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.\"     @(#)vgrindefs.5	8.1 (Berkeley) 6/6/93
.\" $FreeBSD$
.\"
.Dd June 6, 1993
.Dt VGRINDEFS 5
.Os
.Sh NAME
.Nm vgrindefs
.Nd language definition data base for
.Xr vgrind 1
.Sh SYNOPSIS
.Nm
.Sh DESCRIPTION
The
.Nm
file
contains all language definitions for
.Xr vgrind 1 .
The data base is
very similar to
.Xr termcap 5 .
.Sh FIELDS
The following table names and describes each field.
.Bl -column Namexxx Tpexxx
.It Sy "Name	Type	Description"
.It "ab	str	regular expression for the start of an alternate comment"
.It "ae	str	regular expression for the end of an alternate comment"
.It "pb	str	regular expression for start of a procedure"
.It "bb	str	regular expression for start of a lexical block"
.It "be	str	regular expression for the end of a lexical block"
.It "cb	str	regular expression for the start of a comment"
.It "ce	str	regular expression for the end of a comment"
.It "sb	str	regular expression for the start of a string"
.It "se	str	regular expression for the end of a string"
.It "lb	str	regular expression for the start of a character constant"
.It "le	str	regular expression for the end of a character constant"
.It "nc	str	regular expression for a non-comment (see below)"
.It "tl	bool	present means procedures are only defined at the top lexical level"
.It "oc	bool	present means upper and lower case are equivalent"
.It "kw	str	a list of keywords separated by spaces"
.El
.Pp
Non-comments are required to describe a certain context where a
sequence that would normally start a comment loses its special
meaning.
A typical example for this can be found in Perl, where
comments are normally starting with
.Ql # ,
while the string
.Ql $#
is an operator on an array.
.Sh REGULAR EXPRESSIONS
.Nm Vgrindefs
uses regular expression which are very similar to those of
.Xr ex 1
and
.Xr lex 1 .
The characters `^', `$', `:' and `\e'
are reserved characters and must be
"quoted" with a preceding
.Ql \e
if they
are to be included as normal characters.
The metasymbols and their meanings are:
.Bl -tag -width indent
.It $
the end of a line
.It \&^
the beginning of a line
.It \ed
a delimiter (space, tab, newline, start of line)
.It \ea
matches any string of symbols (like .* in lex)
.It \ep
matches any alphanumeric name.
In a procedure definition (pb) the string
that matches this symbol is used as the procedure name.
.It ()
grouping
.It \&|
alternation
.It ?
last item is optional
.It \ee
preceding any string means that the string will not match an
input string if the input string is preceded by an escape character (\e).
This is typically used for languages (like C) which can include the
string delimiter in a string by escaping it.
.El
.Pp
Unlike other regular expressions in the system, these match words
and not characters.
Hence something like "(tramp|steamer)flies?"
would match "tramp", "steamer", "trampflies", or "steamerflies".
.Sh KEYWORD LIST
The keyword list is just a list of keywords in the language separated
by spaces.
If the "oc" boolean is specified, indicating that upper
and lower case are equivalent, then all the keywords should be
specified in lower case.
.Sh FILES
.Bl -tag -width /usr/share/misc/vgrindefs -compact
.It Pa /usr/share/misc/vgrindefs
File containing terminal descriptions.
.El
.Sh EXAMPLES
The following entry, which describes the C language, is
typical of a language entry.
.Bd -literal
C|c:\
:pb=^\ed?*?\ed?\ep\ed?\e(\ea?\e):bb={:be=}:cb=/*:ce=*/:sb=":se=\ee":\e
:lb=':le=\ee':tl:\e
:kw=asm auto break case char continue default do double else enum\e
extern float for fortran goto if int long register return short\e
sizeof static struct switch typedef union unsigned while #define\e
#else #endif #if #ifdef #ifndef #include #undef # define else endif\e
if ifdef ifndef include undef:
.Ed
.Pp
Note that the first field is just the language name (and any variants
of it).
Thus the C language could be specified to
.Xr vgrind 1
as "c" or "C".
.Pp
Entries may continue onto multiple lines by giving a \e as the last
character of a line.
Capabilities in
.Nm
are of two types:
Boolean capabilities which indicate that the language has
some particular feature
and string
capabilities which give a regular expression or
keyword list.
.Sh SEE ALSO
.Xr troff 1 ,
.Xr vgrind 1
.Sh HISTORY
The
.Nm
file format appeared in
.Bx 4.2 .