Annex K
(informative)
Language-Defined Attributes
1 {attribute} This annex summarizes the definitions given elsewhere of the
language-defined 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 access-to-subprogram
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 access-to-object
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 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 run-time 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, language-defined (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.
13.1/2 S'Alignment
For every subtype S:
13.2/2 The value of this attribute is of type universal_integer, and
nonnegative.
13.3/2 For an object X of subtype S, if S'Alignment is not zero, then
X'Alignment is a nonzero integral multiple of S'Alignment
unless specified otherwise by a representation item. See
13.3.
14/1 X'Alignment
For a prefix X that denotes an object:
15 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. If X'Alignment is not
zero, then X is aligned on a storage unit boundary and
X'Address is an integral multiple of X'Alignment (that is, the
Address modulo the Alignment is zero).
16/2 This paragraph was deleted. 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 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 a tagged type T (specific or
class-wide):
32 S'Class denotes a subtype of the class-wide type (called
T'Class in this International Standard) for the class rooted
at T (or if S already denotes a class-wide subtype, then
S'Class is the same as S).
33 {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.
34 S'Class For every subtype S of an untagged private type whose full
view is tagged:
35 Denotes the class-wide 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.
36/1 X'Component_Size
For a 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 run-time check)} Let v
be the value Fraction · T'Machine_Radix(Exponent-k), 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, language-defined (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 run-time 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, language-defined (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 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_Mantissa-digit 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 floating point subtype S:
57 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.
58 S'Digits For every decimal fixed point subtype S:
59 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.
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
class-wide):
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 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 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 N-th index range;
its type is the corresponding index type. See 3.6.2.
71.1/2 R.C'First_Bit
For a component C of a composite, non-array object R:
71.2/2 If the nondefault bit ordering applies to the composite type,
and if a component_clause specifies the placement of C,
denotes the value given for the first_bit of the
component_clause; otherwise, 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.
72 S'Floor For every subtype S of a floating point type T:
73 S'Floor denotes a function with the following specification:
74 function S'Floor (X : T)
return T
75 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.
76 S'Fore For every fixed point subtype S:
77 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 one-character 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.
78 S'Fraction For every subtype S of a floating point type T:
79 S'Fraction denotes a function with the following
specification:
80 function S'Fraction (X : T)
return T
81 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.
82/1 E'Identity For a prefix E that denotes an exception:
83 E'Identity returns the unique identity of the exception. The
type of this attribute is Exception_Id. See 11.4.1.
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 S'Image For every scalar subtype S:
87 S'Image denotes a function with the following specification:
88 function S'Image(Arg : S'Base)
return String
89/2 The function returns an image of the value of Arg as a String.
See 3.5.
90 S'Class'Input
For every subtype S'Class of a class-wide type T'Class:
91 S'Class'Input denotes a function with the following
specification:
92/2 function S'Class'Input(
Stream : not null access Ada.Streams.Root_Stream_Type'Class)
return T'Class
93/2 First reads the external tag from Stream and determines the
corresponding internal tag (by calling
Tags.Descendant_Tag(String'Input(Stream), S'Tag) which might
raise Tag_Error - 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. If the
specific type identified by the internal tag is not covered by
T'Class or is abstract, Constraint_Error is raised. See
13.13.2.
94 S'Input For every subtype S of a specific type T:
95 S'Input denotes a function with the following specification:
96/2 function S'Input(
Stream : not null access Ada.Streams.Root_Stream_Type'Class)
return T
97 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.
98/1 A'Last For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
99 A'Last denotes the upper bound of the first index range; its
type is the corresponding index type. See 3.6.2.
100 S'Last For every scalar subtype S:
101 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.
102/1 A'Last(N) For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
103 A'Last(N) denotes the upper bound of the N-th index range; its
type is the corresponding index type. See 3.6.2.
103.1/2 R.C'Last_Bit
For a component C of a composite, non-array object R:
103.2/2 If the nondefault bit ordering applies to the composite type,
and if a component_clause specifies the placement of C,
denotes the value given for the last_bit of the
component_clause; otherwise, 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.
104 S'Leading_Part
For every subtype S of a floating point type T:
105 S'Leading_Part denotes a function with the following
specification:
106 function S'Leading_Part (X : T;
Radix_Digits : universal_integer)
return T
107 Let v be the value T'Machine_Radix(k-Radix_Digits), where k is
the normalized exponent of X. The function yields the value
108 * Floor(X/v) · v, when X is nonnegative and Radix_Digits is
positive;
109 * Ceiling(X/v) · v, when X is negative and Radix_Digits is
positive.
