note
	description: "[
		Sequences of 32-bit characters, accessible through integer indices
		in a contiguous range.
	]"
	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 14:21:28 +0000 (Tue, 19 May 2020) $"
	revision: "$Revision: 104256 $"

class interface
	STRING_32

create 
	make (n: INTEGER_32)
			-- Allocate space for at least n characters.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			non_negative_size: n >= 0
		ensure -- from READABLE_STRING_GENERAL
			empty_string: count = 0
			area_allocated: capacity >= n

	make_empty
			-- Create empty string.
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
			empty: count = 0
			area_allocated: capacity >= 0

	make_filled (c: CHARACTER_32; n: INTEGER_32)
			-- Create string of length n filled with c.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			valid_count: n >= 0
		ensure -- from READABLE_STRING_32
			count_set: count = n
			area_allocated: capacity >= n
			filled: occurrences (c) = count

	make_from_string (s: READABLE_STRING_32)
			-- Initialize from the characters of s.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			string_exists: s /= Void
		ensure -- from READABLE_STRING_32
			not_shared_implementation: Current /= s implies not shared_with (s)
			initialized: same_string (s)

	make_from_string_general (s: READABLE_STRING_GENERAL)
			-- Initialize from the characters of s.
		require -- from READABLE_STRING_32
			string_exists: s /= Void
		ensure -- from READABLE_STRING_32
			not_shared_implementation: Current /= s
			initialized: same_string_general (s)

	make_from_c (c_string: POINTER)
			-- Initialize from contents of c_string,
			-- a string created by some C function.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			c_string_exists: c_string /= default_pointer

	make_from_c_pointer (c_string: POINTER)
			-- Create new instance from contents of c_string,
			-- a string created by some C function.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			c_string_exists: c_string /= default_pointer

	make_from_c_byte_array (a_byte_array: POINTER; a_character_count: INTEGER_32)
			-- Initialize from contents of a_byte_array for a length of a_character_count,
			-- given that each character is encoded in 4 bytes (little endian).
			-- ex: (char*) "a\000\000\000b\000\000\000c\000\000\000" for unicode STRING_32 "abc"
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			a_byte_array_exists: not a_byte_array.is_default_pointer

	make_from_cil (a_system_string: detachable SYSTEM_STRING)
			-- Initialize Current with a_system_string.
		require -- from READABLE_STRING_32
			is_dotnet: {PLATFORM}.is_dotnet

	make_from_separate (other: separate READABLE_STRING_GENERAL)
			-- Initialize current string from other.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			other_not_void: other /= Void
		ensure -- from READABLE_STRING_32
			same_string: 

convert
	make_from_separate: {SYSTEM_STRING},
	make_from_separate ({SYSTEM_STRING}),
	make_from_separate: {READABLE_STRING_8,
		STRING_8}

feature -- Initialization

	adapt (s: STRING_32): like Current
			-- Object of a type conforming to the type of s,
			-- initialized with attributes from s
		ensure
			adapt_not_void: Result /= Void
			shared_implementation: Result.shared_with (s)

	from_c (c_string: POINTER)
			-- Reset contents of string from contents of c_string,
			-- a string created by some C function.
		require
			c_string_exists: c_string /= default_pointer
		ensure
			no_zero_byte: not has ('%U'.to_character_32)

	from_c_substring (c_string: POINTER; start_pos, end_pos: INTEGER_32)
			-- Reset contents of string from substring of c_string,
			-- a string created by some C function.
		require
			c_string_exists: c_string /= default_pointer
			start_position_big_enough: start_pos >= 1
			end_position_big_enough: start_pos <= end_pos + 1
		ensure
			valid_count: count = end_pos - start_pos + 1

	make (n: INTEGER_32)
			-- Allocate space for at least n characters.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			non_negative_size: n >= 0
		ensure -- from READABLE_STRING_GENERAL
			empty_string: count = 0
			area_allocated: capacity >= n

	make_empty
			-- Create empty string.
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
			empty: count = 0
			area_allocated: capacity >= 0

	make_filled (c: CHARACTER_32; n: INTEGER_32)
			-- Create string of length n filled with c.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			valid_count: n >= 0
		ensure -- from READABLE_STRING_32
			count_set: count = n
			area_allocated: capacity >= n
			filled: occurrences (c) = count

	make_from_c (c_string: POINTER)
			-- Initialize from contents of c_string,
			-- a string created by some C function.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			c_string_exists: c_string /= default_pointer

	make_from_cil (a_system_string: detachable SYSTEM_STRING)
			-- Initialize Current with a_system_string.
		require -- from READABLE_STRING_32
			is_dotnet: {PLATFORM}.is_dotnet

	make_from_string (s: READABLE_STRING_32)
			-- Initialize from the characters of s.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			string_exists: s /= Void
		ensure -- from READABLE_STRING_32
			not_shared_implementation: Current /= s implies not shared_with (s)
			initialized: same_string (s)

	make_from_string_general (s: READABLE_STRING_GENERAL)
			-- Initialize from the characters of s.
		require -- from READABLE_STRING_32
			string_exists: s /= Void
		ensure -- from READABLE_STRING_32
			not_shared_implementation: Current /= s
			initialized: same_string_general (s)
	
feature -- Access

	area: SPECIAL [CHARACTER_32]
			-- Storage for characters

	at alias "@" (i: INTEGER_32): CHARACTER_32 assign put
			-- Character at position i
			-- Was declared in STRING_32 as synonym of item.
		require -- from  READABLE_STRING_32
			True
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TO_SPECIAL
			valid_index: valid_index (i)

	case_insensitive_hash_code: INTEGER_32
			-- Hash code value of the lower case version of Current.
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
			consistent: Result = as_lower.case_insensitive_hash_code

	code (i: INTEGER_32): NATURAL_32
			-- Character at position i
		require -- from READABLE_STRING_GENERAL
			valid_index: valid_index (i)

	False_constant: STRING_8 = "false"
			-- Constant string "false"
			-- (from READABLE_STRING_GENERAL)

	fuzzy_index (other: READABLE_STRING_GENERAL; start: INTEGER_32; fuzz: INTEGER_32): INTEGER_32
			-- Position of first occurrence of other at or after start
			-- with 0..fuzz mismatches between the string and other.
			-- 0 if there are no fuzzy matches
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			other_exists: other /= Void
			other_not_empty: not other.is_empty
			start_large_enough: start >= 1
			start_small_enough: start <= count
			acceptable_fuzzy: fuzz <= other.count

	generating_type: TYPE [detachable STRING_32]
			-- 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

	hash_code: INTEGER_32
			-- Hash code value
			-- (from READABLE_STRING_GENERAL)
		ensure -- from HASHABLE
			good_hash_value: Result >= 0

	index_of (c: CHARACTER_32; start_index: INTEGER_32): INTEGER_32
			-- Position of first occurrence of c at or after start_index;
			-- 0 if none.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			start_large_enough: start_index >= 1
			start_small_enough: start_index <= count + 1
		ensure -- from READABLE_STRING_GENERAL
			valid_result: Result = 0 or (start_index <= Result and Result <= count)
			zero_if_absent: (Result = 0) = not substring (start_index, count).has (c)
			found_if_present: substring (start_index, count).has (c) implies item (Result) = c
			none_before: substring (start_index, count).has (c) implies not substring (start_index, Result - 1).has (c)

