\input texinfo   @c -*- texinfo -*-

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment %**start of header (This is for running Texinfo on a region)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@setfilename  cc-mode.info
@settitle     CC-MODE Version 4 Documentation
@footnotestyle end

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment @setchapternewpage odd !! we don't want blank pages !!
@comment %**end of header (This is for running Texinfo on a region)
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment 
@comment texinfo manual for @file{cc-mode.el} version 4
@comment manual version: 2.55
@comment generated from the original README file by Krishna Padmasola
@comment <krishna@earth-gw.njit.edu>
@comment 
@comment Barry A. Warsaw <bwarsaw@cnri.reston.va.us>
@comment Last modification: 1996/08/21 19:29:16
@comment 
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment The following line inserts the copyright notice 
@comment into the Info file.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ifinfo
Copyright @copyright{} 1995, 1996 Free Software Foundation, Inc.
@end ifinfo

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment !!!The titlepage section does not appear in the Info file.!!!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@titlepage
@sp 10


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment The title is printed in a large font.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@center @titlefont{CC-MODE Version 4}
@sp 2
@center A GNU Emacs mode for editing C, C++, Objective-C, and Java code.
@center (manual revision: 2.55)
@sp 2
@center Barry A. Warsaw


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment  The following two commands start the copyright page
@comment  for the printed manual.  This will not appear in the Info file.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1995 Free Software Foundation, Inc.
@end titlepage


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment The Top node contains the master menu for the Info file.
@comment This appears only in the Info file, not the printed manual.
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@node    Top,       Introduction, (dir),    (dir)
@comment node-name, next,          previous, up


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@menu
* Introduction::                
* Getting Connected::           
* New Indentation Engine::
* Minor Modes::
* Commands::
* Customizing Indentation::
* Syntactic Symbols::
* Performance Issues::
* Frequently Asked Questions::
* Getting the latest cc-mode release::
* Sample .emacs File::
* Limitations and Known Bugs::  
* Mailing Lists and Submitting Bug Reports::  
* Concept Index::               
* Command Index::               Command Index
* Key Index::                   Key Index
* Variable Index::              Variable Index
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@node     Introduction, Getting Connected, Top,      Top
@comment  node-name,    next,            previous, up
@chapter  Introduction
@cindex   Introduction

@cindex BOCM
Welcome to @code{cc-mode}, version 4.  This is a GNU Emacs mode for
editing files containing C, C++, Objective-C, and Java code.
This incarnation of the mode is descendant from @file{c-mode.el} (also
called "Boring Old C Mode" or BOCM @code{:-)}, and @file{c++-mode.el}
version 2, which I have been maintaining since 1992.  @code{cc-mode}
represents a significant milestone in the mode's life.  It has been
fully merged back with Emacs 19's @file{c-mode.el}. Also a new, more
intuitive and flexible mechanism for controlling indentation has been
developed.

@code{cc-mode} version 4 supports the editing of K&R and ANSI C,
@dfn{ARM} @footnote{i.e. ``The Annotated C++ Reference Manual'', by
Ellis and Stroustrup.} C++, Objective-C, and Java files.  In this way,
you can easily set up consistent coding styles for use in editing all C,
C++, Objective-C, and Java programs. @code{cc-mode} does @emph{not}
handle font-locking (a.k.a. syntax coloring, keyword highlighting) or
anything of that nature, for any of the 4 modes.  Those are handled by
other Emacs packages.

This manual will describe the following:

@itemize @bullet
@item
How to get started using @code{cc-mode}.

@item
How the new indentation engine works.

@item
How to customize the new indentation engine.

@end itemize

Note that the name of this file is @file{cc-mode.el}, and I'll often
refer to the package as @code{cc-mode}, but there really is no top level
@code{cc-mode} entry point.  I call it @code{cc-mode} simply to
differentiate it from @file{c-mode.el}.  All of the variables, commands,
and functions in @code{cc-mode} are prefixed with
@code{c-@var{<thing>}}, and @code{c-mode}, @code{c++-mode},
@code{objc-mode}, and @code{java-mode} entry points are provided.  This
file is intended to be a replacement for @file{c-mode.el} and
@file{c++-mode.el}.

@findex c-version
The major version number was incremented to 4 with the addition of
@code{objc-mode}. To find the minor revision number of this release, use
@kbd{M-x c-version RET}.

As of this writing (20-Aug-1996), both Emacs 19.33 and XEmacs 19.14 are
distributed with @code{cc-mode}, however neither have the very latest
version.  In all likelihood, Emacs 19.34 and XEmacs 19.15 will contain
the latest version of @code{cc-mode}.  You may therefore, want to
upgrade your copy of @code{cc-mode}.  See @ref{Getting the latest
cc-mode release}.

@cindex @file{cc-compat.el} file
This distribution also contains a file called @file{cc-compat.el} which
should ease your transition from BOCM to @code{cc-mode}.  It currently
comes unguaranteed and unsupported, but this may change for future
versions.  If you have a BOCM configuration you are really happy with,
and want to postpone learning how to configure @code{cc-mode}, take a
look at that file.  It maps BOCM configuration variables to
@code{cc-mode}'s new indentation model.

A special word of thanks goes to Krishna Padmasola for his work in
converting the original @file{README} file to texinfo format.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@node     Getting Connected, New Indentation Engine, Introduction,      Top
@comment  node-name,       next,                   previous,          up
@chapter  Getting Connected
@cindex   Getting Connected

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@file{cc-mode.el} works well with the 2 main branches of Emacs 19:
XEmacs, maintained by @code{xemacs.org} and the Emacs 19 maintained by
the Free Software Foundation.  Emacs 19 users will want to use Emacs
version 19.21 or better, XEmacs users will want 19.6 or better.  Earlier
versions of these Emacsen have deficiencies and/or bugs which will
adversely affect the performance and usability of @code{cc-mode}.  You
are better off just getting the latest version of Emacs or XEmacs.

@cindex @file{cc-mode-18.el} file
@file{cc-mode.el} will work with Emacs 18 if you use the
@file{cc-mode-18.el} compatibility file, but only moderately well.  A
word of warning though, @emph{Emacs 18 lacks some fundamental
functionality and ultimately, using Emacs 18 is a losing
battle}.  Hence @code{cc-mode} under Emacs 18 is no longer supported and
it is highly recommended that you upgrade to Emacs 19.  If you use
@code{cc-mode} under Emacs 18, you're on your own.  With @code{cc-mode}
version 5, Emacs 18 support will be dropped altogether.

Note that as of XEmacs 19.13 and Emacs 19.30, your Emacs already comes
with @code{cc-mode} version 4 preconfigured for your use.  You should be
able to safely skip the rest of the setup information in this chapter,
unless you want to install the latest version of @code{cc-mode} into one
of these Emacsen.

