note
	description: "A low-level string class to solve some garbage collector problems (mainly objects moving around) when interfacing with C APIs."
	library: "Free implementation of ELKS library"
	status: "See notice at end of class."
	legal: "See notice at end of class."
	date: "$Date: 2020-05-19 14:23:13 +0000 (Tue, 19 May 2020) $"
	revision: "$Revision: 104257 $"

class interface
	C_STRING

create 
	make,
	make_empty,
	make_by_pointer,
	make_by_pointer_and_count,
	make_shared_from_pointer,
	make_shared_from_pointer_and_count,
	own_from_pointer,
	own_from_pointer_and_count

feature -- Initialization

	set_shared_from_pointer (a_ptr: POINTER)
			-- Share a_ptr.
		require
			a_ptr_not_null: a_ptr /= default_pointer

	set_shared_from_pointer_and_count (a_ptr: POINTER; a_length: INTEGER_32)
			-- Share a_ptr of a_length byte.
		require
			a_ptr_not_null: a_ptr /= default_pointer
			a_length_non_negative: a_length >= 0
	
feature -- Access

	substring (start_pos, end_pos: INTEGER_32): STRING_8
			-- Copy of substring containing all characters at indices
			-- between start_pos and end_pos.
		require
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_position_not_too_big: end_pos <= capacity
		ensure
			susbstring_not_void: Result /= Void

	substring_8 (start_pos, end_pos: INTEGER_32): STRING_8
			-- Copy of substring containing all characters at indices
			-- between start_pos and end_pos.
		require
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_position_not_too_big: end_pos <= capacity
		ensure
			susbstring_not_void: Result /= Void

	string: STRING_8
			-- Eiffel string, ignoring count. Reads until a null character is being read.
		ensure
			string_not_void: Result /= Void

	string_8: STRING_8
			-- Eiffel string, ignoring count. Reads until a null character is being read.
		ensure
			string_not_void: Result /= Void

	copy_to_string (a_string: STRING_GENERAL; source_index, destination_index, n: INTEGER_32)
			-- Copy n characters of Current from source_index position to a_string at
			-- destination_index. Other characters of a_string remain unchanged.
		require
			a_string_not_void: a_string /= Void
			source_index_positive: source_index >= 1
			destination_index_positive: destination_index >= 1
			n_non_negative: n >= 0
			n_is_small_enough_for_source: source_index + (n - 1) <= capacity
			n_is_small_enough_for_destination: destination_index + (n - 1) <= a_string.count

	read_substring_into (a_string: STRING_GENERAL; start_pos, end_pos: INTEGER_32)
			-- Copy of substring containing all characters at indices
			-- between start_pos and end_pos into a_string.
		require
			a_string_not_void: a_string /= Void
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_position_not_too_big: end_pos <= capacity
			a_string_large_enough: a_string.count >= end_pos - start_pos + 1

	read_string_into (a_string: STRING_GENERAL)
			-- Copy of substring containing all characters at indices
			-- between start_pos and end_pos into a_string replacing any
			-- existing characters.
		require
			a_string_not_void: a_string /= Void
			a_string_large_enough: a_string.count >= count

	read_substring_into_character_8_area (a_area: SPECIAL [CHARACTER_8]; start_pos, end_pos: INTEGER_32)
			-- Copy of substring containing all characters at indices
			-- between start_pos and end_pos into a_area.
		require
			a_area_not_void: a_area /= Void
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_position_not_too_big: end_pos <= capacity
			a_area_large_enough: a_area.count >= end_pos - start_pos + 1
		ensure
			copied: 

	read_substring_into_character_32_area (a_area: SPECIAL [CHARACTER_32]; start_pos, end_pos: INTEGER_32)
			-- Copy of substring containing all characters at indices
			-- between start_pos and end_pos into a_area.
		require
			a_area_not_void: a_area /= Void
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_position_not_too_big: end_pos <= capacity
			a_area_large_enough: a_area.count >= end_pos - start_pos + 1
		ensure
			copied: 

	read_unicode_substring_into_character_32_area (a_area: SPECIAL [CHARACTER_32]; start_pos, end_pos: INTEGER_32)
			-- Copy of Unicode substring containing all characters at indices
			-- between start_pos and end_pos into a_area.
		require
			a_area_not_void: a_area /= Void
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_position_not_too_big: end_pos <= capacity
			a_area_large_enough: a_area.count >= end_pos - start_pos + 1

	item: POINTER
			-- Get pointer to allocated area.
		ensure
			item_not_null: Result /= default_pointer

	managed_data: MANAGED_POINTER
			-- Hold data of Current.
	
feature -- Measurement

	capacity: INTEGER_32
			-- Number of characters in Current.

	bytes_count: INTEGER_32
			-- Number of bytes represented by the string.

	count: INTEGER_32
			-- Number of characters in Current.

	Character_size: INTEGER_32 = 1
			-- Size of a character
	
feature -- Element change

	set_string (a_string: READABLE_STRING_GENERAL)
			-- Set string with a_string.
		require
			a_string_not_void: a_string /= Void
			a_string_is_string_8: a_string.is_valid_as_string_8

	set_substring (a_string: READABLE_STRING_GENERAL; start_pos, end_pos: INTEGER_32)
			-- Set string with a_string.
		require
			a_string_not_void: a_string /= Void
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
			end_pos_small_enough: end_pos <= a_string.count

	set_count (a_count: INTEGER_32)
			-- Set count with a_count.
			-- Note: Current content from index 1 to
			-- count.min (a_count) is unchanged.
		require
			a_count_non_negative: a_count >= 0
		ensure
			count_set: count = a_count

	fill_blank
			-- Fill Current with zeros.

	fill_value (a_value: INTEGER_8)
			-- Fill Current with a_value.
	
invariant
	managed_data_not_void: managed_data /= Void
	count_not_negative: count >= 0

note
	copyright: "Copyright (c) 1984-2020, 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 C_STRING

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