2.2 Lexical Elements, Separators, and Delimiters
Static Semantics
1
{text of a program}
The text of a program consists of the texts of one
or more
compilations.
{lexical
element} {token:
See lexical element} The text of each
compilation is a sequence of separate
lexical
elements. Each lexical element is formed from a sequence of characters,
and is either a delimiter, an
identifier,
a reserved word, a
numeric_literal, a
character_literal,
a
string_literal, or a comment. The meaning
of a program depends only on the particular sequences of lexical elements
that form its
compilations, excluding
comments.
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The text of a
compilation is divided into
{line} lines.
{end of a line} In
general, the representation for an end of line is implementation defined.
However, a sequence of one or more
format_effectors
other than
the character whose code position is
16#09# (CHARACTER TABULATION) character
tabulation (HT) signifies at least one end of line.
2.a
Implementation defined: The representation
for an end of line.
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{separator} [In
some cases an explicit
separator is required to separate adjacent
lexical elements.] A separator is any of a
separator_space space
character, a
format_effector format
effector, or the end of a line, as follows:
3.a/2
This paragraph
was deleted.Discussion: {
AI95-00285-01}
It might be useful to define “white space”
and use it here.
4/2
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A separator_space space
character is a separator except within a comment,
a string_literal, or a character_literal.
5/2
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The character whose code position is 16#09# (CHARACTER
TABULATION) Character tabulation (HT)
is a separator except within a comment.
6
- The end of a line is always a separator.
7
One or more separators are allowed between any two
adjacent lexical elements, before the first of each compilation,
or after the last. At least one separator is required between an identifier,
a reserved word, or a numeric_literal and
an adjacent identifier, reserved word, or
numeric_literal.
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{delimiter} A
delimiter is either one of the following
special characters
: 9
& ' ( ) * + , – . / : ; < = > |
10
{compound delimiter}
or one of the following
compound delimiters
each composed of two adjacent special characters
11
=> .. ** := /= >= <= << >> <>
12
Each of the special characters listed for single
character delimiters is a single delimiter except if this character is
used as a character of a compound delimiter, or as a character of a comment,
string_literal, character_literal,
or numeric_literal.
13
The following names
are used when referring to compound delimiters:
| delimiter | name | | |
|
| | | | |
|
| => | arrow | | |
|
| .. | double dot | | |
|
| ** | double star, exponentiate | | |
|
| := | assignment (pronounced: | | |
|
| | “becomes”) | | |
|
| /= | inequality (pronounced: | | |
|
| | “not equal”) | | |
|
| >= | greater than or equal | | |
|
| <= | less than or equal | | |
|
| << | left label bracket | | |
|
| >> | right label bracket | | |
|
| <> | box | | |
|
Implementation Requirements
14
An implementation shall support lines of at least
200 characters in length, not counting any characters used to signify
the end of a line. An implementation shall support lexical elements of
at least 200 characters in length. The maximum supported line length
and lexical element length are implementation defined.
14.a
Implementation defined: Maximum supported
line length and lexical element length.
14.b
Discussion: From URG recommendation.
Wording Changes from Ada 95
14.c/2
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The wording was updated to use the new character
categories defined in the preceding clause.
Sponsored by Ada-Europe