@cindex @file{.emacs} file
The first thing you will want to do is put @file{cc-mode.el} somewhere
on your @code{load-path} so Emacs can find it.  Do a @kbd{C-h v
load-path RET} to see all the directories Emacs looks at when loading a
file.  If none of these directories are appropriate, create a new
directory and add it to your @code{load-path}:

@noindent
@emph{[in the shell]}
@example
@group

% cd
% mkdir mylisp
% mv cc-mode.el mylisp
% cd mylisp

@end group
@end example

@noindent
@emph{[in your .emacs file add]}
@example

(setq load-path (cons "~/mylisp" load-path))

@end example

@cindex byte compile
Next you want to @dfn{byte compile} @file{cc-mode.el}.  The mode uses a
lot of macros so if you don't byte compile it, things will be unbearably
slow.  @emph{You can ignore all byte-compiler warnings!}  They are the
result of the supporting different versions of Emacs, and none of the
warnings have any effect on operation. Let me say this again:
@strong{You really can ignore all byte-compiler warnings!}

Here's what to do to byte-compile the file [in emacs]:
@example

M-x byte-compile-file RET ~/mylisp/cc-mode.el RET

@end example

If you are running a version of Emacs or XEmacs that comes with
@code{cc-mode} by default, you can simply add the following to your
@file{.emacs} file in order to upgrade to the latest version of
@code{cc-mode}:
@example

(load "cc-mode")

@end example

Users of even older versions of Emacs 19, Emacs 18, or of the older
Lucid Emacs will probably be running an Emacs that has BOCM
@file{c-mode.el} and possible @file{c++-mode.el} pre-dumped.  If your
Emacs is dumped with either of these files you first need to make Emacs
``forget'' about those older modes.

If you can do a @kbd{C-h v c-mode-map RET} without getting an error, you
need to add these lines at the top of your @file{.emacs} file:
@example
@group

(fmakunbound 'c-mode)
(makunbound  'c-mode-map)
(fmakunbound 'c++-mode)
(makunbound  'c++-mode-map)
(makunbound  'c-style-alist)

@end group
@end example

After those lines you will want to add the following autoloads to your
@file{.emacs} file so that @code{cc-mode} gets loaded at the right time:
@example
@group

(autoload 'c++-mode  "cc-mode" "C++ Editing Mode" t)
(autoload 'c-mode    "cc-mode" "C Editing Mode" t)
(autoload 'objc-mode "cc-mode" "Objective-C Editing Mode" t)
(autoload 'java-mode "cc-mode" "Java Editing Mode" t)

@end group
@end example

Alternatively, if you want to make sure @code{cc-mode} is loaded when
Emacs starts up, you could use this line instead of the autoloads
above:
@example

(require 'cc-mode)

@end example

Next, you will want to set up Emacs so that it edits C files in
@code{c-mode}, C++ files in @code{c++-mode}, Objective-C files in
@code{objc-mode}, and Java files in @code{java-mode}. You should
add the following to your @file{.emacs} file, which assumes
you'll be editing @code{.h} and @code{.c} files as C, @code{.hh},
@code{.cc}, @code{.H}, and @code{.C} files as C++, @code{.m} files as
Objective-C, and @code{.java} files as Java code. YMMV:
@example
@group

(setq auto-mode-alist
  (append
    '(("\\.C$"    . c++-mode)
      ("\\.H$"    . c++-mode)
      ("\\.cc$"   . c++-mode)
      ("\\.hh$"   . c++-mode)
      ("\\.c$"    . c-mode)
      ("\\.h$"    . c-mode)
      ("\\.m$"    . objc-mode)
      ("\\.java$" . java-mode)
     ) auto-mode-alist))

@end group
@end example

You may already have some or all of these settings on your
@code{auto-mode-alist}, but it won't hurt to put them on there again.

That's all you need --- I know, I know, it sounds like a lot @code{:-)},
but after you've done all this, you should only need to quit and restart
Emacs.  The next time you visit a C, C++, Objective-C, or Java file you
should be using @code{cc-mode}.  You can check this easily by hitting
@kbd{M-x c-version RET} in the @code{c-mode}, @code{c++-mode}, or
@code{objc-mode} buffer.  You should see this message in the echo area:
@example

Using @code{cc-mode} version 4.@var{xxx}

Where @var{xxx} is the latest release minor number.

@end example

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     New Indentation Engine, Minor Modes, Getting Connected, Top
@comment  node-name,              next,                    previous,up

@chapter  New Indentation Engine
@cindex   New Indentation Engine
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@code{cc-mode} has a new indentation engine, providing a simplified, yet
flexible and general mechanism for customizing indentation. It breaks
indentation calculation into two steps. First, for the line of code being
indented, @code{cc-mode} analyzes what kind of language construct it's
looking at, then it applies user defined offsets to the current line
based on this analysis.

This section will briefly cover how indentation is calculated in
@code{cc-mode}. It is important to understand the indentation model
being used so that you will know how to customize @code{cc-mode} for
your personal coding style.

@menu
* Syntactic Analysis::
* Indentation Calculation::
@end menu


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Syntactic Analysis, Indentation Calculation, , New Indentation Engine
@comment  node-name,              next,                    previous,up
@section  Syntactic Analysis
@cindex   Syntactic Analysis
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-offsets-alist
@vindex offsets-alist (c-)
@cindex relative buffer position
@cindex syntactic symbol
@cindex syntactic component
@cindex syntactic component list
@cindex relative buffer position
The first thing @code{cc-mode} does when indenting a line of code, is to
analyze the line, determining the @dfn{syntactic component list} of the
construct on that line.  A @dfn{syntactic component} consists of a pair
of information (in lisp parlance, a @emph{cons cell}), where the first
part is a @dfn{syntactic symbol}, and the second part is a @dfn{relative
buffer position}.  Syntactic symbols describe elements of C code
@footnote{or C++, Objective-C, or Java code.  In general, for the rest
of this manual I'll use the term ``C code'' to refer to all the C-like
dialects, unless otherwise noted.}, e.g. @code{statement},
@code{substatement}, @code{class-open}, @code{class-close}, etc.
@xref{Syntactic Symbols}, for a complete list of currently recognized
syntactic symbols and their semantics.  The variable
@code{c-offsets-alist} also contains the list of currently supported
syntactic symbols.

Conceptually, a line of C code is always indented relative to the
indentation of some line higher up in the buffer.  This is represented
by the relative buffer position in the syntactic component.

It might help to see an example. Suppose we had the following code as
the only thing in a @code{c++-mode} buffer @footnote{The line numbers in
this and future examples don't actually appear in the buffer, of course!}:
@example
@group

  1: void swap( int& a, int& b )
  2: @{
  3:     int tmp = a;
  4:     a = b;
  5:     b = tmp;
  6: @}

@end group
@end example

@kindex C-c C-s
@findex c-show-syntactic-information
@findex show-syntactic-information (c-)
We can use the command @kbd{C-c C-s}
(@code{c-show-syntactic-information}) to simply report what the
syntactic analysis is for the current line.  Running this command on
line 4 this example, we'd see in the echo area@footnote{With a universal
argument (i.e. @kbd{C-u C-c C-s}) the analysis is inserted into the
buffer as a comment
on the current line.}:
@example

((statement . 35))

@end example

This tells us that the line is a statement and it is indented relative
to buffer position 35, which happens to be the @samp{i} in @code{int} on
line 3.  If you were to move Point to line 3 and hit @kbd{C-c C-s}, you
would see:
@example

((defun-block-intro . 29))

@end example

This indicates that the @samp{int} line is the first statement in a top
level function block, and is indented relative to buffer position 29,
which is the brace just after the function header.

