ads)
  91
  92    --      The range type is Integer. The default value is Integer'First.
  93    --      This provides a general mapping from strings to integers.
  94
  95    --    GNAT.Spitbol.Table_VString     (file g-sptavs.ads)
  96
  97    --      The range type is VString. The default value is the null string.
  98    --      This provides a general mapping from strings to strings.
  99
 100    --  Finally there is another child package:
 101
 102    --    GNAT.Spitbol.Patterns          (file g-spipat.ads)
 103
 104    --       This child package provides a complete implementation of SPITBOL
 105    --       pattern matching. The spec contains a complete tutorial on the
 106    --       use of pattern matching.
 107
 108    ---------------------------------
 109    -- Standard String Subprograms --
 110    ---------------------------------
 111
 112    --  This section contains some operations on unbounded strings that are
 113    --  closely related to those in the package Unbounded.Strings, but they
 114    --  correspond to the SPITBOL semantics for these operations.
 115
 116    function Char (Num : Natural) return Character;
 117    pragma Inline (Char);
 118    --  Equivalent to Character'Val (Num)
 119
 120    function Lpad
 121      (Str : VString;
 122       Len : Natural;
 123       Pad : Character := ' ') return VString;
 124    function Lpad
 125      (Str : String;
 126       Len : Natural;
 127       Pad : Character := ' ') return VString;
 128    --  If the length of Str is greater than or equal to Len, then Str is
 129    --  returned unchanged. Otherwise, The value returned is obtained by
 130    --  concatenating Length (Str) - Len instances of the Pad character to
 131    --  the left hand side.
 132
 133    procedure Lpad
 134      (Str  : in out VString;
 135       Len  : Natural;
 136       Pad  : Character := ' ');
 137    --  The procedure form is identical to the function form, except that
 138    --  the result overwrites the input argument Str.
 139
 140    function Reverse_String (Str : VString) return VString;
 141    function Reverse_String (Str : String)  return VString;
 142    --  Returns result of reversing the string Str, i.e. the result returned
 143    --  is a mirror image (end-for-end reversal) of the input string.
 144
 145    procedure Reverse_String (Str : in out VString);
 146    --  The procedure form is identical to the function form, except that the
 147    --  result overwrites the input argument Str.
 148
 149    function Rpad
 150      (Str : VString;
 151       Len : Natural;
 152       Pad : Character := ' ') return VString;
 153    function Rpad
 154      (Str : String;
 155       Len : Natural;
 156       Pad : Character := ' ') return VString;
 157    --  If the length of Str is greater than or equal to Len, then Str is
 158    --  returned unchanged. Otherwise, The value returned is obtained by
 159    --  concatenating Length (Str) - Len instances of the Pad character to
 160    --  the right hand side.
 161
 162    procedure Rpad
 163      (Str  : in out VString;
 164       Len  : Natural;
 165       Pad  : Character := ' ');
 166    --  The procedure form is identical to the function form, except that the
 167    --  result overwrites the input argument Str.
 168
 169    function Size (Source : VString) return Natural
 170      renames Ada.Strings.Unbounded.Length;
 171
 172    function Substr
 173      (Str   : VString;
 174       Start : Positive;
 175       Len   : Natural) return  VString;
 176    function Substr
 177      (Str   : String;
 178       Start : Positive;
 179       Len   : Natural) return  VString;
 180    --  Returns the substring starting at the given character position (which
 181    --  is always counted from the start of the string, regardless of bounds,
 182    --  e.g. 2 means starting with the second character of the string), and
 183    --  with the length (Len) given. Index_Error is raised if the starting
 184    --  position is out of range, and Length_Error is raised if Len is too long.
 185
 186    function Trim (Str : VString) return VString;
 187    function Trim (Str : String)  return VString;
 188    --  Returns the string obtained by removing all spaces from the right
 189    --  hand side of the string Str.
 190
 191    procedure Trim (Str : in out VString);
 192    --  The procedure form is identical to the function form, except that the
 193    --  result overwrites the input argument Str.
