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Annex K
(informative)
LanguageDefined Attributes
1
{attribute} This
annex summarizes the definitions given elsewhere of the languagedefined
attributes.
2
 P'Access

For a prefix P that denotes a subprogram:
3
 P'Access yields an access value
that designates the subprogram denoted by P. The type of P'Access is
an accesstosubprogram type (S), as determined by the expected
type. See 3.10.2.
4
 X'Access

For a prefix X that denotes an aliased
view of an object:
5
 X'Access yields an access value
that designates the object denoted by X. The type of X'Access is an accesstoobject
type, as determined by the expected type. The expected type shall be
a general access type. See 3.10.2.
6/1
 X'Address

For a prefix
prefix
X that denotes an object, program unit, or label:
7
 Denotes the address of the first
of the storage elements allocated to X. For a program unit or label,
this value refers to the machine code associated with the corresponding
body or statement. The value of
this attribute is of type System.Address. See 13.3.
8
 S'Adjacent

For every subtype S of a floating point type T:
9
 S'Adjacent
denotes a function with the following specification:
10
function S'Adjacent (X, Towards : T)
return T
11
 {Constraint_Error
(raised by failure of runtime check)} If
Towards = X, the function yields X; otherwise,
it yields the machine number of the type T adjacent to X
in the direction of Towards, if that machine number exists. {Range_Check
[partial]} {check, languagedefined
(Range_Check)} If the result would be
outside the base range of S, Constraint_Error is raised. When T'Signed_Zeros
is True, a zero result has the sign of X. When Towards
is zero, its sign has no bearing on the result. See A.5.3.
12
 S'Aft

For every fixed point subtype S:
13
 S'Aft yields the number of decimal
digits needed after the decimal point to accommodate the delta
of the subtype S, unless the delta of the subtype S is greater
than 0.1, in which case the attribute yields the value one. (S'Aft is
the smallest positive integer N for which (10**N)*S'Delta is greater
than or equal to one.) The value of this attribute is of the type universal_integer.
See 3.5.10.
14/1
 X'Alignment

For a prefix
prefix
X that denotes a subtype or object:
15
 The Address of an object that
is allocated under control of the implementation is an integral multiple
of the Alignment of the object (that is, the Address modulo the Alignment
is zero). The offset of a record component is a multiple of the Alignment
of the component. For an object that is not allocated under control of
the implementation (that is, one that is imported, that is allocated
by a userdefined allocator, whose Address has been specified, or is
designated by an access value returned by an instance of Unchecked_Conversion),
the implementation may assume that the Address is an integral multiple
of its Alignment. The implementation shall not assume a stricter alignment.
16
 The value of this attribute
is of type universal_integer, and nonnegative; zero means that
the object is not necessarily aligned on a storage element boundary.
See 13.3.
17
 S'Base

For every scalar subtype S:
18
 S'Base denotes an unconstrained
subtype of the type of S. This unconstrained subtype is called the base
subtype of the type. See 3.5.
19
 S'Bit_Order

For every specific record subtype S:
20
 Denotes the bit ordering for
the type of S. The value of this attribute is of type System.Bit_Order.
See 13.5.3.
21/1
 P'Body_Version

For a prefix
prefix
P that statically denotes a program unit:
22
 Yields a value of the predefined
type String that identifies the version of the compilation unit that
contains the body (but not any subunits) of the program unit. See E.3.
23
 T'Callable

For a prefix T that is of a task
type (after any implicit dereference):
24
 Yields the value True when the
task denoted by T is callable, and False otherwise; See 9.9.
25
 E'Caller

For a prefix E that denotes an entry_declaration:
26
 Yields a value of the type Task_ID
that identifies the task whose call is now being serviced. Use of this
attribute is allowed only inside an entry_body
or accept_statement corresponding
to the entry_declaration denoted
by E. See C.7.1.
27
 S'Ceiling

For every subtype S of a floating point type T:
28
 S'Ceiling
denotes a function with the following specification:
29
function S'Ceiling (X : T)
return T
30
 The function yields the value
Ceiling(X), i.e., the smallest (most negative) integral
value greater than or equal to X. When X is zero, the result
has the sign of X; a zero result otherwise has a negative sign
when S'Signed_Zeros is True. See A.5.3.
31
 S'Class