Here's another example:
@example 
@group

  1: int add( int val, int incr, int doit )
  2: @{
  3:     if( doit )
  4:         @{
  5:             return( val + incr );
  6:         @}
  7:     return( val );
  8: @}

@end group
@end example

@noindent
Hitting @kbd{C-c C-s} on line 4 gives us:
@example

((substatement-open . 46))

@end example

@cindex substatement
@cindex substatment block
@noindent
which tells us that this is a brace that @emph{opens} a substatement
block. @footnote{A @dfn{substatement} indicates the line after an
@code{if}, @code{else}, @code{while}, @code{do}, @code{switch}, or
@code{for} statement, and a @dfn{substatement block} is a brace block
following one of those constructs.}

@cindex comment only line
Syntactic component lists can contain more than one component, and
individual syntactic components need not have relative buffer positions.
The most common example of this is a line that contains a @dfn{comment
only line}.
@example
@group

  1: void draw_list( List<Drawables>& drawables )
  2: @{
  3:         // call the virtual draw() method on each element in list
  4:     for( int i=0; i < drawables.count(), ++i )
  5:     @{
  6:         drawables[i].draw();
  7:     @}
  8: @}

@end group
@end example

@noindent
Hitting @kbd{C-c C-s} on line 3 of this example gives:
@example

((comment-intro) (defun-block-intro . 46))

@end example

@noindent
and you can see that the syntactic component list contains two syntactic
components.  Also notice that the first component,
@samp{(comment-intro)} has no relative buffer position.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Indentation Calculation, , Syntactic Analysis, New Indentation Engine
@comment  node-name,              next,                    previous,up
@section  Indentation Calculation
@cindex   Indentation Calculation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-offsets-alist
@vindex offsets-alist (c-)
Indentation for the current line is calculated using the syntactic
component list derived in step 1 above (see @ref{Syntactic Analysis}).
Each component contributes to the final total indentation of the line in
two ways.

First, the syntactic symbols are looked up in the @code{c-offsets-alist}
variable, which is an association list of syntactic symbols and the
offsets to apply for those symbols.  These offsets are added to a
running total.

Second, if the component has a relative buffer position, @code{cc-mode}
adds the column number of that position to the running total.  By adding
up the offsets and columns for every syntactic component on the list,
the final total indentation for the current line is computed.

Let's use our two code examples above to see how this works.  Here is
our first example again:
@example
@group

    1: void swap( int& a, int& b )
    2: @{
    3:     int tmp = a;
    4:     a = b;
    5:     b = tmp;
    6: @}

@end group
@end example

@kindex TAB
Let's say Point is on line 3 and we hit the @key{TAB} key to re-indent
the line.  Remember that the syntactic component list for that
line is:
@example

((defun-block-intro . 29))

@end example

@noindent
@code{cc-mode} looks up @code{defun-block-intro} in the
@code{c-offsets-alist} variable.  Let's say it finds the value @samp{4};
it adds this to the running total (initialized to zero), yielding a
running total indentation of 4 spaces.

Next @code{cc-mode} goes to buffer position 29 and asks for the current
column.  This brace is in column zero, so @code{cc-mode}
adds @samp{0} to the running total.  Since there is only one syntactic
component on the list for this line, indentation calculation is
complete, and the total indentation for the line
is 4 spaces.

Here's another example:
@example
@group

    1: int add( int val, int incr, int doit )
    2: @{
    3:     if( doit )
    4:         @{
    5:             return( val + incr );
    6:         @}
    7:     return( val );
    8: @}

@end group
@end example

If we were to hit @kbd{TAB} on line 4 in the above example, the same
basic process is performed, despite the differences in the syntactic
component list.  Remember that the list for this line is:
@example

((substatement-open . 46))

@end example

Here, @code{cc-mode} first looks up the @code{substatement-open} symbol
in @code{c-offsets-alist}. Let's say it finds the value @samp{4}.  This
yields a running total of 4.  @code{cc-mode} then goes to
buffer position 46, which is the @samp{i} in @code{if} on line 3.  This
character is in the fourth column on that line so adding this to the
running total yields an indentation for the line of 8 spaces.

Simple, huh?

Actually, the mode usually just does The Right Thing without you having
to think about it in this much detail.  But when customizing
indentation, it's helpful to understand the general indentation model
being used.

@vindex c-echo-syntactic-information-p
@vindex echo-syntactic-information-p (c-)
@cindex TAB
To help you configure @code{cc-mode}, you can set the variable
@code{c-echo-syntactic-information-p} to non-@code{nil} so that the
syntactic component list and calculated offset will always be echoed in
the minibuffer when you hit @kbd{TAB}.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Minor Modes, Commands, New Indentation Engine, Top
@comment  node-name,              next,                    previous,up

@chapter  Minor Modes
@cindex   Minor Modes
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@code{cc-mode} contains two minor-mode-like features that you should
find useful while you enter new C code.  The first is called
@dfn{auto-newline} mode, and the second is called @dfn{hungry-delete}
mode.  These minor modes can be toggled on and off independently, and
@code{cc-mode} can be configured so that it starts up with any
combination of these minor modes.  By default, both of these minor modes
are turned off.

The state of the minor modes is always reflected in the minor mode list
on the modeline of the @code{cc-mode} buffer.  When auto-newline mode is
enabled, you will see @samp{C/a} on the mode line @footnote{Remember
that the @samp{C} could be replaced with @samp{C++}, @samp{ObjC}, or
@samp{Java}.}.  When hungry delete mode is enabled you would see
@samp{C/h} and when both modes are enabled, you'd see @samp{C/ah}.

@kindex C-c C-a
@kindex C-c C-d
@kindex C-c C-t
@findex c-toggle-hungry-state
@findex c-toggle-auto-state
@findex c-toggle-auto-hungry-state
@findex toggle-hungry-state (c-)
@findex toggle-auto-state (c-)
@findex toggle-auto-hungry-state (c-)
@code{cc-mode} provides keybindings which allow you to toggle the minor
modes on the fly while editing code.  To toggle just the auto-newline
state, hit @kbd{C-c C-a} (@code{c-toggle-auto-state}).  When you do
this, you should see the @samp{a} indicator either appear or disappear
on the modeline.  Similarly, to toggle just the hungry-delete state, use
@kbd{C-c C-d} (@code{c-toggle-hungry-state}), and to toggle both states,
use @kbd{C-c C-t} (@code{c-toggle-auto-hungry-state}).

To set up the auto-newline and hungry-delete states to your preferred
values, you would need to add some lisp to your @file{.emacs} file that
called one of the @code{c-toggle-*-state} functions directly.  When
called programmatically, each function takes a numeric value, where
a positive number enables the minor mode, a negative number disables the
mode, and zero toggles the current state of the mode.

So for example, if you wanted to enable both auto-newline and
hungry-delete for all your C file editing, you could add the following
to your @file{.emacs} file:
@example

(add-hook 'c-mode-common-hook '(lambda () (c-toggle-auto-hungry-state 1)))

@end example


@cindex electric characters

@menu
* Auto-newline insertion::
* Hungry-deletion of whitespace::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Auto-newline insertion, Hungry-deletion of whitespace, , Minor Modes
@comment  node-name,              next,                    previous,up

@section  Auto-newline insertion
@cindex   Auto-newline insertion
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex electric commands
Auto-newline minor mode works by enabling certain @dfn{electric
commands}.  Electric commands are typically bound to special characters
such as the left and right braces, colons, semi-colons, etc., which when
typed, perform some magic formatting in addition to inserting the typed
character.  As a general rule, electric commands are only electric when
the following conditions apply:

@itemize @bullet
@item
Auto-newline minor mode is enabled, as evidenced by a @samp{C/a} or
@samp{C/ah} indicator on the modeline.

