indexing
	description: "Access to command-line arguments. This class may be used as ancestor by classes needing its facilities."

class interface
	ARGUMENTS

feature -- Access

	argument (i: INTEGER): STRING
			-- i-th argument of command that started system execution
			-- (the command name if i = 0)
		require
			index_large_enough: i >= 0;
			index_small_enough: i <= argument_count

	argument_array: ARRAY [STRING]
			-- Array containing command name (position 0) and arguments

	command_line: STRING
			-- Total command line
		ensure
			Result.count >= command_name.count

	command_name: STRING
			-- Name of command that started system execution
		ensure
			definition: Result.is_equal (argument (0))
	
feature -- Measurement

	argument_count: INTEGER
			-- Number of arguments given to command that started
			-- system execution (command name does not count)
		ensure
			Result >= 0
	
feature -- Status report

	coalesced_character_option_value (o: CHARACTER): STRING
			-- The value, if any, specified for character option o on
			-- the command line.
			-- Defined as follows (where 'X' is the current 'option_sign' and
			-- 'xx' is an arbitrary, possibly empty sequence of characters):
			--   val if command line includes an argument of the form Xxxoval
			--	   (this may be an empty string if argument is just Xxxo).
			--   Void otherwise.
		require
			o_non_null: o /= '%U'

	coalesced_word_option_value (opt: STRING): STRING
			-- The value, if any, specified for word option opt on the
			-- command line.
			-- Defined as follows (where X is the current option_sign):
			--   val if command line includes an argument of the form Xoptval
			--	   (this may be an empty string if argument is just Xopt).
			--   Void otherwise.
		require
			opt_non_void: opt /= void;
			opt_meaningful: not opt.empty

	index_of_beginning_with_word_option (opt: STRING): INTEGER
			-- Does command line specify argument beginning with word
			-- option opt and, if so, at what position?
			-- If one of the arguments in list of space-separated arguments
			-- is Xoptxx, where X is the current option_sign, 'xx'
			-- is arbitrary, possibly empty sequence of characters,
			-- then index of this argument in list;
			-- else 0.
		require
			opt_non_void: opt /= void;
			opt_meaningful: not opt.empty

	index_of_character_option (o: CHARACTER): INTEGER
			-- Does command line specify character option o and, if so,
			-- at what position?
			-- If one of the space-separated arguments is of the form Xxxoyy,
			-- where X is the current option_sign, xx and yy
			-- are arbitrary, possibly empty sequences of characters,
			-- then index of this argument in list of arguments;
			-- else 0.
		require
			o_non_null: o /= '%U'

	index_of_word_option (opt: STRING): INTEGER
			-- Does command line specify word option opt and, if so,
			-- at what position?
			-- If one of the arguments in list of space-separated arguments
			-- is Xopt, where X is the current option_sign,
			-- then index of this argument in list;
			-- else 0.
		require
			opt_non_void: opt /= void;
			opt_meaningful: not opt.empty

	option_sign: CHARACTER_REF
			-- The character used to signal options on the command line.
			-- This can be '%U' if no sign is necesary for the argument
			-- to be an option
			-- Default is '-'

	separate_character_option_value (o: CHARACTER): STRING
			-- The value, if any, specified after character option o on
			-- the command line.
			-- This is one of the following (where X is the current
			-- option_sign, xx and 'yy' are arbitrary, possibly empty
			-- sequences of characters):
			--   val if command line includes two consecutive arguments
			--	   of the form Xxxoyy and val respectively.
			--   Empty string if command line includes argument Xxxoyy, which is
			--	   either last argument or followed by argument starting with X.
			--   Void if there is no argument of the form Xxxoyy.
		require
			o_non_null: o /= '%U'

	separate_word_option_value (opt: STRING): STRING
			-- The value, if any, specified after word option opt on the
			-- command line.
			-- This is one of the following (where X is the current option_sign):
			--   val if command line includes two consecutive arguments
			--	   of the form Xopt and val respectively.
			--   Empty string if command line includes argument Xopt, which is
			--	   either last argument or followed by argument starting with X.
			--   Void if no Xopt argument.
		require
			opt_non_void: opt /= void;
			opt_meaningful: not opt.empty
	
feature -- Status setting

	set_option_sign (c: CHARACTER)
			-- Make c the option sign.
			-- Use'%U' if no sign is necesary for the argument to
			-- be an option
	
invariant

		-- from GENERAL
	reflexive_equality: standard_is_equal (Current);
	reflexive_conformance: conforms_to (Current);

end -- class ARGUMENTS