note
	description: "Abstract class to dispatch tracing events to user using TYPE and STRING data."
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2013-05-20 23:15:17 +0000 (Mon, 20 May 2013) $"
	revision: "$Revision: 92557 $"

deferred class 
	STRING_TRACING_HANDLER

feature {NONE} -- Initialization

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

	generating_type: TYPE [detachable STRING_TRACING_HANDLER]
			-- 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
	
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 alias "≡≡≡" (other: STRING_TRACING_HANDLER): 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: STRING_TRACING_HANDLER): 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 alias "≜" (other: STRING_TRACING_HANDLER): 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: STRING_TRACING_HANDLER)
			-- 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: STRING_TRACING_HANDLER)
			-- 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: STRING_TRACING_HANDLER
			-- 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

	duplicated: STRING_TRACING_HANDLER
			-- New duplication of Current not necessarly equal to Current. This duplicate
			-- version is used for each new threads to perform tracing.
			-- (from TRACING_HANDLER)
		do
			Result := twin
		ensure -- from TRACING_HANDLER
			duplicated_not_void: Result /= Void
		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: STRING_TRACING_HANDLER)
			-- 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: STRING_TRACING_HANDLER
			-- 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: STRING_TRACING_HANDLER
			-- 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 STRING_TRACING_HANDLER
		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 STRING_TRACING_HANDLER
			-- 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 -- Implementation

	frozen internal_trace (a_type_id: INTEGER_32; a_c_class_name, a_c_feature_name: POINTER; a_depth: INTEGER_32; a_is_entering: BOOLEAN)
			-- Convert arguments a_c_class_name and a_c_feature_name to STRINGs and execute trace.
		require -- from TRACING_HANDLER
			a_type_id_non_negative: a_type_id >= 0
			a_depth_non_negative: a_depth >= 0
		local
			l_class_name: STRING_8
			l_type: TYPE [detachable ANY]
			l_buffer: like C_buffer
		do
			l_type := Internal.type_of_type (a_type_id)
			if a_c_class_name /= default_pointer and a_c_feature_name /= default_pointer then
				l_buffer := C_buffer;
				l_buffer.set_shared_from_pointer (a_c_class_name)
				l_class_name := l_buffer.string;
				l_buffer.set_shared_from_pointer (a_c_feature_name)
				trace (l_type, l_class_name, l_buffer.string, a_depth, a_is_entering)
			else
				trace (l_type, Void, Void, a_depth, a_is_entering)
			end
		end
	
feature {NONE} -- Implementation

	C_buffer: C_STRING
			-- Buffer to convert C strings to Eiffel strings
		once ("THREAD")
			create Result.make_empty (0)
		ensure
			c_buffer_not_void: Result /= Void
		end

	frozen c_set_tracer (a_tracer: POINTER; a_fnptr: POINTER)
			-- Register Current to the runtime to handle all the tracing calls.
			-- (from TRACING_HANDLER)
		external
			"C inline use %"eif_eiffel.h%""
		alias
			"eif_set_tracer ($a_tracer, $a_fnptr);"
		end

	Internal: REFLECTOR
			-- Quick access to features of INTERNAL
		once ("THREAD")
			create Result
		ensure
			internal_not_void: Result /= Void
		end

	frozen per_thread_trace (a_type_id: INTEGER_32; a_c_class_name, a_c_feature_name: POINTER; a_depth: INTEGER_32; a_is_entering: BOOLEAN)
			-- Thread safe tracing. Each time the runtime triggers a trace event,
			-- the per thread TRACE_HANDLER will be called avoiding any race condition.
			-- (from TRACING_HANDLER)
		require -- from TRACING_HANDLER
			a_type_id_non_negative: a_type_id >= 0
			a_depth_non_negative: a_depth >= 0
		do
			Per_thread_tracer.trace (a_type_id, a_c_class_name, a_c_feature_name, a_depth, a_is_entering)
		end

	frozen Per_thread_tracer: TRACING_HANDLER
			-- Per thread instance of Current used
			-- (from TRACING_HANDLER)
		once ("THREAD")
			Result := duplicated
		ensure -- from TRACING_HANDLER
			per_thread_tracer_not_void: Result /= 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)
		local
			s: READABLE_STRING_8
		do
			if attached o then
				s := o.out
				if attached {READABLE_STRING_32} s as s32 then
					Io.put_string_32 (s32)
				elseif attached {READABLE_STRING_8} s as s8 then
					Io.put_string (s8)
				else
					Io.put_string_32 (s.as_string_32)
				end
			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_32
			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: ".as_string_32)
				create l_exc;
				l_msg.append (generating_type.name_32);
				l_exc.raise_retrieval_exception (l_msg)
			end
		end
	
feature -- Tracing

	frozen activate
			-- Register Current to the runtime and for all running threads to handle
			-- all the tracing calls.
			-- (from TRACING_HANDLER)
		require -- from TRACING_HANDLER
			valid_platform: not {PLATFORM}.is_dotnet
		do
			c_set_tracer ($Current.to_pointer, $per_thread_trace)
		end

	frozen deactivate
			-- Remove runtime tracing for all running threads.
			-- (from TRACING_HANDLER)
		require -- from TRACING_HANDLER
			valid_platform: not {PLATFORM}.is_dotnet
		local
			l_default: TYPED_POINTER [TRACING_HANDLER]
		do
			c_set_tracer (l_default.to_pointer, default_pointer)
		end

	trace (a_type: TYPE [detachable ANY]; a_class_name, a_feature_name: detachable STRING_8; a_depth: INTEGER_32; a_is_entering: BOOLEAN)
			-- Trigger a trace operation from a feature represented by a_feature_name defined in
			-- class a_class_name and applied to an object of type a_type at a call depth a_depth.
			-- If a_is_entering we are entering the routine, otherwise we are exiting it.			
		require
			a_depth_non_negative: a_depth >= 0
		deferred
		end
	
invariant
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

note
	library: "EiffelBase: Library of reusable components for Eiffel."
	copyright: "Copyright (c) 1984-2013, 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 STRING_TRACING_HANDLER

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