@cindex literal
@cindex syntactic whitespace
@item
The character was not typed inside of a literal @footnote{A
@dfn{literal} is defined in @code{cc-mode} as any comment,
string, or cpp macro definition.  These constructs are also known as
@dfn{syntactic whitespace} since they are usually ignored when scanning
C code.}.

@item
@kindex C-u
No numeric argument was supplied to the command (i.e. it was typed as
normal, with no @kbd{C-u} prefix).

@end itemize

Certain other conditions may apply on a language specific basis.  For
example, the second slash (@kbd{/}) of a C++ style line comment is
electric in @code{c++-mode}, @code{objc-mode}, and @code{java-mode}, but
not in @code{c-mode}.


@menu
* Hanging Braces::
* Hanging Colons::
* Hanging Semi-colons and commas::
* Other electric commands::
* Clean-ups::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Hanging Braces, Hanging Colons, , Auto-newline insertion
@comment  node-name,              next,                    previous,up

@subsection  Hanging Braces
@cindex   Hanging Braces
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@findex c-electric-brace
@findex electric-brace (c-)
@vindex c-hanging-braces-alist
@vindex hanging-braces-alist (c-)
@vindex c-offsets-alist
@vindex offsets-alist (c-)
When you type either an open or close brace (i.e. @kbd{@{} or @kbd{@}}),
the electric command @code{c-electric-brace} gets run.  This command has
two electric formatting behaviors.  First, it will perform some
re-indentation of the line the brace was typed on, and second, it will
add various newlines before and/or after the typed brace.
Re-indentation occurs automatically whenever the electric behavior is
enabled.  If the brace ends up on a line other than the one it was typed
on, then that line is also indented according to
@code{c-offsets-alist}.

@cindex class-open syntactic symbol
@cindex class-close syntactic symbol
@cindex defun-open syntactic symbol
@cindex defun-close syntactic symbol
@cindex inline-open syntactic symbol
@cindex inline-close syntactic symbol
@cindex brace-list-open syntactic symbol
@cindex brace-list-close syntactic symbol
@cindex brace-list-intro syntactic symbol
@cindex brace-list-entry syntactic symbol
@cindex block-open syntactic symbol
@cindex block-close syntactic symbol
@cindex substatement-open syntactic symbol
@cindex statement-case-open syntactic symbol
@cindex extern-lang-open syntactic symbol
@cindex extern-lang-close syntactic symbol

The insertion of newlines is controlled by the
@code{c-hanging-braces-alist} variable.  This variable contains a
mapping between syntactic symbols related to braces, and a list of
places to insert a newline.  The syntactic symbols that are useful for
this list are: @code{class-open}, @code{class-close}, @code{defun-open},
@code{defun-close}, @code{inline-open}, @code{inline-close},
@code{brace-list-open}, @code{brace-list-close},
@code{brace-list-intro}, @code{brace-list-entry}, @code{block-open},
@code{block-close}, @code{substatement-open}, 
@code{statement-case-open},
@code{extern-lang-open}, and @code{extern-lang-close}.
@xref{Syntactic Symbols} for a more
detailed description of these syntactic symbols.

@cindex custom indentation function
The value associated with each syntactic symbol in this association list
is called an @var{ACTION} which can be either a function or a list.
@xref{Custom Brace and Colon Hanging} for a more detailed discussion of
using a function as a brace hanging @var{ACTION}.

When the @var{ACTION} is a list, it can contain any combination of the
symbols @code{before} and @code{after}, directing @code{cc-mode} where to
put newlines in relationship to the brace being inserted.  Thus, if the
list contains only the symbol @code{after}, then the brace is said to
@dfn{hang} on the right side of the line, as in:
@example
@group

// here, open braces always `hang'
void spam( int i ) @{
    if( i == 7 ) @{
        dosomething(i);
    @}
@}


@end group
@end example

When the list contains both @code{after} and @code{before}, the braces
will appear on a line by themselves, as shown by the close braces in the
above example.  The list can also be empty, in which case no newlines
are added either before or after the brace.

For example, the default value of @code{c-hanging-braces-alist} is:
@example
@group

(defvar c-hanging-braces-alist '((brace-list-open)
                                 (substatement-open after)
                                 (block-close . c-snug-do-while)
                                 (extern-lang-open after)))

@end group
@end example

@noindent
which says that @code{brace-list-open} braces should both hang on the
right side, and allow subsequent text to follow on the same line as the
brace.  Also, @code{substatement-open} and @code{extern-lang-open}
braces should hang on the right side, but subsequent text should follow
on the next line.  Here, in the @code{block-close} entry, you also see
an example of using a function as an @var{ACTION}.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Hanging Colons, Hanging Semi-colons and commas, Hanging Braces, Auto-newline insertion
@comment  node-name,              next,                    previous,up

@subsection  Hanging Colons
@cindex   Hanging Colons
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex hanging-colons-alist (c-)
@vindex c-hanging-colons-alist
Using a mechanism similar to brace hanging (see @ref{Hanging Braces}),
colons can also be made to hang using the variable
@code{c-hanging-colons-alist}.  The syntactic symbols appropriate for
this assocation list are: @code{case-label}, @code{label},
@code{access-label}, @code{member-init-intro}, and @code{inher-intro}.
Note however, that for @code{c-hanging-colons-alist} @var{ACTION}s as
functions are not supported. See also @ref{Custom Brace and Colon
Hanging} for details.

@cindex clean-ups
In C++, double-colons are used as a scope operator but because these
colons always appear right next to each other, newlines before and after
them are controlled by a different mechanism, called @dfn{clean-ups} in
@code{cc-mode}.  @xref{Clean-ups} for details.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Hanging Semi-colons and commas, Other electric commands, Hanging Colons, Auto-newline insertion
@comment  node-name,              next,                    previous,up

@subsection  Hanging Semi-colons and commas
@cindex   Hanging Semi-colons and commas
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Semicolons and commas are also electric in @code{cc-mode}, but since
these characters do not correspond directly to syntactic symbols, a
different mechanism is used to determine whether newlines should be
automatically inserted after these characters.  @xref{Customizing
Semi-colons and Commas} for details.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Other electric commands, Clean-ups, Hanging Semi-colons and commas, Auto-newline insertion
@comment  node-name,              next,                    previous,up

@subsection  Other electric commands
@cindex   Other electric commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@kindex #
@findex c-electric-pound
@vindex c-electric-pound-behavior
@findex electric-pound (c-)
@vindex electric-pound-behavior (c-)
@vindex c-offsets-alist
@vindex offsets-alist (c-)
A few other keys also provide electric behavior.  For example
@kbd{#} (@code{c-electric-pound}) is electric when typed as
the first non-whitespace character on a line.  In this case, the
variable @code{c-electric-pound-behavior} is consulted for the electric
behavior.  This variable takes a list value, although the only element
currently defined is @code{alignleft}, which tells this command to force
the @samp{#} character into column zero.  This is useful for entering
cpp macro definitions.

