note
	description: "Common ancestors to all STRING classes. Read-only interface."
	library: "Free implementation of ELKS library"
	status: "See notice at end of class."
	legal: "See notice at end of class."
	date: "$Date: 2020-05-12 20:58:01 +0000 (Tue, 12 May 2020) $"
	revision: "$Revision: 104181 $"

deferred class interface
	READABLE_STRING_GENERAL

convert
	as_string_32: {READABLE_STRING_32,
		STRING_32}

feature -- Access

	code (i: INTEGER_32): NATURAL_32
			-- Code at position i
		require
			valid_index: valid_index (i)

	item alias "[]" (i: INTEGER_32): CHARACTER_32
			-- Character at position i.
		require
			valid_index: valid_index (i)

	index_of (c: like item; 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)

	last_index_of (c: like item; 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
			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)

	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.
		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_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)

	last_index_of_code (c: like code; 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
			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)

	False_constant: STRING_8 = "false"
			-- Constant string "false"

	True_constant: STRING_8 = "true"
			-- Constant string "true"

	hash_code: INTEGER_32
			-- Hash code value

	case_insensitive_hash_code: INTEGER_32
			-- Hash code value of the lower case version of Current.
		ensure
			consistent: Result = as_lower.case_insensitive_hash_code
	
feature -- Status report

	is_immutable: BOOLEAN
			-- Can the character sequence of Current be not changed?

	valid_index (i: INTEGER_32): BOOLEAN
			-- Is i within the bounds of the string?
		ensure
			definition: Result = (1 <= i and i <= count)

	valid_code (v: like code): BOOLEAN
			-- Is v a valid code for Current?

	is_string_8: BOOLEAN
			-- Is Current a sequence of CHARACTER_8?

	is_string_32: BOOLEAN
			-- Is Current a sequence of CHARACTER_32?

	is_valid_as_string_8: BOOLEAN
			-- Is Current convertible to a sequence of CHARACTER_8 without information loss?

	is_empty: BOOLEAN
			-- Is structure empty?

	is_whitespace: BOOLEAN
			-- Is structure containing only whitespace characters?

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

	has (c: like item): BOOLEAN
			-- Does string include c?
		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?
		ensure then
			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_number_sequence: BOOLEAN
			-- Does Current represent a number sequence?

	is_real_sequence: BOOLEAN
			-- Does Current represent a real sequence?

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

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

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

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

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

	is_integer_8: BOOLEAN
			-- Does Current represent an INTEGER_8?

	is_integer_16: BOOLEAN
			-- Does Current represent an INTEGER_16?

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

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

	is_integer_64: BOOLEAN
			-- Does Current represent an INTEGER_64?

	is_natural_8: BOOLEAN
			-- Does Current represent a NATURAL_8?

	is_natural_16: BOOLEAN
			-- Does Current represent a NATURAL_16?

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

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

	is_natural_64: BOOLEAN
			-- Does Current represent a NATURAL_64?
	
feature -- Measurement

	count: INTEGER_32
			-- Number of characters in Current
		ensure
			count_non_negative: Result >= 0

	capacity: INTEGER_32
			-- Number of characters allocated in Current
		ensure
			capacity_non_negative: Result >= 0

	occurrences (c: CHARACTER_32): INTEGER_32
			-- Number of times c appears in the string
		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

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

	same_caseless_characters (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.
		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)
		ensure
			same_characters: Result = substring (index_pos, index_pos + end_pos - start_pos).is_case_insensitive_equal (other.substring (start_pos, end_pos))

	has_substring (other: READABLE_STRING_GENERAL): 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))

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

	same_characters (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.
		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)
		ensure
			same_characters: Result = substring (index_pos, index_pos + end_pos - start_pos).same_string (other.substring (start_pos, end_pos))

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

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

	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.
		require
			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
			correct_place: Result > 0 implies other.same_string (substring (Result, Result + other.count - 1))

	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
		require
			other_not_void: other /= Void
			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)

	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
		require
			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
	
feature -- Conversion

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

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

	as_string_32: STRING_32
			-- Convert Current as a STRING_32.
			-- Was declared in READABLE_STRING_GENERAL as synonym of to_string_32.
		ensure
			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_32: STRING_32
			-- Convert Current as a STRING_32.
			-- Was declared in READABLE_STRING_GENERAL as synonym of as_string_32.
		ensure
			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_lower: like Current
			-- New object with all letters in lower case.
		ensure
			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_upper: like Current
			-- New object with all letters in upper case
		ensure
			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

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

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

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

	to_integer_32: INTEGER_32
			-- 32-bit integer value
			-- Was declared in READABLE_STRING_GENERAL 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_natural_8: NATURAL_8
			-- 8-bit natural value
		require
			is_natural_8: is_natural_8

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

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

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

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

	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.
		require
			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.
		require
			represents_a_real: is_real

	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.
		require
			represents_a_double: is_double

	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.
		require
			represents_a_double: is_double

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

	split (a_separator: CHARACTER_32): LIST [like Current]
			-- Split on a_separator.
		ensure
				Result /= Void
	
feature -- Duplication

	substring (start_index, end_index: INTEGER_32): like Current
			-- Copy of substring containing all characters at indices
			-- between start_index and end_index
		ensure
			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)

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

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

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