------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- A D A . S T R I N G S . S E A R C H --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2023, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- . --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- Note: This code is derived from the ADAR.CSH public domain Ada 83
-- versions of the Appendix C string handling packages (code extracted
-- from Ada.Strings.Fixed). A significant change is that we optimize the
-- case of identity mappings for Count and Index, and also Index_Non_Blank
-- is specialized (rather than using the general Index routine).
-- Ghost code, loop invariants and assertions in this unit are meant for
-- analysis only, not for run-time checking, as it would be too costly
-- otherwise. This is enforced by setting the assertion policy to Ignore.
pragma Assertion_Policy (Ghost => Ignore,
Loop_Invariant => Ignore,
Assert => Ignore);
with Ada.Strings.Maps; use Ada.Strings.Maps;
with System; use System;
package body Ada.Strings.Search with SPARK_Mode is
-----------------------
-- Local Subprograms --
-----------------------
function Belongs
(Element : Character;
Set : Maps.Character_Set;
Test : Membership) return Boolean;
pragma Inline (Belongs);
-- Determines if the given element is in (Test = Inside) or not in
-- (Test = Outside) the given character set.
-------------
-- Belongs --
-------------
function Belongs
(Element : Character;
Set : Maps.Character_Set;
Test : Membership) return Boolean
is
(if Test = Inside then
Is_In (Element, Set)
else not (Is_In (Element, Set)));
-----------
-- Count --
-----------
function Count
(Source : String;
Pattern : String;
Mapping : Maps.Character_Mapping := Maps.Identity) return Natural
is
PL1 : constant Integer := Pattern'Length - 1;
Num : Natural;
Ind : Natural;
begin
if Pattern = "" then
raise Pattern_Error;
end if;
-- Isolating the null string case to ensure Source'First, Source'Last in
-- Positive.
if Source = "" then
return 0;
end if;
Num := 0;
Ind := Source'First - 1;
-- Unmapped case
if Is_Identity (Mapping) then
while Ind < Source'Last - PL1 loop
Ind := Ind + 1;
if Pattern = Source (Ind .. Ind + PL1) then
Num := Num + 1;
Ind := Ind + PL1;
end if;
pragma Loop_Invariant (Num <= Ind - (Source'First - 1));
pragma Loop_Invariant (Ind >= Source'First);
pragma Loop_Variant (Increases => Ind);
end loop;
-- Mapped case
else
while Ind < Source'Last - PL1 loop
Ind := Ind + 1;
for K in Pattern'Range loop
if Pattern (K) /= Value (Mapping,
Source (Ind + (K - Pattern'First)))
then
pragma Assert (not (Match (Source, Pattern, Mapping, Ind)));
goto Cont;
end if;
pragma Loop_Invariant
(for all J in Pattern'First .. K =>
Pattern (J) = Value (Mapping,
Source (Ind + (J - Pattern'First))));
end loop;
pragma Assert (Match (Source, Pattern, Mapping, Ind));
Num := Num + 1;
Ind := Ind + PL1;
<>
null;
pragma Loop_Invariant (Num <= Ind - (Source'First - 1));
pragma Loop_Invariant (Ind >= Source'First);
pragma Loop_Variant (Increases => Ind);
end loop;
end if;
-- Return result
return Num;
end Count;
function Count
(Source : String;
Pattern : String;
Mapping : Maps.Character_Mapping_Function) return Natural
is
PL1 : constant Integer := Pattern'Length - 1;
Num : Natural;
Ind : Natural;
begin
if Pattern = "" then
raise Pattern_Error;
end if;
-- Isolating the null string case to ensure Source'First, Source'Last in
-- Positive.