@findex c-electric-star
@findex c-electric-slash
@findex electric-star (c-)
@findex electric-slash (c-)
@cindex comment-only line
Stars and slashes (i.e. @kbd{*} and @kbd{/}, @code{c-electric-star} and
@code{c-electric-slash} respectively) are also electric under
certain circumstances.  If a star is inserted as the second character of
a C style block comment on a @dfn{comment-only} line, then the comment
delimiter is indented as defined by @code{c-offsets-alist}.  A
comment-only line is defined as a line which contains only a comment, as
in:
@example
@group

void spam( int i ) 
@{
        // this is a comment-only line...
    if( i == 7 )                             // but this is not
    @{
        dosomething(i);
    @}
@}

@end group
@end example

Likewise, if a slash is inserted as the second slash in a C++ style line
comment (also only on a comment-only line), then the line is indented as
defined by @code{c-offsets-alist}.

@findex c-electric-lt-gt
@findex electric-lt-gt (c-)
@kindex <
@kindex >
Less-than and greater-than signs (@code{c-electric-lt-gt}) are also
electric, but only in C++ mode.  Hitting the second of two @kbd{<} or
@kbd{>} keys re-indents the line if it is a C++ style stream operator.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Clean-ups, , Other electric commands, Auto-newline insertion
@comment  node-name,              next,                    previous,up

@subsection  Clean-ups
@cindex   Clean-ups
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@dfn{Clean-ups} are a mechanism complementary to colon and brace
hanging.  On the surface, it would seem that clean-ups overlap the
functionality provided by the @code{c-hanging-*-alist} variables, and
similarly, clean-ups are only enabled when auto-newline minor mode is
enabled.  Clean-ups are used however to adjust code ``after-the-fact'',
i.e. to eliminate some whitespace that isn't inserted by electric
commands, or whitespace that contains intervening constructs.

@cindex literal
You can configure @code{cc-mode}'s clean-ups by setting the variable
@code{c-cleanup-list}, which is a list of clean-up symbols.  By default,
@code{cc-mode} cleans up only the @code{scope-operator} construct, which
is necessary for proper C++ support.  Note that clean-ups are only
performed when the construct does not occur within a literal (see
@ref{Auto-newline insertion}), and when there is nothing but whitespace
appearing between the individual components of the construct.

@vindex c-cleanup-list
@vindex cleanup-list (c-)
There are currently only five specific constructs that @code{cc-mode}
can clean up, as indicated by these symbols:

@itemize @bullet
@item
@code{brace-else-brace} --- cleans up @samp{@} else @{} constructs by
placing the entire construct on a single line.  Clean-up occurs when the
open brace after the @samp{else} is typed.  So for example, this:
@example
@group

void spam(int i)
@{
    if( i==7 )
    @{
        dosomething();
    @}
    else
    @{

@end group
@end example
@noindent
appears like this after the open brace is typed:
@example
@group

void spam(int i)
@{
    if( i==7 ) @{
        dosomething();
    @} else @{

@end group
@end example

@item
@code{empty-defun-braces} --- cleans up braces following a top-level
function or class definition that contains no body.  Clean up occurs
when the closing brace is typed.  Thus the following:
@example
@group

class Spam
@{
@}

@end group
@end example
@noindent
is transformed into this when the close brace is typed:
@example
@group

class Spam
@{@}

@end group
@end example

@item
@code{defun-close-semi} --- cleans up the terminating semi-colon on
top-level function or class definitions when they follow a close
brace. Clean up occurs when the semi-colon is typed.
So for example, the following:
@example
@group

class Spam
@{
@}
;

@end group
@end example
@noindent
is transformed into this when the semi-colon is typed:

@example
@group

class Spam
@{
@};

@end group
@end example

@item
@code{list-close-comma} --- cleans up commas following braces in array
and aggregate initializers.  Clean up occurs when the comma is typed.

@item
@code{scope-operator} --- cleans up double colons which may designate a
C++ scope operator split across multiple lines@footnote{Certain C++
constructs introduce ambiguous situations, so @code{scope-operator}
clean-ups may not always be correct.  This usually only occurs when
scoped identifiers appear in switch label tags.}.  Clean up occurs when
the second colon is typed.  You will always want @code{scope-operator}
in the @code{c-cleanup-list} when you are editing C++ code.

@end itemize


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Hungry-deletion of whitespace, , Auto-newline insertion, Minor Modes
@comment  node-name,              next,                    previous,up

@section  Hungry-deletion of whitespace
@cindex   Hungry-deletion of whitespace
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Hungry deletion of whitespace, or as it more commonly called,
@dfn{hungry-delete mode}, is a simple feature that some people find
extremely useful.  In fact, you might find yourself wanting
hungry-delete in @strong{all} your editing modes!

@kindex DEL
In a nutshell, when hungry-delete mode is enabled, hitting the @kbd{DEL}
character will consume all preceding whitespace, including newlines and
tabs.  This can really cut down on the number of @kbd{DEL}'s you have to
type if, for example you made a mistake on the preceding line.

@findex c-electric-delete
@findex electric-delete (c-)
@vindex c-delete-function
@vindex delete-function (c-)
@cindex literal
By default, @code{cc-mode} actually runs the command
@code{c-electric-delete} when you hit @kbd{DEL}.  When this command is
used to delete a single character (i.e. when it is called interactively
with no numeric argument), it really runs the function contained in the
variable @code{c-delete-function}.  This function is called with a
single argument, which is the number of characters to delete.
@code{c-delete-function} is also called when the @kbd{DEL} key is typed
inside a literal (see @ref{Auto-newline insertion}.  Inside a literal,
@code{c-electric-delete} is not electric, which is typical of all the
so-called electric commands.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Commands, Customizing Indentation, Minor Modes, Top
@comment  node-name,              next,                    previous,up

@chapter  Commands
@cindex   Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@menu
* Indentation Commands::
* Other Commands::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Indentation Commands, Other Commands, , Commands
@comment  node-name,              next,                    previous,up

@section  Indentation Commands
@cindex   Indentation Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@findex c-set-style
@findex set-style (c-)
Various commands are provided which allow you to conveniently re-indent
C constructs.  There are several things to
note about these indentation commands.  First, when you
change your programming style, either interactively or through some
other means, your file does @emph{not} automatically get re-indented.
When you change style parameters, you will typically need to reformat
the line, expression, or buffer to see the effects of your changes.

@cindex c-hanging- functions
@findex c-hanging-braces-alist
@findex hanging-braces-alist (c-)
Second, changing some variables have no effect on existing code, even
when you do re-indent.  For example, the @code{c-hanging-*} variables
and @code{c-cleanup-list} only affect new code as it is typed in.  So
for example, changing @code{c-hanging-braces-alist} and re-indenting the
buffer will not adjust placement of braces already in the file.

@vindex c-progress-interval
@vindex progress-interval (c-)
Third, re-indenting large portions of code is currently rather
inefficient.  Improvements have been made since previous releases of
@code{cc-mode}, and much more radical improvements are planned, but for
now you need to be aware of this @footnote{In particular, I have had
people complain about the speed that @code{cc-mode} re-indents
@code{lex(1)} output.  Lex, yacc, and other code generators usually
output some pretty perversely formatted code.  @emph{Don't} try to
indent this stuff with @code{cc-mode}!}.  Some provision has been made
to at least inform you as to the progress of the re-indentation.  The
variable @code{c-progress-interval} controls how often a progress
message is displayed.  Set this variable to @code{nil} to inhibit
progress messages.  Note that this feature only works with Emacs 19.