For every subtype S of an untagged private type whose full view is tagged:
32
 Denotes the classwide subtype
corresponding to the full view of S. This attribute is allowed only from
the beginning of the private part in which the full view is declared,
until the declaration of the full view. After the full view, the Class
attribute of the full view can be used. See 7.3.1.
33
 S'Class

For every subtype S of a tagged type T (specific or classwide):
34
 S'Class denotes a subtype of
the classwide type (called T'Class in this International Standard)
for the class rooted at T (or if S already denotes a classwide
subtype, then S'Class is the same as S).
35
 {unconstrained
(subtype)} {constrained
(subtype)} S'Class is unconstrained. However,
if S is constrained, then the values of S'Class are only those that when
converted to the type T belong to S. See 3.9.
36/1
 X'Component_Size

For a prefix
prefix
X that denotes an array subtype or array object (after any implicit dereference):
37
 Denotes the size in bits of
components of the type of X. The value of this attribute is of type universal_integer.
See 13.3.
38
 S'Compose

For every subtype S of a floating point type T:
39
 S'Compose
denotes a function with the following specification:
40
function S'Compose (Fraction : T;
Exponent : universal_integer)
return T
41
 {Constraint_Error
(raised by failure of runtime check)} Let
v be the value Fraction · T'Machine_Radix^{Exponentk},
where k is the normalized exponent of Fraction. If v
is a machine number of the type T, or if v >= T'Model_Small,
the function yields v; otherwise, it yields either one of the
machine numbers of the type T adjacent to v. {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is optionally
raised if v is outside the base range of S. A zero result has
the sign of Fraction when S'Signed_Zeros is True. See A.5.3.
42
 A'Constrained

For a prefix A that is of a discriminated
type (after any implicit dereference):
43
 Yields the value True if A denotes
a constant, a value, or a constrained variable, and False otherwise.
See 3.7.2.
44
 S'Copy_Sign

For every subtype S of a floating point type T:
45
 S'Copy_Sign
denotes a function with the following specification:
46
function S'Copy_Sign (Value, Sign : T)
return T
47
 {Constraint_Error
(raised by failure of runtime check)} If
the value of Value is nonzero, the function yields a result whose
magnitude is that of Value and whose sign is that of Sign;
otherwise, it yields the value zero. {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is optionally
raised if the result is outside the base range of S. A zero result has
the sign of Sign when S'Signed_Zeros is True. See A.5.3.
48
 E'Count

For a prefix E that denotes an entry
of a task or protected unit:
49
 Yields the number of calls presently
queued on the entry E of the current instance of the unit. The value
of this attribute is of the type universal_integer. See 9.9.
50/1
 S'Definite

For a prefix
prefix
S that denotes a formal indefinite subtype:
51
 S'Definite yields True if the
actual subtype corresponding to S is definite; otherwise it yields False.
The value of this attribute is of the predefined type Boolean. See 12.5.1.
52
 S'Delta

For every fixed point subtype S:
53
 S'Delta denotes the delta
of the fixed point subtype S. The value of this attribute is of the type
universal_real. See 3.5.10.
54
 S'Denorm

For every subtype S of a floating point type T:
55
 Yields the value True if every
value expressible in the form
± mantissa · T'Machine_Radix^{T'Machine_Emin}
where mantissa is a nonzero T'Machine_Mantissadigit fraction
in the number base T'Machine_Radix, the first digit of which is
zero, is a machine number (see 3.5.7) of
the type T; yields the value False otherwise. The value of this
attribute is of the predefined type Boolean. See A.5.3.
56
 S'Digits

For every decimal fixed point subtype S:
57
 S'Digits denotes the digits
of the decimal fixed point subtype S, which corresponds to the number
of decimal digits that are representable in objects of the subtype. The
value of this attribute is of the type universal_integer. See
3.5.10.
58
 S'Digits

For every floating point subtype S:
59
 S'Digits denotes the requested
decimal precision for the subtype S. The value of this attribute is of
the type universal_integer. See 3.5.8.
60
 S'Exponent

For every subtype S of a floating point type T:
61
 S'Exponent
denotes a function with the following specification:
62
function S'Exponent (X : T)
return universal_integer
63
 The function yields the normalized
exponent of X. See A.5.3.
64
 S'External_Tag

