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------------------------------------------------------------------------------
-- --
-- ASIS Tester And iNTerpreter (ASIStant) COMPONENTS --
-- --
-- A S I S T A N T . L _ P A R S E R --
-- --
-- B o d y --
-- --
-- Copyright (c) 1997-2006, Free Software Foundation, Inc. --
-- --
-- ASIStant is free software; you can redistribute it and/or modify it --
-- under terms of the GNU General Public License as published by the Free --
-- Software Foundation; either version 2, or (at your option) any later --
-- version. ASIStant is distributed in the hope that it will be useful, --
-- but WITHOUT ANY WARRANTY; without even the implied warranty of MER- --
-- CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General --
-- Public License for more details. You should have received a copy of the --
-- GNU General Public License distributed with GNAT; see file COPYING. If --
-- not, write to the Free Software Foundation, 51 Franklin Street, Fifth --
-- Floor, Boston, MA 02110-1301, USA. --
-- --
-- ASIStant is an evolution of ASIStint tool that was created by Vasiliy --
-- Fofanov as part of a collaboration between Software Engineering --
-- Laboratory of the Swiss Federal Institute of Technology in Lausanne, --
-- Switzerland, and the Scientific Research Computer Center of the Moscow --
-- University, Russia, supported by the Swiss National Science Foundation --
-- grant #7SUPJ048247, "Development of ASIS for GNAT with industry quality" --
-- --
-- ASIStant is distributed as a part of the ASIS implementation for GNAT --
-- (ASIS-for-GNAT) and is maintained by AdaCore (http://www.adacore.com). --
------------------------------------------------------------------------------
with Ada.Strings; use Ada.Strings;
with Ada.Strings.Wide_Fixed; use Ada.Strings.Wide_Fixed;
with ASIStant.String_Handling; use ASIStant.String_Handling;
package body ASIStant.L_Parser is
------------------------------------------------------------------------------
-- This package provides token parsing for the ASIStant language interpreter
------------------------------------------------------------------------------
procedure Next_Token (TS : in out Token_Stream) is
-- advances to the next token in stream
TStart : Natural;
TEnd : Natural := TS.Cur_Token_End;
begin
TS.Prev_Token_Start := TS.Cur_Token_Start;
TS.Prev_Token_End := TS.Cur_Token_End;
loop
if TEnd = 0 and TS.Cur_Token_Start = 0 then
return;
end if;
TStart := TEnd + 1;
while TStart < TS.Text'Last
and then Is_In (TS.Text (TStart), CS_White_Spaces)
loop
TStart := TStart + 1;
end loop;
if TStart >= TS.Text'Last then
TS.Cur_Token_Start := 0;
TS.Cur_Token_End := 0;
return;
end if;
if not Is_In (TS.Text (TStart), CS_Special_Tokens) then
Find_Token (TS.Text (TStart .. TS.Text'Last),
CS_Token_Separators,
Outside,
TStart,
TEnd);
exit;
end if;
TEnd := TStart;
if TStart < TS.Text'Last and then TS.Text (TStart) = '-' then
if TS.Text (TStart + 1) = '-' then
-- Ada-style comments
TEnd := Next_Line (TS.Text (TEnd .. TS.Text'Last)) - 1;
elsif TS.Text (TStart + 1) in '0' .. '9' then
-- Negative integer
Find_Token (TS.Text (TStart + 1 .. TS.Text'Last),
CS_Token_Separators,
Outside,
TStart,
TEnd);
TStart := TStart - 1;
exit;
else
Error (ERR_BADINTEGER);
end if;
elsif TStart < TS.Text'Last and then TS.Text (TStart) = '"' then
TEnd := TStart + 1;
loop
TEnd := Find_Symbol (TS.Text (TEnd .. TS.Text'Last), '"');
if TEnd = 0 then
Error (ERR_BADSTRING);
end if;
exit when TEnd = TS.Text'Last or else TS.Text (TEnd + 1) /= '"';
-- Otherwise, this is an Ada-style quote in string
TEnd := TEnd + 2;
end loop;
exit;
else
exit;
end if;
end loop;
TS.Cur_Token_Start := TStart;
TS.Cur_Token_End := TEnd;
end Next_Token;
procedure Prev_Token (TS : in out Token_Stream) is
-- undoes the last Next_Token call, but may retreat only one token back
begin
if TS.Prev_Token_Start = 0 then return; end if;
TS.Cur_Token_Start := TS.Prev_Token_Start;
TS.Cur_Token_End := TS.Prev_Token_End;
TS.Prev_Token_Start := 0;
TS.Prev_Token_End := 0;
end Prev_Token;
function Cur_Token (TS : Token_Stream) return Wide_String is
-- returns current token in stream
begin
return TS.Text (TS.Cur_Token_Start .. TS.Cur_Token_End);
end Cur_Token;
function Is_ID (TS : Token_Stream) return Boolean is
-- returns True if the current token is correct ID, False otherwise;
-- the correct ID is a combination of letters, digits and underline
-- characters starting with a letter or underline.
-- Side effect: '.' is replaced by '_'
begin
if not Is_Active (TS) then
return False;
end if;
if TS.Text (TS.Cur_Token_Start) not in 'A' .. 'Z'
and TS.Text (TS.Cur_Token_Start) not in 'a' .. 'z'
then
return False;
end if;
for I in TS.Cur_Token_Start + 1 .. TS.Cur_Token_End loop
if TS.Text (I) /= '_' and TS.Text (I) /= '.' and
TS.Text (I) not in 'A' .. 'Z' and
TS.Text (I) not in 'a' .. 'z' and
TS.Text (I) not in '0' .. '9'
then
return False;
end if;
if TS.Text (I) = '.' then
TS.Text (I) := '_';
end if;
end loop;
return True;
end Is_ID;
function Is_Active (TS : Token_Stream) return Boolean is
-- returns True if the token stream still has tokens, False otherwise
begin
return TS.Cur_Token_Start /= 0;
end Is_Active;
function Next_Line (S : Wide_String) return Natural is
-- Skips to next line in stream (warning: when there are no more lines in
-- stream, the value is returned that is outside the range. Boundary check
-- should be provided outside)
begin
for i in S'Range loop
if S (i) = To_Wide_Character (ASCII.NUL) then
return i + 1;
end if;
end loop;
return 0;
end Next_Line;
end ASIStant.L_Parser;
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