indexing
	description: "[
		Sequences of characters, accessible through integer indices
		in a contiguous range.
	]"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2006-08-09 17:26:02 -0700 (Wed, 09 Aug 2006) $"
	revision: "$Revision: 62378 $"

class interface
	STRING_32

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

	make_empty
			-- Create empty string.
		ensure
			empty: count = 0
			area_allocated: capacity >= 0

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

	make_from_string (s: STRING_32)
			-- Initialize from the characters of `s'.
			-- (Useful in proper descendants of class STRING_32,
			-- to initialize a string-like object from a manifest string.)
		require
			string_exists: s /= Void
		ensure
			not_shared_implementation: Current /= s implies not shared_with (s)
			initialized: same_string (s)

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

	make_from_cil (a_system_string: SYSTEM_STRING)
			-- Initialize Current with `a_system_string'.
		require
			is_dotnet: {PLATFORM}.is_dotnet

convert
	make_from_cil: {SYSTEM_STRING},
	make_from_cil ({SYSTEM_STRING}),
	make_from_cil: {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')

	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.
		require
			non_negative_size: n >= 0
		ensure
			empty_string: count = 0
			area_allocated: capacity >= n

	make_empty
			-- Create empty string.
		ensure
			empty: count = 0
			area_allocated: capacity >= 0

	make_filled (c: CHARACTER_32; n: INTEGER_32)
			-- Create string of length `n' filled with `c'.
		require
			valid_count: n >= 0
		ensure
			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
		require
			c_string_exists: c_string /= default_pointer

	make_from_cil (a_system_string: SYSTEM_STRING)
			-- Initialize Current with `a_system_string'.
		require
			is_dotnet: {PLATFORM}.is_dotnet

	make_from_string (s: STRING_32)
			-- Initialize from the characters of `s'.
			-- (Useful in proper descendants of class STRING_32,
			-- to initialize a string-like object from a manifest string.)
		require
			string_exists: s /= Void
		ensure
			not_shared_implementation: Current /= s implies not shared_with (s)
			initialized: same_string (s)
	
feature -- Access

	area: SPECIAL [CHARACTER_32]
			-- Special data zone
			-- (from TO_SPECIAL)

	code (i: INTEGER_32): NATURAL_32
			-- Numeric code of character at position `i'
		require -- from STRING_GENERAL
			valid_index: valid_index (i)

	false_constant: STRING_8 is "false"
			-- Constant string "false"

	fuzzy_index (other: STRING_32; 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
		require
			other_exists: other /= Void
			other_valid_string_8: other.is_valid_as_string_8
			other_not_empty: not other.is_empty
			start_large_enough: start >= 1
			start_small_enough: start <= count
			acceptable_fuzzy: fuzz <= other.count

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)

	hash_code: INTEGER_32
			-- Hash code value
		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.
		require
			start_large_enough: start_index >= 1
			start_small_enough: start_index <= count + 1
		ensure
			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 STRING_GENERAL)
		require -- from STRING_GENERAL
			start_large_enough: start_index >= 1
			start_small_enough: start_index <= count + 1
		ensure -- from 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 (i: INTEGER_32): CHARACTER_32 assign put
			-- Character at position `i'
			-- Was declared in STRING_32 as synonym of infix "@".
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TO_SPECIAL
			valid_index: valid_index (i)

	item_code (i: INTEGER_32): INTEGER_32
			-- Numeric code of character at position `i'
		require
			index_small_enough: i <= count
			index_large_enough: i > 0

	last_index_of (c: CHARACTER_32; start_index_from_end: INTEGER_32): INTEGER_32
			-- Position of last occurrence of `c'.
			-- 0 if none
		require
			start_index_small_enough: start_index_from_end <= count
			start_index_large_enough: start_index_from_end >= 1
		ensure
			last_index_of_non_negative: Result >= 0
			correct_place: Result > 0 implies item (Result) = c

	shared_with (other: STRING_32): BOOLEAN
			-- Does string share the text of `other'?