For every subtype S of a tagged type T (specific or classwide):
65
 {External_Tag
clause} {specifiable
(of External_Tag for a tagged type) [partial]} S'External_Tag
denotes an external string representation for S'Tag; it is of the predefined
type String. External_Tag may be specified for a specific tagged type
via an attribute_definition_clause;
the expression of such a clause shall be static. The default external
tag representation is implementation defined. See 3.9.2
and 13.13.2. See 13.3.
66/1
 A'First

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
67
 A'First denotes the lower bound
of the first index range; its type is the corresponding index type. See
3.6.2.
68
 S'First

For every scalar subtype S:
69
 S'First denotes the lower bound
of the range of S. The value of this attribute is of the type of S. See
3.5.
70/1
 A'First(N)

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
71
 A'First(N) denotes the lower
bound of the Nth index range; its type is the corresponding index type.
See 3.6.2.
72
 R.C'First_Bit

For a component C of a composite, nonarray object R:
73
 Denotes the offset, from the
start of the first of the storage elements occupied by C, of the first
bit occupied by C. This offset is measured in bits. The first bit of
a storage element is numbered zero. The value of this attribute is of
the type universal_integer. See 13.5.2.
74
 S'Floor

For every subtype S of a floating point type T:
75
 S'Floor
denotes a function with the following specification:
76
function S'Floor (X : T)
return T
77
 The function yields the value
Floor(X), i.e., the largest (most positive) integral value
less than or equal to X. When X is zero, the result has
the sign of X; a zero result otherwise has a positive sign. See
A.5.3.
78
 S'Fore

For every fixed point subtype S:
79
 S'Fore yields the minimum number
of characters needed before the decimal point for the decimal representation
of any value of the subtype S, assuming that the representation does
not include an exponent, but includes a onecharacter prefix that is
either a minus sign or a space. (This minimum number does not include
superfluous zeros or underlines, and is at least 2.) The value of this
attribute is of the type universal_integer. See 3.5.10.
80
 S'Fraction

For every subtype S of a floating point type T:
81
 S'Fraction
denotes a function with the following specification:
82
function S'Fraction (X : T)
return T
83
 The function yields the value
X · T'Machine_Radix^{k},
where k is the normalized exponent of X. A zero result,
which can only occur when X is zero, has the sign of X.
See A.5.3.
84
 T'Identity

For a prefix T that is of a task
type (after any implicit dereference):
85
 Yields a value of the type Task_ID
that identifies the task denoted by T. See C.7.1.
86/1
 E'Identity

For a prefix
prefix
E that denotes an exception:
87
 E'Identity returns the unique
identity of the exception. The type of this attribute is Exception_Id.
See 11.4.1.
88
 S'Image

For every scalar subtype S:
89
 S'Image
denotes a function with the following specification:
90
function S'Image(Arg : S'Base)
return String
91
 The function returns an image
of the value of Arg as a String. See 3.5.
92
 S'Class'Input

For every subtype S'Class of a classwide type T'Class:
93
 S'Class'Input
denotes a function with the following specification:
94
function S'Class'Input(
Stream : access Ada.Streams.Root_Stream_Type'Class)
return T'Class
95
 First reads the external tag
from Stream and determines the corresponding internal tag (by
calling Tags.Internal_Tag(String'Input(Stream))  see 3.9)
and then dispatches to the subprogram denoted by the Input attribute
of the specific type identified by the internal tag; returns that result.
See 13.13.2.
96
 S'Input

For every subtype S of a specific type T:
97
 S'Input
denotes a function with the following specification:
98
function S'Input(
Stream : access Ada.Streams.Root_Stream_Type'Class)
return T
99
 S'Input reads and returns one
value from Stream, using any bounds or discriminants written by
a corresponding S'Output to determine how much to read. See 13.13.2.
100/1
 A'Last

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
101
 A'Last denotes the upper bound
of the first index range; its type is the corresponding index type. See
3.6.2.
102
 S'Last

For every scalar subtype S:
103
 S'Last denotes the upper bound
of the range of S. The value of this attribute is of the type of S. See
3.5.
104/1
 A'Last(N)

