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------------------------------------------------------------------------------
-- --
-- GNATCHECK COMPONENTS --
-- --
-- G N A T C H E C K . T R A V E R S A L _ S T A C K --
-- --
-- S p e c --
-- --
-- Copyright (C) 2004-2007, AdaCore --
-- --
-- GNATCHECK 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. GNATCHECK is distributed in the hope that it will be useful, --
-- but WITHOUT ANY WARRANTY; without even the implied warranty of --
-- MERCHANTABILITY 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. --
-- --
-- GNATCHECK is maintained by AdaCore (http://www.adacore.com). --
-- --
------------------------------------------------------------------------------
-- This package defines the data structure that represents the current state
-- of the traversal of the argument unit: starting from the top element of the
-- traversing down to the element that encloses the currently visited.
-- The structure is the combination of the unlimited stack and the table
-- that allows the direct access to the elements using.
--
-- This structure provides the effective (comparing with Enclosing_Element)
-- way of investigating the enclosing context of the Element being visited
with Asis;
package Gnatcheck.Traversal_Stack is
-- The traversal stack (it can also be called a traversal table) contains
-- for each ASIS Element some record containing this Element and some
-- characteristics of this Element. We keep the corresponding structure
-- invisible for the clients by defining it in the package body. If you
-- would like to add a new rule check that needs some new information
-- to be added and retrieved from the traversal stack, you should add
-- the corresponding flag or field in the Element_Record in the body and
-- to provide the corresponding interface routines.
type Elmt_Idx is new Natural;
-- Index of the Element in the traversal stack
No_Element : constant Elmt_Idx := 0;
Stack_Error : exception;
function Present (Idx : Elmt_Idx) return Boolean;
-- Checks that its argument is not equal to No_Element
procedure Push (E : Asis.Element);
procedure Pop;
-- These two procedures implement the basic stack abstraction. The first
-- procedure is called in pre-operation, it puts the record corresponding
-- to the argument Element to the top of the stack. The last procedure is
-- called in post-operation and removes the element record from the top of
-- the stack (Pop raises Stack_Error if called for an empty stack)
function Get_Element (From_Idx : Elmt_Idx) return Asis.Element;
-- Returns the ASIS Element corresponding to the given index. Raises
-- Stack_Error if the argument exceeds the number of the elements currently
-- stored in the traversal stack.
function Get_Enclosing_Element
(Steps_Up : Elmt_Idx := 0)
return Asis.Element;
-- Gets the enclosing element for the currently visited element, taking
-- the Steps_Up steps up the structure being traversed. Raises Stack_Error
-- if stepping up exceeds this structure. If Steps_Up is 0, this function
-- is equivalent to Asis.Elements.Enclosing_Element called to the Element
-- being visited during the traversal. The main reason to use this function
-- instead of Asis.Elements.Enclosing_Element is to improve the
-- performance.
procedure Initialize;
-- Initializes internal tables and puts Nil_Element to the bottom of the
-- stack to make Get_Enclosing_Element working correctly on top-level
-- Elements
-------------------------------------------------------------------
-- Functions that get specific elements from the traversal stack --
-------------------------------------------------------------------
-- Functions that defined in this section are looking for some specific
-- element in the chain of elements that ends up with the element currently
-- being visited during the traversal. Most of them start from the top of
-- the stack and go to the bottom, looking for the element of interest.
-- That's why these functions do not have any argument
function Enclosing_Subprogram_Body return Elmt_Idx;
-- Looks for the nearest enclosing subprogram body, entry body or accept
-- statement. Returns No_Element if there is no such construct.
--------------------------------------------------
-- Retrieving and modifying elements properties --
--------------------------------------------------
function Has_Return (El : Elmt_Idx) return Boolean;
-- Provided that El represents a function body, returns the flag that says
-- that a return statement has already been encountered in this body
procedure Set_Has_Return (El : Elmt_Idx);
-- Provided that El represents a function body, sets ON the flag that says
-- that a return statement has already been encountered in this body
end Gnatcheck.Traversal_Stack;
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