System.Security.SecurityDocument.GetChildrenPositionForElement C# (CSharp) Method

        public ArrayList GetChildrenPositionForElement( int position )
        {
            if (m_data.Length <= position)
                throw new XmlSyntaxException();

            if (m_data[position++] != c_element)
                throw new XmlSyntaxException();

            ArrayList children = new ArrayList();

            // This is to move past the tag string
            GetString( ref position );

            while (m_data[position] == c_attribute)
            {
                position++;
                // Read name and value, then throw them away
                GetString( ref position, false );
                GetString( ref position, false );
            }

            if (m_data[position] == c_text)
            {
                position++;
                // Read text, then throw it away.
                GetString( ref position, false );
            }

            while (m_data[position] != c_children)
            {
                children.Add( position );
                InternalGetElement( ref position, false );
            }
            position++;

            return children;
        }

        internal virtual void FromXml( SecurityDocument doc, int position, bool allowInternalOnly )
        {
            if (doc == null)
                throw new ArgumentNullException("doc");
            Contract.EndContractBlock();
            
            if (!doc.GetTagForElement( position ).Equals(s_str_PermissionSet))
                throw new ArgumentException(String.Format( null, Environment.GetResourceString( "Argument_InvalidXMLElement" ), "PermissionSet", this.GetType().FullName) );
            
            Reset();
            m_allPermissionsDecoded = false;
            Exception savedException = null;
            String strUnrestricted = doc.GetAttributeForElement( position, "Unrestricted" );
            if (strUnrestricted != null)
                m_Unrestricted = strUnrestricted.Equals( "True" ) || strUnrestricted.Equals( "true" ) || strUnrestricted.Equals( "TRUE" );
            else
                m_Unrestricted = false;

            ArrayList childrenIndices = doc.GetChildrenPositionForElement( position );
            int childCount = childrenIndices.Count;
            for (int i = 0; i < childCount; ++i)
            {
                int childIndex = (int)childrenIndices[i];
                if (IsPermissionTag( doc.GetTagForElement( childIndex ), allowInternalOnly ))
                {
                    try
                    {
                        String className = doc.GetAttributeForElement( childIndex, "class" );

                        PermissionToken token;
                        Object objectToInsert;
                        
                        if (className != null)
                        {
                            token = PermissionToken.GetToken( className );
                            if (token == null)
                            {
                                objectToInsert = CreatePerm( doc.GetElement( childIndex, true ) );

                                if (objectToInsert != null)
                                {
#if _DEBUG
                                    PermissionToken tokenDebug = PermissionToken.GetToken( (IPermission)objectToInsert );
                                    Contract.Assert((tokenDebug != null), "PermissionToken.GetToken returned null ");
                                    Contract.Assert( (tokenDebug.m_type & PermissionTokenType.BuiltIn) != 0, "This should only be called for built-ins" );
#endif
                                    Contract.Assert( objectToInsert.GetType().Module.Assembly == System.Reflection.Assembly.GetExecutingAssembly(),
                                        "PermissionToken.GetToken returned null for non-mscorlib permission" );
                                    token = PermissionToken.GetToken( (IPermission)objectToInsert );
                                    Contract.Assert((token != null), "PermissionToken.GetToken returned null ");
                                    Contract.Assert( (token.m_type & PermissionTokenType.DontKnow) == 0, "We should always know the permission type when getting a token from an instance" );
                                }
                            }
                            else
                            {
                                objectToInsert = ((ISecurityElementFactory)new SecurityDocumentElement(doc, childIndex)).CreateSecurityElement();
                            }
                        }
                        else
                        {
                            IPermission ip = CreatePerm( doc.GetElement( childIndex, true ) );
                            if (ip == null)
                            {
                                token = null;
                                objectToInsert = null;
                            }
                            else
                            {
                                token = PermissionToken.GetToken( ip );
                                Contract.Assert( PermissionToken.IsTokenProperlyAssigned( ip, token ),
                                                 "PermissionToken was improperly assigned" );
                                objectToInsert = ip;
                            }
                        }

                        if (token != null && objectToInsert != null)
                        {
                            if (m_permSet == null)
                                m_permSet = new TokenBasedSet();

                            IPermission permInSlot = null;
                            if (this.m_permSet.GetItem( token.m_index ) != null)
                            {
                                // If there is already something in that slot, let's union them
                                // together.
                                
                                if (this.m_permSet.GetItem( token.m_index ) is IPermission)
                                    permInSlot = (IPermission)this.m_permSet.GetItem( token.m_index );
                                else
                                    permInSlot = CreatePerm( this.m_permSet.GetItem( token.m_index ) );
                            }

                            if (permInSlot != null)
                            {
                                if (objectToInsert is IPermission)
                                    objectToInsert = permInSlot.Union((IPermission)objectToInsert);
                                else
                                    objectToInsert = permInSlot.Union(CreatePerm( objectToInsert ));
                            }

                            if(m_Unrestricted && objectToInsert is IPermission)
                                objectToInsert = null;

                            this.m_permSet.SetItem( token.m_index, objectToInsert );
                        }
                    }
                    catch (Exception e)
                    {
#if _DEBUG
                        if (debug)
                            DEBUG_WRITE( "error while decoding permission set =\n" + e.ToString() );
#endif
                        if (savedException == null)
                            savedException = e;

                    }
                }
            }

            if (savedException != null)
                throw savedException;
                
        }