395 lines
17 KiB
Ada
395 lines
17 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT LIBRARY COMPONENTS --
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-- --
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-- G N A T . S P I T B O L --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1997-2012, AdaCore --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- SPITBOL-like interface facilities
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-- This package provides a set of interfaces to semantic operations copied
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-- from SPITBOL, including a complete implementation of SPITBOL pattern
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-- matching. The code is derived from the original SPITBOL MINIMAL sources,
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-- created by Robert Dewar. The translation is not exact, but the
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-- algorithmic approaches are similar.
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with Ada.Finalization; use Ada.Finalization;
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with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
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with Interfaces; use Interfaces;
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package GNAT.Spitbol is
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pragma Preelaborate;
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-- The Spitbol package relies heavily on the Unbounded_String package,
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-- using the synonym VString for variable length string. The following
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-- declarations define this type and other useful abbreviations.
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subtype VString is Ada.Strings.Unbounded.Unbounded_String;
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function V (Source : String) return VString
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renames Ada.Strings.Unbounded.To_Unbounded_String;
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function S (Source : VString) return String
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renames Ada.Strings.Unbounded.To_String;
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Nul : VString renames Ada.Strings.Unbounded.Null_Unbounded_String;
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-------------------------
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-- Facilities Provided --
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-------------------------
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-- The SPITBOL support in GNAT consists of this package together with
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-- several child packages. In this package, we have first a set of
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-- useful string functions, copied exactly from the corresponding
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-- SPITBOL functions, except that we had to rename REVERSE because
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-- reverse is a reserved word (it is now Reverse_String).
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-- The second element of the parent package is a generic implementation
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-- of a table facility. In SPITBOL, the TABLE function allows general
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-- mappings from any datatype to any other datatype, and of course, as
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-- always, we can freely mix multiple types in the same table.
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-- The Ada version of tables is strongly typed, so the indexing type and
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-- the range type are always of a consistent type. In this implementation
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-- we only provide VString as an indexing type, since this is by far the
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-- most common case. The generic instantiation specifies the range type
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-- to be used.
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-- Three child packages provide standard instantiations of this table
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-- package for three common datatypes:
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-- GNAT.Spitbol.Table_Boolean (file g-sptabo.ads)
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-- The range type is Boolean. The default value is False. This
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-- means that this table is essentially a representation of a set.
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-- GNAT.Spitbol.Table_Integer (file g-sptain.ads)
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-- The range type is Integer. The default value is Integer'First.
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-- This provides a general mapping from strings to integers.
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-- GNAT.Spitbol.Table_VString (file g-sptavs.ads)
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-- The range type is VString. The default value is the null string.
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-- This provides a general mapping from strings to strings.
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-- Finally there is another child package:
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-- GNAT.Spitbol.Patterns (file g-spipat.ads)
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-- This child package provides a complete implementation of SPITBOL
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-- pattern matching. The spec contains a complete tutorial on the
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-- use of pattern matching.
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---------------------------------
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-- Standard String Subprograms --
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---------------------------------
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-- This section contains some operations on unbounded strings that are
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-- closely related to those in the package Unbounded.Strings, but they
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-- correspond to the SPITBOL semantics for these operations.
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function Char (Num : Natural) return Character;
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pragma Inline (Char);
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-- Equivalent to Character'Val (Num)
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function Lpad
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(Str : VString;
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Len : Natural;
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Pad : Character := ' ') return VString;
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function Lpad
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(Str : String;
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Len : Natural;
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Pad : Character := ' ') return VString;
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-- If the length of Str is greater than or equal to Len, then Str is
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-- returned unchanged. Otherwise, The value returned is obtained by
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-- concatenating Length (Str) - Len instances of the Pad character to
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-- the left hand side.
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procedure Lpad
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(Str : in out VString;
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Len : Natural;
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Pad : Character := ' ');
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-- The procedure form is identical to the function form, except that
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-- the result overwrites the input argument Str.
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function Reverse_String (Str : VString) return VString;
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function Reverse_String (Str : String) return VString;
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-- Returns result of reversing the string Str, i.e. the result returned
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-- is a mirror image (end-for-end reversal) of the input string.