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
105
 A'Last(N) denotes the upper
bound of the Nth index range; its type is the corresponding index type.
See 3.6.2.
106
 R.C'Last_Bit

For a component C of a composite, nonarray object R:
107
 Denotes the offset, from the
start of the first of the storage elements occupied by C, of the last
bit occupied by C. This offset is measured in bits. The value of this
attribute is of the type universal_integer. See 13.5.2.
108
 S'Leading_Part

For every subtype S of a floating point type T:
109
 S'Leading_Part
denotes a function with the following specification:
110
function S'Leading_Part (X : T;
Radix_Digits : universal_integer)
return T
111
 Let v be the value T'Machine_Radix^{kRadix_Digits},
where k is the normalized exponent of X. The function yields
the value
112
 Floor(X/v)
· v, when X is nonnegative and Radix_Digits
is positive;
113
 Ceiling(X/v)
· v, when X is negative and Radix_Digits
is positive.
114
 {Constraint_Error
(raised by failure of runtime check)} {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is raised
when Radix_Digits is zero or negative. A zero result, which can
only occur when X is zero, has the sign of X. See A.5.3.
115/1
 A'Length

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
116
 A'Length denotes the number
of values of the first index range (zero for a null range); its type
is universal_integer. See 3.6.2.
117/1
 A'Length(N)

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
118
 A'Length(N) denotes the number
of values of the Nth index range (zero for a null range); its type is
universal_integer. See 3.6.2.
119
 S'Machine

For every subtype S of a floating point type T:
120
 S'Machine
denotes a function with the following specification:
121
function S'Machine (X : T)
return T
122
 {Constraint_Error
(raised by failure of runtime check)} If
X is a machine number of the type T, the function yields
X; otherwise, it yields the value obtained by rounding or truncating
X to either one of the adjacent machine numbers of the type T.
{Range_Check [partial]} {check,
languagedefined (Range_Check)} Constraint_Error
is raised if rounding or truncating X to the precision of the
machine numbers results in a value outside the base range of S. A zero
result has the sign of X when S'Signed_Zeros is True. See A.5.3.
123
 S'Machine_Emax

For every subtype S of a floating point type T:
124
 Yields the largest (most positive)
value of exponent such that every value expressible in the canonical
form (for the type T), having a mantissa of T'Machine_Mantissa
digits, is a machine number (see 3.5.7) of
the type T. This attribute yields a value of the type universal_integer.
See A.5.3.
125
 S'Machine_Emin

For every subtype S of a floating point type T:
126
 Yields the smallest (most negative)
value of exponent such that every value expressible in the canonical
form (for the type T), having a mantissa of T'Machine_Mantissa
digits, is a machine number (see 3.5.7) of
the type T. This attribute yields a value of the type universal_integer.
See A.5.3.
127
 S'Machine_Mantissa

For every subtype S of a floating point type T:
128
 Yields the largest value of
p such that every value expressible in the canonical form (for
the type T), having a pdigit mantissa and an exponent
between T'Machine_Emin and T'Machine_Emax, is a machine
number (see 3.5.7) of the type T.
This attribute yields a value of the type universal_integer. See
A.5.3.
129
 S'Machine_Overflows

For every subtype S of a fixed point type T:
130
 Yields the value True if overflow
and dividebyzero are detected and reported by raising Constraint_Error
for every predefined operation that yields a result of the type T;
yields the value False otherwise. The value of this attribute is of the
predefined type Boolean. See A.5.4.
131
 S'Machine_Overflows

For every subtype S of a floating point type T:
132
 Yields the value True if overflow
and dividebyzero are detected and reported by raising Constraint_Error
for every predefined operation that yields a result of the type T;
yields the value False otherwise. The value of this attribute is of the
predefined type Boolean. See A.5.3.
133
 S'Machine_Radix

For every subtype S of a fixed point type T:
134
 Yields the radix of the hardware
representation of the type T. The value of this attribute is of
the type universal_integer. See A.5.4.
135
 S'Machine_Radix

For every subtype S of a floating point type T:
136
 Yields the radix of the hardware
representation of the type T. The value of this attribute is of
the type universal_integer. See A.5.3.
137
 S'Machine_Rounds

