note
	description: "Keeper for nested contexts."

deferred class AST_NESTING_KEEPER

feature -- Status report: nesting

	nesting_level: INTEGER
			-- Current nesting level of a compound
		deferred
		end

feature {AST_COLLECTION_KEEPER, AST_CONTEXT, AST_VISITOR} -- Modification: nesting

	enter_realm
			-- Enter a new complex instruction with inner compound parts.
		deferred
		ensure
			is_nesting_level_incremented: nesting_level = old nesting_level + 1
		end

	update_realm
			-- Update realm variable information from the current state.
		deferred
		ensure
			is_nesting_level_preserved: nesting_level = old nesting_level
		end

	save_sibling
			-- Save scope information of a sibling in a complex instrution and restart recording using the outer scope.
			-- For example, Then_part of Elseif condition.
		require
			is_nested: nesting_level > 0
		deferred
		ensure
			is_nesting_level_preserved: nesting_level = old nesting_level
		end

	update_sibling
			-- Update scope information of a sibling in a complex instrution and reuse it for the current scope.
			-- For example, Loop body.
		require
			is_nested: nesting_level > 0
		deferred
		ensure
			is_nesting_level_preserved: nesting_level = old nesting_level
		end

	leave_realm
			-- Leave a complex instruction and promote variable information to the outer compound.
		require
			is_nested: nesting_level > 0
		deferred
		ensure
			is_nesting_level_decremented: nesting_level = old nesting_level - 1
		end

	leave_optional_realm
			-- Leave a complex instruction and discard its variable information.
			-- For example, Debug instruction.
		require
			is_nested: nesting_level > 0
		deferred
		ensure
			is_nesting_level_decremented: nesting_level = old nesting_level - 1
		end

note
	date: "$Date$"
	revision: "$Revision$"
	copyright:	"Copyright (c) 1984-2013, Eiffel Software"
	license:	"GPL version 2 (see http://www.eiffel.com/licensing/gpl.txt)"
	licensing_options:	"http://www.eiffel.com/licensing"
	copying: "[
			This file is part of Eiffel Software's Eiffel Development Environment.
			
			Eiffel Software's Eiffel Development Environment 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, version 2 of the License
			(available at the URL listed under "license" above).
			
			Eiffel Software's Eiffel Development Environment 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 Eiffel Software's Eiffel Development
			Environment; if not, write to the Free Software Foundation,
			Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
		]"
	source: "[
			Eiffel Software
			5949 Hollister Ave., Goleta, CA 93117 USA
			Telephone 805-685-1006, Fax 805-685-6869
			Website http://www.eiffel.com
			Customer support http://support.eiffel.com
		]"

end