 194
 195    -----------------------
 196    -- Utility Functions --
 197    -----------------------
 198
 199    --  In SPITBOL, integer values can be freely treated as strings. The
 200    --  following definitions help provide some of this capability in
 201    --  some common cases.
 202
 203    function "&" (Num : Integer; Str : String)  return String;
 204    function "&" (Str : String;  Num : Integer) return String;
 205    function "&" (Num : Integer; Str : VString) return VString;
 206    function "&" (Str : VString; Num : Integer) return VString;
 207    --  In all these concatenation operations, the integer is converted to
 208    --  its corresponding decimal string form, with no leading blank.
 209
 210    function S (Num : Integer) return String;
 211    function V (Num : Integer) return VString;
 212    --  These operators return the given integer converted to its decimal
 213    --  string form with no leading blank.
 214
 215    function N (Str : VString) return Integer;
 216    --  Converts string to number (same as Integer'Value (S (Str)))
 217
 218    -------------------
 219    -- Table Support --
 220    -------------------
 221
 222    --  So far, we only provide support for tables whose indexing data values
 223    --  are strings (or unbounded strings). The values stored may be of any
 224    --  type, as supplied by the generic formal parameter.
 225
 226    generic
 227
 228       type Value_Type is private;
 229       --  Any non-limited type can be used as the value type in the table
 230
 231       Null_Value : Value_Type;
 232       --  Value used to represent a value that is not present in the table
 233
 234       with function Img (A : Value_Type) return String;
 235       --  Used to provide image of value in Dump procedure
 236
 237       with function "=" (A, B : Value_Type) return Boolean is <>;
 238       --  This allows a user-defined equality function to override the
 239       --  predefined equality function.
 240
 241    package Table is
 242
 243       ------------------------
 244       -- Table Declarations --
 245       ------------------------
 246
 247       type Table (N : Unsigned_32) is private;
 248       --  This is the table type itself. A table is a mapping from string
 249       --  values to values of Value_Type. The discriminant is an estimate of
 250       --  the number of values in the table. If the estimate is much too
 251       --  high, some space is wasted, if the estimate is too low, access to
 252       --  table elements is slowed down. The type Table has copy semantics,
 253       --  not reference semantics. This means that if a table is copied
 254       --  using simple assignment, then the two copies refer to entirely
 255       --  separate tables.
 256
 257       -----------------------------
 258       -- Table Access Operations --
 259       -----------------------------
 260
 261       function Get (T : Table; Name : VString)   return Value_Type;
 262       function Get (T : Table; Name : Character) return Value_Type;
 263       pragma Inline (Get);
 264       function Get (T : Table; Name : String)    return Value_Type;
 265
 266       --  If an entry with the given name exists in the table, then the
 267       --  corresponding Value_Type value is returned. Otherwise Null_Value
 268       --  is returned.
 269
 270       function Present (T : Table; Name : VString)   return Boolean;
 271       function Present (T : Table; Name : Character) return Boolean;
 272       pragma Inline (Present);
 273       function Present (T : Table; Name : String)    return Boolean;
 274       --  Determines if an entry with the given name is present in the table.
 275       --  A returned value of True means that it is in the table, otherwise
 276       --  False indicates that it is not in the table.
 277
 278       procedure Delete (T : in out Table; Name : VString);
 279       procedure Delete (T : in out Table; Name : Character);
 280       pragma Inline (Delete);
 281       procedure Delete (T : in out Table; Name : String);
 282       --  Deletes the table element with the given name from the table. If
 283       --  no element in the table has this name, then the call has no effect.
 284
 285       procedure Set (T : in out Table; Name  : VString;   Value : Value_Type);
 286       procedure Set (T : in out Table; Name  : Character; Value : Value_Type);
 287       pragma Inline (Set);
 288       procedure Set (T : in out Table; Name  : String;    Value : Value_Type);
 289       --  Sets the value of the element with the given name to the given
 290       --  value. If Value is equal to Null_Value, the effect is to remove
 291       --  the entry from the table. If no element with the given name is
 292       --  currently in the table, then a new element with the given value
 293       --  is created.
