indent.9

操作系统设计与实现源码

.CD "indent \(en reformat the layout of a program"
.SX "indent \fIin_file\fR [\fIout_file\fR] [\fIoptions\fR]
.FL "\fR(many)"
.EX "indent \(enbr \(enc25 prog.c " "Indent \fIprog.c\fR
.EX "indent \(ennpcs prog.c newprog.c" "Put output on \fInewprog.c"
.PP
\fIIndent\fR reads a C program in, rearranges the layout, and outputs a
new C program that will compile to the same executable binary as the original
one.
The difference between the input and output is that the output is in a standard
layout determined by a large number of options.
For most of the options there are two choices, one that enables it and one
that disables it.
.PP
If \fIindent\fR is called with no file files, it operates as a filter.
If called with one file name, that file is reformatted and the result
replaces the original file.
A backup is created, however, with the suffix \fI.BAK\fR.
If it is called with two file names, the first one is the input file and
the second one is the output file.
Only one file can be reformatted at a time (e.g., one cannot call \fIindent\fR
with *.c as argument; this is an error and will not work.).
.SS "Options"
.PP
Many options are available.
If you want to format a program to the \*(OQofficial\*(CQ MINIX format, use 
\fIpretty\fR, which calls \fIindent\fR with the proper options and then
postprocesses the output.
The options listed below control the formatting style.

OPTION: \fB\(enbad\fR, \fB\(ennbad\fR
.PP
If \fB\(enbad\fR is specified, a blank line is forced
after every block of declarations.  Default: \fB\(ennbad\fR.

OPTION: \fB\(enbap\fR, \fB\(ennbap\fR
.PP
If \fB\(enbap\fR is specified, a blank line is forced
after every procedure body.  Default: \fB\(ennbap\fR.

OPTION: \fB\(enbbb\fR, \fB\(ennbbb\fR
.PP
If \fB\(enbbb\fR is specified, a blank line is forced
before every block comment.  Default: \fB\(ennbbb\fR.

OPTION: \fB\(enbc\fR, \fB\(ennbc\fR
.PP
If \fB\(enbc\fR is specified, then a newline is forced
after each comma in a declaration. \fB\(ennbc\fR turns
off this option.  The default is \fB\(ennbc\fR.

OPTION: \fB\(enbl\fR, \fB\(enbr\fR
.PP
Specifying \fB\(enbl\fR lines up compound statements
like this:
.HS
   if (...)
   {
       code
   }
.HS
Specifying \fB\(enbr\fR (the default) makes them look
like this:
.HS
   if (...) {
       code
   }
.HS

OPTION: \fB\(enc\fIn\fR
.PP
The column in which comments on code start.
The default is 33.

OPTION: \fB\(encd\fIn\fR
.PP
The column in which comments on declarations
start.  The default is for these comments to
start in the same column as those on code.

OPTION: \fB\(encdb\fR, \fB\(enncdb\fR
.PP
Enables (disables) the placement of comment
delimiters on blank lines.  With this option
enabled, comments look like this:
.HS
    /*
     * this is a comment
     */
.HS
Rather than like this:
.HS
    /* this is a comment */
.HS
This only affects block comments, not comments to the 
right of code. The default is \fB\(encdb\fR.

OPTION: \fB\(ence\fR, \fB\(ennce\fR
.PP
Enables (disables) forcing \*(OQelse\*(CQs to cuddle
up to the immediately preceding \*(OQ}\*(CQ.  The
default is \fB\(ence\fR.

OPTION: \fB\(enci\fIn\fR
.PP
Sets the continuation indent to be \fIn\fR.  Continuation lines will be indented 
that far from the beginning of the first line of the
statement.  Parenthesized expressions have
extra indentation added to indicate the nesting, unless \fB\(enlp\fR 
is in effect.  \fB\(enci\fR defaults
to the same value as \fB\(eni\fR.

OPTION: \fB\(encli\fIn\fR
.PP
Causes case labels to be indented \fIn\fR tab stops
to the right of the containing switch statement.  \fB\(encli\fR0.5 causes 
case labels to be
indented half a tab stop.  The default is \fB\(encli\fR0.  
(This is the only option that takes a fractional argument.)

OPTION: \fB\(end\fI\s+2n\s0\fR
.PP
Controls the placement of comments which are
not to the right of code.  Specifying \fB\(end\fR1
means that such comments are placed one
indentation level to the left of code.  The
default \fB\(end\fR0 lines up these comments with the
code.  See the section on comment indentation
below.

OPTION: \fB\(endi\fI\s+2n\s0\fR
.PP
Specifies the indentation, in character positions, from a declaration keyword 
to the following identifier.  The default is \fB\(endi\fR16.

OPTION: \fB\(endj\fR, \fB\(enndj\fR
.PP
\fB\(endj\fR left justifies declarations.  \fB\(enndj\fR
indents declarations the same as code.  The
default is \fB\(enndj\fR.

OPTION: \fB\(enei\fR, \fB\(ennei\fR
.PP
Enables (disables) special else\fB\(enif\fR processing.  
If enabled, ifs following elses will
have the same indentation as the preceding if
statement.  The default is \fB\(enei\fR.

OPTION: \fB\(enfc\fR1, \fB\(ennfc\fR1
.PP
Enables (disables) the formatting of comments
that start in column 1.  Often, comments
whose leading \*(OQ/\*(CQ is in column 1 have been
carefully hand formatted by the programmer.
In such cases, \fB\(ennfc\fR1 should be used.  The
default is \fB\(enfc\fR1.