if Source = "" then
return 0;
end if;
-- Check for null pointer in case checks are off
if Mapping = null then
raise Constraint_Error;
end if;
Num := 0;
Ind := Source'First - 1;
while Ind < Source'Last - PL1 loop
Ind := Ind + 1;
for K in Pattern'Range loop
if Pattern (K) /= Mapping (Source (Ind + (K - Pattern'First))) then
pragma Annotate (GNATprove, False_Positive,
"call via access-to-subprogram",
"function Mapping must always terminate");
pragma Assert (not (Match (Source, Pattern, Mapping, Ind)));
goto Cont;
end if;
pragma Loop_Invariant
(for all J in Pattern'First .. K =>
Pattern (J) = Mapping (Source (Ind + (J - Pattern'First))));
pragma Annotate (GNATprove, False_Positive,
"call via access-to-subprogram",
"function Mapping must always terminate");
end loop;
pragma Assert (Match (Source, Pattern, Mapping, Ind));
Num := Num + 1;
Ind := Ind + PL1;
<>
null;
pragma Loop_Invariant (Num <= Ind - (Source'First - 1));
pragma Loop_Invariant (Ind >= Source'First);
pragma Loop_Variant (Increases => Ind);
end loop;
return Num;
end Count;
function Count
(Source : String;
Set : Maps.Character_Set) return Natural
is
N : Natural := 0;
begin
for J in Source'Range loop
pragma Loop_Invariant (N <= J - Source'First);
if Is_In (Source (J), Set) then
N := N + 1;
end if;
end loop;
return N;
end Count;
----------------
-- Find_Token --
----------------
procedure Find_Token
(Source : String;
Set : Maps.Character_Set;
From : Positive;
Test : Membership;
First : out Positive;
Last : out Natural)
is
begin
-- AI05-031: Raise Index error if Source non-empty and From not in range
if Source'Length /= 0 and then From not in Source'Range then
raise Index_Error;
end if;
-- If Source is the empty string, From may still be out of its
-- range. The following ensures that in all cases there is no
-- possible erroneous access to a non-existing character.
for J in Integer'Max (From, Source'First) .. Source'Last loop
if Belongs (Source (J), Set, Test) then
First := J;
if J < Source'Last then
for K in J + 1 .. Source'Last loop
if not Belongs (Source (K), Set, Test) then
Last := K - 1;
return;
end if;
pragma Loop_Invariant
(for all L in J .. K =>
Belongs (Source (L), Set, Test));
end loop;
end if;
-- Here if J indexes first char of token, and all chars after J
-- are in the token.
Last := Source'Last;
return;
end if;
pragma Loop_Invariant
(for all K in Integer'Max (From, Source'First) .. J =>
not (Belongs (Source (K), Set, Test)));
end loop;
-- Here if no token found
First := From;
Last := 0;
end Find_Token;
procedure Find_Token
(Source : String;
Set : Maps.Character_Set;
Test : Membership;
First : out Positive;
Last : out Natural)
is
begin
for J in Source'Range loop
if Belongs (Source (J), Set, Test) then
First := J;
if J < Source'Last then
for K in J + 1 .. Source'Last loop
if not Belongs (Source (K), Set, Test) then
Last := K - 1;
return;
end if;
pragma Loop_Invariant
(for all L in J .. K =>
Belongs (Source (L), Set, Test));
end loop;
end if;
-- Here if J indexes first char of token, and all chars after J
-- are in the token.
Last := Source'Last;
return;
end if;
pragma Loop_Invariant
(for all K in Source'First .. J =>
not (Belongs (Source (K), Set, Test)));
end loop;
-- Here if no token found
-- RM 2005 A.4.3 (68/1) specifies that an exception must be raised if
-- Source'First is not positive and is assigned to First. Formulation
-- is slightly different in RM 2012, but the intent seems similar, so
-- we check explicitly for that condition.