 294
 295       ----------------------------
 296       -- Allocation and Copying --
 297       ----------------------------
 298
 299       --  Table is a controlled type, so that all storage associated with
 300       --  tables is properly reclaimed when a Table value is abandoned.
 301       --  Tables have value semantics rather than reference semantics as
 302       --  in Spitbol, i.e. when you assign a copy you end up with two
 303       --  distinct copies of the table, as though COPY had been used in
 304       --  Spitbol. It seems clearly more appropriate in Ada to require
 305       --  the use of explicit pointers for reference semantics.
 306
 307       procedure Clear (T : in out Table);
 308       --  Clears all the elements of the given table, freeing associated
 309       --  storage. On return T is an empty table with no elements.
 310
 311       procedure Copy (From : Table; To : in out Table);
 312       --  First all the elements of table To are cleared (as described for
 313       --  the Clear procedure above), then all the elements of table From
 314       --  are copied into To. In the case where the tables From and To have
 315       --  the same declared size (i.e. the same discriminant), the call to
 316       --  Copy has the same effect as the assignment of From to To. The
 317       --  difference is that, unlike the assignment statement, which will
 318       --  cause a Constraint_Error if the source and target are of different
 319       --  sizes, Copy works fine with different sized tables.
 320
 321       ----------------
 322       -- Conversion --
 323       ----------------
 324
 325       type Table_Entry is record
 326          Name  : VString;
 327          Value : Value_Type;
 328       end record;
 329
 330       type Table_Array is array (Positive range <>) of Table_Entry;
 331
 332       function Convert_To_Array (T : Table) return Table_Array;
 333       --  Returns a Table_Array value with a low bound of 1, and a length
 334       --  corresponding to the number of elements in the table. The elements
 335       --  of the array give the elements of the table in unsorted order.
 336
 337       ---------------
 338       -- Debugging --
 339       ---------------
 340
 341       procedure Dump (T : Table; Str : String := "Table");
 342       --  Dump contents of given table to the standard output file. The
 343       --  string value Str is used as the name of the table in the dump.
 344
 345       procedure Dump (T : Table_Array; Str : String := "Table_Array");
 346       --  Dump contents of given table array to the current output file. The
 347       --  string value Str is used as the name of the table array in the dump.
 348
 349    private
 350
 351       ------------------
 352       -- Private Part --
 353       ------------------
 354
 355       --  A Table is a pointer to a hash table which contains the indicated
 356       --  number of hash elements (the number is forced to the next odd value
 357       --  if it is even to improve hashing performance). If more than one
 358       --  of the entries in a table hashes to the same slot, the Next field
 359       --  is used to chain entries from the header. The chains are not kept
 360       --  ordered. A chain is terminated by a null pointer in Next. An unused
 361       --  chain is marked by an element whose Name is null and whose value
 362       --  is Null_Value.
 363
 364       type Hash_Element;
 365       type Hash_Element_Ptr is access all Hash_Element;
 366
 367       type Hash_Element is record
 368          Name  : String_Access    := null;
 369          Value : Value_Type       := Null_Value;
 370          Next  : Hash_Element_Ptr := null;
 371       end record;
 372
 373       type Hash_Table is
 374         array (Unsigned_32 range <>) of aliased Hash_Element;
 375
 376       type Table (N : Unsigned_32) is new Controlled with record
 377          Elmts : Hash_Table (1 .. N);
 378       end record;
 379
 380       pragma Finalize_Storage_Only (Table);
 381
 382       overriding procedure Adjust (Object : in out Table);
 383       --  The Adjust procedure does a deep copy of the table structure
 384       --  so that the effect of assignment is, like other assignments
 385       --  in Ada, value-oriented.
 386
 387       overriding procedure Finalize (Object : in out Table);
 388       --  This is the finalization routine that ensures that all storage
 389       --  associated with a table is properly released when a table object
 390       --  is abandoned and finalized.
 391
 392    end Table;
 393
 394 end GNAT.Spitbol;