	string: STRING_32
			-- New STRING_32 having same character sequence as `Current'.
		ensure
			string_not_void: Result /= Void
			string_type: Result.same_type ("")
			first_item: count > 0 implies Result.item (1) = item (1)
			recurse: count > 1 implies Result.substring (2, count).is_equal (substring (2, count).string)

	substring_index (other: STRING_32; start_index: INTEGER_32): INTEGER_32
			-- Index of first occurrence of other at or after start_index;
			-- 0 if none
		require
			other_not_void: other /= Void
			other_valid_string_8: other.is_valid_as_string_8
			valid_start_index: start_index >= 1 and start_index <= count + 1
		ensure
			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: STRING_32; 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.
		require
			other_nonvoid: other /= Void
			other_valid_string_8: other.is_valid_as_string_8
			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
			correct_place: Result > 0 implies other.is_equal (substring (Result, Result + other.count - 1))

	true_constant: STRING_8 is "true"
			-- Constant string "true"

	infix "@" (i: INTEGER_32): CHARACTER_32 assign put
			-- Character at position `i'
			-- Was declared in STRING_32 as synonym of item.
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TO_SPECIAL
			valid_index: valid_index (i)
	
feature -- Measurement

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

	capacity: INTEGER_32
			-- Allocated space
		require -- from  BOUNDED
			True
		require -- from  STRING_GENERAL
			True
		ensure -- from STRING_GENERAL
			capacity_non_negative: Result >= 0

	count: INTEGER_32
			-- Actual number of characters making up the string

	growth_percentage: INTEGER_32 is 50
			-- Percentage by which structure will grow automatically
			-- (from RESIZABLE)

	index_set: INTEGER_INTERVAL
			-- Range of acceptable indexes
		require -- from  INDEXABLE
			True
		ensure -- from INDEXABLE
			not_void: Result /= Void
		ensure then
			Result.count = count

	minimal_increase: INTEGER_32 is 5
			-- Minimal number of additional items
			-- (from RESIZABLE)

	occurrences (c: CHARACTER_32): INTEGER_32
			-- Number of times `c' appears in the string
		require -- from  BAG
			True
		ensure -- from BAG
			non_negative_occurrences: Result >= 0
		ensure then
			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 (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies some.same_type (other)
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	is_case_insensitive_equal (other: like Current): BOOLEAN
			-- Is string made of same character sequence as `other' regardless of casing
			-- (possibly with a different capacity)?
		require
			is_valid_as_string_8: is_valid_as_string_8
			other_not_void: other /= Void
			other_is_valid_as_string_8: other.is_valid_as_string_8
		ensure
			symmetric: Result implies other.is_case_insensitive_equal (Current)
			consistent: standard_is_equal (other) implies Result
			valid_result: as_lower.is_equal (other.as_lower) implies Result

	is_equal (other: like Current): BOOLEAN
			-- Is string made of same character sequence as `other'
			-- (possibly with a different capacity)?
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other.is_equal (Current)
			consistent: standard_is_equal (other) implies Result
		ensure then -- from COMPARABLE
			trichotomy: Result = (not (Current < other) and not (other < Current))

	max (other: like Current): like Current
			-- 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 (other: like Current): like Current
			-- 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_string (other: STRING_32): BOOLEAN
			-- Do `Current' and `other' have same character sequence?
		require
			other_not_void: other /= Void
		ensure
			definition: Result = string.is_equal (other.string)

	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' 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
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: like Current): 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)

	three_way_comparison (other: like Current): 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) = is_equal (other)
			smaller_negative: (Result = -1) = (Current < other)
			greater_positive: (Result = 1) = (Current > other)

	infix "<" (other: like Current): BOOLEAN
			-- Is string lexicographically lower than `other'?
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			asymmetric: Result implies not (other < Current)

	infix "<=" (other: like Current): 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 is_equal (other))

	infix ">" (other: like Current): 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)

	infix ">=" (other: like Current): 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)
	
feature -- Status report

	changeable_comparison_criterion: BOOLEAN is False

	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

	extendible: BOOLEAN is True
			-- May new items be added? (Answer: yes.)

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

	has (c: CHARACTER_32): BOOLEAN
			-- Does string include `c'?
		require -- from  CONTAINER
			True
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty
		ensure then
			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))

	has_code (c: like code): BOOLEAN
			-- Does string include `c'?
			-- (from STRING_GENERAL)
		ensure then -- from 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))

	has_substring (other: STRING_32): BOOLEAN
			-- Does `Current' contain `other'?
		require
			other_not_void: other /= Void
		ensure
			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_boolean: BOOLEAN
			-- Does `Current' represent a BOOLEAN?
		ensure
			is_boolean: Result = (true_constant.same_string (as_lower.as_string_8) or false_constant.same_string (as_lower.as_string_8))

	is_double: BOOLEAN
			-- Does `Current' represent a DOUBLE?