For every subtype S of a fixed point type T:
138
 Yields the value True if rounding
is performed on inexact results of every predefined operation that yields
a result of the type T; yields the value False otherwise. The
value of this attribute is of the predefined type Boolean. See A.5.4.
139
 S'Machine_Rounds

For every subtype S of a floating point type T:
140
 Yields the value True if rounding
is performed on inexact results of every predefined operation that yields
a result of the type T; yields the value False otherwise. The
value of this attribute is of the predefined type Boolean. See A.5.3.
141
 S'Max

For every scalar subtype S:
142
 S'Max
denotes a function with the following specification:
143
function S'Max(Left, Right : S'Base)
return S'Base
144
 The function returns the greater
of the values of the two parameters. See 3.5.
145
 S'Max_Size_In_Storage_Elements

For every subtype S:
146
 Denotes the maximum value for
Size_In_Storage_Elements that will be requested via Allocate for an access
type whose designated subtype is S. The value of this attribute is of
type universal_integer. See 13.11.1.
147
 S'Min

For every scalar subtype S:
148
 S'Min
denotes a function with the following specification:
149
function S'Min(Left, Right : S'Base)
return S'Base
150
 The function returns the lesser
of the values of the two parameters. See 3.5.
151
 S'Model

For every subtype S of a floating point type T:
152
 S'Model
denotes a function with the following specification:
153
function S'Model (X : T)
return T
154
 If the Numerics Annex is not
supported, the meaning of this attribute is implementation defined; see
G.2.2 for the definition that applies to
implementations supporting the Numerics Annex. See A.5.3.
155
 S'Model_Emin

For every subtype S of a floating point type T:
156
 If the Numerics Annex is not
supported, this attribute yields an implementation defined value that
is greater than or equal to the value of T'Machine_Emin. See G.2.2
for further requirements that apply to implementations supporting the
Numerics Annex. The value of this attribute is of the type universal_integer.
See A.5.3.
157
 S'Model_Epsilon

For every subtype S of a floating point type T:
158
 Yields the value T'Machine_Radix^{1
 T'Model_Mantissa}. The value of this attribute
is of the type universal_real. See A.5.3.
159
 S'Model_Mantissa

For every subtype S of a floating point type T:
160
 If the Numerics Annex is not
supported, this attribute yields an implementation defined value that
is greater than or equal to Ceiling(d · log(10)
/ log(T'Machine_Radix)) + 1, where d is the requested decimal
precision of T, and less than or equal to the value of T'Machine_Mantissa.
See G.2.2 for further requirements that apply
to implementations supporting the Numerics Annex. The value of this attribute
is of the type universal_integer. See A.5.3.
161
 S'Model_Small

For every subtype S of a floating point type T:
162
 Yields the value T'Machine_Radix^{T'Model_Emin
 1}. The value of this attribute is of the type universal_real.
See A.5.3.
163
 S'Modulus

For every modular subtype S:
164
 S'Modulus yields the modulus
of the type of S, as a value of the type universal_integer. See
3.5.4.
165
 S'Class'Output

For every subtype S'Class of a classwide type T'Class:
166
 S'Class'Output
denotes a procedure with the following specification:
167
procedure S'Class'Output(
Stream : access Ada.Streams.Root_Stream_Type'Class;
Item : in T'Class)
168
 First writes the external tag
of Item to Stream (by calling String'Output(Tags.External_Tag(Item'Tag)
 see 3.9) and then dispatches to the subprogram
denoted by the Output attribute of the specific type identified by the
tag. See 13.13.2.
169
 S'Output

For every subtype S of a specific type T:
170
 S'Output
denotes a procedure with the following specification:
171
procedure S'Output(
Stream : access Ada.Streams.Root_Stream_Type'Class;
Item : in T)
172
 S'Output writes the value of
Item to Stream, including any bounds or discriminants.
See 13.13.2.
173/1
 D'Partition_ID

For a prefix
prefix
D that denotes a librarylevel declaration, excepting a declaration of
or within a declaredpure library unit:
174
 Denotes a value of the type
universal_integer that identifies the partition in which D was
elaborated. If D denotes the declaration of a remote call interface library
unit (see E.2.3) the given partition is the
one where the body of D was elaborated. See E.1.
175
 S'Pos