	index_of_code (c: like code; start_index: INTEGER_32): INTEGER_32
			-- Position of first occurrence of c at or after start_index;
			-- 0 if none.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			start_large_enough: start_index >= 1
			start_small_enough: start_index <= count + 1
		ensure -- from READABLE_STRING_GENERAL
			valid_result: Result = 0 or (start_index <= Result and Result <= count)
			zero_if_absent: (Result = 0) = not substring (start_index, count).has_code (c)
			found_if_present: substring (start_index, count).has_code (c) implies code (Result) = c
			none_before: substring (start_index, count).has_code (c) implies not substring (start_index, Result - 1).has_code (c)

	item alias "[]" (i: INTEGER_32): CHARACTER_32 assign put
			-- Character at position i
			-- Was declared in STRING_32 as synonym of at.
		require -- from READABLE_STRING_GENERAL
			valid_index: valid_index (i)
		require -- from READABLE_INDEXABLE
			valid_index: valid_index (i)
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TO_SPECIAL
			valid_index: valid_index (i)

	last_index_of (c: CHARACTER_32; start_index_from_end: INTEGER_32): INTEGER_32
			-- Position of last occurrence of c.
			-- 0 if none.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			start_index_small_enough: start_index_from_end <= count
			start_index_large_enough: start_index_from_end >= 1
		ensure -- from READABLE_STRING_GENERAL
			valid_result: 0 <= Result and Result <= start_index_from_end
			zero_if_absent: (Result = 0) = not substring (1, start_index_from_end).has (c)
			found_if_present: substring (1, start_index_from_end).has (c) implies item (Result) = c
			none_after: substring (1, start_index_from_end).has (c) implies not substring (Result + 1, start_index_from_end).has (c)

	last_index_of_code (c: like code; start_index_from_end: INTEGER_32): INTEGER_32
			-- Position of last occurrence of c.
			-- 0 if none.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			start_index_small_enough: start_index_from_end <= count
			start_index_large_enough: start_index_from_end >= 1
		ensure -- from READABLE_STRING_GENERAL
			valid_result: 0 <= Result and Result <= start_index_from_end
			zero_if_absent: (Result = 0) = not substring (1, start_index_from_end).has_code (c)
			found_if_present: substring (1, start_index_from_end).has_code (c) implies code (Result) = c
			none_after: substring (1, start_index_from_end).has_code (c) implies not substring (Result + 1, start_index_from_end).has_code (c)

	new_cursor: STRING_32_ITERATION_CURSOR
			-- Fresh cursor associated with current structure
			-- (from READABLE_STRING_32)
		require -- from  ITERABLE
			True
		ensure -- from ITERABLE
			result_attached: Result /= Void

	shared_with (other: READABLE_STRING_32): BOOLEAN
			-- Does string share the text of other?
			-- (from READABLE_STRING_32)

	string: STRING_32
			-- New STRING_32 having same character sequence as Current.
			-- (from READABLE_STRING_32)
		ensure -- from READABLE_STRING_32
			string_not_void: Result /= Void
			string_type: Result.same_type (create {STRING_32}.make_empty)
			first_item: count > 0 implies Result.item (1) = item (1)
			recurse: count > 1 implies Result.substring (2, count) ~ substring (2, count).string

	string_representation: STRING_32
			-- Similar to string but only create a new object if Current is not of dynamic type STRING_32.
			-- (from READABLE_STRING_32)
		ensure -- from READABLE_STRING_32
			result_not_void: Result /= Void
			correct_type: Result.same_type (create {STRING_32}.make_empty)
			first_item: count > 0 implies Result.item (1) = item (1)
			recurse: count > 1 implies Result.substring (2, count) ~ substring (2, count).string

	substring_index (other: READABLE_STRING_GENERAL; start_index: INTEGER_32): INTEGER_32
			-- Index of first occurrence of other at or after start_index;
			-- 0 if none
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			other_not_void: other /= Void
			valid_start_index: start_index >= 1 and start_index <= count + 1
		ensure -- from READABLE_STRING_GENERAL
			valid_result: Result = 0 or else (start_index <= Result and Result <= count - other.count + 1)
			zero_if_absent: (Result = 0) = not substring (start_index, count).has_substring (other)
			at_this_index: Result >= start_index implies other.same_string (substring (Result, Result + other.count - 1))
			none_before: Result > start_index implies not substring (start_index, Result + other.count - 2).has_substring (other)

	substring_index_in_bounds (other: READABLE_STRING_GENERAL; start_pos, end_pos: INTEGER_32): INTEGER_32
			-- Position of first occurrence of other at or after start_pos
			-- and to or before end_pos;
			-- 0 if none.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			other_nonvoid: other /= Void
			other_notempty: not other.is_empty
			start_pos_large_enough: start_pos >= 1
			start_pos_small_enough: start_pos <= count
			end_pos_large_enough: end_pos >= start_pos
			end_pos_small_enough: end_pos <= count
		ensure -- from READABLE_STRING_GENERAL
			correct_place: Result > 0 implies other.same_string (substring (Result, Result + other.count - 1))

	True_constant: STRING_8 = "true"
			-- Constant string "true"
			-- (from READABLE_STRING_GENERAL)
	
feature -- Measurement

	additional_space: INTEGER_32
			-- Proposed number of additional items
			-- (from RESIZABLE)
		ensure -- from RESIZABLE
			at_least_one: Result >= 1

	capacity: INTEGER_32
			-- Number of characters allocated in Current
			-- (from READABLE_STRING_32)
		require -- from  READABLE_STRING_GENERAL
			True
		require -- from  BOUNDED
			True
		ensure -- from READABLE_STRING_GENERAL
			capacity_non_negative: Result >= 0
		ensure -- from BOUNDED
			capacity_non_negative: Result >= 0

	count: INTEGER_32
			-- Actual number of characters making up the string.
			-- (from READABLE_STRING_32)

	Growth_percentage: INTEGER_32 = 50
			-- Percentage by which structure will grow automatically
			-- (from RESIZABLE)

	Lower: INTEGER_32 = 1
			-- Minimum index.
			-- (from READABLE_STRING_32)

	Minimal_increase: INTEGER_32 = 5
			-- Minimal number of additional items
			-- (from RESIZABLE)

	occurrences (c: CHARACTER_32): INTEGER_32
			-- Number of times c appears in the string
			-- (from READABLE_STRING_32)
		require -- from  READABLE_STRING_GENERAL
			True
		require -- from  BAG
			True
		ensure then -- from READABLE_STRING_GENERAL
			zero_if_empty: count = 0 implies Result = 0
			recurse_if_not_found_at_first_position: (count > 0 and then item (1) /= c) implies Result = substring (2, count).occurrences (c)
			recurse_if_found_at_first_position: (count > 0 and then item (1) = c) implies Result = 1 + substring (2, count).occurrences (c)
		ensure -- from BAG
			non_negative_occurrences: Result >= 0
		ensure then -- from READABLE_STRING_32
			zero_if_empty: count = 0 implies Result = 0
			recurse_if_not_found_at_first_position: (count > 0 and then item (1) /= c) implies Result = substring (2, count).occurrences (c)
			recurse_if_found_at_first_position: (count > 0 and then item (1) = c) implies Result = 1 + substring (2, count).occurrences (c)
	