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

	is_hashable: BOOLEAN
			-- May current object be hashed?
			-- (True if it is not its type's default.)
			-- (from HASHABLE)
		ensure -- from HASHABLE
			ok_if_not_default: Result implies (Current /= default)

	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?
			-- Was declared in STRING_32 as synonym of is_integer_32.

	is_integer_16: BOOLEAN
			-- Does `Current' represent an INTEGER_16?

	is_integer_32: BOOLEAN
			-- Does `Current' represent an INTEGER?
			-- Was declared in STRING_32 as synonym of is_integer.

	is_integer_64: BOOLEAN
			-- Does `Current' represent an INTEGER_64?

	is_integer_8: BOOLEAN
			-- Does `Current' represent an INTEGER_8?

	is_natural: BOOLEAN
			-- Does `Current' represent a NATURAL_32?
			-- Was declared in STRING_32 as synonym of is_natural_32.

	is_natural_16: BOOLEAN
			-- Does `Current' represent a NATURAL_16?

	is_natural_32: BOOLEAN
			-- Does `Current' represent a NATURAL_32?
			-- Was declared in STRING_32 as synonym of is_natural.

	is_natural_64: BOOLEAN
			-- Does `Current' represent a NATURAL_64?

	is_natural_8: BOOLEAN
			-- Does `Current' represent a NATURAL_8?

	is_number_sequence: BOOLEAN
			-- Does `Current' represent a number sequence?

	is_real: BOOLEAN
			-- Does `Current' represent a REAL?

	is_string_32: BOOLEAN is True
			-- Current is a STRING_32 instance

	is_string_8: BOOLEAN is False
			-- Current is not a STRING_8 instance

	is_valid_as_string_8: BOOLEAN
			-- Is `Current' convertible to STRING_8 without information loss?

	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.)

	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))

	valid_code (v: NATURAL_32): BOOLEAN
			-- Is `v' a valid code for a CHARACTER_32?

	valid_index (i: INTEGER_32): BOOLEAN
			-- Is `i' within the bounds of the string?
		require -- from  TABLE
			True
		require -- from  STRING_GENERAL
			True
		require -- from  TO_SPECIAL
			True
		ensure then -- from INDEXABLE
			only_if_in_index_set: Result implies ((i >= index_set.lower) and (i <= index_set.upper))
	
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

	append (s: STRING_32)
			-- Append a copy of `s' at end.
		require
			argument_not_void: s /= Void
		ensure
			new_count: count = old count + old s.count
			appended: elks_checking implies is_equal (old twin + old s.twin)

	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).is_equal (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).is_equal (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_real (r: REAL_32)
			-- Append the string representation of `r' at end.

	append_string (s: STRING_32)
			-- Append a copy of `s', if not void, at end.
		ensure
			appended: s /= Void implies (elks_checking implies is_equal (old twin + old s.twin))

	append_string_general (s: STRING_GENERAL)
			-- Append a copy 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 to_string_32.is_equal (old to_string_32.twin + old s.to_string_32.twin)

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

	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 -- from BAG
			one_more_occurrence: occurrences (c) = old (occurrences (c)) + 1
		ensure then
			item_inserted: item (count) = c
			new_count: count = old count + 1
			stable_before: elks_checking implies substring (1, count - 1).is_equal (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'.
		ensure
			filled: full
			same_size: (count = capacity) and (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).is_equal (old substring (1, i - 1))
			stable_after_i: elks_checking implies substring (i + 1, count).is_equal (old substring (i, count))

	insert_string (s: 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 (is_equal (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
			non_negative_argument: n >= 0
		ensure
			new_count: count = n.min (old count)
			kept: elks_checking implies is_equal (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
			non_negative_argument: n >= 0
		ensure
			new_count: count = n.min (old count)
			kept: elks_checking implies is_equal (old substring (count - n.min (count) + 1, count))

	left_adjust
			-- Remove leading whitespace.
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			valid_count: count <= old count
			new_count: not is_empty implies not item (1).is_space
			kept: elks_checking implies is_equal ((old twin).substring (old count - count + 1, old count))

	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: STRING_32)
			-- Prepend a copy of `s' at front.
		require
			argument_not_void: s /= Void
		ensure
			new_count: count = old (count + s.count)
			inserted: elks_checking implies string.is_equal (old (s.twin) + old substring (1, count))

	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: STRING_32)
			-- Prepend a copy of `s', if not void, at front.