For every discrete subtype S:
176
 S'Pos
denotes a function with the following specification:
177
function S'Pos(Arg : S'Base)
return universal_integer
178
 This function returns the position
number of the value of Arg, as a value of type universal_integer.
See 3.5.5.
179
 R.C'Position

For a component C of a composite, nonarray object R:
180
 Denotes the same value as R.C'Address
 R'Address. The value of this attribute is of the type universal_integer.
See 13.5.2.
181
 S'Pred

For every scalar subtype S:
182
 S'Pred
denotes a function with the following specification:
183
function S'Pred(Arg : S'Base)
return S'Base
184
 {Constraint_Error
(raised by failure of runtime check)} For
an enumeration type, the function returns the value whose position number
is one less than that of the value of Arg; {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is raised
if there is no such value of the type. For an integer type, the function
returns the result of subtracting one from the value of Arg. For
a fixed point type, the function returns the result of subtracting small
from the value of Arg. For a floating point type, the function
returns the machine number (as defined in 3.5.7)
immediately below the value of Arg; {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is raised
if there is no such machine number. See 3.5.
185/1
 A'Range

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
186
 A'Range is equivalent to the
range A'First .. A'Last, except that the prefix
A is only evaluated once. See 3.6.2.
187
 S'Range

For every scalar subtype S:
188
 S'Range is equivalent to the
range S'First .. S'Last. See 3.5.
189/1
 A'Range(N)

For a prefix
prefix
A that is of an array type (after any implicit dereference), or denotes
a constrained array subtype:
190
 A'Range(N) is equivalent to
the range A'First(N) .. A'Last(N), except that the prefix
A is only evaluated once. See 3.6.2.
191
 S'Class'Read

For every subtype S'Class of a classwide type T'Class:
192
 S'Class'Read
denotes a procedure with the following specification:
193
procedure S'Class'Read(
Stream : access Ada.Streams.Root_Stream_Type'Class;
Item : out T'Class)
194
 Dispatches to the subprogram
denoted by the Read attribute of the specific type identified by the
tag of Item. See 13.13.2.
195
 S'Read

For every subtype S of a specific type T:
196
 S'Read
denotes a procedure with the following specification:
197
procedure S'Read(
Stream : access Ada.Streams.Root_Stream_Type'Class;
Item : out T)
198
 S'Read reads the value of Item
from Stream. See 13.13.2.
199
 S'Remainder

For every subtype S of a floating point type T:
200
 S'Remainder
denotes a function with the following specification:
201
function S'Remainder (X, Y : T)
return T
202
 {Constraint_Error
(raised by failure of runtime check)} For
nonzero Y, let v be the value X  n ·
Y, where n is the integer nearest to the exact value of
X/Y; if n  X/Y = 1/2, then
n is chosen to be even. If v is a machine number of the
type T, the function yields v; otherwise, it yields zero.
{Division_Check [partial]} {check,
languagedefined (Division_Check)} Constraint_Error
is raised if Y is zero. A zero result has the sign of X
when S'Signed_Zeros is True. See A.5.3.
203
 S'Round

For every decimal fixed point subtype S:
204
 S'Round
denotes a function with the following specification:
205
function S'Round(X : universal_real)
return S'Base
206
 The function returns the value
obtained by rounding X (away from 0, if X is midway between two values
of the type of S). See 3.5.10.
207
 S'Rounding

For every subtype S of a floating point type T:
208
 S'Rounding
denotes a function with the following specification:
209
function S'Rounding (X : T)
return T
210
 The function yields the integral
value nearest to X, rounding away from zero if X lies exactly
halfway between two integers. A zero result has the sign of X
when S'Signed_Zeros is True. See A.5.3.
211
 S'Safe_First

For every subtype S of a floating point type T:
212
 Yields the lower bound of the
safe range (see 3.5.7) of the type T.
If the Numerics Annex is not supported, the value of this attribute is
implementation defined; see G.2.2 for the
definition that applies to implementations supporting the Numerics Annex.
The value of this attribute is of the type universal_real. See
A.5.3.
213
 S'Safe_Last

For every subtype S of a floating point type T:
214
 Yields the upper bound of the
safe range (see 3.5.7) of the type T.
If the Numerics Annex is not supported, the value of this attribute is
implementation defined; see G.2.2 for the
definition that applies to implementations supporting the Numerics Annex.
The value of this attribute is of the type universal_real. See
A.5.3.
215
 S'Scale