Also, except as noted below, re-indentation is always driven by the
same mechanisms that control on-the-fly indentation of code.  @xref{New
Indentation Engine} for details.

@findex c-indent-command
@findex indent-command (c-)
@vindex c-tab-always-indent
@vindex tab-always-indent (c-)
@kindex TAB
@cindex literal
@vindex indent-tabs-mode
@vindex c-insert-tab-function
@vindex insert-tab-function (c-)
@findex tab-to-tab-stop
To indent a single line of code, use @kbd{TAB}
(@code{c-indent-command}).  The behavior of this command is controlled
by the variable @code{c-tab-always-indent}.  When this variable is
@code{t}, @kbd{TAB} always just indents the current line.  When
@code{nil}, the line is indented only if Point is at the left margin, or
on or before the first non-whitespace character on the line, otherwise
@emph{something else happens}@footnote{Actually what happens is that the
function stored in the variable @code{c-insert-tab-function} is called.
Normally this just inserts a real tab character, or the equivalent
number of spaces, depending on the setting of the variable
@code{indent-tabs-mode}.  If you preferred, you could set
@code{c-insert-tab-function} to @code{tab-to-tab-stop} for example.}.
If the value of @code{c-tab-always-indent} is something other than
@code{t} or @code{nil} (e.g. @code{'other}), then a real tab
character@footnote{The caveat about @code{indent-tabs-mode} in the
previous footnote also applies here.}  is inserted only when Point is
inside a literal (see @ref{Auto-newline insertion}), otherwise the line
is indented.

@kindex M-C-q
@findex c-indent-exp
@findex indent-exp (c-)
To indent an entire balanced brace or parenthesis expression, use
@kbd{M-C-q} (@code{c-indent-exp}).  Note that Point should be on
the opening brace or parenthesis of the expression you want to indent.

@kindex C-c C-q
@findex c-indent-defun
@findex indent-defun (c-)
Another very convenient keystroke is @kbd{C-c C-q}
(@code{c-indent-defun}) when re-indents the entire top-level function or
class definition that encompases Point.  It leaves Point at the
same position within the buffer.

@kindex M-C-\
@findex indent-region
To indent any arbitrary region of code, use @kbd{M-C-\}
(@code{indent-region}).   This is a standard Emacs command, specially
tailored for C code in a @code{cc-mode} buffer.  Note that of course,
Point and Mark must delineate the region you
want to indent.

@kindex M-C-h
@findex c-mark-function
@findex mark-function (c-)
While not strictly an indentation function, @kbd{M-C-h}
(@code{c-mark-function}) is useful for marking the current top-level
function or class definition as the current region.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Other Commands, , Indentation Commands, Commands
@comment  node-name,              next,                    previous,up

@section  Other Commands
@cindex   Other Commands
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@code{cc-mode} contains other useful command for moving around in C
code.

@table @code
@item C-c C-u (c-up-conditional)
@kindex C-c C-u
@findex c-up-conditional
@findex up-conditional (c-)
Move Point back to the containing preprocessor conditional, leaving the
Mark behind.  A prefix argument acts as a repeat count.  With a negative
argument, move Point forward to the end of the containing
preprocessor conditional.  When going backwards, @code{#elif} is treated
like @code{#else} followed by @code{#if}.  When going forwards,
@code{#elif} is ignored.@refill

@item C-c C-p (c-backward-conditional)
@kindex C-c C-p
@findex c-backward-conditional
@findex backward-conditional (c-)
Move Point back over a preprocessor conditional, leaving Mark
behind.  A prefix argument acts as a repeat count.  With a negative
argument, move forward.

@item C-c C-n (c-forward-conditional)
@kindex C-c C-n
@findex c-forward-conditional
@findex forward-conditional (c-)
Move Point forward across a preprocessor conditional, leaving Mark
behind.  A prefix argument acts as a repeat count.  With a negative
argument, move backward.

@item M-a (c-beginning-of-statement)
@kindex ESC a
@findex c-beginning-of-statement
@findex beginning-of-statement (c-)
Move Point to the beginning of the innermost C statement.  If Point is
already at the beginning of a statement, it moves to the beginning of
the preceding statement.  With prefix argument @var{n}, move back
@var{n} @minus{} 1 statements.

If Point is within a string or comment, or next to a comment (only
whitespace between them), this command moves by sentences instead of
statements.

When called from a program, this function takes two optional arguments:
the numeric prefix argument, and a buffer position limit (don't move
back before that place).

@item M-e (c-end-of-statement)
@kindex ESC e
@findex c-end-of-statement
@findex end-of-statement (c-)
Move Point to the end of the innermost C statement.  If Point is at the
end of a statement, move to the end of the next statement.  With prefix
argument @var{n}, move forward @var{n} @minus{} 1 statements.

If Point is within a string or comment, or next to a comment (only
whitespace between them), this command moves by sentences instead of
statements.

When called from a program, this function takes two optional arguments:
the numeric prefix argument, and a buffer position limit (don't move
past that place).

@item M-x c-forward-into-nomenclature
@findex c-forward-into-nomenclature
@findex forward-into-nomenclature (c-)
A popular programming style, especially for object-oriented languages
such as C++ is to write symbols in a mixed case format, where the first
letter of each word is capitalized, and not separated by underscores.
E.g. @samp{SymbolsWithMixedCaseAndNoUnderlines}.

This command moves Point forward to end of a C++ nomenclature
section or word.  With prefix argument @var{n}, move @var{n} times.

@item M-x c-backward-into-nomenclature
@findex c-backward-into-nomenclature
@findex backward-into-nomenclature (c-)
Move Point backward to beginning of a C++ nomenclature
section or word.  With prefix argument @var{n}, move @var{n} times.  If
@var{n} is negative, move forward.

@kindex C-c :
@findex c-scope-operator
@findex scope-operator (c-)
@item C-c : (c-scope-operator)
In C++, it is also sometimes desirable to insert the double-colon scope
operator without performing the electric behavior of colon insertion.
@kbd{C-c :} does just this.

@end table

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Customizing Indentation, Syntactic Symbols, Commands, Top
@comment  node-name,              next,                    previous,up

@chapter  Customizing Indentation
@cindex   Customizing Indentation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex c-set-offset
@cindex set-offset (c-)
The @code{c-offsets-alist} variable is where you customize all your
indentations.  You simply need to decide what additional offset you want
to add for every syntactic symbol.  You can use the command @kbd{C-c
C-o} (@code{c-set-offset}) as the way to set offsets, both interactively
and from your mode hook.  Also, you can set up @emph{styles} of
indentation just like in BOCM.  Most likely, you'll
find one of the pre-defined styles will suit your needs, but if not,
this section will describe how to set up basic editing configurations.
@xref{Styles} for an explanation of how to set up named styles.

