indexing
	description: "Common ancestors to all STRING classes."
	library: "Free implementation of ELKS library"
	copyright: "Copyright (c) 1986-2008, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see forum.txt)"
	date: "$Date: $"
	revision: "$Revision: $"

deferred class interface
	STRING_GENERAL


convert
	as_string_32: {STRING_32},
	to_cil: {SYSTEM_STRING}

feature -- Access

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

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void
			generating_type_not_empty: not Result.is_empty

	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 HASHABLE)
		ensure -- from HASHABLE
			good_hash_value: Result >= 0

	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)
	
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 (other /= Void and then 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))

	frozen is_deep_equal (other: STRING_GENERAL): 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_GENERAL): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object and identical to it?
			-- (from COMPARABLE)
		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: STRING_GENERAL): STRING_GENERAL
			-- 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: STRING_GENERAL): STRING_GENERAL
			-- 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

	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: STRING_GENERAL): 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: STRING_GENERAL): 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: STRING_GENERAL): BOOLEAN
			-- Is current object less than `other'?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			asymmetric: Result implies not (other < Current)

	infix "<=" (other: STRING_GENERAL): 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: STRING_GENERAL): 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: STRING_GENERAL): 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

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

	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

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

	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_empty: BOOLEAN
			-- Is structure empty?

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

	is_string_32: BOOLEAN
			-- Is `Current' a STRING_32?

	is_string_8: BOOLEAN
			-- Is `Current' a STRING_8?

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

	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: like code): BOOLEAN
			-- Is `v' a valid code for Current?

	valid_index (i: INTEGER_32): BOOLEAN
			-- Is `i' within the bounds of the string?
	
feature -- Element change

	append (s: STRING_GENERAL)
			-- Append a copy of `s' at end.
		require
			argument_not_void: s /= Void
			compatible_strings: is_string_8 implies s.is_valid_as_string_8
		ensure
			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)

	append_code (c: like code)
			-- Append `c' at end.
		require
			valid_code: valid_code (c)
		ensure then
			item_inserted: code (count) = c
			new_count: count = old count + 1
			stable_before: elks_checking implies substring (1, count - 1).is_equal (old twin)
	
feature -- Removal

	remove (i: INTEGER_32)
			-- Remove `i'-th character.
		require
			valid_index: valid_index (i)
		ensure
			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)
	
feature -- Resizing

	resize (newsize: INTEGER_32)
			-- Rearrange string so that it can accommodate
			-- at least `newsize' characters.
			-- Do not lose any previously entered character.
		require
			new_size_non_negative: newsize >= 0
	
feature -- Conversion

	as_string_32: STRING_32
			-- Convert `Current' as a STRING_32.
			-- Was declared in STRING_GENERAL as synonym of to_string_32.
		ensure
			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.
		ensure
			as_string_8_not_void: Result /= Void
			identity: (is_string_8 and Result = Current) or (not is_string_8 and Result /= Current)

	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_32: STRING_32
			-- Convert `Current' as a STRING_32.
			-- Was declared in STRING_GENERAL as synonym of as_string_32.
		ensure
			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.
		require
			is_valid_as_string_8: is_valid_as_string_8
		ensure
			as_string_8_not_void: Result /= Void
			identity: (is_string_8 and Result = Current) or (not is_string_8 and Result /= Current)
	
feature -- Duplication

	copy (other: STRING_GENERAL)
			-- Update current object using fields of object attached
			-- to `other', so as to yield equal objects.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)

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

	frozen standard_copy (other: STRING_GENERAL)
			-- 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_GENERAL
			-- 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'
		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.code (1) = code (start_index)
			recurse: Result.count > 0 implies Result.substring (2, Result.count).is_equal (substring (start_index + 1, end_index))

	frozen twin: STRING_GENERAL
			-- 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: ?STRING_GENERAL
			-- 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 -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		ensure -- from ANY
			io_not_void: Result /= Void

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		ensure -- from ANY
			out_not_void: Result /= Void

	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
			-- (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
			operating_environment_not_void: Result /= Void
	
feature -- Settings

	put_code (v: like code; i: INTEGER_32)
			-- Put code `v' at position `i'.
		require
			valid_code: valid_code (v)
			valid_index: valid_index (i)
		ensure
			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))
	
invariant
		-- from COMPARABLE
	irreflexive_comparison: not (Current < Current)

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

end -- class STRING_GENERAL