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)

	ends_with_general (s: READABLE_STRING_GENERAL): BOOLEAN
			-- Does string finish with s?
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			argument_not_void: s /= Void
		ensure -- from READABLE_STRING_GENERAL
			definition: Result = s.same_string (substring (count - s.count + 1, count))

	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))

	has_substring (other: READABLE_STRING_GENERAL): BOOLEAN
			-- Does Current contain other?
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			other_not_void: other /= Void
		ensure -- from READABLE_STRING_GENERAL
			false_if_too_small: count < other.count implies not Result
			true_if_initial: (count >= other.count and then other.same_string (substring (1, other.count))) implies Result
			recurse: (count >= other.count and then not other.same_string (substring (1, other.count))) implies (Result = substring (2, count).has_substring (other))

	is_case_insensitive_equal_general (other: READABLE_STRING_GENERAL): BOOLEAN
			-- Is string made of same character sequence as other regardless of casing
			-- (possibly with a different capacity)?
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
			symmetric: Result implies other.is_case_insensitive_equal (Current)
			consistent: attached {STRING_32} other as l_other implies (standard_is_equal (l_other) implies Result)
			valid_result: as_lower ~ other.as_lower implies Result

	is_case_insensitive_equal (other: READABLE_STRING_32): BOOLEAN
			-- Is string made of same character sequence as other regardless of casing
			-- (possibly with a different capacity)?
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			other_not_void: other /= Void
		ensure -- from READABLE_STRING_32
			symmetric: Result implies other.is_case_insensitive_equal (Current)
			consistent: attached {STRING_32} other as l_other implies (standard_is_equal (l_other) implies Result)
			valid_result: as_lower.same_string (other.as_lower) implies Result

	frozen is_deep_equal alias "≡≡≡" (other: STRING_32): 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: STRING_32): BOOLEAN
			-- Is string made of same character sequence as other
			-- (possibly with a different capacity)?
			-- (from READABLE_STRING_32)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other ~ Current
			consistent: standard_is_equal (other) implies Result
		ensure then -- from COMPARABLE
			trichotomy: Result = (not (Current < other) and not (other < Current))

	is_greater alias ">" (other: STRING_32): BOOLEAN
			-- Is current object greater than other?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			definition: Result = (other < Current)

	is_greater_equal alias ">=" alias "≥" (other: STRING_32): BOOLEAN
			-- Is current object greater than or equal to other?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			definition: Result = (other <= Current)

	is_less alias "<" (other: STRING_32): BOOLEAN
			-- Is string lexicographically lower than other?
			-- (from READABLE_STRING_32)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			asymmetric: Result implies not (other < Current)

	is_less_equal alias "<=" alias "≤" (other: STRING_32): BOOLEAN
			-- Is current object less than or equal to other?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			definition: Result = ((Current < other) or (Current ~ other))

	max alias "∨" (other: STRING_32): STRING_32
			-- The greater of current object and other
			-- (from COMPARABLE)
		require -- from COMPARABLE
			other_exists: other /= Void
		ensure -- from COMPARABLE
			current_if_not_smaller: Current >= other implies Result = Current
			other_if_smaller: Current < other implies Result = other

	min alias "∧" (other: STRING_32): STRING_32
			-- The smaller of current object and other
			-- (from COMPARABLE)
		require -- from COMPARABLE
			other_exists: other /= Void
		ensure -- from COMPARABLE
			current_if_not_greater: Current <= other implies Result = Current
			other_if_greater: Current > other implies Result = other

	same_caseless_characters_general (other: READABLE_STRING_GENERAL; start_pos, end_pos, index_pos: INTEGER_32): BOOLEAN
			-- Are characters of other within bounds start_pos and end_pos
			-- caseless identical to characters of current string starting at index index_pos.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			other_not_void: other /= Void
			valid_start_pos: other.valid_index (start_pos)
			valid_end_pos: other.valid_index (end_pos)
			valid_bounds: (start_pos <= end_pos) or (start_pos = end_pos + 1)
			valid_index_pos: valid_index (index_pos)
		ensure -- from READABLE_STRING_GENERAL
			same_characters: Result = substring (index_pos, index_pos + end_pos - start_pos).is_case_insensitive_equal_general (other.substring (start_pos, end_pos))

	same_caseless_characters (other: READABLE_STRING_32; start_pos, end_pos, index_pos: INTEGER_32): BOOLEAN
			-- Are characters of other within bounds start_pos and end_pos
			-- caseless identical to characters of current string starting at index index_pos.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			other_not_void: other /= Void
			valid_start_pos: other.valid_index (start_pos)
			valid_end_pos: other.valid_index (end_pos)
			valid_bounds: (start_pos <= end_pos) or (start_pos = end_pos + 1)
			valid_index_pos: valid_index (index_pos)
		ensure -- from READABLE_STRING_32
			same_characters: Result = substring (index_pos, index_pos + end_pos - start_pos).is_case_insensitive_equal (other.substring (start_pos, end_pos))

	same_characters_general (other: READABLE_STRING_GENERAL; start_pos, end_pos, index_pos: INTEGER_32): BOOLEAN
			-- Are characters of other within bounds start_pos and end_pos
			-- identical to characters of current string starting at index index_pos.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			other_not_void: other /= Void
			valid_start_pos: other.valid_index (start_pos)
			valid_end_pos: other.valid_index (end_pos)
			valid_bounds: (start_pos <= end_pos) or (start_pos = end_pos + 1)
			valid_index_pos: valid_index (index_pos)
		ensure -- from READABLE_STRING_GENERAL
			same_characters: Result = substring (index_pos, index_pos + end_pos - start_pos).same_string_general (other.substring (start_pos, end_pos))

	same_characters (other: READABLE_STRING_32; start_pos, end_pos, index_pos: INTEGER_32): BOOLEAN
			-- Are characters of other within bounds start_pos and end_pos
			-- identical to characters of current string starting at index index_pos.
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			other_not_void: other /= Void
			valid_start_pos: other.valid_index (start_pos)
			valid_end_pos: other.valid_index (end_pos)
			valid_bounds: (start_pos <= end_pos) or (start_pos = end_pos + 1)
			valid_index_pos: valid_index (index_pos)
		ensure -- from READABLE_STRING_32
			same_characters: Result = substring (index_pos, index_pos + end_pos - start_pos).same_string (other.substring (start_pos, end_pos))

	same_string (other: READABLE_STRING_32): BOOLEAN
			-- Do Current and other have same character sequence?
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			other_not_void: other /= Void
		ensure -- from READABLE_STRING_32
			definition: Result = (string ~ other.string)

	same_string_general (other: READABLE_STRING_GENERAL): BOOLEAN
			-- Does other represent the same string as Current?
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			other_not_void: other /= Void

	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: STRING_32): 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)

	starts_with_general (s: READABLE_STRING_GENERAL): BOOLEAN
			-- Does string begin with s?
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			argument_not_void: s /= Void
		ensure -- from READABLE_STRING_GENERAL
			definition: Result = s.same_string (substring (1, s.count))

	three_way_comparison alias "⋚" (other: STRING_32): INTEGER_32
			-- If current object equal to other, 0;
			-- if smaller, -1; if greater, 1
			-- (from COMPARABLE)
		require -- from COMPARABLE
			other_exists: other /= Void
		ensure -- from COMPARABLE
			equal_zero: (Result = 0) = (Current ~ other)
			smaller_negative: (Result = -1) = (Current < other)
			greater_positive: (Result = 1) = (Current > other)
	
feature -- Status report

	Changeable_comparison_criterion: BOOLEAN = False
			-- May object_comparison be changed?
			-- (Answer: yes by default.)

