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-- Chain handling.
-- Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold
--
-- GHDL is free software; you can redistribute it and/or modify it under
-- the terms of the GNU General Public License as published by the Free
-- Software Foundation; either version 2, or (at your option) any later
-- version.
--
-- GHDL 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
-- along with GHDL; see the file COPYING. If not, write to the Free
-- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
with Vhdl.Nodes; use Vhdl.Nodes;
with Vhdl.Nodes_Meta;
package Vhdl.Nodes_Utils is
-- Chains are simply linked list of iirs.
-- Elements of the chain are ordered.
-- Each element of a chain have a Chain field, which points to the next
-- element.
-- All elements of a chain have the same parent. This parent contains
-- a field which points to the first element of the chain.
-- Note: the parent is often the value of the Parent field, but sometimes
-- not.
-- Chains can be covered very simply:
-- El : Iir;
-- begin
-- El := Get_xxx_Chain (Parent);
-- while El /= Null_Iir loop
-- * Handle element EL of the chain.
-- El := Get_Chain (El);
-- end loop;
-- However, building a chain is a little bit more difficult if elements
-- have to be appended. Indeed, there is no direct access to the last
-- element of a chain.
-- An efficient way to build a chain is to keep the last element of it.
-- Return the number of elements in a chain starting with FIRST.
-- Not very efficient since O(N).
function Get_Chain_Length (First : Iir) return Natural;
-- Append CHAIN to the chain FIELD of node N. Not very efficient.
procedure Append_Chain
(N : Iir; Field : Vhdl.Nodes_Meta.Fields_Enum; Chain : Iir);
-- These two subprograms can be used to build a sub-chain.
-- FIRST and LAST designates respectively the first and last element of
-- the sub-chain.
-- Set FIRST and LAST to Null_Iir.
procedure Chain_Init (First, Last : out Iir);
pragma Inline (Chain_Init);
-- Append element EL to the sub-chain.
procedure Chain_Append (First, Last : in out Iir; El : Iir);
pragma Inline (Chain_Append);
-- Append chain to the sub-chain. FIRST_SUB and LAST_SUB must not be
-- Null_Iir.
procedure Chain_Append_Chain (First, Last : in out Iir;
First_Sub, Last_Sub : Iir);
procedure Chain_Append_Subchain (First, Last : in out Iir;
Sub : Iir);
-- Return TRUE iff CHAIN is of length one, ie CHAIN is not NULL_IIR
-- and chain (CHAIN) is NULL_IIR.
function Is_Chain_Length_One (Chain : Iir) return Boolean;
pragma Inline (Is_Chain_Length_One);
-- Insert EL after LAST and set LAST to EL.
procedure Insert_Incr (Last : in out Iir; El : Iir);
end Vhdl.Nodes_Utils;
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