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procedure Reverse_String (Str : in out VString);
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-- The procedure form is identical to the function form, except that the
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-- result overwrites the input argument Str.
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function Rpad
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(Str : VString;
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Len : Natural;
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Pad : Character := ' ') return VString;
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function Rpad
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(Str : String;
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Len : Natural;
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Pad : Character := ' ') return VString;
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-- If the length of Str is greater than or equal to Len, then Str is
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-- returned unchanged. Otherwise, The value returned is obtained by
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-- concatenating Length (Str) - Len instances of the Pad character to
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-- the right hand side.
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procedure Rpad
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(Str : in out VString;
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Len : Natural;
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Pad : Character := ' ');
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-- The procedure form is identical to the function form, except that the
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-- result overwrites the input argument Str.
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function Size (Source : VString) return Natural
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renames Ada.Strings.Unbounded.Length;
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function Substr
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(Str : VString;
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Start : Positive;
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Len : Natural) return VString;
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function Substr
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(Str : String;
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Start : Positive;
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Len : Natural) return VString;
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-- Returns the substring starting at the given character position (which
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-- is always counted from the start of the string, regardless of bounds,
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-- e.g. 2 means starting with the second character of the string), and
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-- with the length (Len) given. Index_Error is raised if the starting
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-- position is out of range, and Length_Error is raised if Len is too long.
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function Trim (Str : VString) return VString;
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function Trim (Str : String) return VString;
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-- Returns the string obtained by removing all spaces from the right
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-- hand side of the string Str.
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procedure Trim (Str : in out VString);
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-- The procedure form is identical to the function form, except that the
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-- result overwrites the input argument Str.
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-----------------------
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-- Utility Functions --
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-----------------------
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-- In SPITBOL, integer values can be freely treated as strings. The
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-- following definitions help provide some of this capability in
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-- some common cases.
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function "&" (Num : Integer; Str : String) return String;
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function "&" (Str : String; Num : Integer) return String;
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function "&" (Num : Integer; Str : VString) return VString;
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function "&" (Str : VString; Num : Integer) return VString;
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-- In all these concatenation operations, the integer is converted to
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-- its corresponding decimal string form, with no leading blank.
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function S (Num : Integer) return String;
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function V (Num : Integer) return VString;
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-- These operators return the given integer converted to its decimal
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-- string form with no leading blank.
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function N (Str : VString) return Integer;
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-- Converts string to number (same as Integer'Value (S (Str)))
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-------------------
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-- Table Support --
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-------------------
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-- So far, we only provide support for tables whose indexing data values
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-- are strings (or unbounded strings). The values stored may be of any
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-- type, as supplied by the generic formal parameter.
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generic
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type Value_Type is private;
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-- Any non-limited type can be used as the value type in the table
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Null_Value : Value_Type;
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-- Value used to represent a value that is not present in the table
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with function Img (A : Value_Type) return String;
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-- Used to provide image of value in Dump procedure
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with function "=" (A, B : Value_Type) return Boolean is <>;
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-- This allows a user-defined equality function to override the
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-- predefined equality function.
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package Table is
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------------------------
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-- Table Declarations --
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------------------------
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type Table (N : Unsigned_32) is private;
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-- This is the table type itself. A table is a mapping from string
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-- values to values of Value_Type. The discriminant is an estimate of
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-- the number of values in the table. If the estimate is much too
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-- high, some space is wasted, if the estimate is too low, access to
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-- table elements is slowed down. The type Table has copy semantics,
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-- not reference semantics. This means that if a table is copied
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-- using simple assignment, then the two copies refer to entirely
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-- separate tables.
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-----------------------------
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-- Table Access Operations --
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-----------------------------
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function Get (T : Table; Name : VString) return Value_Type;
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function Get (T : Table; Name : Character) return Value_Type;
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pragma Inline (Get);
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function Get (T : Table; Name : String) return Value_Type;
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-- If an entry with the given name exists in the table, then the
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-- corresponding Value_Type value is returned. Otherwise Null_Value
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-- is returned.
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function Present (T : Table; Name : VString) return Boolean;
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function Present (T : Table; Name : Character) return Boolean;
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pragma Inline (Present);
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function Present (T : Table; Name : String) return Boolean;
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-- Determines if an entry with the given name is present in the table.
