note
	description: "The objects available from the environment at time of execution"
	library: "Free implementation of ELKS library"
	status: "See notice at end of class."
	legal: "See notice at end of class."
	date: "$Date: 2019-02-18 11:07:51 +0000 (Mon, 18 Feb 2019) $"
	revision: "$Revision: 102848 $"

class interface
	EXECUTION_ENVIRONMENT

create 
	default_create
			-- Process instances of classes with no creation clause.
			-- (Default: do nothing.)
			-- (from ANY)

feature -- Access

	Arguments: ARGUMENTS_32
			-- Arguments that were used to start current execution.
		ensure
			instance_free: class

	available_cpu_count: NATURAL_32
			-- Number of available CPUs.
		ensure
			instance_free: class

	current_working_path: PATH
			-- Directory of current execution.
		ensure
			instance_free: class
			result_not_void: Result /= Void

	Default_shell: STRING_32
			-- Default shell
		ensure
			instance_free: class

	generating_type: TYPE [detachable EXECUTION_ENVIRONMENT]
			-- Type of current object
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generator_not_void: Result /= Void
			generator_not_empty: not Result.is_empty

	Home_directory_path: detachable PATH
			-- Directory name corresponding to the home directory.
		require
			home_directory_supported: Operating_environment.home_directory_supported
		ensure
			instance_free: class

	item (s: READABLE_STRING_GENERAL): detachable STRING_32
			-- Value of s if it is an environment variable and has been set;
			-- void otherwise.
		require
			s_exists: s /= Void
			not_has_null_character: not s.has ('%U'.to_character_32)
		ensure
			instance_free: class

	Root_directory_name: STRING_8
			-- Directory name corresponding to the root directory.
		require
			root_directory_supported: Operating_environment.root_directory_supported
		ensure
			instance_free: class
			result_not_void: Result /= Void

	starting_environment: HASH_TABLE [STRING_32, STRING_32]
			-- Table of environment variables when current process starts,
			-- indexed by variable name
		ensure
			instance_free: class
			result_attached: Result /= Void

	Temporary_directory_path: detachable PATH
			-- Temporary directory name.
			-- On Windows:  %SystemDrive%\Users\%USERNAME%\AppData\Local\Temp (%USERPROFILE%\AppData\Local\Temp).
			-- On Unix: /tmp and /var/tmp.
			-- On VMS: /sys$scratch	
			-- Otherwise Void	
		ensure
			instance_free: class

	User_directory_path: detachable PATH
			-- Directory name corresponding to the user directory
			-- On Windows: C:\Users\manus\Documents
			-- On Unix & Mac: $HOME
			-- Otherwise Void
		ensure
			instance_free: class
	
feature -- Comparison

	frozen deep_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			shallow_implies_deep: standard_equal (a, b) implies Result
			both_or_none_void: (a = Void) implies (Result = (b = Void))
			same_type: (Result and (a /= Void)) implies (b /= Void and then a.same_type (b))
			symmetric: Result implies deep_equal (b, a)

	frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b))

	frozen is_deep_equal alias "≡≡≡" (other: EXECUTION_ENVIRONMENT): BOOLEAN
			-- Are Current and other attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			shallow_implies_deep: standard_is_equal (other) implies Result
			same_type: Result implies same_type (other)
			symmetric: Result implies other.is_deep_equal (Current)

	is_equal (other: EXECUTION_ENVIRONMENT): BOOLEAN
			-- Is other attached to an object considered
			-- equal to current object?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other ~ Current
			consistent: standard_is_equal (other) implies Result

	frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b))

	frozen standard_is_equal alias "" (other: EXECUTION_ENVIRONMENT): BOOLEAN
			-- Is other attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
feature -- Status report

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of other (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of other?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
	
feature -- Status setting

	change_working_path (path: PATH)
			-- Set the current directory to path

	launch (s: READABLE_STRING_GENERAL)
			-- Pass to the operating system an asynchronous request to
			-- execute s interpreted as a Unicode string.
			-- If s is empty, use the default shell as command.
		require
			s_not_void: s /= Void
		ensure
			instance_free: class

	put (value, key: READABLE_STRING_GENERAL)
			-- Set the environment variable key to value treating both
			-- value and key as Unicode characters.
		require
			key_exists: key /= Void
			key_meaningful: not key.is_empty
			not_key_has_null_character: not key.has ('%U'.to_character_32)
			value_exists: value /= Void
			not_value_has_null_character: not value.has ('%U'.to_character_32)
		ensure
			variable_set: return_code = 0 implies ((value.is_empty and then item (key) = Void) or else not value.is_empty and then attached item (key) as k and then k.same_string_general (value))

	sleep (nanoseconds: INTEGER_64)
			-- Suspend thread execution for interval specified in
			-- nanoseconds (1 nanosecond = 10^(-9) second).
		require
			non_negative_nanoseconds: nanoseconds >= 0
		ensure
			instance_free: class

	system (s: READABLE_STRING_GENERAL)
			-- Pass to the operating system a request to execute s interpreted as a Unicode string.
			-- If s is empty, use the default shell as command.
		require
			s_exists: s /= Void
	
feature -- Duplication

	copy (other: EXECUTION_ENVIRONMENT)
			-- Update current object using fields of object attached
			-- to other, so as to yield equal objects.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: Current ~ other

	frozen deep_copy (other: EXECUTION_ENVIRONMENT)
			-- Effect equivalent to that of:
			--		copy (other . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: EXECUTION_ENVIRONMENT
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: EXECUTION_ENVIRONMENT)
			-- Copy every field of other onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: EXECUTION_ENVIRONMENT
			-- New object field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: EXECUTION_ENVIRONMENT
			-- New object equal to Current
			-- twin calls copy; to change copying/twinning semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result ~ Current
	
feature -- Basic operations

	frozen default: detachable EXECUTION_ENVIRONMENT
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type POINTER
			-- (Avoid the need to write p.default for
			-- some p of type POINTER.)
			-- (from ANY)
		ensure -- from ANY
			instance_free: class

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
	
feature -- Output

	Io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			io_not_void: Result /= Void

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		ensure -- from ANY
			out_not_void: Result /= Void

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		ensure -- from ANY
			tagged_out_not_void: Result /= Void
	
feature -- Platform

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
	
feature -- Status

	return_code: INTEGER_32
			-- Status code set by last call to system or put
	
invariant
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

note
	copyright: "Copyright (c) 1984-2019, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		5949 Hollister Ave., Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class EXECUTION_ENVIRONMENT

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