------------------------------------------------------------------------------
-- Copyright (c) 2013, Natacha Porté --
-- --
-- Permission to use, copy, modify, and distribute this software for any --
-- purpose with or without fee is hereby granted, provided that the above --
-- copyright notice and this permission notice appear in all copies. --
-- --
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES --
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF --
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR --
-- ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES --
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN --
-- ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF --
-- OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. --
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------------------------------------------------------------------------------
-- Natools.String_Slices provide an object that represents a substring of a --
-- shared parent string. --
------------------------------------------------------------------------------
private with Natools.References;
private with Natools.Storage_Pools;
package Natools.String_Slices is
pragma Preelaborate (String_Slices);
-----------------------
-- String range type --
-----------------------
type String_Range is record
First : Positive;
Length : Natural;
end record;
function Is_In (Point : Natural; Reference : String_Range) return Boolean;
function Is_Subrange (Sample, Reference : String_Range) return Boolean;
-- Inclusion tests
function Last (Self : String_Range) return Natural;
-- Return last bound of the given range
function To_Range (First : Positive; Last : Natural) return String_Range;
-- Create a range with the given bounds
function Get_Range (S : String) return String_Range;
-- Return the String_Range representation of S index range.
-- Semantically equivalent to (To_Range (S'First, S'Last))
-- and to (String_Range'(First => S'First, Length => S'Length)).
procedure Set_First (Self : in out String_Range; New_First : in Positive);
-- Update first bound keeping last bound intact
procedure Set_Last (Self : in out String_Range; New_Last : in Natural);
-- Update range for the given last bound, keeping the first one intact
procedure Set_Length (Self : in out String_Range; New_Length : in Natural);
-- Basic mutator included for completeness sake
function Image (Interval : String_Range) return String;
-- Interval representation of the given range
----------------
-- Slice type --
----------------
type Slice is tagged private;
pragma Preelaborable_Initialization (Slice);
Null_Slice : constant Slice;
--------------------------
-- Conversion functions --
--------------------------
function To_Slice (S : String) return Slice;
-- Create a new slice containing the whole given string
function To_String (S : Slice) return String;
-- Return the string represented by the slice
---------------
-- Accessors --
---------------
procedure Export (S : in Slice; Output : out String);
-- Fill Output with string contents in S
-- Raise Constraint_Error when Output'Length /= Length(S)
procedure Query
(S : in Slice;
Process : not null access procedure (Text : in String));
-- Query the string object directly from memory
function Get_Range (S : Slice) return String_Range;
-- Return the range embedded in S
function First (S : Slice) return Positive;
-- Return the lowest index of S
function Last (S : Slice) return Natural;
-- Return the largest index of S
function Length (S : Slice) return Natural;
-- Return the length of S
---------------
-- Extenders --
---------------
-- These subprograms allow access to the parent string beyond the
-- current range. However Constraint_Error is raised when trying to reach
-- beyond the parent string range.
function Parent (S : Slice) return Slice;
-- Return a slice representing the whole string available
function Extend (S : Slice; New_Range : in String_Range) return Slice;
function Extend (S : Slice; First : Positive; Last : Natural) return Slice;
procedure Extend (S : in out Slice; New_Range : in String_Range);
procedure Extend (S : in out Slice; First : in Positive; Last : in Natural);
-- Extend the range represented by S
-----------------
-- Restrictors --
-----------------
-- All the subprograms here raise Constraint_Error when the new range
-- is not a subrange of the source range.
function Subslice (S : Slice; New_Range : String_Range) return Slice;
function Subslice (S : Slice; First : Positive; Last : Natural)
return Slice;
-- Return a subslice of S
procedure Restrict (S : in out Slice; New_Range : in String_Range);
procedure Restrict
(S : in out Slice; First : in Positive; Last : in Natural);
-- Update the range in S
procedure Set_First (S : in out Slice; New_First : in Positive);
-- Update the range of S keeping the upper bound intact
procedure Set_Last (S : in out Slice; New_Last : in Natural);
-- Update the range of S keeping the lower bound intact
procedure Set_Length (S : in out Slice; New_Length : in Natural);
-- Truncate S range to the given length, keeping the lower bound intact
----------------------
-- Slice comparison --
----------------------
function Is_Empty (S : Slice) return Boolean;
-- Return whether the slice represents an empty string.
-- Semantically equivalent to (To_String (S) = "").
function Is_Null (S : Slice) return Boolean;
-- Return whether the slice has a parent string
function Is_Related (Left, Right : Slice) return Boolean;
-- Return whether both slices have the same parent string
function Is_Subslice (S, Reference : Slice) return Boolean;
-- Return whether S represent of a subrange of Reference with the
-- same parent string.
function Duplicate (S : Slice) return Slice;
-- Create a new parent string and a slice designating it.
-- This does not copy parts of S parent string outside of S range.
-- Semantically equivalent to (To_Slice (To_String (S))).
private
package String_Refs is new References
(String,
Storage_Pools.Access_In_Default_Pool'Storage_Pool,
Storage_Pools.Access_In_Default_Pool'Storage_Pool);
type Slice is tagged record
Bounds : String_Range := (1, 0);
Ref : String_Refs.Reference;
end record;
Null_Slice : constant Slice := ((1, 0), Ref => <>);
end Natools.String_Slices;