	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

	ends_with (s: READABLE_STRING_32): BOOLEAN
			-- Does string finish with s?
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			argument_not_void: s /= Void
		ensure -- from READABLE_STRING_32
			definition: Result = s.same_string (substring (count - s.count + 1, count))

	Extendible: BOOLEAN = True
			-- May new items be added? (Answer: yes.)

	full: BOOLEAN
			-- Is structure full?
			-- (from BOUNDED)

	has (c: CHARACTER_32): BOOLEAN
			-- Does string include c?
			-- (from READABLE_STRING_32)
		require -- from  READABLE_STRING_GENERAL
			True
		require -- from  CONTAINER
			True
		ensure then -- from READABLE_STRING_GENERAL
			false_if_empty: count = 0 implies not Result
			true_if_first: count > 0 and then item (1) = c implies Result
			recurse: (count > 0 and then item (1) /= c) implies (Result = substring (2, count).has (c))
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty

	has_code (c: like code): BOOLEAN
			-- Does string include c?
			-- (from READABLE_STRING_GENERAL)
		ensure then -- from READABLE_STRING_GENERAL
			false_if_empty: count = 0 implies not Result
			true_if_first: count > 0 and then code (1) = c implies Result
			recurse: (count > 0 and then code (1) /= c) implies (Result = substring (2, count).has_code (c))

	is_boolean: BOOLEAN
			-- Does Current represent a BOOLEAN?
			-- (from READABLE_STRING_32)
		require -- from  READABLE_STRING_GENERAL
			True
		ensure -- from READABLE_STRING_GENERAL
			is_boolean: Result = (True_constant.same_string_general (as_lower) or False_constant.same_string_general (as_lower))

	is_double: BOOLEAN
			-- Does Current represent a REAL_64?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_real_64.
			-- (from READABLE_STRING_GENERAL)

	is_empty: BOOLEAN
			-- Is structure empty?
			-- (from FINITE)
		require -- from  CONTAINER
			True
		require -- from  READABLE_STRING_GENERAL
			True

	is_hashable: BOOLEAN
			-- May current object be hashed?
			-- (True by default.)
			-- (from HASHABLE)

	is_immutable: BOOLEAN
			-- Can the character sequence of Current be not changed?
			-- (from READABLE_STRING_GENERAL)

	is_inserted (v: CHARACTER_32): BOOLEAN
			-- Has v been inserted by the most recent insertion?
			-- (By default, the value returned is equivalent to calling 
			-- has (v). However, descendants might be able to provide more
			-- efficient implementations.)
			-- (from COLLECTION)

	is_integer: BOOLEAN
			-- Does Current represent an INTEGER_32?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_integer_32.
			-- (from READABLE_STRING_GENERAL)

	is_integer_16: BOOLEAN
			-- Does Current represent an INTEGER_16?
			-- (from READABLE_STRING_GENERAL)

	is_integer_32: BOOLEAN
			-- Does Current represent an INTEGER_32?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_integer.
			-- (from READABLE_STRING_GENERAL)

	is_integer_64: BOOLEAN
			-- Does Current represent an INTEGER_64?
			-- (from READABLE_STRING_GENERAL)

	is_integer_8: BOOLEAN
			-- Does Current represent an INTEGER_8?
			-- (from READABLE_STRING_GENERAL)

	is_natural: BOOLEAN
			-- Does Current represent a NATURAL_32?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_natural_32.
			-- (from READABLE_STRING_GENERAL)

	is_natural_16: BOOLEAN
			-- Does Current represent a NATURAL_16?
			-- (from READABLE_STRING_GENERAL)

	is_natural_32: BOOLEAN
			-- Does Current represent a NATURAL_32?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_natural.
			-- (from READABLE_STRING_GENERAL)

	is_natural_64: BOOLEAN
			-- Does Current represent a NATURAL_64?
			-- (from READABLE_STRING_GENERAL)

	is_natural_8: BOOLEAN
			-- Does Current represent a NATURAL_8?
			-- (from READABLE_STRING_GENERAL)

	is_number_sequence: BOOLEAN
			-- Does Current represent a number sequence?
			-- (from READABLE_STRING_GENERAL)

	is_real: BOOLEAN
			-- Does Current represent a REAL_32?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_real_32.
			-- (from READABLE_STRING_GENERAL)

	is_real_32: BOOLEAN
			-- Does Current represent a REAL_32?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_real.
			-- (from READABLE_STRING_GENERAL)

	is_real_64: BOOLEAN
			-- Does Current represent a REAL_64?
			-- Was declared in READABLE_STRING_GENERAL as synonym of is_double.
			-- (from READABLE_STRING_GENERAL)

	is_real_sequence: BOOLEAN
			-- Does Current represent a real sequence?
			-- (from READABLE_STRING_GENERAL)

	Is_string_32: BOOLEAN = True
			-- Is Current a sequence of CHARACTER_32?
			-- (from READABLE_STRING_32)

	Is_string_8: BOOLEAN = False
			-- Is Current a sequence of CHARACTER_8?
			-- (from READABLE_STRING_32)

	is_substring_whitespace (start_index, end_index: INTEGER_32): BOOLEAN
			-- Is substring between start_index and end_index containing only whitespace characters?
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_GENERAL
			start_index_big_enough: 1 <= start_index
			end_index_small_enough: end_index <= count
			consistent_indexes: start_index - 1 <= end_index

	is_valid_as_string_8: BOOLEAN
			-- Is Current convertible to a sequence of CHARACTER_8 without information loss?
			-- (from READABLE_STRING_32)
		require -- from  READABLE_STRING_GENERAL
			True

	is_whitespace: BOOLEAN
			-- Is structure containing only whitespace characters?
			-- (from READABLE_STRING_GENERAL)

	object_comparison: BOOLEAN
			-- Must search operations use equal rather than =
			-- for comparing references? (Default: no, use =.)
			-- (from CONTAINER)

	prunable: BOOLEAN
			-- May items be removed? (Answer: yes.)
			-- (from DYNAMIC_TABLE)
		require -- from  COLLECTION
			True

	resizable: BOOLEAN
			-- May capacity be changed? (Answer: yes.)
			-- (from RESIZABLE)

