note
	description: "Access to decimal math constants and shared context"
	library: "Gobo Eiffel Decimal Arithmetic Library"
	copyright: "Copyright (c) 2004-2018, Paul G. Crismer and others"
	license: "MIT License"
	date: "$Date: 2019-02-07 22:54:15 +0000 (Thu, 07 Feb 2019) $"
	revision: "$Revision: 102807 $"

class 
	MA_DECIMAL_CONSTANTS

create 
	default_create

feature {NONE} -- Initialization

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

	Default_context: MA_DECIMAL_CONTEXT
			-- Default context for general purpose arithmetic
			-- (from MA_SHARED_DECIMAL_CONTEXT)
		once
			create Result.make_default
		ensure -- from MA_SHARED_DECIMAL_CONTEXT
			instance_free: class
			default_context_not_void: Result /= Void
		end

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

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

	Infinity: MA_DECIMAL
			-- Infinity
		once
			Result := Zero.Infinity
		ensure
			instance_free: class
			infinity_not_void: Result /= Void
		end

	Maximum_integer: MA_DECIMAL
			-- Maximum value convertible to integer
		local
			ctx: MA_DECIMAL_CONTEXT
		once
			create ctx.make_double_extended
			create Result.make_from_string_ctx (Platform.Maximum_integer.out, ctx)
		ensure
			instance_free: class
			maximum_integer_not_void: Result /= Void
		end

	Minimum_integer: MA_DECIMAL
			-- Minimum value convertible to integer
		local
			ctx: MA_DECIMAL_CONTEXT
		once
			create ctx.make_double_extended
			create Result.make_from_string_ctx (Platform.Minimum_integer.out, ctx)
		ensure
			instance_free: class
			minimum_integer_not_void: Result /= Void
		end

	Minus_one: MA_DECIMAL
			-- Minus one
		once
			Result := Zero.Minus_one
		ensure
			instance_free: class
			minus_not_void: Result /= Void
		end

	Negative_infinity: MA_DECIMAL
			-- Negative infinity
		once
			Result := Zero.Negative_infinity
		ensure
			instance_free: class
			negative_infinity_not_void: Result /= Void
		end

	Negative_zero: MA_DECIMAL
			-- Negative zero
		once
			Result := Zero.Negative_zero
		ensure
			instance_free: class
			negative_zero_not_void: Result /= Void
		end

	Not_a_number: MA_DECIMAL
			-- Not a Number
		once
			Result := Zero.Nan
		ensure
			instance_free: class
			not_a_number: Result /= Void
		end

	One: MA_DECIMAL
			-- Neutral element for "*" and "/"
		once
			Result := Zero.one
		ensure
			instance_free: class
			one_not_void: Result /= Void
		end

	shared_decimal_context: MA_DECIMAL_CONTEXT
			-- Decimal context for operations where it does not explicitly appear in the signature;
			-- Return Default_context by default, but can be changed by calling set_shared_decimal_context
			-- (from MA_SHARED_DECIMAL_CONTEXT)
		do
			Result := Cell.item
		ensure -- from MA_SHARED_DECIMAL_CONTEXT
			instance_free: class
			shared_decimal_context_not_void: Result /= Void
		end

	Signaling_not_a_number: MA_DECIMAL
			-- Signaling Not a Number
		once
			Result := Zero.Snan
		ensure
			instance_free: class
			signaling_not_a_number: Result /= Void
		end

	Zero: MA_DECIMAL
			-- Neutral element for "+" and "-"
		once
			create Result.make (1)
			Result := Result.zero
		ensure
			instance_free: class
			zero_not_void: Result /= Void
		end
	
feature {NONE} -- Access

	Platform: KL_PLATFORM
			-- Platform-dependent properties
			-- (from KL_SHARED_PLATFORM)
		once
			create Result
		ensure -- from KL_SHARED_PLATFORM
			instance_free: class
			platform_not_void: Result /= Void
		end
	
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)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_deep_equal (b)
			end
		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)
		end

	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)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_equal (b)
			end
		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))
		end

	frozen is_deep_equal (other: MA_DECIMAL_CONSTANTS): BOOLEAN
			-- Are Current and other attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		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)
		end

