EiffelBase class
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Eiffel Class
indexing
description: "Bit sequences of length `count%', with binary operations";
status: "See notice at end of class";
date: "$Date: 2007-03-30 19:10:11 +0000 (Fri, 30 Mar 2007) $";
revision: "$Revision: 95354 $"
class BIT_REF
inherit
ANY
redefine
c_standard_is_equal, c_standard_copy, c_standard_clone, out, generator, conforms_to
end
feature -- Access
item (i: INTEGER): BOOLEAN is
-- i-th bit
-- Was declared in BIT_REF as synonym of item and @.
require
index_large_enough: i >= 1;
index_small_enough: i <= count
do
Result := b_item ($Current, i)
end;
infix "@" (i: INTEGER): BOOLEAN is
-- i-th bit
-- Was declared in BIT_REF as synonym of item and @.
require
index_large_enough: i >= 1;
index_small_enough: i <= count
do
Result := b_item ($Current, i)
end;
generator: STRING is
-- Name of the current object's generating class.
do
create Result.make (10);
Result.append ("BIT ");
Result.append_integer (count)
end;
conforms_to (other: BIT_REF): BOOLEAN is
-- Is dynamic type of current object a descendant of
-- dynamic type of other?
do
Result := count <= other.count
end;
feature -- Measurement
count: INTEGER is
-- Size of the current bit object
do
Result := b_count ($Current)
end;
feature -- Element change
put (value: BOOLEAN; i: INTEGER) is
-- Set the i-th bit to 1 if value is True, 0 if False
require
index_large_enough: i >= 1;
index_small_enough: i <= count
do
b_put ($Current, value, i)
ensure
value_inserted: item (i) = value
end;
feature -- Basic operations
infix "^" (s: INTEGER): like Current is
-- Result of shifting bit sequence by s positions
-- (Positive s shifts right, negative s shifts left;
-- bits falling off the sequence's bounds are lost.)
do
Result := b_shift ($Current, s)
end;
infix "#" (s: INTEGER): like Current is
-- Result of rotating bit sequence by s positions
-- (Positive s rotates right, negative s rotates left.)
do
Result := b_rotate ($Current, s)
end;
infix "and" (other: BIT_REF): BIT_REF is
-- Bit-by-bit boolean conjunction with other
require
other_exists: other /= void;
conformance: other.count <= count
do
Result := b_and ($Current, $other)
end;
infix "implies" (other: BIT_REF): BIT_REF is
-- Bit-by-bit boolean implication of other
require
other_exists: other /= void;
conformance: other.count <= count
do
Result := b_implies ($Current, $other)
end;
infix "or" (other: BIT_REF): BIT_REF is
-- Bit-by-bi boolean disjunction with other
require
other_exists: other /= void;
conformance: other.count <= count
do
Result := b_or ($Current, $other)
end;
infix "xor" (other: BIT_REF): BIT_REF is
-- Bit-by-bit exclusive or with other
require
other_exists: other /= void;
conformance: other.count <= count
do
Result := b_xor ($Current, $other)
end;
prefix "not": like Current is
-- Bit-by-bit negation
do
Result := b_not ($Current)
end;
feature -- Output
out: STRING is
-- Tagged printable representation.
do
Result := c_out ($Current)
end;
feature {NONE} -- Implementation
b_item (a_bit: POINTER; index: INTEGER): BOOLEAN is
-- Boolean item at position i in a_bit
external
"C | %"eif_bits.h%""
end;
b_count (a_bit: POINTER): INTEGER is
-- Size of a_bit
external
"C | %"eif_bits.h%""
end;
c_standard_is_equal (target, source: POINTER): BOOLEAN is
-- C external performing standard equality
external
"C | %"eif_bits.h%""
alias
"b_equal"
end;
b_shift (a_bit: POINTER; s: INTEGER): BIT_REF is
-- Result of shifting a_bit by s positions
external
"C | %"eif_bits.h%""
end;
b_rotate (a_bit: POINTER; s: INTEGER): BIT_REF is
-- Result of rotating a_bit by s positions
external
"C | %"eif_bits.h%""
end;
b_and (a_bit1, a_bit2: POINTER): BIT_REF is
-- Conjunction of a_bit1 with a_bit2
external
"C | %"eif_bits.h%""
end;
b_implies (a_bit1, a_bit2: POINTER): BIT_REF is
-- Implication for a_bit1 of a_bit2
external
"C | %"eif_bits.h%""
end;
b_or (a_bit1, a_bit2: POINTER): BIT_REF is
-- Disjunction of a_bit1 with a_bit2
external
"C | %"eif_bits.h%""
end;
b_xor (a_bit1, a_bit2: POINTER): BIT_REF is
-- Exclusive or of a_bit1 with a_bit2
external
"C | %"eif_bits.h%""
end;
b_not (a_bit: POINTER): BIT_REF is
-- Negation of a_bit
external
"C | %"eif_bits.h%""
end;
c_standard_copy (source, target: POINTER) is
-- Copy of bit sequence
external
"C | %"eif_bits.h%""
alias
"b_copy"
end;
c_standard_clone (other: POINTER): BIT_REF is
-- New object of same dynamic type as other
external
"C | %"eif_bits.h%""
alias
"b_clone"
end;
b_put (a_bit: POINTER; val: BOOLEAN; index: INTEGER) is
-- Put val in a_bit at position index.
external
"C | %"eif_bits.h%""
end;
c_out (b: POINTER): STRING is
-- Out representation of Current
external
"C | %"eif_bits.h%""
alias
"b_eout"
end;
end -- class BIT_REF
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