110 {Constraint_Error (raised by failure of run-time check)}
{Range_Check [partial]}
{check, language-defined (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.
111/1 A'Length For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
112 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.
113/1 A'Length(N)
For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
114 A'Length(N) denotes the number of values of the N-th index
range (zero for a null range); its type is universal_integer.
See 3.6.2.
115 S'Machine For every subtype S of a floating point type T:
116 S'Machine denotes a function with the following specification:
117 function S'Machine (X : T)
return T
118 {Constraint_Error (raised by failure of run-time 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, language-defined (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.
119 S'Machine_Emax
For every subtype S of a floating point type T:
120 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.
121 S'Machine_Emin
For every subtype S of a floating point type T:
122 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.
123 S'Machine_Mantissa
For every subtype S of a floating point type T:
124 Yields the largest value of p such that every value
expressible in the canonical form (for the type T), having a
p-digit 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.
125 S'Machine_Overflows
For every subtype S of a floating point type T:
126 Yields the value True if overflow and divide-by-zero 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.
127 S'Machine_Overflows
For every subtype S of a fixed point type T:
128 Yields the value True if overflow and divide-by-zero 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.
129 S'Machine_Radix
For every subtype S of a floating point type T:
130 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.
131 S'Machine_Radix
For every subtype S of a fixed point type T:
132 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.
132.1/2 S'Machine_Rounding
For every subtype S of a floating point type T:
132.2/2 S'Machine_Rounding denotes a function with the following
specification:
132.3/2 function S'Machine_Rounding (X : T)
return T
132.4/2 The function yields the integral value nearest to X. If X lies
exactly halfway between two integers, one of those integers is
returned, but which of them is returned is unspecified. A zero
result has the sign of X when S'Signed_Zeros is True. This
function provides access to the rounding behavior which is
most efficient on the target processor.{unspecified
[partial]} See A.5.3.
133 S'Machine_Rounds
For every subtype S of a floating point type T:
134 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.
135 S'Machine_Rounds
For every subtype S of a fixed point type T:
136 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.
137 S'Max For every scalar subtype S:
138 S'Max denotes a function with the following specification:
139 function S'Max(Left, Right : S'Base)
return S'Base
140 The function returns the greater of the values of the two
parameters. See 3.5.
140.1/2 S'Max_Size_In_Storage_Elements
For every subtype S:
140.2/2 Denotes the maximum value for Size_In_Storage_Elements that
could be requested by the implementation via Allocate for an
access type whose designated subtype is S. For a type with
access discriminants, if the implementation allocates space
for a coextension in the same pool as that of the object
having the access discriminant, then this accounts for any
calls on Allocate that could be performed to provide space for
such coextensions. The value of this attribute is of type
universal_integer. See 13.11.1.
141 S'Min For every scalar subtype S:
142 S'Min denotes a function with the following specification:
143 function S'Min(Left, Right : S'Base)
return S'Base
144 The function returns the lesser of the values of the two
parameters. See 3.5.
144.1/2 S'Mod For every modular subtype S:
144.2/2 S'Mod denotes a function with the following specification:
144.3/2 function S'Mod (Arg : universal_integer)
return S'Base
144.4/2 This function returns Arg mod S'Modulus, as a value of the
type of S. See 3.5.4.
145 S'Model For every subtype S of a floating point type T:
146 S'Model denotes a function with the following specification:
147 function S'Model (X : T)
return T
148 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.
149 S'Model_Emin
For every subtype S of a floating point type T:
150 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.
151 S'Model_Epsilon
For every subtype S of a floating point type T:
152 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.
153 S'Model_Mantissa
For every subtype S of a floating point type T:
154 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.
155 S'Model_Small
For every subtype S of a floating point type T:
156 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.
157 S'Modulus For every modular subtype S:
158 S'Modulus yields the modulus of the type of S, as a value of
the type universal_integer. See 3.5.4.
159 S'Class'Output
For every subtype S'Class of a class-wide type T'Class:
160 S'Class'Output denotes a procedure with the following
specification:
161/2 procedure S'Class'Output(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T'Class)
162/2 First writes the external tag of Item to Stream (by calling
String'Output(Stream, 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.
Tag_Error is raised if the tag of Item identifies a type
declared at an accessibility level deeper than that of S. See
13.13.2.
163 S'Output For every subtype S of a specific type T:
164 S'Output denotes a procedure with the following specification:
165/2 procedure S'Output(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T)
166 S'Output writes the value of Item to Stream, including any
bounds or discriminants. See 13.13.2.
