indexing
	Description: "Description of a constant value"
	date: "$Date$"
	revision: "$Revision$"

deferred class
	VALUE_I 

inherit
	ANY

	BYTE_CONST
		export
			{NONE} all
		end

	SHARED_ARRAY_BYTE
		export
			{NONE} all
		end

	SHARED_IL_CODE_GENERATOR
		export
			{NONE} all
		end
	
feature -- Comparison

	is_equivalent (other: like Current): BOOLEAN is
			-- Is `other' equivalent to the current object ?
		require
			arg_non_void: other /= Void
			same_type: same_type (other)
		deferred
		end

feature -- Status report

	valid_type (t: TYPE_A): BOOLEAN is
			-- Is the current value compatible with `t' ?
		require
			good_argument: t /= Void
		deferred
		end

	is_integer: BOOLEAN is
			-- Is the constant an integer constant ?
		do
		end

	is_boolean: BOOLEAN is
			-- Is the constant a real constant ?
		do
		end

	is_character: BOOLEAN is
			-- is the constant a character constant ?
		do
			-- Do nothing
		end

	is_real: BOOLEAN is
			-- is the constant a real constant ?
		do
			-- Do nothing
		end

	is_double: BOOLEAN is
			-- Is the constant a double constant ?
		do
			-- Do nothing
		end

	is_string: BOOLEAN is
			-- Is the constant a string constant ?
		do
			-- Do nothing
		end

	is_bit: BOOLEAN is
			-- Is the constant a bit constant ?
		do
			-- Do nothing
		end

	is_no_value: BOOLEAN is
			-- Is current representing no value?
		do
		end
		
	is_numeric: BOOLEAN is
			-- Is current a numeric value?
		do
			Result := is_integer or is_real or is_double
		ensure
			is_numeric_definition: is_integer or is_real or is_double
		end
		

	is_propagation_equivalent (other: like Current): BOOLEAN is
			-- Is `Current' equivalent for propagation of pass2/pass3?
		do
			Result := same_type (other) and then is_equivalent (other)
		end

	boolean_value: BOOLEAN is
		require
			is_boolean: is_boolean
		do
		end

	no_value: NO_VALUE_I is
			-- Shared instance of `NO_VALUE_I'.
		once
			create Result
		ensure
			no_value_not_void: Result /= Void
		end

feature -- Settings

	set_real_type (t: TYPE_A) is
			-- Sometime type of constants needs to be changed.
			-- For example by default an integer constant is of type
			-- INTEGER, but type of constant might be INTEGER_8 and
			-- therefore current instance should be updated accordingly.
			-- Same thing with real constant which can be either DOUBLE or
			-- REAL.
			-- Same thing with BIT_VALUE_I
		require
			t_not_void: t /= Void
		do
		end

feature -- Code generation

	generate (buffer: GENERATION_BUFFER) is
			-- Generate value in `buffer'.
		require
			good_argument: buffer /= Void
		deferred
		end

	generate_il is
			-- Generate IL code for constant value.
		deferred
		end

	make_byte_code (ba: BYTE_ARRAY) is
			-- Generate byte code for a constant value.
		require
			good_argument: ba /= Void
		deferred
		end

	append_signature (st: STRUCTURED_TEXT) is
		require
			st_not_void: st /= Void
		do
			st.add_string (dump)
		end

	dump: STRING is
		deferred
		end

	string_value: STRING is
		do
			Result := dump
		end

feature -- Unary operators

	unary_plus: VALUE_I is
			-- Apply `+' operator to Current.
		require
			is_operation_valid: is_numeric or is_no_value
		do
			Result := Current
		ensure
			unary_plus_not_void: Result /= Void
		end

	unary_minus: VALUE_I is
			-- Apply `-' operator to Current.
		require
			is_operation_valid: is_numeric or is_no_value
		do
				-- Proper definition is made in descendants that are `is_numeric'
			check
				is_no_value: is_no_value
			end
			Result := no_value
		ensure
			unary_minus_not_void: Result /= Void
		end

	unary_not: VALUE_I is
			-- Apply `not operator to Current.
		require
			is_operation_valid: is_boolean or is_no_value
		do
			if is_boolean then
				create {BOOL_VALUE_I} Result.make (not boolean_value)
			else
				Result := no_value
			end
		ensure
			unary_not_not_void: Result /= Void
		end

feature -- Debugging

	trace is
		do
			io.error.putstring (dump)
		end

end