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-- A returned value of True means that it is in the table, otherwise
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-- False indicates that it is not in the table.
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procedure Delete (T : in out Table; Name : VString);
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procedure Delete (T : in out Table; Name : Character);
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pragma Inline (Delete);
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procedure Delete (T : in out Table; Name : String);
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-- Deletes the table element with the given name from the table. If
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-- no element in the table has this name, then the call has no effect.
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procedure Set (T : in out Table; Name : VString; Value : Value_Type);
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procedure Set (T : in out Table; Name : Character; Value : Value_Type);
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pragma Inline (Set);
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procedure Set (T : in out Table; Name : String; Value : Value_Type);
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-- Sets the value of the element with the given name to the given
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-- value. If Value is equal to Null_Value, the effect is to remove
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-- the entry from the table. If no element with the given name is
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-- currently in the table, then a new element with the given value
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-- is created.
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----------------------------
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-- Allocation and Copying --
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----------------------------
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-- Table is a controlled type, so that all storage associated with
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-- tables is properly reclaimed when a Table value is abandoned.
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-- Tables have value semantics rather than reference semantics as
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-- in Spitbol, i.e. when you assign a copy you end up with two
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-- distinct copies of the table, as though COPY had been used in
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-- Spitbol. It seems clearly more appropriate in Ada to require
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-- the use of explicit pointers for reference semantics.
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procedure Clear (T : in out Table);
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-- Clears all the elements of the given table, freeing associated
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-- storage. On return T is an empty table with no elements.
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procedure Copy (From : Table; To : in out Table);
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-- First all the elements of table To are cleared (as described for
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-- the Clear procedure above), then all the elements of table From
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-- are copied into To. In the case where the tables From and To have
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-- the same declared size (i.e. the same discriminant), the call to
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-- Copy has the same effect as the assignment of From to To. The
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-- difference is that, unlike the assignment statement, which will
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-- cause a Constraint_Error if the source and target are of different
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-- sizes, Copy works fine with different sized tables.
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----------------
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-- Conversion --
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----------------
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type Table_Entry is record
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Name : VString;
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Value : Value_Type;
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end record;
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type Table_Array is array (Positive range <>) of Table_Entry;
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function Convert_To_Array (T : Table) return Table_Array;
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-- Returns a Table_Array value with a low bound of 1, and a length
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-- corresponding to the number of elements in the table. The elements
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-- of the array give the elements of the table in unsorted order.
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---------------
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-- Debugging --
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---------------
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procedure Dump (T : Table; Str : String := "Table");
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-- Dump contents of given table to the standard output file. The
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-- string value Str is used as the name of the table in the dump.
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procedure Dump (T : Table_Array; Str : String := "Table_Array");
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-- Dump contents of given table array to the current output file. The
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-- string value Str is used as the name of the table array in the dump.
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private
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------------------
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-- Private Part --
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------------------
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-- A Table is a pointer to a hash table which contains the indicated
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-- number of hash elements (the number is forced to the next odd value
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-- if it is even to improve hashing performance). If more than one
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-- of the entries in a table hashes to the same slot, the Next field
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-- is used to chain entries from the header. The chains are not kept
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-- ordered. A chain is terminated by a null pointer in Next. An unused
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-- chain is marked by an element whose Name is null and whose value
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-- is Null_Value.
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type Hash_Element;
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type Hash_Element_Ptr is access all Hash_Element;
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type Hash_Element is record
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Name : String_Access := null;
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Value : Value_Type := Null_Value;
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Next : Hash_Element_Ptr := null;
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end record;
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type Hash_Table is
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array (Unsigned_32 range <>) of aliased Hash_Element;
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type Table (N : Unsigned_32) is new Controlled with record
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Elmts : Hash_Table (1 .. N);
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end record;
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pragma Finalize_Storage_Only (Table);
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procedure Adjust (Object : in out Table);
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-- The Adjust procedure does a deep copy of the table structure
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-- so that the effect of assignment is, like other assignments
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-- in Ada, value-oriented.
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procedure Finalize (Object : in out Table);
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-- This is the finalization routine that ensures that all storage
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-- associated with a table is properly released when a table object
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-- is abandoned and finalized.
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end Table;
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end GNAT.Spitbol;
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