	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))

	starts_with (s: READABLE_STRING_32): BOOLEAN
			-- Does string begin with s?
			-- (from READABLE_STRING_32)
		require -- from READABLE_STRING_32
			argument_not_void: s /= Void
		ensure -- from READABLE_STRING_32
			definition: Result = s.same_string (substring (1, s.count))

	valid_code (v: NATURAL_32): BOOLEAN
			-- Is v a valid code for a CHARACTER_32?
			-- (from READABLE_STRING_32)
		require -- from  READABLE_STRING_GENERAL
			True

	valid_index (i: INTEGER_32): BOOLEAN
			-- Is i within the bounds of the string?
			-- (from READABLE_STRING_GENERAL)
		require -- from  READABLE_INDEXABLE
			True
		require -- from  TABLE
			True
		require -- from  TO_SPECIAL
			True
		ensure -- from READABLE_INDEXABLE
			only_if_in_index_set: Result implies (Lower <= i and i <= count)
		ensure -- from READABLE_STRING_GENERAL
			definition: Result = (1 <= i and i <= count)
	
feature -- Status setting

	compare_objects
			-- Ensure that future search operations will use equal
			-- rather than = for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: Changeable_comparison_criterion
		ensure -- from CONTAINER
				object_comparison

	compare_references
			-- Ensure that future search operations will use =
			-- rather than equal for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: Changeable_comparison_criterion
		ensure -- from CONTAINER
			reference_comparison: not object_comparison
	
feature -- Element change

	adjust
			-- Remove leading and/or trailing whitespace.
			-- (from STRING_GENERAL)
		ensure -- from STRING_GENERAL
			valid_count: count <= old count
			new_count_left: not is_empty implies not item (1).is_space
			new_count_right: not is_empty implies not item (count).is_space
			kept: Elks_checking implies (old twin).has_substring (Current)
			only_spaces_removed_before: Elks_checking implies (old twin).is_substring_whitespace (1, (old twin).substring_index (Current, 1) - 1)
			only_spaces_removed_after: Elks_checking implies (old twin).is_substring_whitespace ((old twin).substring_index (Current, 1) + count, old count)

	append (s: READABLE_STRING_32)
			-- Append characters of s at end.
		require
			argument_not_void: s /= Void
		ensure
			new_count: count = old count + old s.count
			appended: Elks_checking implies same_string (old (Current + s))

	append_boolean (b: BOOLEAN)
			-- Append the string representation of b at end.

	append_character (c: CHARACTER_32)
			-- Append c at end.
			-- Was declared in STRING_32 as synonym of extend.
		ensure then
			item_inserted: item (count) = c
			new_count: count = old count + 1
			stable_before: Elks_checking implies substring (1, count - 1) ~ (old twin)

	append_code (c: like code)
			-- Append c at end.
			-- (from STRING_GENERAL)
		require -- from STRING_GENERAL
			valid_code: valid_code (c)
		ensure then -- from STRING_GENERAL
			item_inserted: code (count) = c
			new_count: count = old count + 1
			stable_before: Elks_checking implies substring (1, count - 1) ~ (old twin)

	append_double (d: REAL_64)
			-- Append the string representation of d at end.

	append_integer (i: INTEGER_32)
			-- Append the string representation of i at end.

	append_integer_16 (i: INTEGER_16)
			-- Append the string representation of i at end.

	append_integer_64 (i: INTEGER_64)
			-- Append the string representation of i at end.

	append_integer_8 (i: INTEGER_8)
			-- Append the string representation of i at end.

	append_natural_16 (i: NATURAL_16)
			-- Append the string representation of i at end.

	append_natural_32 (i: NATURAL_32)
			-- Append the string representation of i at end.

	append_natural_64 (i: NATURAL_64)
			-- Append the string representation of i at end.

	append_natural_8 (i: NATURAL_8)
			-- Append the string representation of i at end.

	append_real (r: REAL_32)
			-- Append the string representation of r at end.

	append_string (s: detachable READABLE_STRING_32)
			-- Append a copy of s, if not void, at end.
		ensure
			appended: s /= Void implies (Elks_checking implies Current ~ (old twin + old s.twin))

	append_string_general (s: READABLE_STRING_GENERAL)
			-- Append characters of s at end.
		require -- from STRING_GENERAL
			argument_not_void: s /= Void
			compatible_strings: Is_string_8 implies s.is_valid_as_string_8
		ensure -- from STRING_GENERAL
			new_count: count = old count + old s.count
			appended: Elks_checking implies same_string_general (old (to_string_32 + s.as_string_32))

	append_substring (s: READABLE_STRING_32; start_index, end_index: INTEGER_32)
			-- Append characters of s.substring (start_index, end_index) at end.
		require
			argument_not_void: s /= Void
			start_index_valid: start_index >= 1
			end_index_valid: end_index <= s.count
			valid_bounds: start_index <= end_index + 1
		ensure
			new_count: count = old count + (end_index - start_index + 1)
			appended: Elks_checking implies same_string (old (Current + s.substring (start_index, end_index)))

	append_substring_general (s: READABLE_STRING_GENERAL; start_index, end_index: INTEGER_32)
			-- Append characters of s.substring (start_index, end_index) at end.
			-- (from STRING_GENERAL)
		require -- from STRING_GENERAL
			argument_not_void: s /= Void
			compatible_strings: Is_string_8 implies s.is_valid_as_string_8
			start_index_valid: start_index >= 1
			end_index_valid: end_index <= s.count
			valid_bounds: start_index <= end_index + 1
		ensure -- from STRING_GENERAL
			new_count: count = old count + end_index - start_index + 1
			appended: Elks_checking implies same_string_general (old (to_string_32 + s.substring (start_index, end_index).as_string_32))

	extend (c: CHARACTER_32)
			-- Append c at end.
			-- Was declared in STRING_32 as synonym of append_character.
		require -- from COLLECTION
			extendible: Extendible
		ensure -- from COLLECTION
			item_inserted: is_inserted (c)
		ensure then
			item_inserted: item (count) = c
			new_count: count = old count + 1
			stable_before: Elks_checking implies substring (1, count - 1) ~ (old twin)

	fill (other: CONTAINER [CHARACTER_32])
			-- Fill with as many items of other as possible.
			-- The representations of other and current structure
			-- need not be the same.
			-- (from COLLECTION)
		require -- from COLLECTION
			other_not_void: other /= Void
			extendible: Extendible

	fill_blank
			-- Fill with capacity blank characters.
		ensure
			filled: full
			same_size: (count = capacity) and (capacity = old capacity)

	fill_character (c: CHARACTER_32)
			-- Fill with capacity characters all equal to c.
			-- (from READABLE_STRING_32)
		ensure -- from READABLE_STRING_32
			filled: count = capacity
			same_size: capacity = old capacity

	fill_with (c: CHARACTER_32)
			-- Replace every character with c.
		ensure
			same_count: (count = old count) and (capacity = old capacity)
			filled: Elks_checking implies occurrences (c) = count

	insert_character (c: CHARACTER_32; i: INTEGER_32)
			-- Insert c at index i, shifting characters between ranks
			-- i and count rightwards.
		require
			valid_insertion_index: 1 <= i and i <= count + 1
		ensure
			one_more_character: count = old count + 1
			inserted: item (i) = c
			stable_before_i: Elks_checking implies substring (1, i - 1) ~ (old substring (1, i - 1))
			stable_after_i: Elks_checking implies substring (i + 1, count) ~ (old substring (i, count))

	insert_string (s: READABLE_STRING_32; i: INTEGER_32)
			-- Insert s at index i, shifting characters between ranks
			-- i and count rightwards.
		require
			string_exists: s /= Void
			valid_insertion_index: 1 <= i and i <= count + 1
		ensure
			inserted: Elks_checking implies (Current ~ (old substring (1, i - 1) + old (s.twin) + old substring (i, count)))