	put (c: CHARACTER_32; i: INTEGER_32)
			-- Replace character at position `i' by `c'.
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TO_SPECIAL
			valid_index: valid_index (i)
		ensure then -- from INDEXABLE
			insertion_done: 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).is_equal (old substring (1, i - 1))
			stable_after_i: elks_checking implies substring (i + 1, count).is_equal (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).is_equal (old substring (1, i - 1))
			stable_after_i: elks_checking implies substring (i + 1, count).is_equal (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 (' ') = count

	replace_substring (s: 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 (is_equal (old (substring (1, start_index - 1) + s + substring (end_index + 1, count))))

	replace_substring_all (original, new: like Current)
			-- Replace every occurrence of `original' with `new'.
		require
			original_exists: original /= Void
			new_exists: new /= Void
			original_not_empty: not original.is_empty
			original_is_valid_as_string_8: original.is_valid_as_string_8

	right_adjust
			-- Remove trailing whitespace.
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			valid_count: count <= old count
			new_count: (count /= 0) implies ((item (count) /= ' ') and (item (count) /= '%T') and (item (count) /= '%R') and (item (count) /= '%N'))
			kept: elks_checking implies is_equal ((old twin).substring (1, count))

	set (t: like Current; 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: is_equal (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: like Current; 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 (is_equal (old substring (1, index_pos - 1) + old other.substring (start_pos, end_pos) + old substring (index_pos + (end_pos - start_pos + 1), count)))

	infix "+" (s: STRING_32): like Current
			-- Append a copy of 's' at the end of a copy of Current,
			-- Then return the Result.
		require
			argument_not_void: s /= Void
		ensure
			result_exists: Result /= Void
			new_count: Result.count = count + s.count
			initial: elks_checking implies Result.substring (1, count).is_equal (Current)
			final: elks_checking implies Result.substring (count + 1, count + s.count).same_string (s)
	
feature -- Removal

	clear_all
			-- Reset all characters.
		ensure
			is_empty: count = 0
			same_capacity: capacity = old capacity

	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)
		ensure -- from STRING_GENERAL
			new_count: count = old count - 1
			removed: elks_checking implies to_string_32.is_equal (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
			n_non_negative: n >= 0
		ensure
			removed: elks_checking implies is_equal (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
			valid_start_index: 1 <= start_index
			valid_end_index: end_index <= count
			meaningful_interval: start_index <= end_index + 1
		ensure
			removed: elks_checking implies is_equal (old substring (1, start_index - 1) + old substring (end_index + 1, count))

	remove_tail (n: INTEGER_32)
			-- Remove last `n' characters;
			-- if `n' > count, remove all.
		require
			n_non_negative: n >= 0
		ensure
			removed: elks_checking implies is_equal (old substring (1, count - n.min (count)))

	wipe_out
			-- Remove all characters.
		require -- from COLLECTION
			prunable: prunable
		ensure -- from COLLECTION
			wiped_out: is_empty
		ensure then
			is_empty: count = 0
			empty_capacity: capacity = 0
	
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)
		ensure -- from RESIZABLE
			increased_capacity: capacity >= old capacity + old capacity * growth_percentage // 100

	grow (newsize: INTEGER_32)
			-- Ensure that the capacity is at least `newsize'.
		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_non_negative: newsize >= 0
	
feature -- Conversion

	as_lower: like Current
			-- New object with all letters in lower case.
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			length: Result.count = count
			anchor: count > 0 implies Result.item (1) = item (1).as_lower
			recurse: count > 1 implies Result.substring (2, count).is_equal (substring (2, count).as_lower)

	as_string_32: STRING_32
			-- Convert `Current' as a STRING_32.
			-- Was declared in STRING_GENERAL as synonym of to_string_32.
			-- (from STRING_GENERAL)
		ensure -- from STRING_GENERAL
			as_string_32_not_void: Result /= Void
			identity: (is_string_32 and Result = Current) or (not is_string_32 and Result /= Current)

	as_string_8: STRING_8
			-- Convert `Current' as a STRING_8. If a code of `Current' is
			-- node a valid code for a STRING_8 it is replaced with the null
			-- character.
			-- (from STRING_GENERAL)
		ensure -- from STRING_GENERAL
			as_string_8_not_void: Result /= Void
			identity: (is_string_8 and Result = Current) or (not is_string_8 and Result /= Current)

	as_upper: like Current
			-- New object with all letters in upper case
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			length: Result.count = count
			anchor: count > 0 implies Result.item (1) = item (1).as_upper
			recurse: count > 1 implies Result.substring (2, count).is_equal (substring (2, count).as_upper)

	center_justify
			-- Center justify Current using count as width.
		require
			is_valid_as_string_8: is_valid_as_string_8