if Source'First not in Positive then
raise Constraint_Error;
else
First := Source'First;
Last := 0;
end if;
end Find_Token;
-----------
-- Index --
-----------
function Index
(Source : String;
Pattern : String;
Going : Direction := Forward;
Mapping : Maps.Character_Mapping := Maps.Identity) return Natural
is
PL1 : constant Integer := Pattern'Length - 1;
begin
if Pattern = "" then
raise Pattern_Error;
end if;
-- If Pattern is longer than Source, it can't be found
if Pattern'Length > Source'Length then
return 0;
end if;
-- Forwards case
if Going = Forward then
-- Unmapped forward case
if Is_Identity (Mapping) then
for Ind in Source'First .. Source'Last - PL1 loop
if Pattern = Source (Ind .. Ind + PL1) then
pragma Assert (Match (Source, Pattern, Mapping, Ind));
return Ind;
end if;
pragma Loop_Invariant
(for all J in Source'First .. Ind =>
not (Match (Source, Pattern, Mapping, J)));
end loop;
-- Mapped forward case
else
for Ind in Source'First .. Source'Last - PL1 loop
for K in Pattern'Range loop
if Pattern (K) /= Value (Mapping,
Source (Ind + (K - Pattern'First)))
then
goto Cont1;
end if;
pragma Loop_Invariant
(for all J in Pattern'First .. K =>
Pattern (J) = Value (Mapping,
Source (Ind + (J - Pattern'First))));
end loop;
pragma Assert (Match (Source, Pattern, Mapping, Ind));
return Ind;
<>
pragma Loop_Invariant
(for all J in Source'First .. Ind =>
not (Match (Source, Pattern, Mapping, J)));
null;
end loop;
end if;
-- Backwards case
else
-- Unmapped backward case
if Is_Identity (Mapping) then
for Ind in reverse Source'First .. Source'Last - PL1 loop
if Pattern = Source (Ind .. Ind + PL1) then
pragma Assert (Match (Source, Pattern, Mapping, Ind));
return Ind;
end if;
pragma Loop_Invariant
(for all J in Ind .. Source'Last - PL1 =>
not (Match (Source, Pattern, Mapping, J)));
end loop;
-- Mapped backward case
else
for Ind in reverse Source'First .. Source'Last - PL1 loop
for K in Pattern'Range loop
if Pattern (K) /= Value (Mapping,
Source (Ind + (K - Pattern'First)))
then
goto Cont2;
end if;
pragma Loop_Invariant
(for all J in Pattern'First .. K =>
Pattern (J) = Value (Mapping,
Source (Ind + (J - Pattern'First))));
end loop;
pragma Assert (Match (Source, Pattern, Mapping, Ind));
return Ind;
<>
pragma Loop_Invariant
(for all J in Ind .. Source'Last - PL1 =>
not (Match (Source, Pattern, Mapping, J)));
null;
end loop;
end if;
end if;
-- Fall through if no match found. Note that the loops are skipped
-- completely in the case of the pattern being longer than the source.
return 0;
end Index;
function Index
(Source : String;
Pattern : String;
Going : Direction := Forward;
Mapping : Maps.Character_Mapping_Function) return Natural
is
PL1 : constant Integer := Pattern'Length - 1;
begin
if Pattern = "" then
raise Pattern_Error;
end if;
-- Check for null pointer in case checks are off
if Mapping = null then
raise Constraint_Error;
end if;
-- If Pattern longer than Source it can't be found
if Pattern'Length > Source'Length then
return 0;
end if;
-- Forwards case
if Going = Forward then
for Ind in Source'First .. Source'Last - PL1 loop
for K in Pattern'Range loop
if Pattern (K) /= Mapping.all
(Source (Ind + (K - Pattern'First)))
then
pragma Annotate (GNATprove, False_Positive,
"call via access-to-subprogram",
"function Mapping must always terminate");
goto Cont1;
end if;
pragma Loop_Invariant
(for all J in Pattern'First .. K =>
Pattern (J) = Mapping (Source (Ind + (J - Pattern'First))));
pragma Annotate (GNATprove, False_Positive,
"call via access-to-subprogram",
"function Mapping must always terminate");
end loop;
pragma Assert (Match (Source, Pattern, Mapping, Ind));
return Ind;
<>
pragma Loop_Invariant
(for all J in Source'First .. Ind =>
not (Match (Source, Pattern, Mapping, J)));
null;
end loop;
-- Backwards case
else
for Ind in reverse Source'First .. Source'Last - PL1 loop
for K in Pattern'Range loop
if Pattern (K) /= Mapping.all
(Source (Ind + (K - Pattern'First)))
then
pragma Annotate (GNATprove, False_Positive,
"call via access-to-subprogram",
"function Mapping must always terminate");
goto Cont2;
end if;
pragma Loop_Invariant
(for all J in Pattern'First .. K =>
Pattern (J) = Mapping (Source (Ind + (J - Pattern'First))));
pragma Annotate (GNATprove, False_Positive,
"call via access-to-subprogram",
"function Mapping must always terminate");
end loop;
return Ind;
<>
pragma Loop_Invariant
(for all J in Ind .. Source'Last - PL1 =>
not (Match (Source, Pattern, Mapping, J)));
null;
end loop;
end if;
-- Fall through if no match found. Note that the loops are skipped
-- completely in the case of the pattern being longer than the source.
