A.1 The Package Standard
This subclause outlines the specification of the
package Standard containing all predefined identifiers in the language.
The corresponding package body is not specified by
the language.
The operators that are predefined for the types declared
in the package Standard are given in comments since they are implicitly
declared.
Italics are used for pseudo-names of anonymous
types (such as
root_real) and for undefined information (such
as
implementation-defined).
Static Semantics
The library package
Standard has the following declaration:
package Standard
is
pragma Pure(Standard);
type Boolean
is (False, True);
-- The predefined relational operators for this type are as follows:
-- function "=" (Left, Right : Boolean'Base) return Boolean;
-- function "/=" (Left, Right : Boolean'Base) return Boolean;
-- function "<" (Left, Right : Boolean'Base) return Boolean;
-- function "<=" (Left, Right : Boolean'Base) return Boolean;
-- function ">" (Left, Right : Boolean'Base) return Boolean;
-- function ">=" (Left, Right : Boolean'Base) return Boolean;
-- The predefined logical operators and the predefined logical
-- negation operator are as follows:
-- function "and" (Left, Right : Boolean'Base) return Boolean'Base;
-- function "or" (Left, Right : Boolean'Base) return Boolean'Base;
-- function "xor" (Left, Right : Boolean'Base) return Boolean'Base;
-- function "not" (Right : Boolean'Base) return Boolean'Base;
-- The integer type root_integer and the
-- corresponding universal type universal_integer are predefined.
type Integer
is range implementation-defined;
subtype Natural
is Integer
range 0 .. Integer'Last;
subtype Positive
is Integer
range 1 .. Integer'Last;
-- The predefined operators for type Integer are as follows:
-- function "=" (Left, Right : Integer'Base) return Boolean;
-- function "/=" (Left, Right : Integer'Base) return Boolean;
-- function "<" (Left, Right : Integer'Base) return Boolean;
-- function "<=" (Left, Right : Integer'Base) return Boolean;
-- function ">" (Left, Right : Integer'Base) return Boolean;
-- function ">=" (Left, Right : Integer'Base) return Boolean;
-- function "+" (Right : Integer'Base) return Integer'Base;
-- function "-" (Right : Integer'Base) return Integer'Base;
-- function "abs" (Right : Integer'Base) return Integer'Base;
-- function "+" (Left, Right : Integer'Base) return Integer'Base;
-- function "-" (Left, Right : Integer'Base) return Integer'Base;
-- function "*" (Left, Right : Integer'Base) return Integer'Base;
-- function "/" (Left, Right : Integer'Base) return Integer'Base;
-- function "rem" (Left, Right : Integer'Base) return Integer'Base;
-- function "mod" (Left, Right : Integer'Base) return Integer'Base;
-- function "**" (Left : Integer'Base; Right : Natural)
-- return Integer'Base;
-- The specification of each operator for the type
-- root_integer, or for any additional predefined integer
-- type, is obtained by replacing Integer by the name of the type
-- in the specification of the corresponding operator of the type
-- Integer. The right operand of the exponentiation operator
-- remains as subtype Natural.
-- The floating point type root_real and the
-- corresponding universal type universal_real are predefined.
type Float
is digits implementation-defined;
-- The predefined operators for this type are as follows:
-- function "=" (Left, Right : Float) return Boolean;
-- function "/=" (Left, Right : Float) return Boolean;
-- function "<" (Left, Right : Float) return Boolean;
-- function "<=" (Left, Right : Float) return Boolean;
-- function ">" (Left, Right : Float) return Boolean;
-- function ">=" (Left, Right : Float) return Boolean;
-- function "+" (Right : Float) return Float;
-- function "-" (Right : Float) return Float;
-- function "abs" (Right : Float) return Float;
-- function "+" (Left, Right : Float) return Float;
-- function "-" (Left, Right : Float) return Float;
-- function "*" (Left, Right : Float) return Float;
-- function "/" (Left, Right : Float) return Float;
-- function "**" (Left : Float; Right : Integer'Base) return Float;
-- The specification of each operator for the type root_real, or for
-- any additional predefined floating point type, is obtained by
-- replacing Float by the name of the type in the specification of the
-- corresponding operator of the type Float.
-- In addition, the following operators are predefined for the root
-- numeric types:
function "*" (Left : root_integer; Right : root_real)
return root_real;
function "*" (Left : root_real; Right : root_integer)
return root_real;
function "/" (Left : root_real; Right : root_integer)
return root_real;
-- The type universal_fixed is predefined.