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

	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)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.standard_is_equal (b)
			end
		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))
		end

	frozen standard_is_equal (other: MA_DECIMAL_CONSTANTS): 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
		external
			"built_in"
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
		end
	
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
		external
			"built_in"
		end

	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
		external
			"built_in"
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
		end
	
feature -- Duplication

	frozen clone (other: detachable ANY): like other
		obsolete "Use `twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- equal to other
			--
			-- For non-void other, clone calls copy;
			-- to change copying/cloning semantics, redefine copy.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.twin
			end
		ensure -- from ANY
			instance_free: class
			equal: Result ~ other
		end

	copy (other: MA_DECIMAL_CONSTANTS)
			-- 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)
		external
			"built_in"
		ensure -- from ANY
			is_equal: Current ~ other
		end

	frozen deep_clone (other: detachable ANY): like other
		obsolete "Use `deep_twin' instead. [2017-05-31]"
			-- Void if other is void: otherwise, new object structure
			-- recursively duplicated from the one attached to other
			-- (from ANY)
		do
			if other /= Void then
				Result := other.deep_twin
			end
		ensure -- from ANY
			instance_free: class
			deep_equal: deep_equal (other, Result)
		end

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

	frozen deep_twin: MA_DECIMAL_CONSTANTS
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)
		end

	frozen standard_clone (other: detachable ANY): like other
		obsolete "Use `standard_twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.standard_twin
			end
		ensure -- from ANY
			instance_free: class
			equal: standard_equal (Result, other)
		end

	frozen standard_copy (other: MA_DECIMAL_CONSTANTS)
			-- 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)
		external
			"built_in"
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)
		end

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

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

	frozen as_attached: attached MA_DECIMAL_CONSTANTS
		obsolete "Remove calls to this feature. [2017-05-31]"
			-- Attached version of Current.
			-- (Can be used during transitional period to convert
			-- non-void-safe classes to void-safe ones.)
			-- (from ANY)
		do
			Result := Current
		end

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

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

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

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end
	
feature {NONE} -- Implementation

	Cell: KL_CELL [MA_DECIMAL_CONTEXT]
			-- Cell containing shared decimal context
			-- (from MA_SHARED_DECIMAL_CONTEXT)
		once
			create Result.make (Default_context)
		ensure -- from MA_SHARED_DECIMAL_CONTEXT
			instance_free: class
			cell_not_void: Result /= Void
			context_not_void: Cell.item /= Void
		end
	
feature -- Output

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

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

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		do
			if o /= Void then
				Io.put_string (o.out)
			end
		ensure -- from ANY
			instance_free: class
		end

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

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		once
			create Result
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
		end
	
feature {NONE} -- Retrieval

	frozen internal_correct_mismatch
			-- Called from runtime to perform a proper dynamic dispatch on correct_mismatch
			-- from MISMATCH_CORRECTOR.
			-- (from ANY)
		local
			l_msg: STRING_8
			l_exc: EXCEPTIONS
		do
			if attached {MISMATCH_CORRECTOR} Current as l_corrector then
				l_corrector.correct_mismatch
			else
				create l_msg.make_from_string ("Mismatch: ")
				create l_exc
				l_msg.append (generating_type.name)
				l_exc.raise_retrieval_exception (l_msg)
			end
		end
	
feature -- Setting

	set_shared_decimal_context (new_context: MA_DECIMAL_CONTEXT)
			-- Set shared_decimal_context to new_context.
			-- It is best practice to call this routine once and for all
			-- at the beginning of the application to avoid unexpected
			-- behaviors.
			-- (from MA_SHARED_DECIMAL_CONTEXT)
		require -- from MA_SHARED_DECIMAL_CONTEXT
			new_context_not_void: new_context /= Void
		do
			Cell.put (new_context)
		ensure -- from MA_SHARED_DECIMAL_CONTEXT
			instance_free: class
			context_set: shared_decimal_context = new_context
		end
	
invariant
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

end -- class MA_DECIMAL_CONSTANTS

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