@cindex c-basic-offset
@cindex basic-offset (c-)
As mentioned previously, the variable @code{c-offsets-alist} is an
association list of syntactic symbols and the offsets to be applied for
those symbols.  In fact, these offset values can be any of an integer,
a function or variable name, or one of the following symbols: @code{+},
@code{-}, @code{++}, @code{--}, @code{*}, or @code{/}.  These symbols
describe offset in multiples of the value of the variable
@code{c-basic-offset}.  By defining a style's indentation in terms of
this fundamental variable, you can change the amount of whitespace given
to an indentation level while leaving the same relationship between
levels.  Here are the values that the special
symbols correspond to:

@table @code

@item +
@code{c-basic-offset} times 1
@item -
@code{c-basic-offset} times -1
@item ++
@code{c-basic-offset} times 2
@item --
@code{c-basic-offset} times -2
@item *
@code{c-basic-offset} times 0.5
@item /
@code{c-basic-offset} times -0.5

@end table

@noindent
So, for example, because most of the default offsets are defined in
terms of @code{+}, @code{-}, and @code{0}, if you like the general
indentation style, but you use 4 spaces instead of 2 spaces per level,
you can probably achieve your style just by changing
@code{c-basic-offset} like so (in your @file{.emacs} file)@footnote{The
reason you need to use @code{setq-default} instead of @code{setq} is
that @code{c-basic-offset} is a buffer local variable, as are most of
the @code{cc-mode} configuration variables.  If you were to put this
code in, e.g. your @code{c-mode-common-hook} function, you could use
@code{setq}.}:
@example

(setq-default c-basic-offset 4)

@end example

@noindent
This would change
@example
@group

int add( int val, int incr, int doit )
@{
  if( doit )
    @{
      return( val + incr );
    @}
  return( val );
@}

@end group
@end example
@noindent
to
@example
@group

int add( int val, int incr, int doit )
@{
    if( doit )
        @{
            return( val + incr );
        @}
    return( val );
@}

@end group
@end example


To change indentation styles more radically, you will want to change the
value associated with the syntactic symbols in the
@code{c-offsets-alist} variable.  First, I'll show you how to do that
interactively, then I'll describe how to make changes to your
@file{.emacs} file so that your changes are more permanent.

@menu
* Interactive Customization::
* Permanent Customization::
* Styles::
* Advanced Customizations::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Interactive Customization, Permanent Customization, , Customizing Indentation
@comment  node-name,              next,                    previous,up

@section  Interactive Customization
@cindex   Interactive Customization
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

As an example of how to customize indentation, let's change the
style of this example@footnote{In this an subsequent examples, the
original code is formatted using the @samp{gnu} style unless otherwise
indicated. @xref{Styles}.}:
@example
@group

1: int add( int val, int incr, int doit )
2: @{
3:   if( doit )
4:     @{
5:       return( val + incr );
6:     @}
7:   return( val );
8: @}

@end group
@end example
@noindent
to:
@example
@group

1: int add( int val, int incr, int doit )
2: @{
3:   if( doit )
4:   @{
5:     return( val + incr );
6:   @}
7:   return( val );
8: @}

@end group
@end example

In other words, we want to change the indentation of braces that open a
block following a condition so that the braces line up under the
conditional, instead of being indented.  Notice that the construct we
want to change starts on line 4.  To change the indentation of a line,
we need to see which syntactic components affect the offset calculations
for that line.  Hitting @kbd{C-c C-s} on line 4 yields:
@example

((substatement-open . 44))

@end example

@findex c-set-offset
@findex set-offset (c-)
@kindex C-c C-o
@noindent
so we know that to change the offset of the open brace, we need to
change the indentation for the @code{substatement-open} syntactic
symbol.  To do this interactively, just hit @kbd{C-c C-o}
(@code{c-set-offset}).  This prompts you for the syntactic symbol to
change, providing a reasonable default.  In this case, the default is
@code{substatement-open}, which is just the syntactic symbol we want to
change!

After you hit return, @code{cc-mode} will then prompt you for the new
offset value, with the old value as the default.  The default in this
case is @samp{+}, but we want no extra indentation so enter
@samp{0} and @kbd{RET}.  This will associate the offset 0 with the
syntactic symbol @code{substatement-open} in the @code{c-offsets-alist}
variable.

@findex c-indent-defun
@findex indent-defun (c-)
@kindex C-c C-q
To check your changes quickly, just hit @kbd{C-c C-q}
(@code{c-indent-defun}) to reindent the entire function.  The example
should now look like:
@example
@group

1: int add( int val, int incr, int doit )
2: @{
3:   if( doit )
4:   @{
5:     return( val + incr );
6:   @}
7:   return( val );
8: @}

@end group
@end example

Notice how just changing the open brace offset on line 4 is all we
needed to do.  Since the other affected lines are indented relative to
line 4, they are automatically indented the way you'd expect.  For more
complicated examples, this may not always work.  The general approach to
take is to always start adjusting offsets for lines higher up in the
file, then re-indent and see if any following lines need further
adjustments.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Permanent Customization, Styles, Interactive Customization, Customizing Indentation
@comment  node-name,              next,                    previous,up

@section  Permanent Indentation
@cindex   Permanent Indentation
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-mode-common-hook
@vindex c-mode-hook
@vindex c++-mode-hook
@vindex objc-mode-hook
@vindex java-mode-hook
@cindex hooks
To make this change permanent, you need to add some lisp code to your
@file{.emacs} file.  @code{cc-mode} provides several hooks that you can
use to customize the mode according to your coding style.  Each language
mode has its own hook, adhering to standard to Emacs major mode
conventions.  There is also one general hook:

@itemize @bullet

@item
@code{c-mode-hook} --- for C buffers only
@item
@code{c++-mode-hook} --- for C++ buffers only
@item
@code{objc-mode-hook} --- for Objective-C buffers only
@item
@code{java-mode-hook} --- for Java buffers only
@item
@code{c-mode-common-hook} --- common across all languages

@end itemize

The language hooks get run as the last thing when you enter that
language-specific mode.  The @code{c-mode-common-hook} is run by all
supported modes @emph{before} the language specific hook, and thus can
contain customizations that are common across all languages.  Most of
the examples in this section will assume you are using the common
hook@footnote{The interaction between @code{java-mode} and the hook
variables is slightly different than for the other modes.
@code{java-mode} sets the style (see @ref{Styles}) of the buffer to
@samp{java} @emph{before} running the @code{c-mode-common-hook} or
@code{java-mode-hook}.  You need to be aware of this so any style
settings in @code{c-mode-common-hook} doesn't clobber your Java style.}.

Here's a simplified example of what you can add to your @file{.emacs}
file to make the changes described in the previous section
(@ref{Interactive Customization}) more permanent.  See the Emacs
manuals for more information on customizing Emacs via hooks.
@xref{Sample .emacs File} for a more complete sample @file{.emacs} file.
@footnote{The use of @code{add-hook} in this example only works for
Emacs 19.  Workarounds are available if you are using Emacs 18.}
@example
@group

(defun my-c-mode-common-hook ()
  ;; my customizations for all of c-mode, c++-mode, objc-mode, java-mode
  (c-set-offset 'substatement-open 0)
  ;; other customizations can go here
  )
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)

@end group
@end example

For complex customizations, you will probably want to set up a
@emph{style} that groups all your customizations under a single
name.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Styles, Advanced Customizations, Permanent Customization, Customizing Indentation
@comment  node-name,              next,                    previous,up

@section  Styles
@cindex   Styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Most people only need to edit code formatted in just a few well-defined
and consistent styles.  For example, their organization might impose a
``blessed'' style that all its programmers must conform to.  Similarly,
people who work on GNU software will have to use the GNU coding style on
C code.  Some shops are more lenient, allowing some variety of coding
styles, and as programmers come and go, there could be a number of
styles in use.  For this reason, @code{cc-mode} makes it convenient for
you to set up logical groupings of customizations called @dfn{styles},
associate a single name for any particular style, and pretty easily
start editing new or existing code using these styles.  This section
describes how to set up styles and how to edit your C code using styles.

