⟦9f3054557⟧

E3 Source Code





--  DISCUSSION:
--
--\x09This package implements the type "variable-length string" (vstring)
--\x09using generics.  The alternative approaches are to use a discriminant
--\x09record in which the discriminant controls the length of a STRING inside
--\x09the record, or a record containing an access type which points to a
--      string, which can be deallocated and reallocated when necessary.
--
--\x09Advantages of this package:
--\x09  * The other approaches force the vstring to be a limited private
--          type.  Thus, their vstrings cannot appear on the left side of
--          the assignment operator; ie., their vstrings cannot be given
--          initial values or values by direct assignment.  This package
--          uses a private type; therefore, these things can be done.
--
--\x09  * The other approach stores the vstring in a string whose length
--\x09    is determined dynamically.  This package uses a fixed length
--          string.  This difference might be reflected in faster and more
--          consistent execution times (this has NOT been verified).
--
--\x09Disadvantages of this package:
--\x09  * Different instantiations must be used to declare vstrings with
--\x09    different maximum lengths (this may be desirable, since
--\x09    CONSTRAINT_ERROR will be raised if the maximum is exceeded).
--
--\x09  * A second declaration is required to give the type declared by
--\x09    the instantiation a name other than "VSTRING."
--
--\x09  * The storage required for a vstring is determined by the generic
--\x09    parameter LAST and not the actual length of its contents.  Thus,
--          each object is allocated the maximum amount of storage, regardless
--          of its actual size.
--
--  MISCELLANEOUS:
--     Constraint checking is done explicitly in the code; thus, it cannot
--     be suppressed.  On the other hand, constraint checking is not lost
--     if pragma suppress is supplied to the compilation (-S option)
--     (The robustness of the explicit constraint checking has NOT been
--     determined).
--
--     Compiling with the optimizer (-O option) may significantly reduce
--     the size (and possibly execution time) of the resulting executable.
--
--     Compiling an instantiation of VSTRINGS is roughly equivelent to
--     recompiling VSTRINGS.  Since this takes a significant amount of time,
--     and the instantiation does not depend on any other library units,
--     it is STRONGLY recommended that the instantiation be compiled
--     separately, and thus done only ONCE.
--
--  USAGE: with VSTRINGS;
--         package package_name is new VSTRINGS(maximum_length);
-- .......................................................................... --
pragma Page;


with Text_Io;
use Text_Io;
generic
    Last : Natural;
package Vstrings is

    subtype Strindex is Natural;
    First : constant Strindex := Strindex'First + 1;
    type Vstring is private;
    Nul : constant Vstring;

-- Attributes of a VSTRING

    function Len (From : Vstring) return Strindex;
    function Max (From : Vstring) return Strindex;
    function Str (From : Vstring) return String;
    function Char (From : Vstring; Position : Strindex := First)
                  return Character;

-- Comparisons

    function "<" (Left : Vstring; Right : Vstring) return Boolean;
    function ">" (Left : Vstring; Right : Vstring) return Boolean;
    function "<=" (Left : Vstring; Right : Vstring) return Boolean;
    function ">=" (Left : Vstring; Right : Vstring) return Boolean;
    -- "=" and "/=" are predefined

-- Input/Output

    procedure Put (File : in File_Type; Item : in Vstring);
    procedure Put (Item : in Vstring);

    procedure Put_Line (File : in File_Type; Item : in Vstring);
    procedure Put_Line (Item : in Vstring);

    procedure Get (File : in File_Type;
                   Item : out Vstring;
                   Length : in Strindex := Last);
    procedure Get (Item : out Vstring; Length : in Strindex := Last);

    procedure Get_Line (File : in File_Type; Item : in out Vstring);
    procedure Get_Line (Item : in out Vstring);

-- Extraction

    function Slice (From : Vstring; Front, Back : Strindex) return Vstring;
    function Substr (From : Vstring; Start, Length : Strindex) return Vstring;
    function Delete (From : Vstring; Front, Back : Strindex) return Vstring;

