deferred class
	EL_FILE_OPEN_ROUTINES

inherit
	EL_ENCODING_TYPE
		rename
			Other as Other_class,
			Latin as Latin_class,
			Utf as Utf_class,
			Windows as Windows_class
		export
			{NONE} all
		end

	EL_MODULE_ENCODING
		rename
			Encoding as Encoding_
		end

feature {NONE} -- Basic operations

	frozen open (path: READABLE_STRING_GENERAL; mode: NATURAL): EL_PLAIN_TEXT_FILE
		require
			valid_mode: valid_file_mode (mode)
			parent_exists: parent_path_exists (path)
		do
			if bit_set (mode, Notifying) then
				create {EL_NOTIFYING_PLAIN_TEXT_FILE} Result.make_with_name (path)
			else
				create Result.make_with_name (path)
			end
			open_file (Result, mode)
		end

	frozen open_lines (path: READABLE_STRING_GENERAL; a_encoding: NATURAL): EL_PLAIN_TEXT_LINE_SOURCE
		-- open file for reading using LINEAR iterator
		require
			valid_encoding: Encoding_.is_valid (a_encoding)
			parent_exists: parent_path_exists (path)
		local
			file_path: FILE_PATH
		do
			create file_path.make (path)
			if file_path.exists then
				create Result.make (a_encoding, path)
			else
				create Result.make_default
			end
		end

	frozen open_raw (path: READABLE_STRING_GENERAL; mode: NATURAL): RAW_FILE
		require
			valid_mode: valid_file_mode (mode)
			parent_exists: parent_path_exists (path)
		do
			if bit_set (mode, Notifying) then
				create {EL_NOTIFYING_RAW_FILE} Result.make_with_name (path)
			else
				create Result.make_with_name (path)
			end
			open_file (Result, mode)
		end

feature {NONE} -- Implementation

	frozen open_file (file: FILE; mode: NATURAL)
		require
			valid_mode: valid_file_mode (mode)
		do
			if bit_set (mode, Read) then
				if bit_set (mode, Append) then
					file.open_read_append

				elseif bit_set (mode, Write) then
					if bit_set (mode, Create_) then
						file.create_read_write
					else
						file.open_read_write
					end
				elseif file.exists then
					file.open_read
				end
			elseif bit_set (mode, Write) then
				file.open_write
			elseif bit_set (mode, Append) then
				file.open_append
			end
		end

	bit_set (bitmap, flag: NATURAL): BOOLEAN
		do
			Result := (bitmap & flag) > 0
		end

feature {NONE} -- Contract Support

	frozen valid_file_mode (mode: NATURAL): BOOLEAN
		do
			inspect mode
				when Append, Closed, Create_, Notifying, Read, Write then
					Result := True
			else
			end
		end

	parent_path_exists (a_path: READABLE_STRING_GENERAL): BOOLEAN
		local
			l_path: FILE_PATH
		do
			create l_path.make (a_path)
			Result := l_path.has_parent implies l_path.parent.exists
		end

feature {NONE} -- Mode bitmaps

	Append: NATURAL = 1

	Closed: NATURAL = 0

	Create_: NATURAL = 2

	Notifying: NATURAL = 16

	Read: NATURAL = 4

	Write: NATURAL = 8

end