indexing
	description : "alias_calculus application root class"
	date        : "$Date$"
	revision    : "$Revision$"

class
	APPLICATION

inherit
	ARGUMENTS
	APPLICATION_CONSTANTS

create
	make

feature {NONE} -- Initialization

	make
			-- Build a program and compute its aliases.
		do
			create aliases.make (Expression_count)
			create {COMPOUND} program.make

			build_program
			program.display
			compute_aliases
			print_aliases
		end

feature -- Access

	program: INSTRUCTION
	aliases: ALIAS_RELATION


feature -- Basic operations
	build_program
			-- Build a program.
		do
			set (x, y)
			set (y, z)
		end

	compute_aliases
			-- Compute aliases.
		do
			program.update (aliases)
		end


	print_aliases
			-- Compute aliases.
		do
			aliases.printout
		end

feature -- Program construction

	start_then
			-- Start new conditional instruction.
		local
			new: COMPOUND
		do
			create new.make
			new.outer := program
			program := new
		end

	end_compound
			-- End current compound.
		require
			started: program.outer /= Void
		do
			program := program.outer
		end

	set (e: VARIABLE; f: EXPRESSION)
			-- Add at end of current block
			-- the assignment `e' := `f'.
		require
			attached {COMPOUND} program
		local
			sa: SIMPLE_ASSIGNMENT
		do
			create sa.make (e, f)
			if attached {COMPOUND} program as pr then
				pr.extend (sa)
			end
		end

invariant
	program_exists: program /= Void
	aliases_exist: aliases /= Void
end