	keep_head (n: INTEGER_32)
			-- Remove all characters except for the first n;
			-- do nothing if n >= count.
		require -- from STRING_GENERAL
			non_negative_argument: n >= 0
		ensure -- from STRING_GENERAL
			new_count: count = n.min (old count)
			kept: Elks_checking implies Current ~ (old substring (1, n.min (count)))

	keep_tail (n: INTEGER_32)
			-- Remove all characters except for the last n;
			-- do nothing if n >= count.
		require -- from STRING_GENERAL
			non_negative_argument: n >= 0
		ensure -- from STRING_GENERAL
			new_count: count = n.min (old count)
			kept: Elks_checking implies Current ~ (old substring (count - n.min (count) + 1, count))

	left_adjust
			-- Remove leading whitespace.
		ensure -- from STRING_GENERAL
			valid_count: count <= old count
			new_count: not is_empty implies not item (1).is_space
			kept: Elks_checking implies Current ~ (old twin).substring (old count - count + 1, old count)
			only_spaces_removed_before: Elks_checking implies (old twin).is_substring_whitespace (1, (old twin).substring_index (Current, 1) - 1)

	precede (c: CHARACTER_32)
			-- Add c at front.
			-- Was declared in STRING_32 as synonym of prepend_character.
		ensure
			new_count: count = old count + 1

	prepend (s: READABLE_STRING_32)
			-- Prepend characters of s at front.
		require
			argument_not_void: s /= Void
		ensure
			new_count: count = old (count + s.count)
			inserted: Elks_checking implies same_string (old (s + Current))

	prepend_boolean (b: BOOLEAN)
			-- Prepend the string representation of b at front.

	prepend_character (c: CHARACTER_32)
			-- Add c at front.
			-- Was declared in STRING_32 as synonym of precede.
		ensure
			new_count: count = old count + 1

	prepend_double (d: REAL_64)
			-- Prepend the string representation of d at front.

	prepend_integer (i: INTEGER_32)
			-- Prepend the string representation of i at front.

	prepend_real (r: REAL_32)
			-- Prepend the string representation of r at front.

	prepend_string (s: detachable READABLE_STRING_32)
			-- Prepend characters of s, if not void, at front.

	prepend_string_general (s: READABLE_STRING_GENERAL)
			-- Prepend characters of s at front.
		require -- from STRING_GENERAL
			argument_not_void: s /= Void
			compatible_strings: Is_string_8 implies s.is_valid_as_string_8
		ensure -- from STRING_GENERAL
			new_count: count = old (count + s.count)
			inserted: Elks_checking implies same_string_general (old (s.to_string_32 + Current.as_string_32))

	prepend_substring_general (s: READABLE_STRING_GENERAL; start_index, end_index: INTEGER_32)
			-- Prepend characters of s.substring (start_index, end_index) at front.
			-- (from STRING_GENERAL)
		require -- from STRING_GENERAL
			argument_not_void: s /= Void
			compatible_strings: Is_string_8 implies s.is_valid_as_string_8
			start_index_valid: start_index >= 1
			end_index_valid: end_index <= s.count
			valid_bounds: start_index <= end_index + 1
		ensure -- from STRING_GENERAL
			new_count: count = old count + end_index - start_index + 1
			inserted: Elks_checking implies same_string_general (old (s.substring (start_index, end_index).to_string_32 + Current.as_string_32))

	prepend_substring (s: READABLE_STRING_32; start_index, end_index: INTEGER_32)
			-- Prepend characters of s.substring (start_index, end_index) at front.
		require
			argument_not_void: s /= Void
			start_index_valid: start_index >= 1
			end_index_valid: end_index <= s.count
			valid_bounds: start_index <= end_index + 1
		ensure
			new_count: count = old count + end_index - start_index + 1
			inserted: Elks_checking implies same_string (old (s.substring (start_index, end_index) + Current))

	put (c: CHARACTER_32; i: INTEGER_32)
			-- Replace character at position i by c.
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TO_SPECIAL
			valid_index: valid_index (i)
		ensure -- from TABLE
			inserted: item (i) = c
		ensure -- from TO_SPECIAL
			inserted: item (i) = c
		ensure then
			stable_count: count = old count
			stable_before_i: Elks_checking implies substring (1, i - 1) ~ (old substring (1, i - 1))
			stable_after_i: Elks_checking implies substring (i + 1, count) ~ (old substring (i + 1, count))

	put_code (v: NATURAL_32; i: INTEGER_32)
			-- Replace character at position i by character of code v.
		require -- from STRING_GENERAL
			valid_code: valid_code (v)
			valid_index: valid_index (i)
		ensure -- from STRING_GENERAL
			inserted: code (i) = v
			stable_count: count = old count
			stable_before_i: Elks_checking implies substring (1, i - 1) ~ (old substring (1, i - 1))
			stable_after_i: Elks_checking implies substring (i + 1, count) ~ (old substring (i + 1, count))

	replace_blank
			-- Replace all current characters with blanks.
		ensure
			same_size: (count = old count) and (capacity = old capacity)
			all_blank: Elks_checking implies occurrences (' '.to_character_32) = count

	replace_substring (s: READABLE_STRING_32; start_index, end_index: INTEGER_32)
			-- Replace characters from start_index to end_index with s.
		require
			string_not_void: s /= Void
			valid_start_index: 1 <= start_index
			valid_end_index: end_index <= count
			meaningfull_interval: start_index <= end_index + 1
		ensure
			new_count: count = old count + old s.count - end_index + start_index - 1
			replaced: Elks_checking implies (Current ~ (old (substring (1, start_index - 1) + s + substring (end_index + 1, count))))

	replace_substring_all (original, new: READABLE_STRING_32)
			-- Replace every occurrence of original with new.
		require
			original_exists: original /= Void
			new_exists: new /= Void
			original_not_empty: not original.is_empty

	right_adjust
			-- Remove trailing whitespace.
		ensure -- from STRING_GENERAL
			valid_count: count <= old count
			new_count: not is_empty implies not item (count).is_space
			kept: Elks_checking implies Current ~ (old twin).substring (1, count)
			only_spaces_removed_after: Elks_checking implies (old twin).is_substring_whitespace ((old twin).substring_index (Current, 1) + count, old count)

	set (t: READABLE_STRING_32; n1, n2: INTEGER_32)
			-- Set current string to substring of t from indices n1
			-- to n2, or to empty string if no such substring.
		require
			argument_not_void: t /= Void
		ensure
			is_substring: same_string (t.substring (n1, n2))

	share (other: STRING_32)
			-- Make current string share the text of other.
			-- Subsequent changes to the characters of current string
			-- will also affect other, and conversely.
		require
			argument_not_void: other /= Void
		ensure
			shared_count: other.count = count
			shared_area: other.area = area

	subcopy (other: READABLE_STRING_32; start_pos, end_pos, index_pos: INTEGER_32)
			-- Copy characters of other within bounds start_pos and
			-- end_pos to current string starting at index index_pos.
		require
			other_not_void: other /= Void
			valid_start_pos: other.valid_index (start_pos)
			valid_end_pos: other.valid_index (end_pos)
			valid_bounds: start_pos <= end_pos or start_pos = end_pos + 1
			valid_index_pos: valid_index (index_pos)
			enough_space: count - index_pos >= end_pos - start_pos
		ensure
			same_count: count = old count
			copied: Elks_checking implies (Current ~ (old substring (1, index_pos - 1) + old other.substring (start_pos, end_pos) + old substring (index_pos + (end_pos - start_pos + 1), count)))
	
feature -- Removal

	prune (c: CHARACTER_32)
			-- Remove first occurrence of c, if any.
		require -- from COLLECTION
			prunable: prunable
		require else
				True

	prune_all (c: CHARACTER_32)
			-- Remove all occurrences of c.
		require -- from COLLECTION
			prunable: prunable
		require else
				True
		ensure -- from COLLECTION
			no_more_occurrences: not has (c)
		ensure then
			changed_count: count = (old count) - (old occurrences (c))

	prune_all_leading (c: CHARACTER_32)
			-- Remove all leading occurrences of c.