167/1 D'Partition_Id
For a prefix D that denotes a library-level declaration,
excepting a declaration of or within a declared-pure library
unit:
168 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.
169 S'Pos For every discrete subtype S:
170 S'Pos denotes a function with the following specification:
171 function S'Pos(Arg : S'Base)
return universal_integer
172 This function returns the position number of the value of Arg,
as a value of type universal_integer. See 3.5.5.
172.1/2 R.C'Position
For a component C of a composite, non-array object R:
172.2/2 If the nondefault bit ordering applies to the composite type,
and if a component_clause specifies the placement of C,
denotes the value given for the position of the
component_clause; otherwise, 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.
173 S'Pred For every scalar subtype S:
174 S'Pred denotes a function with the following specification:
175 function S'Pred(Arg : S'Base)
return S'Base
176 {Constraint_Error (raised by failure of run-time 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, language-defined (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, language-defined (Range_Check)} Constraint_Error is
raised if there is no such machine number. See 3.5.
176.1/2 P'Priority
For a prefix P that denotes a protected object:
176.2/2 Denotes a non-aliased component of the protected object P.
This component is of type System.Any_Priority and its value is
the priority of P. P'Priority denotes a variable if and only
if P denotes a variable. A reference to this attribute shall
appear only within the body of P. See D.5.2.
177/1 A'Range For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
178 A'Range is equivalent to the range A'First .. A'Last, except
that the prefix A is only evaluated once. See 3.6.2.
179 S'Range For every scalar subtype S:
180 S'Range is equivalent to the range S'First .. S'Last. See
3.5.
181/1 A'Range(N)
For a prefix A that is of an array type (after any implicit
dereference), or denotes a constrained array subtype:
182 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.
183 S'Class'Read
For every subtype S'Class of a class-wide type T'Class:
184 S'Class'Read denotes a procedure with the following
specification:
185/2 procedure S'Class'Read(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : out T'Class)
186 Dispatches to the subprogram denoted by the Read attribute of
the specific type identified by the tag of Item. See 13.13.2.
187 S'Read For every subtype S of a specific type T:
188 S'Read denotes a procedure with the following specification:
189/2 procedure S'Read(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : out T)
190 S'Read reads the value of Item from Stream. See 13.13.2.
191 S'Remainder For every subtype S of a floating point type T:
192 S'Remainder denotes a function with the following
specification:
193 function S'Remainder (X, Y : T)
return T
194 {Constraint_Error (raised by failure of run-time 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, language-defined (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.
195 S'Round For every decimal fixed point subtype S:
196 S'Round denotes a function with the following specification:
197 function S'Round(X : universal_real)
return S'Base
198 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.
199 S'Rounding For every subtype S of a floating point type T:
200 S'Rounding denotes a function with the following
specification:
201 function S'Rounding (X : T)
return T
202 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.
203 S'Safe_First
For every subtype S of a floating point type T:
204 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.
205 S'Safe_Last For every subtype S of a floating point type T:
206 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.
207 S'Scale For every decimal fixed point subtype S:
208 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.
209 S'Scaling For every subtype S of a floating point type T:
210 S'Scaling denotes a function with the following specification:
211 function S'Scaling (X : T;
Adjustment : universal_integer)
return T
212 {Constraint_Error (raised by failure of run-time 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, language-defined (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.
213 S'Signed_Zeros
For every subtype S of a floating point type T:
214 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.
215 S'Size For every subtype S:
216 If S is definite, denotes the size (in bits) that the
implementation would choose for the following objects of
subtype S:
217 * A record component of subtype S when the record type is
packed.
218 * The formal parameter of an instance of
Unchecked_Conversion that converts from subtype S to some
other subtype.
219 If S is indefinite, the meaning is implementation defined. The
value of this attribute is of the type universal_integer. See
13.3.
220/1 X'Size For a prefix X that denotes an object:
221 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.
222 S'Small For every fixed point subtype S:
223 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.
224 S'Storage_Pool
For every access-to-object subtype S:
225 Denotes the storage pool of the type of S. The type of this
attribute is Root_Storage_Pool'Class. See 13.11.
226 S'Storage_Size
For every access-to-object subtype S:
227 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.
228/1 T'Storage_Size
For a prefix T that denotes a task object (after any implicit
dereference):
229 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.