OPTION: \fB\(eni\fI\s+1n\s0\fR
.PP
The number of spaces for one indentation
level.  The default is 8.

OPTION: \fB\(enip\fR, \fB\(ennip\fR
.PP
Enables (disables) the indentation of parameter declarations from the 
left margin.  The default is \fB\(enip\fR.

OPTION: \fB\(enln\fR
.PP
Maximum length of an output line.  The default is 78.

OPTION: \fB\(enlp\fR, \fB\(ennlp\fR
.PP
Lines up code surrounded by parenthesis in
continuation lines.  If a line has a left
paren which is not closed on that line, then
continuation lines will be lined up to start
at the character position just after the left
paren. 

OPTION: \fB\(ennpro\fR
.PP
Causes the profile files, \fI.indent.pro\fR in both the current directory
and the user's home directory to be ignored.

OPTION: \fB\(enpcs\fR, \fB\(ennpcs\fR
.PP
If true (\fB\(enpcs\fR) all procedure calls will have
a space inserted between the name and the \*(OQ(\*(CQ.  
The default is \fB\(ennpcs\fR.

OPTION: \fB\(enps\fR, \fB\(ennps\fR
.PP
If true (\fB\(enps\fR) the pointer following operator \*(OQ\(en>\*(CQ will be surrounded by 
spaces on either side.  The default is \fB\(ennps\fR.

OPTION: \fB\(enpsl\fR, \fB\(ennpsl\fR
.PP
If true (\fB\(enpsl\fR) the names of procedures being
defined are placed in column 1 \(en their types,
if any, will be left on the previous lines.
The default is \fB\(enpsl\fR.

OPTION: \fB\(ensc\fR, \fB\(ennsc\fR
.PP
Enables (disables) the placement of asterisks
(*) at the left edge of all comments.  The default is \fB\(ensc\fR.

OPTION: \fB\(ensob\fR, \fB\(ennsob\fR
.PP
If \fB\(ensob\fR is specified, \fIindent\fR will swallow
optional blank lines.  You can use this to
get rid of blank lines after declarations. The default is \fB\(ennsob\fR.

OPTION: \fB\(enst\fR
.PP
Causes \fIindent\fR to take its input from \fIstdin\fR, and put its output 
to \fIstdout\fR.

OPTION: \fB\(enT\fItypename\fR
.PP
Adds typename to the list of type keywords.
Names accumulate: \fB\(enT\fR can be specified more
than once.  You need to specify all the
typenames that appear in your program that
are defined by #typedefs. Nothing will be
harmed if you miss a few, but the program
will not be formatted as nicely as it should.
This sounds like a painful thing to have to
do, but it is really a symptom of a problem in
C: typedef causes a syntactic change in the
language and \fIindent\fR cannot find all typedefs.

OPTION: \fB\(entroff\fR
.PP
Causes \fIindent\fR to format the program for processing by \fItroff\fR.  
It will produce a fancy listing in much the same spirit as \fIvgrind\fR.
If the output file is not specified, the
default is standard output, rather than formatting in place.

OPTION: \fB\(env\fR, \fB\(ennv\fR
.PP
The \fB\(env\fR flag turns on verbose mode; \fB\(ennv\fR turns it off.
When in verbose mode, \fIindent\fR reports when it
splits one line of input into two or more
lines of output, and gives some size statistics at completion. The 
default is \fB\(ennv\fR.
.SS "User Profiles"
.PP
You may set up your own profile of defaults to \fIindent\fR by
creating a file called \fI.indent.pro\fR in either your login
directory and/or the current directory and including whatever switches 
you like.  Switches in \fI.indent.pro\fR in the
current directory override those in your login directory
(with the exception of \fB\(enT\fR type definitions, which just accumulate).  
If \fIindent\fR is run and a profile file exists, then
it is read to set up the program's defaults.  The switches
should be separated by spaces, tabs or newlines.  Switches
on the command line, however, override profile switches.
.SS "Comments"
.PP
\fIIndent\fR assumes that any comment with a dash
or star immediately after the start of comment (that is, \*(OQ/*\(en\*(CQ 
or \*(OQ/**\*(CQ) is a 
comment surrounded by a box of stars.
Each line of such a comment is left unchanged, except that
its indentation may be adjusted to account for the change in
indentation of the first line of the comment.
.PP
All other comments are treated as straight
text.  Indent fits as many words (separated by blanks, tabs,
or newlines) on a line as possible.  Blank lines break paragraphs.
.PP
If a comment is on a line with code it is started in the
comment column, which is set by the \fB\(encn\fR command line
parameter.  Otherwise, the comment is started at \fIn\fR indentation levels 
less than where code is currently being placed,
where n is specified by the \fB\(endn\fR command line parameter.  If
the code on a line extends past the comment column, the comment starts 
further to the right, and the right margin may
be automatically extended in extreme cases.
.SS "Preprocessor Lines"
.PP
In general, \fIindent\fR leaves preprocessor lines alone.  The
only reformatting that it will do is to straighten up trailing comments.  
It leaves embedded comments alone.  Conditional compilation 
(#ifdef...#endif) is recognized and
\fIindent\fR attempts to correctly compensate for the syntactic
peculiarities introduced.
.SS "C Syntax"
.PP
Indent understands a substantial amount about the syntax of
C, but it has a forgiving parser.  It attempts to cope
with the usual sorts of incomplete and misformed syntax.  In
particular, the use of macros like:
.HS
        #define forever for(;;)
.HS
is handled properly.