	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 /= ' '
			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
			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'.
		ensure
			Result /= Void

	to_boolean: BOOLEAN
			-- Boolean value;
			-- "True" yields `True', "False" yields `False'
			-- (case-insensitive)
		require
			is_boolean: is_boolean
		ensure
			to_boolean: (Result = true_constant.same_string (as_lower.as_string_8)) or (not Result = false_constant.same_string (as_lower.as_string_8))

	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 STRING_GENERAL)
		require -- from STRING_GENERAL
			is_dotnet: {PLATFORM}.is_dotnet
		ensure -- from 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)
		require
			represents_a_double: is_double

	to_integer: INTEGER_32
			-- 32-bit integer value
			-- Was declared in STRING_32 as synonym of to_integer_32.
		require
			is_integer: is_integer_32

	to_integer_16: INTEGER_16
			-- 16-bit integer value
		require
			is_integer_16: is_integer_16

	to_integer_32: INTEGER_32
			-- 32-bit integer value
			-- Was declared in STRING_32 as synonym of to_integer.
		require
			is_integer: is_integer_32

	to_integer_64: INTEGER_64
			-- 64-bit integer value
		require
			is_integer_64: is_integer_64

	to_integer_8: INTEGER_8
			-- 8-bit integer value
		require
			is_integer_8: is_integer_8

	to_lower
			-- Convert to lower case.
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			length_end_content: elks_checking implies is_equal (old as_lower)

	to_natural: NATURAL_32
			-- 32-bit natural value
			-- Was declared in STRING_32 as synonym of to_natural_32.
		require
			is_natural: is_natural

	to_natural_16: NATURAL_16
			-- 16-bit natural value
		require
			is_natural_16: is_natural_16

	to_natural_32: NATURAL_32
			-- 32-bit natural value
			-- Was declared in STRING_32 as synonym of to_natural.
		require
			is_natural: is_natural

	to_natural_64: NATURAL_64
			-- 64-bit natural value
		require
			is_natural_64: is_natural_64

	to_natural_8: NATURAL_8
			-- 8-bit natural value
		require
			is_natural_8: is_natural_8

	to_real: REAL_32
			-- Real value;
			-- for example, when applied to "123.0", will yield 123.0
		require
			represents_a_real: is_real

	to_string_32: STRING_32
			-- Convert `Current' as a STRING_32.
			-- Was declared in STRING_GENERAL as synonym of as_string_32.
			-- (from STRING_GENERAL)
		ensure -- from STRING_GENERAL
			as_string_32_not_void: Result /= Void
			identity: (is_string_32 and Result = Current) or (not is_string_32 and Result /= Current)

	to_string_8: STRING_8
			-- Convert `Current' as a STRING_8.
			-- (from STRING_GENERAL)
		require -- from STRING_GENERAL
			is_valid_as_string_8: is_valid_as_string_8
		ensure -- from STRING_GENERAL
			as_string_8_not_void: Result /= Void
			identity: (is_string_8 and Result = Current) or (not is_string_8 and Result /= Current)

	to_upper
			-- Convert to upper case.
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			length_end_content: elks_checking implies is_equal (old as_upper)
	
feature -- Duplication

	frozen deep_copy (other: like Current)
			-- 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: like Current
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_equal: deep_equal (Current, Result)

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

	frozen standard_copy (other: like Current)
			-- 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: like Current
			-- 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  STRING_GENERAL
			True
		ensure -- from STRING_GENERAL
			substring_not_void: Result /= Void
			substring_count: Result.count = end_index - start_index + 1 or Result.count = 0
			first_item: Result.count > 0 implies Result.code (1) = code (start_index)
			recurse: Result.count > 0 implies Result.substring (2, Result.count).is_equal (substring (start_index + 1, end_index))
		ensure then
			first_item: Result.count > 0 implies Result.item (1) = item (start_index)
			recurse: Result.count > 0 implies Result.substring (2, Result.count).is_equal (substring (start_index + 1, end_index))

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

	frozen default: like Current
			-- 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)

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

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
	
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)

	out: STRING_8
			-- Printable representation
		require -- from  ANY
			True
		ensure then
			out_not_void: Result /= Void
			same_items: same_type ("") implies Result.same_string (as_string_8)

	print (some: ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of out.
			-- (from ANY)
	
feature -- Platform

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
	
invariant
	extendible: extendible
	compare_character: not object_comparison
	index_set_has_same_count: index_set.count = count
	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 INDEXABLE
	index_set_not_void: index_set /= Void

		-- 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)
	non_negative_count: count >= 0

indexing
	library: "EiffelBase: Library of reusable components for Eiffel."
	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		356 Storke Road, 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