229.1/2 S'Stream_Size
For every subtype S of an elementary type T:
229.2/2 Denotes the number of bits occupied in a stream by items of
subtype S. Hence, the number of stream elements required per
item of elementary type T is:
229.3/2 T'Stream_Size / Ada.Streams.Stream_Element'Size
229.4/2 The value of this attribute is of type universal_integer and
is a multiple of Stream_Element'Size. See 13.13.2.
230 S'Succ For every scalar subtype S:
231 S'Succ denotes a function with the following specification:
232 function S'Succ(Arg : S'Base)
return S'Base
233 {Constraint_Error (raised by failure of run-time 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, language-defined (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, language-defined (Range_Check)} Constraint_Error is
raised if there is no such machine number. See 3.5.
234 S'Tag For every subtype S of a tagged type T (specific or
class-wide):
235 S'Tag denotes the tag of the type T (or if T is class-wide,
the tag of the root type of the corresponding class). The
value of this attribute is of type Tag. See 3.9.
236 X'Tag For a prefix X that is of a class-wide tagged type (after any
implicit dereference):
237 X'Tag denotes the tag of X. The value of this attribute is of
type Tag. See 3.9.
238 T'Terminated
For a prefix T that is of a task type (after any implicit
dereference):
239 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.
240 S'Truncation
For every subtype S of a floating point type T:
241 S'Truncation denotes a function with the following
specification:
242 function S'Truncation (X : T)
return T
243 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.
244 S'Unbiased_Rounding
For every subtype S of a floating point type T:
245 S'Unbiased_Rounding denotes a function with the following
specification:
246 function S'Unbiased_Rounding (X : T)
return T
247 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.
248 X'Unchecked_Access
For a prefix X that denotes an aliased view of an object:
249 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.
250 S'Val For every discrete subtype S:
251 S'Val denotes a function with the following specification:
252 function S'Val(Arg : universal_integer)
return S'Base
253 {evaluation (Val) [partial]}
{Constraint_Error (raised by failure of run-time check)} This
function returns a value of the type of S whose position
number equals the value of Arg. See 3.5.5.
254 X'Valid For a prefix X that denotes a scalar object (after any
implicit dereference):
255 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.
256 S'Value For every scalar subtype S:
257 S'Value denotes a function with the following specification:
258 function S'Value(Arg : String)
return S'Base
259 This function returns a value given an image of the value as a
String, ignoring any leading or trailing spaces. See 3.5.
260/1 P'Version For a prefix P that statically denotes a program unit:
261 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.
262 S'Wide_Image
For every scalar subtype S:
263 S'Wide_Image denotes a function with the following
specification:
264 function S'Wide_Image(Arg : S'Base)
return Wide_String
265/2 {image (of a value)} The function returns an image of the
value of Arg as a Wide_String. See 3.5.
266 S'Wide_Value
For every scalar subtype S:
267 S'Wide_Value denotes a function with the following
specification:
268 function S'Wide_Value(Arg : Wide_String)
return S'Base
269 This function returns a value given an image of the value as a
Wide_String, ignoring any leading or trailing spaces. See
3.5.
269.1/2 S'Wide_Wide_Image
For every scalar subtype S:
269.2/2 S'Wide_Wide_Image denotes a function with the following
specification:
269.3/2 function S'Wide_Wide_Image(Arg : S'Base)
return Wide_Wide_String
269.4/2 {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.
269.5/2 S'Wide_Wide_Value
For every scalar subtype S:
269.6/2 S'Wide_Wide_Value denotes a function with the following
specification:
269.7/2 function S'Wide_Wide_Value(Arg : Wide_Wide_String)
return S'Base
269.8/2 This function returns a value given an image of the value as a
Wide_Wide_String, ignoring any leading or trailing spaces. See
3.5.
269.9/2 S'Wide_Wide_Width
For every scalar subtype S:
269.10/2 S'Wide_Wide_Width denotes the maximum length of a
Wide_Wide_String returned by S'Wide_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.
270 S'Wide_Width
For every scalar subtype S:
271 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.
272 S'Width For every scalar subtype S:
273 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.
274 S'Class'Write
For every subtype S'Class of a class-wide type T'Class:
275 S'Class'Write denotes a procedure with the following
specification:
276/2 procedure S'Class'Write(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T'Class)
277 Dispatches to the subprogram denoted by the Write attribute of
the specific type identified by the tag of Item. See 13.13.2.
278 S'Write For every subtype S of a specific type T:
279 S'Write denotes a procedure with the following specification:
280/2 procedure S'Write(
Stream : not null access Ada.Streams.Root_Stream_Type'Class;
Item : in T)
281 S'Write writes the value of Item to Stream. See 13.13.2.
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