-- The only multiplying operators defined between
-- fixed point types are
function "*" (Left : universal_fixed; Right : universal_fixed)
return universal_fixed;
function "/" (Left : universal_fixed; Right : universal_fixed)
return universal_fixed;
-- The type universal_access is predefined.
-- The following equality operators are predefined:
function "=" (Left, Right: universal_access) return Boolean;
function "/=" (Left, Right: universal_access) return Boolean;
--
The declaration of type Character is based on the standard ISO 8859-1 character set.
--
There are no character literals corresponding to the positions for control characters.
--
They are indicated in italics in this definition. See 3.5.2.
type Character
is
(
nul,
soh,
stx,
etx,
eot,
enq,
ack,
bel, --
0 (16#00#) .. 7 (16#07#)
bs,
ht,
lf,
vt,
ff,
cr,
so,
si, --
8 (16#08#) .. 15 (16#0F#)
dle,
dc1,
dc2,
dc3,
dc4,
nak,
syn,
etb, --
16 (16#10#) .. 23 (16#17#)
can,
em,
sub,
esc,
fs,
gs,
rs,
us, --
24 (16#18#) .. 31 (16#1F#)
' ', '!', '"', '#', '$', '%', '&', ''', --
32 (16#20#) .. 39 (16#27#)
'(', ')', '*', '+', ',', '-', '.', '/', --
40 (16#28#) .. 47 (16#2F#)
'0', '1', '2', '3', '4', '5', '6', '7', --
48 (16#30#) .. 55 (16#37#)
'8', '9', ':', ';', '<', '=', '>', '?', --
56 (16#38#) .. 63 (16#3F#)
'@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', --
64 (16#40#) .. 71 (16#47#)
'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', --
72 (16#48#) .. 79 (16#4F#)
'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', --
80 (16#50#) .. 87 (16#57#)
'X', 'Y', 'Z', '[', '\', ']', '^', '_', --
88 (16#58#) .. 95 (16#5F#)
'`', 'a', 'b', 'c', 'd', 'e', 'f', 'g', --
96 (16#60#) .. 103 (16#67#)
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', --
104 (16#68#) .. 111 (16#6F#)
'p', 'q', 'r', 's', 't', 'u', 'v', 'w', --
112 (16#70#) .. 119 (16#77#)
'x', 'y', 'z', '{', '|', '}', '~',
del, --
120 (16#78#) .. 127 (16#7F#)
reserved_128,
reserved_129,
bph,
nbh, --
128 (16#80#) .. 131 (16#83#)
reserved_132,
nel,
ssa,
esa, --
132 (16#84#) .. 135 (16#87#)
hts,
htj,
vts,
pld,
plu,
ri,
ss2,
ss3, --
136 (16#88#) .. 143 (16#8F#)
dcs,
pu1,
pu2,
sts,
cch,
mw,
spa,
epa, --
144 (16#90#) .. 151 (16#97#)
sos,
reserved_153,
sci,
csi, --
152 (16#98#) .. 155 (16#9B#)
st,
osc,
pm,
apc, --
156 (16#9C#) .. 159 (16#9F#)
' ', '¡', '¢', '£', '¤', '¥', '¦', '§', --
160 (16#A0#) .. 167 (16#A7#)
'¨', '©', 'ª', '«', --
168 (16#A8#) .. 171 (16#AB#)
¬',
soft_hyphen, '®', '¯', --
172 (16#AC#) .. 175 (16#AF#)
'°', '±', '²', '³', '´', 'µ', '¶', '·', --
176 (16#B0#) .. 183 (16#B7#)
'¸', '¹', 'º', '»', '¼', '½', '¾', '¿', --
184 (16#B8#) .. 191 (16#BF#)
'À', 'Á', 'Â', 'Ã', 'Ä', 'Å', 'Æ', 'Ç', --
192 (16#C0#) .. 199 (16#C7#)
'È', 'É', 'Ê', 'Ë', 'Ì', 'Í', 'Î', 'Ï', --
200 (16#C8#) .. 207 (16#CF#)
'Ð', 'Ñ', 'Ò', 'Ó', 'Ô', 'Õ', 'Ö', '×', --
208 (16#D0#) .. 215 (16#D7#)
'Ø', 'Ù', 'Ú', 'Û', 'Ü', 'Ý', 'Þ', 'ß', --
216 (16#D8#) .. 223 (16#DF#)
'à', 'á', 'â', 'ã', 'ä', 'å', 'æ', 'ç', --
224 (16#E0#) .. 231 (16#E7#)
'è', 'é', 'ê', 'ë', 'ì', 'í', 'î', 'ï', --
232 (16#E8#) .. 239 (16#EF#)
'ð', 'ñ', 'ò', 'ó', 'ô', 'õ', 'ö', '÷', --
240 (16#F0#) .. 247 (16#F7#)
'ø', 'ù', 'ú', 'û', 'ü', 'ý', 'þ', 'ÿ');--
248 (16#F8#) .. 255 (16#FF#)
-- The predefined operators for the type Character are the same as for
-- any enumeration type.