For every decimal fixed point subtype S:
216
 S'Scale denotes the scale
of the subtype S, defined as the value N such that S'Delta = 10.0**(N).
{scale (of a decimal fixed point subtype)}
The scale indicates the position of the point relative
to the rightmost significant digits of values of subtype S. The value
of this attribute is of the type universal_integer. See 3.5.10.
217
 S'Scaling

For every subtype S of a floating point type T:
218
 S'Scaling
denotes a function with the following specification:
219
function S'Scaling (X : T;
Adjustment : universal_integer)
return T
220
 {Constraint_Error
(raised by failure of runtime check)} Let
v be the value X · T'Machine_Radix^{Adjustment}.
If v is a machine number of the type T, or if v
>= T'Model_Small, the function yields v; otherwise, it
yields either one of the machine numbers of the type T adjacent
to v. {Range_Check [partial]} {check,
languagedefined (Range_Check)} Constraint_Error
is optionally raised if v is outside the base range of S. A zero
result has the sign of X when S'Signed_Zeros is True. See A.5.3.
221
 S'Signed_Zeros

For every subtype S of a floating point type T:
222
 Yields the value True if the
hardware representation for the type T has the capability of representing
both positively and negatively signed zeros, these being generated and
used by the predefined operations of the type T as specified in
IEC 559:1989; yields the value False otherwise. The value of this attribute
is of the predefined type Boolean. See A.5.3.
223
 S'Size

For every subtype S:
224
 If
S is definite, denotes the size (in bits) that the implementation would
choose for the following objects of subtype S:
225
 A record component of subtype
S when the record type is packed.
226
 The formal parameter of an
instance of Unchecked_Conversion that converts from subtype S to some
other subtype.
227
 If S is indefinite, the meaning
is implementation defined. The value of this attribute is of the type
universal_integer. See 13.3.
228/1
 X'Size

For a prefix
prefix
X that denotes an object:
229
 Denotes the size in bits of
the representation of the object. The value of this attribute is of the
type universal_integer. See 13.3.
230
 S'Small

For every fixed point subtype S:
231
 S'Small denotes the small
of the type of S. The value of this attribute is of the type universal_real.
See 3.5.10.
232
 S'Storage_Pool

For every access subtype S:
233
 Denotes the storage pool of
the type of S. The type of this attribute is Root_Storage_Pool'Class.
See 13.11.
234
 S'Storage_Size

For every access subtype S:
235
 Yields the result of calling
Storage_Size(S'Storage_Pool), which is intended to be a measure of the
number of storage elements reserved for the pool. The type of this attribute
is universal_integer. See 13.11.
236/1
 T'Storage_Size

For a prefix
prefix
T that denotes a task object (after any implicit dereference):
237
 Denotes the number of storage
elements reserved for the task. The value of this attribute is of the
type universal_integer. The Storage_Size includes the size of
the task's stack, if any. The language does not specify whether or not
it includes other storage associated with the task (such as the ``task
control block'' used by some implementations.) See 13.3.
238
 S'Succ

For every scalar subtype S:
239
 S'Succ
denotes a function with the following specification:
240
function S'Succ(Arg : S'Base)
return S'Base
241
 {Constraint_Error
(raised by failure of runtime check)} For
an enumeration type, the function returns the value whose position number
is one more than that of the value of Arg; {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is raised
if there is no such value of the type. For an integer type, the function
returns the result of adding one to the value of Arg. For a fixed
point type, the function returns the result of adding small to
the value of Arg. For a floating point type, the function returns
the machine number (as defined in 3.5.7)
immediately above the value of Arg; {Range_Check
[partial]} {check, languagedefined
(Range_Check)} Constraint_Error is raised
if there is no such machine number. See 3.5.
242
 X'Tag

For a prefix X that is of a classwide
tagged type (after any implicit dereference):
243
 X'Tag denotes the tag of X.
The value of this attribute is of type Tag. See 3.9.
244
 S'Tag

For every subtype S of a tagged type T (specific or classwide):
245
 S'Tag denotes the tag of the
type T (or if T is classwide, the tag of the root type
of the corresponding class). The value of this attribute is of type Tag.
See 3.9.
246
 T'Terminated

