indexing
	description	: "Byte code for multi-branch instruction."
	date		: "$Date$"
	revision	: "$Revision$"

class INSPECT_B 

inherit
	INSTR_B
		redefine
			analyze, generate, enlarge_tree, make_byte_code,
			assigns_to, is_unsafe, generate_il,
			optimized_byte_node, calls_special_features,
			size, inlined_byte_code, pre_inlined_code
		end

	VOID_REGISTER
		export
			{NONE} all
		end
	
feature -- Access

	switch: EXPR_B
			-- Expression to inspect

	case_list: BYTE_LIST [BYTE_NODE]
			-- Alternaltives {list of CASE_B}: can be Void

	else_part: BYTE_LIST [BYTE_NODE]
			-- Default compound {list of INSTR_B}: can be Void

	end_location: TOKEN_LOCATION
			-- Line number where `end' keyword is located

feature -- Status setting

	set_switch (s: like switch) is
			-- Assign `s' to `switch'.
		do
			switch := s
		end

	set_case_list (c: like case_list) is
			-- Assign `c' to `case_list'.
		do
			case_list := c
		end

	set_else_part (e: like else_part) is
			-- Assign `e' to `else_part'.
		do
			else_part := e
		end

	set_end_location (e: like end_location) is
			-- Set `end_location' with `e'.
		require
			e_not_void: e /= Void
		do
			end_location := e
		ensure
			end_location_set: end_location = e
		end

feature -- Basic operations

	enlarge_tree is
			-- Enlarge the inspect statement
		do
			switch := switch.enlarged
			if case_list /= Void then
				case_list.enlarge_tree
			end
			if else_part /= Void then
				else_part.enlarge_tree
			end
		end

	analyze is
			-- Builds a proper context (for C code).
		do
			context.init_propagation
			switch.propagate (No_register)
			switch.analyze
			switch.free_register
			if case_list /= Void then
				case_list.analyze
			end
			if else_part /= Void then
				else_part.analyze
			end
		end

feature -- C code generation

	generate is
			-- Generate C code in `buffer'.
		local
			buf: GENERATION_BUFFER
		do
			buf := buffer
			generate_line_info
			buf.new_line
			generate_frozen_debugger_hook
			switch.generate
			buf.putstring ("switch (")
			switch.print_register
			buf.putstring (") {")
			buf.new_line
			buf.indent
			if case_list /= Void then
				case_list.generate
			end
			if else_part = Void or else not else_part.is_empty then
				buf.putstring ("default:")
				buf.new_line
				buf.indent
				if else_part = Void then
						-- Raise an exception
					buf.putstring ("RTEC(EN_WHEN);")
				else
					else_part.generate
					buf.putstring ("break;")
				end
				buf.new_line
				buf.exdent
			end
			buf.exdent
			buf.putchar ('}')
			buf.new_line
		end

feature -- IL code generation

	generate_il is
			-- Generate IL code for a multi-branch instruction.
		local
			l_case: like case_list
			end_label: IL_LABEL
			case_b: CASE_B
		do
			end_label := il_label_factory.new_label
			generate_il_line_info

				-- Generate switch expression byte code
			switch.generate_il

			if case_list /= Void then
				from
					l_case := case_list
					l_case.start
				until
					l_case.after
				loop
						-- Generate code
					case_b ?= l_case.item
					case_b.generate_il_case (end_label)
					l_case.forth
				end
			end

			if else_part /= Void then
				else_part.generate_il
			else
					-- Throw an exception	
			end

			il_generator.mark_label (end_label)

				-- Either there was nothing in the inspect and therefore we need to
				-- pop the value on which we were inspecting as it is not used. Or if
				-- there was some `when' parts we need to remove the duplication made
				-- for case comparison.
			il_generator.pop
			
			check
				end_location_not_void: end_location /= Void
			end
			
			il_generator.put_silent_debug_info (end_location)
		end

feature -- Byte code generation

	make_byte_code (ba: BYTE_ARRAY) is
			-- Generate byte code for a multi-branch instruction
		local
			i: INTEGER
			case: CASE_B
		do
			generate_melted_debugger_hook (ba)

				-- Generate switch expression byte code
			switch.make_byte_code (ba)
			if case_list /= Void then
				from
					i := case_list.count
				until
					i < 1
				loop
					case ?= case_list.i_th (i)
					case.make_range (ba)
					i := i - 1
				end
				ba.append (Bc_jmp)
				ba.mark_forward3		-- To else part
				case_list.make_byte_code (ba)
				ba.write_forward3
			end
			if else_part /= Void then
				else_part.make_byte_code (ba)
			else
				ba.append (Bc_inspect_excep)
			end
				-- Jumps for cases compounds
			if case_list /= Void then
				from
					i := case_list.count
				until
					i < 1
				loop
					ba.write_forward
					i := i - 1
				end
			end
			ba.append (Bc_inspect)
		end

feature -- Array optimization

	assigns_to (i: INTEGER): BOOLEAN is
		do
			Result := (case_list /= Void and then case_list.assigns_to (i)) or else
				(else_part /= Void and then else_part.assigns_to (i))
		end

	calls_special_features (array_desc: INTEGER): BOOLEAN is
		do
			Result := (case_list /= Void and then case_list.calls_special_features (array_desc))
				or else (else_part /= Void and then else_part.calls_special_features (array_desc))
				or else switch.calls_special_features (array_desc)
		end

	is_unsafe: BOOLEAN is
		do
			Result := (case_list /= Void and then case_list.is_unsafe)
				or else (else_part /= Void and then else_part.is_unsafe)
				or else switch.is_unsafe
		end

	optimized_byte_node: like Current is
		do
			Result := Current
			switch := switch.optimized_byte_node
			if case_list /= Void then
				case_list := case_list.optimized_byte_node
			end
			if else_part /= Void then
				else_part := else_part.optimized_byte_node
			end
		end

feature -- Inlining

	size: INTEGER is
		do
			Result := 1 + switch.size
			if case_list /= Void then
				Result := Result + case_list.size
			end
			if else_part /= Void then
				Result := Result + else_part.size
			end
		end

	pre_inlined_code: like Current is
		do
			Result := Current
			if case_list /= Void then
				case_list := case_list.pre_inlined_code
			end
			if else_part /= Void then
				else_part := else_part.pre_inlined_code
			end
			switch := switch.pre_inlined_code
		end

	inlined_byte_code: like Current is
		do
			Result := Current
			if case_list /= Void then
				case_list := case_list.inlined_byte_code
			end
			if else_part /= Void then
				else_part := else_part.inlined_byte_code
			end
			switch := switch.inlined_byte_code
		end
end