--
The declaration of type Wide_Character is based on the standard ISO/IEC 10646:2011 BMP character
--
set. The first 256 positions have the same contents as type Character. See 3.5.2.
type Wide_Character
is (
nul,
soh ...
Hex_0000FFFE,
Hex_0000FFFF);
--
The declaration of type Wide_Wide_Character is based on the full
--
ISO/IEC 10646:2011 character set. The first 65536 positions have the
--
same contents as type Wide_Character. See 3.5.2.
type Wide_Wide_Character
is (
nul,
soh ...
Hex_7FFFFFFE,
Hex_7FFFFFFF);
for Wide_Wide_Character'Size
use 32;
package ASCII
is ...
end ASCII; --
Obsolescent; see J.5
--
Predefined string types:
type String
is array(Positive
range <>)
of Character
with Pack;
-- The predefined operators for this type are as follows:
-- function "=" (Left, Right: String) return Boolean;
-- function "/=" (Left, Right: String) return Boolean;
-- function "<" (Left, Right: String) return Boolean;
-- function "<=" (Left, Right: String) return Boolean;
-- function ">" (Left, Right: String) return Boolean;
-- function ">=" (Left, Right: String) return Boolean;
-- function "&" (Left: String; Right: String) return String;
-- function "&" (Left: Character; Right: String) return String;
-- function "&" (Left: String; Right: Character) return String;
-- function "&" (Left: Character; Right: Character) return String;
type Wide_String
is array(Positive
range <>)
of Wide_Character
with Pack;
-- The predefined operators for this type correspond to those for String.
type Wide_Wide_String
is array (Positive
range <>)
of Wide_Wide_Character
with Pack;
-- The predefined operators for this type correspond to those for String.
type Duration
is delta implementation-defined range implementation-defined;
-- The predefined operators for the type Duration are the same as for
-- any fixed point type.
-- The predefined exceptions:
Constraint_Error:
exception;
Program_Error :
exception;
Storage_Error :
exception;
Tasking_Error :
exception;
end Standard;
Standard has no private part.
In each of the types Character, Wide_Character,
and Wide_Wide_Character, the character literals for the space character
(position 32) and the non-breaking space character (position 160) correspond
to different values. Unless indicated otherwise, each occurrence of the
character literal ' ' in this International Standard refers to the space
character. Similarly, the character literals for hyphen (position 45)
and soft hyphen (position 173) correspond to different values. Unless
indicated otherwise, each occurrence of the character literal '–'
in this International Standard refers to the hyphen character.
Dynamic Semantics
Elaboration of the body of Standard
has no effect.
Implementation Permissions
An implementation may provide additional predefined
integer types and additional predefined floating point types. Not all
of these types need have names.
Implementation Advice
If an implementation provides additional named predefined
integer types, then the names should end with “Integer” as
in “Long_Integer”. If an implementation provides additional
named predefined floating point types, then the names should end with
“Float” as in “Long_Float”.
1 Certain aspects of the predefined entities
cannot be completely described in the language itself. For example, although
the enumeration type Boolean can be written showing the two enumeration
literals False and True, the short-circuit control forms cannot be expressed
in the language.
2 As explained in
8.1,
“
Declarative Region” and
10.1.4,
“
The Compilation Process”, the
declarative region of the package Standard encloses every library unit
and consequently the main subprogram; the declaration of every library
unit is assumed to occur within this declarative region.
Library_items
are assumed to be ordered in such a way that there are no forward semantic
dependences. However, as explained in
8.3,
“
Visibility”, the only library
units that are visible within a given compilation unit are the library
units named by all
with_clauses
that apply to the given unit, and moreover, within the declarative region
of a given library unit, that library unit itself.
3 If all
block_statements
of a program are named, then the name of each program unit can always
be written as an expanded name starting with Standard (unless Standard
is itself hidden). The name of a library unit cannot be a homograph of
a name (such as Integer) that is already declared in Standard.
4 The exception Standard.Numeric_Error
is defined in
J.6.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe