sequences ::= sequences are
sequence_1`,'sequence_2...
end sequences
sequence ::= rulein_faceclose_optexceptions_opt
| C-string
| C-char
;
close_opt ::= rule
| closers are
rules
end closers
| <nothing>
;
exceptions_opt ::= exceptions are
rules
end exceptions
| <nothing>
;
The rules are:
The default face is then in_face.
If no closing rule is given, `"\n"' (i.e., end-of-line) is used.
As a first example, here is the correct definition for a C string:
sequences are
"\"" Plain String "\"" Plain
exceptions are
"\\\\", "\\\""
end exceptions
end sequences
Since a great deal of languages uses this kind of constructs, you may
use C-string to mean exactly this, and C-char for
manifest characters defined the C way.
The following example comes from `ssh.ssh', the style sheet for
style sheet files, in which there are two kinds of pseudo-strings: the
strings (`"example"'), and the regular expressions
(`/example/'). We do not want the content of the pseudo-strings in
the face String.
sequences are
# The comments
"#" Comment,
# The name of the style sheet
"style " Keyword_strong (Label + Index1) " is" Keyword_strong,
# Strings are exactly the C-strings, though we don't want to
# have them in the "string" face
"\"" Plain "\""
exceptions are
"\\\\", "\\\""
end exceptions,
# Regexps
"/" Plain "/"
exceptions are
"\\\\", "\\\/"
end exceptions
end sequences
The order between sequences does matter. For instance in Java,
`/**' introduces strong comments, and `/*' comments.
`/**'must be declared before `/*', or it will be
hidden.
There are actually some sequences that could have been implemented as
operators with a specific regular expression (that goes up to the
closer). Nevertheless be aware of a big difference: regular expression
are applied to a single line of the source file, hence, they cannot
match on several lines. For instance, the C comments,
/*
* a comment
*/
cannot be implemented with operators, though C++ comments can:
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