-- Editing

    function Insert
                (Target : Vstring; Item : Vstring; Position : Strindex := First)
                return Vstring;
    function Insert
                (Target : Vstring; Item : String; Position : Strindex := First)
                return Vstring;
    function Insert (Target : Vstring;
                     Item : Character;
                     Position : Strindex := First) return Vstring;

    function Append (Target : Vstring; Item : Vstring; Position : Strindex)
                    return Vstring;
    function Append (Target : Vstring; Item : String; Position : Strindex)
                    return Vstring;
    function Append (Target : Vstring; Item : Character; Position : Strindex)
                    return Vstring;

    function Append (Target : Vstring; Item : Vstring) return Vstring;
    function Append (Target : Vstring; Item : String) return Vstring;
    function Append (Target : Vstring; Item : Character) return Vstring;

    function Replace
                (Target : Vstring; Item : Vstring; Position : Strindex := First)
                return Vstring;
    function Replace
                (Target : Vstring; Item : String; Position : Strindex := First)
                return Vstring;
    function Replace (Target : Vstring;
                      Item : Character;
                      Position : Strindex := First) return Vstring;

-- Concatenation

    function "&" (Left : Vstring; Right : Vstring) return Vstring;
    function "&" (Left : Vstring; Right : String) return Vstring;
    function "&" (Left : Vstring; Right : Character) return Vstring;
    function "&" (Left : String; Right : Vstring) return Vstring;
    function "&" (Left : Character; Right : Vstring) return Vstring;

-- Determine the position of a substring

    function Index (Whole : Vstring; Part : Vstring; Occurrence : Natural := 1)
                   return Strindex;
    function Index (Whole : Vstring; Part : String; Occurrence : Natural := 1)
                   return Strindex;
    function Index (Whole : Vstring;
                    Part : Character;
                    Occurrence : Natural := 1) return Strindex;


    function Rindex (Whole : Vstring; Part : Vstring; Occurrence : Natural := 1)
                    return Strindex;
    function Rindex (Whole : Vstring; Part : String; Occurrence : Natural := 1)
                    return Strindex;
    function Rindex (Whole : Vstring;
                     Part : Character;
                     Occurrence : Natural := 1) return Strindex;

-- Conversion from other associated types

    function Vstr (From : String) return Vstring;
    function Vstr (From : Character) return Vstring;
    function "+" (From : String) return Vstring;
    function "+" (From : Character) return Vstring;

    generic
        type From is private;
        type To is private;
        with function Str (X : From) return String is <>;
        with function Vstr (Y : String) return To is <>;
    function Convert (X : From) return To;

    pragma Page;


private
    type Vstring is
        record
            Len : Strindex := Strindex'First;
            Value : String (First .. Last) := (others => Ascii.Nul);
        end record;

    Nul : constant Vstring := (Strindex'First, (others => Ascii.Nul));
end Vstrings;
--
-- .......................................................................... --
--
-- DISTRIBUTION AND COPYRIGHT:
--
-- This software is released to the Public Domain (note:
--   software released to the Public Domain is not subject
--   to copyright protection).
-- Restrictions on use or distribution:  NONE
--
-- DISCLAIMER:
--
-- This software and its documentation are provided "AS IS" and
-- without any expressed or implied warranties whatsoever.
-- No warranties as to performance, merchantability, or fitness
-- for a particular purpose exist.
--
-- Because of the diversity of conditions and hardware under
-- which this software may be used, no warranty of fitness for
-- a particular purpose is offered.  The user is advised to
-- test the software thoroughly before relying on it.  The user
-- must assume the entire risk and liability of using this
-- software.
--
-- In no event shall any person or organization of people be
-- held responsible for any direct, indirect, consequential
-- or inconsequential damages or lost profits.
DataMuseum.dk

Rational R1000/400

⟦9f3054557⟧ Ada Source

Derivation

E3 Source Code

E3 Meta Data