	prune_all_trailing (c: CHARACTER_32)
			-- Remove all trailing occurrences of c.

	remove (i: INTEGER_32)
			-- Remove i-th character.
		require -- from STRING_GENERAL
			valid_index: valid_index (i)
		require -- from DYNAMIC_TABLE
			prunable: prunable
			valid_key: valid_index (i)
		ensure -- from STRING_GENERAL
			new_count: count = old count - 1
			removed: Elks_checking implies to_string_32 ~ (old substring (1, i - 1).to_string_32 + old substring (i + 1, count).to_string_32)

	remove_head (n: INTEGER_32)
			-- Remove first n characters;
			-- if n > count, remove all.
		require -- from STRING_GENERAL
			n_non_negative: n >= 0
		ensure -- from STRING_GENERAL
			removed: Elks_checking implies Current ~ (old substring (n.min (count) + 1, count))

	remove_substring (start_index, end_index: INTEGER_32)
			-- Remove all characters from start_index
			-- to end_index inclusive.
		require -- from STRING_GENERAL
			valid_start_index: 1 <= start_index
			valid_end_index: end_index <= count
			meaningful_interval: start_index <= end_index + 1
		ensure -- from STRING_GENERAL
			removed: Elks_checking implies Current.as_string_32 ~ (old substring (1, start_index - 1).as_string_32 + old substring (end_index + 1, count).as_string_32)

	remove_tail (n: INTEGER_32)
			-- Remove last n characters;
			-- if n > count, remove all.
		require -- from STRING_GENERAL
			n_non_negative: n >= 0
		ensure -- from STRING_GENERAL
			removed: Elks_checking implies Current ~ (old substring (1, count - n.min (count)))

	wipe_out
			-- Remove all characters.
		require -- from  STRING_GENERAL
			True
		require -- from COLLECTION
			prunable: prunable
		ensure -- from STRING_GENERAL
			is_empty: count = 0
			same_capacity: capacity = old capacity
		ensure -- from COLLECTION
			wiped_out: is_empty
	
feature -- Resizing

	adapt_size
			-- Adapt the size to accommodate count characters.

	automatic_grow
			-- Change the capacity to accommodate at least
			-- Growth_percentage more items.
			-- (from RESIZABLE)
		require -- from RESIZABLE
			resizable: resizable
		ensure -- from RESIZABLE
			increased_capacity: capacity >= old capacity + old additional_space

	grow (newsize: INTEGER_32)
			-- Ensure that the capacity is at least newsize.
		require -- from RESIZABLE
			resizable: resizable
		ensure -- from RESIZABLE
			new_capacity: capacity >= newsize

	resize (newsize: INTEGER_32)
			-- Rearrange string so that it can accommodate
			-- at least newsize characters.
			-- Do not lose any previously entered character.
		require -- from STRING_GENERAL
			new_size_large_enough: newsize >= count
		ensure -- from STRING_GENERAL
			same_count: count = old count
			capacity_large_enough: capacity >= newsize
			same_content: Elks_checking implies same_string_general (old twin)

	trim
			-- Decrease capacity to the minimum value.
			-- Apply to reduce allocated storage.
		require -- from  RESIZABLE
			True
		ensure -- from RESIZABLE
			same_count: count = old count
			minimal_capacity: capacity = count
		ensure then
			same_string: same_string (old twin)
	
feature -- Transformation

	correct_mismatch
			-- Attempt to correct object mismatch during retrieve using Mismatch_information.
	
feature -- Conversion

	as_lower: like Current
			-- New object with all letters in lower case.
		ensure -- from READABLE_STRING_GENERAL
			as_lower_attached: Result /= Void
			length: Result.count = count
			anchor: count > 0 implies Result.item (1) = item (1).as_lower
			recurse: count > 1 implies Result.substring (2, count) ~ substring (2, count).as_lower

	as_string_32: STRING_32
			-- Convert Current as a STRING_32.
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_string_32.
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
			as_string_32_not_void: Result /= Void
			identity: (conforms_to (create {STRING_32}.make_empty) and Result = Current) or (not conforms_to (create {STRING_32}.make_empty) and Result /= Current)

	as_upper: like Current
			-- New object with all letters in upper case
		ensure -- from READABLE_STRING_GENERAL
			as_upper_attached: Result /= Void
			length: Result.count = count
			anchor: count > 0 implies Result.item (1) = item (1).as_upper
			recurse: count > 1 implies Result.substring (2, count) ~ substring (2, count).as_upper

	center_justify
			-- Center justify Current using count as width.

	character_justify (pivot: CHARACTER_32; position: INTEGER_32)
			-- Justify a string based on a pivot
			-- and the position it needs to be in
			-- the final string.
			-- This will grow the string if necessary
			-- to get the pivot in the correct place.
		require
			valid_position: position <= capacity
			positive_position: position >= 1
			pivot_not_space: pivot /= ' '.to_character_32
			not_empty: not is_empty

	left_justify
			-- Left justify Current using count as witdth.

	linear_representation: LINEAR [CHARACTER_32]
			-- Representation as a linear structure

	mirror
			-- Reverse the order of characters.
			-- "Hello world" -> "dlrow olleH".
		ensure
			same_count: count = old count

	mirrored: like Current
			-- Mirror image of string;
			-- Result for "Hello world" is "dlrow olleH".
		ensure -- from READABLE_STRING_32
			same_count: Result.count = count

	right_justify
			-- Right justify Current using count as width.
		ensure
			same_count: count = old count

	split (a_separator: CHARACTER_32): LIST [STRING_32]
			-- Split on a_separator.
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
				Result /= Void

	to_boolean: BOOLEAN
			-- Boolean value;
			-- "True" yields True, "False" yields False
			-- (case-insensitive)
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_boolean: is_boolean
		ensure -- from READABLE_STRING_GENERAL
			to_boolean: (Result = as_lower.same_string_general (True_constant)) or (not Result = as_lower.same_string_general (False_constant))

	frozen to_c: ANY
			-- A reference to a C form of current string.
			-- Useful only for interfacing with C software.
		require
			not_is_dotnet: not {PLATFORM}.is_dotnet

	frozen to_cil: SYSTEM_STRING
			-- Create an instance of SYSTEM_STRING using characters
			-- of Current between indices 1 and count.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_dotnet: {PLATFORM}.is_dotnet
		ensure -- from READABLE_STRING_GENERAL
			to_cil_not_void: Result /= Void