For a prefix T that is of a task
type (after any implicit dereference):
247
 Yields the value True if the
task denoted by T is terminated, and False otherwise. The value of this
attribute is of the predefined type Boolean. See 9.9.
248
 S'Truncation

For every subtype S of a floating point type T:
249
 S'Truncation
denotes a function with the following specification:
250
function S'Truncation (X : T)
return T
251
 The function yields the value
Ceiling(X) when X is negative, and Floor(X)
otherwise. A zero result has the sign of X when S'Signed_Zeros
is True. See A.5.3.
252
 S'Unbiased_Rounding

For every subtype S of a floating point type T:
253
 S'Unbiased_Rounding
denotes a function with the following specification:
254
function S'Unbiased_Rounding (X : T)
return T
255
 The function yields the integral
value nearest to X, rounding toward the even integer if X
lies exactly halfway between two integers. A zero result has the sign
of X when S'Signed_Zeros is True. See A.5.3.
256
 X'Unchecked_Access

For a prefix X that denotes an aliased
view of an object:
257
 All rules and semantics that
apply to X'Access (see 3.10.2) apply also
to X'Unchecked_Access, except that, for the purposes of accessibility
rules and checks, it is as if X were declared immediately within a library
package. See 13.10.
258
 S'Val

For every discrete subtype S:
259
 S'Val
denotes a function with the following specification:
260
function S'Val(Arg : universal_integer)
return S'Base
261
 {evaluation
(Val) [partial]} {Constraint_Error
(raised by failure of runtime check)} This
function returns a value of the type of S whose position number equals
the value of Arg. See 3.5.5.
262
 X'Valid

For a prefix X that denotes a scalar
object (after any implicit dereference):
263
 Yields True if and only if the
object denoted by X is normal and has a valid representation. The value
of this attribute is of the predefined type Boolean. See 13.9.2.
264
 S'Value

For every scalar subtype S:
265
 S'Value
denotes a function with the following specification:
266
function S'Value(Arg : String)
return S'Base
267
 This function returns a value
given an image of the value as a String, ignoring any leading or trailing
spaces. See 3.5.
268/1
 P'Version

For a prefix
prefix
P that statically denotes a program unit:
269
 Yields a value of the predefined
type String that identifies the version of the compilation unit that
contains the declaration of the program unit. See E.3.
270
 S'Wide_Image

For every scalar subtype S:
271
 S'Wide_Image
denotes a function with the following specification:
272
function S'Wide_Image(Arg : S'Base)
return Wide_String
273
 {image (of
a value)} The function returns an image
of the value of Arg, that is, a sequence of characters representing
the value in display form. See 3.5.
274
 S'Wide_Value

For every scalar subtype S:
275
 S'Wide_Value
denotes a function with the following specification:
276
function S'Wide_Value(Arg : Wide_String)
return S'Base
277
 This function returns a value
given an image of the value as a Wide_String, ignoring any leading or
trailing spaces. See 3.5.
278
 S'Wide_Width

For every scalar subtype S:
279
 S'Wide_Width denotes the maximum
length of a Wide_String returned by S'Wide_Image over all values of the
subtype S. It denotes zero for a subtype that has a null range. Its type
is universal_integer. See 3.5.
280
 S'Width

For every scalar subtype S:
281
 S'Width denotes the maximum
length of a String returned by S'Image over all values of the subtype
S. It denotes zero for a subtype that has a null range. Its type is universal_integer.
See 3.5.
282
 S'Class'Write

For every subtype S'Class of a classwide type T'Class:
283
 S'Class'Write
denotes a procedure with the following specification:
284
procedure S'Class'Write(
Stream : access Ada.Streams.Root_Stream_Type'Class;
Item : in T'Class)
285
 Dispatches to the subprogram
denoted by the Write attribute of the specific type identified by the
tag of Item. See 13.13.2.
286
 S'Write

For every subtype S of a specific type T:
287
 S'Write
denotes a procedure with the following specification:
288
procedure S'Write(
Stream : access Ada.Streams.Root_Stream_Type'Class;
Item : in T)
289
 S'Write writes the value of
Item to Stream. See 13.13.2.
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