return 0;
end Index;
function Index
(Source : String;
Set : Maps.Character_Set;
Test : Membership := Inside;
Going : Direction := Forward) return Natural
is
begin
-- Forwards case
if Going = Forward then
for J in Source'Range loop
if Belongs (Source (J), Set, Test) then
return J;
end if;
pragma Loop_Invariant
(for all C of Source (Source'First .. J) =>
not (Belongs (C, Set, Test)));
end loop;
-- Backwards case
else
for J in reverse Source'Range loop
if Belongs (Source (J), Set, Test) then
return J;
end if;
pragma Loop_Invariant
(for all C of Source (J .. Source'Last) =>
not (Belongs (C, Set, Test)));
end loop;
end if;
-- Fall through if no match
return 0;
end Index;
function Index
(Source : String;
Pattern : String;
From : Positive;
Going : Direction := Forward;
Mapping : Maps.Character_Mapping := Maps.Identity) return Natural
is
Result : Natural;
PL1 : constant Integer := Pattern'Length - 1;
begin
-- AI05-056: If source is empty result is always zero
if Source'Length = 0 then
return 0;
elsif Going = Forward then
if From < Source'First then
raise Index_Error;
end if;
Result :=
Index (Source (From .. Source'Last), Pattern, Forward, Mapping);
pragma Assert
(if (for some J in From .. Source'Last - PL1 =>
Match (Source, Pattern, Mapping, J))
then Result in From .. Source'Last - PL1
else Result = 0);
else
if From > Source'Last then
raise Index_Error;
end if;
Result :=
Index (Source (Source'First .. From), Pattern, Backward, Mapping);
pragma Assert
(if (for some J in Source'First .. From - PL1 =>
Match (Source, Pattern, Mapping, J))
then Result in Source'First .. From - PL1
else Result = 0);
end if;
return Result;
end Index;
function Index
(Source : String;
Pattern : String;
From : Positive;
Going : Direction := Forward;
Mapping : Maps.Character_Mapping_Function) return Natural
is
begin
-- AI05-056: If source is empty result is always zero
if Source'Length = 0 then
return 0;
elsif Going = Forward then
if From < Source'First then
raise Index_Error;
end if;
return Index
(Source (From .. Source'Last), Pattern, Forward, Mapping);
else
if From > Source'Last then
raise Index_Error;
end if;
return Index
(Source (Source'First .. From), Pattern, Backward, Mapping);
end if;
end Index;
function Index
(Source : String;
Set : Maps.Character_Set;
From : Positive;
Test : Membership := Inside;
Going : Direction := Forward) return Natural
is
begin
-- AI05-056 : if source is empty result is always 0.
if Source'Length = 0 then
return 0;
elsif Going = Forward then
if From < Source'First then
raise Index_Error;
end if;
return
Index (Source (From .. Source'Last), Set, Test, Forward);
else
if From > Source'Last then
raise Index_Error;
end if;
return
Index (Source (Source'First .. From), Set, Test, Backward);
end if;
end Index;
---------------------
-- Index_Non_Blank --
---------------------
function Index_Non_Blank
(Source : String;
Going : Direction := Forward) return Natural
is
begin
if Going = Forward then
for J in Source'Range loop
if Source (J) /= ' ' then
return J;
end if;
pragma Loop_Invariant
(for all C of Source (Source'First .. J) => C = ' ');
end loop;
else -- Going = Backward
for J in reverse Source'Range loop
if Source (J) /= ' ' then
return J;
end if;
pragma Loop_Invariant
(for all C of Source (J .. Source'Last) => C = ' ');
end loop;
end if;
-- Fall through if no match
return 0;
end Index_Non_Blank;
function Index_Non_Blank
(Source : String;
From : Positive;
Going : Direction := Forward) return Natural
is
begin
-- For equivalence with Index, if Source is empty the result is 0
if Source'Length = 0 then
return 0;
end if;
if Going = Forward then
if From < Source'First then
raise Index_Error;
end if;
return
Index_Non_Blank (Source (From .. Source'Last), Forward);
else
if From > Source'Last then
raise Index_Error;
end if;
return
Index_Non_Blank (Source (Source'First .. From), Backward);
end if;
end Index_Non_Blank;
function Is_Identity
(Mapping : Maps.Character_Mapping) return Boolean
with SPARK_Mode => Off
is
begin
return Mapping'Address = Maps.Identity'Address;
end Is_Identity;
end Ada.Strings.Search;