	to_double: REAL_64
			-- "Double" value;
			-- for example, when applied to "123.0", will yield 123.0 (double)
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_real_64.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			represents_a_double: is_double

	to_integer: INTEGER_32
			-- 32-bit integer value
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_integer_32.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_integer: is_integer_32

	to_integer_16: INTEGER_16
			-- 16-bit integer value
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_integer_16: is_integer_16

	to_integer_32: INTEGER_32
			-- 32-bit integer value
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_integer.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_integer: is_integer_32

	to_integer_64: INTEGER_64
			-- 64-bit integer value
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_integer_64: is_integer_64

	to_integer_8: INTEGER_8
			-- 8-bit integer value
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_integer_8: is_integer_8

	to_lower
			-- Convert to lower case.
		ensure
			length_and_content: Elks_checking implies Current ~ (old as_lower)

	to_natural: NATURAL_32
			-- 32-bit natural value
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_natural_32.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_natural: is_natural_32

	to_natural_16: NATURAL_16
			-- 16-bit natural value
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_natural_16: is_natural_16

	to_natural_32: NATURAL_32
			-- 32-bit natural value
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_natural.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_natural: is_natural_32

	to_natural_64: NATURAL_64
			-- 64-bit natural value
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_natural_64: is_natural_64

	to_natural_8: NATURAL_8
			-- 8-bit natural value
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_natural_8: is_natural_8

	to_real: REAL_32
			-- Real value;
			-- for example, when applied to "123.0", will yield 123.0
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_real_32.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			represents_a_real: is_real

	to_real_32: REAL_32
			-- Real value;
			-- for example, when applied to "123.0", will yield 123.0
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_real.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			represents_a_real: is_real

	to_real_64: REAL_64
			-- "Double" value;
			-- for example, when applied to "123.0", will yield 123.0 (double)
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_double.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			represents_a_double: is_double

	to_string_32: STRING_32
			-- Convert Current as a STRING_32.
			-- Was declared in READABLE_STRING_GENERAL as synonym of as_string_32.
			-- (from READABLE_STRING_GENERAL)
		ensure -- from READABLE_STRING_GENERAL
			as_string_32_not_void: Result /= Void
			identity: (conforms_to (create {STRING_32}.make_empty) and Result = Current) or (not conforms_to (create {STRING_32}.make_empty) and Result /= Current)

	to_string_8: STRING_8
			-- Convert Current as a STRING_8.
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			is_valid_as_string_8: is_valid_as_string_8
		ensure -- from READABLE_STRING_GENERAL
			as_string_8_not_void: Result /= Void
			identity: (conforms_to ("") and Result = Current) or (not conforms_to ("") and Result /= Current)

	to_upper
			-- Convert to upper case.
		ensure
			length_and_content: Elks_checking implies Current ~ (old as_upper)
	
feature -- Duplication

	copy (other: STRING_32)
			-- Reinitialize by copying the characters of other.
			-- (This is also used by twin.)
			-- (from READABLE_STRING_32)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: Current ~ other
		ensure then -- from READABLE_STRING_32
			new_result_count: count = other.count

	frozen deep_copy (other: STRING_32)
			-- 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: STRING_32
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)

	head (n: INTEGER_32): STRING_32
			-- Prefix, retaining first n characters (or as many as available).
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			non_negative_argument: n >= 0
		ensure -- from READABLE_STRING_GENERAL
			same_count: count = old count
			new_count: Result.count = n.min (count)

	multiply (n: INTEGER_32)
			-- Duplicate a string within itself
			-- ("hello").multiply(3) => "hellohellohello"
		require
			meaningful_multiplier: n >= 1

	frozen standard_copy (other: STRING_32)
			-- 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: STRING_32
			-- 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)

	substring (start_index, end_index: INTEGER_32): like Current
			-- Copy of substring containing all characters at indices
			-- between start_index and end_index
		require -- from  READABLE_STRING_GENERAL
			True
		ensure -- from READABLE_STRING_GENERAL
			substring_not_void: Result /= Void
			substring_count: Result.count = end_index - start_index + 1 or Result.count = 0
			first_code: Result.count > 0 implies Result.item (1) = item (start_index)
			recurse: Result.count > 0 implies Result.substring (2, Result.count) ~ substring (start_index + 1, end_index)

	tail (n: INTEGER_32): STRING_32
			-- Suffix, retaining last n characters (or as many as available).
			-- (from READABLE_STRING_GENERAL)
		require -- from READABLE_STRING_GENERAL
			non_negative_argument: n >= 0
		ensure -- from READABLE_STRING_GENERAL
			same_count: count = old count
			new_count: Result.count = n.min (count)

	frozen twin: STRING_32
			-- 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 STRING_32
			-- 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

	plus alias "+" (s: READABLE_STRING_32): like Current
			-- Concatenation with s.
		require -- from READABLE_STRING_32
			argument_attached: attached s
		ensure -- from READABLE_STRING_32
			plus_attached: attached Result
			new_count: Result.count = count + s.count
			initial: Elks_checking implies Result.substring (1, count) ~ Current
			final: Elks_checking implies Result.substring (count + 1, count + s.count).same_string (s)

	plus_general (s: READABLE_STRING_GENERAL): like Current
			-- Concatenation of the current string with s.
		require -- from READABLE_STRING_GENERAL
			argument_not_void: s /= Void
			compatible_strings: Is_string_8 implies s.is_valid_as_string_8
		ensure -- from READABLE_STRING_GENERAL
			plus_not_void: Result /= Void
			new_count: Result.count = count + s.count
			initial: Elks_checking implies Result.substring (1, count) ~ Current
			final: Elks_checking implies Result.substring (count + 1, count + s.count).same_string_general (s)
	
feature -- Inapplicable

	bag_put (v: CHARACTER_32)
			-- Ensure that structure includes v.
			-- (from TABLE)
		require -- from COLLECTION
			extendible: Extendible
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
	
feature -- Access: Cursor

	new_character_32_cursor: STRING_ITERATION_CURSOR
			-- Fresh cursor for this string that iterates over code points (see code)
			-- exposed as CHARACTER_32.
			-- (from READABLE_STRING_GENERAL)
	
feature -- Correction

	Mismatch_information: MISMATCH_INFORMATION
			-- Original attribute values of mismatched object
			-- (from MISMATCH_CORRECTOR)
	
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
			-- Printable representation.
			-- (from READABLE_STRING_32)
		require -- from  ANY
			True
		ensure -- from ANY
			out_not_void: Result /= Void
		ensure then -- from READABLE_STRING_32
			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
	
invariant
	extendible: Extendible
	compare_character: not object_comparison

		-- from READABLE_STRING_32
	area_not_void: area /= Void

		-- from COMPARABLE
	irreflexive_comparison: not (Current < Current)

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from READABLE_INDEXABLE
	consistent_boundaries: Lower <= count or else Lower = count + 1

		-- from STRING_GENERAL
	mutable: not is_immutable

		-- from RESIZABLE
	increase_by_at_least_one: Minimal_increase >= 1

		-- from BOUNDED
	valid_count: count <= capacity
	full_definition: full = (count = capacity)

		-- from FINITE
	empty_definition: is_empty = (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 STRING_32