@menu
* Built-in Styles::
* Adding Styles::
* File Styles::
@end menu


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Built-in Styles, Adding Styles, , Styles
@comment  node-name,              next,                    previous,up

@subsection  Built-in Styles
@cindex   Built-in Styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If you're lucky, one of @code{cc-mode}'s built-in styles might be just
what you're looking for.  Some of the most common C and C++ styles are
already built-in.  These include:

@itemize @bullet
@item
@cindex GNU style
@code{gnu} --- coding style blessed by the Free Software Foundation
for C code in GNU programs.

@item
@cindex K&R style
@code{k&r} --- The classic Kernighan and Ritchie style for C code.

@item
@cindex BSD style
@code{bsd} --- Also known as ``Allman style'' after Eric Allman.

@item
@cindex Whitesmith style
@code{whitesmith} --- Popularized by the examples that came with
Whitesmiths C, an early commercial C compiler.

@item
@cindex Stroustrup style
@code{stroustrup} --- The classic Stroustrup style for C++ code.

@item
@cindex Ellemtel style
@code{ellemtel} --- Popular C++ coding standards as defined by
``Programming in C++, Rules and Recommendations'', Erik Nyquist and Mats
Henricson, Ellemtel @footnote{This document is ftp'able from
@code{euagate.eua.ericsson.se}}.

@item
@cindex Java style
@cindex java-mode
@code{java} --- The style for editing Java code.  Note that this style is
automatically installed when you enter @code{java-mode}.

@end itemize

@findex c-set-style
@findex set-style (c-)
If you'd like to experiment with these built-in styles you can simply
type the following in a @code{cc-mode} buffer:
@example
@group

@kbd{M-x c-set-style RET @var{STYLE-NAME} RET}

@end group
@end example
@noindent
Note that all style names are case insensitive, even the ones you define.

Setting a style in this way does @emph{not} automatically re-indent your
file.  For commands that you can use to view the effect of your changes,
see @ref{Commands}.

Once you find a built-in style you like, you can make the change
permanent by adding a call to your @file{.emacs} file.  Let's say for
example that you want to use the @samp{ellemtel} style in all your
files.  You would add this:
@example
@group

(defun my-c-mode-common-hook ()
  ;; use Ellemtel style for all C like languages
  (c-set-style "ellemtel")
  ;; other customizations can go here
  )
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)

@end group
@end example

There is one other special style you can use, called @samp{cc-mode}
style.  This style is special because all other styles implicitly
inherit from it; in other words, whenever you set a style,
@samp{cc-mode} is applied before the one you selected.  This means
your style need only define the differences between it and
@samp{cc-mode} style.

Note that for BOCM compatibility, @samp{gnu} is the default
style, and any non-style based customizations you make (i.e. in
@code{c-mode-common-hook} in your
@file{.emacs} file) will be based on @samp{gnu} style unless you do
a @code{c-set-style} as the first thing in your hook.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Adding Styles, File Styles, Built-in Styles, Styles
@comment  node-name,              next,                    previous,up

@subsection  Adding Styles
@cindex   Adding Styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-style-alist
@vindex style-alist (c-)
@findex c-add-style
@findex add-style (c-)
If none of the built-in styles is appropriate, you'll probably want to
add a new @dfn{style definition}.  Styles are kept in the
@code{c-style-alist} variable, but you should never modify this variable
directly.  Instead, @code{cc-mode} provides the function
@code{c-add-style} that you can use to easily add new styles or change
existing styles.  This function takes two arguments, a @var{stylename}
string, and an association list @var{description} of style
customizations.  If @var{stylename} is not already in
@code{c-style-alist}, the new style is added, otherwise the style is
changed to the new @var{description}.
This function also takes an optional third argument, which if
non-@code{nil}, automatically applies the new style to the current
buffer.

The sample @file{.emacs} file provides a concrete example of how a new
style can be added and automatically set.  @xref{Sample .emacs File}.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     File Styles, ,  Adding Styles, Styles
@comment  node-name,              next,                    previous,up

@subsection  File Styles
@cindex   File Styles
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex local variables
The Emacs manual describes how you can customize certain variables on a
per-file basis by including a @dfn{Local Variable} block at the end of
the file.  So far, you've only seen a functional interface to
@code{cc-mode}, which is highly inconvenient for use in a Local Variable
block.  @code{cc-mode} provides two variables that make it easier for
you to customize your style on a per-file basis.

@vindex c-file-style
@vindex file-style (c-)
@vindex c-file-offsets
@vindex file-offsets (c-)

The variable @code{c-file-style} can be set to a style name string.
When the file is visited, @code{cc-mode} will automatically set the
file's style to this style using @code{c-set-style}.

@vindex c-offsets-alist
@vindex offsets-alist (c-)
@findex c-set-offset
@findex set-offset (c-)
Another variable, @code{c-file-offsets}, takes an association list
similar to what is allowed in @code{c-offsets-alist}.  When the file is
visited, @code{cc-mode} will automatically institute these offets using
@code{c-set-offset}.

Note that file style settings (i.e. @code{c-file-style}) are applied
before file offset settings (i.e. @code{c-file-offsets})@footnote{File
styles are only supported since XEmacs 19.12 and Emacs 19.29.  They work
via the standard Emacs hook variable @code{hack-local-variables-hook}.}.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Advanced Customizations, , Styles, Customizing Indentation
@comment  node-name,              next,                    previous,up

@section  Advanced Customizations
@cindex   Advanced Customizations
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-style-alist
@vindex style-alist (c-)
@vindex c-basic-offset
@vindex basic-offset (c-)
For most users, @code{cc-mode} will support their coding styles with
very little need for more advanced customizations.  Usually, one of the
standard styles defined in @code{c-style-alist} will do the trick.  At
most, perhaps one of the syntactic symbol offsets will need to be
tweaked slightly, or maybe @code{c-basic-offset} will need to be
changed.  However, some styles require a more flexible framework for
customization, and one of the real strengths of @code{cc-mode} is that
the syntactic analysis model provides just such a framework. This allows
you to implement special indentation calculations for situations not
handled by the mode directly.

@menu
* Custom Indentation Functions::
* Custom Brace and Colon Hanging::
* Customizing Semi-colons and Commas::
* Other Special Indentations::
@end menu

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Custom Indentation Functions, Custom Brace and Colon Hanging, , Advanced Customizations
@comment  node-name,              next,                    previous,up

@subsection  Custom Indentation Functions
@cindex   Custom Indentation Functions
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex custom indentation functions
One of the most common ways to customize @code{cc-mode} is by writing
@dfn{custom indentation functions} and associating them with specific
syntactic symbols (see @ref{Syntactic Symbols}).  @code{cc-mode} itself
uses custom indentation functions to provide more sophisticated
indentation, for example when lining up C++ stream operator blocks:
@example
@group

1: void main(int argc, char**)
2: @{
3:   cout << "There were "
4:     << argc
5:     << "arguments passed to the program"
6:     << endl;
7: @}

@end group
@end example

In this example, lines 4 through 6 are assigned the @code{stream-op}
syntactic symbol.  Here, @code{stream-op} has an offset of @code{+}, and
with a @code{c-basic-offset} of 2, you can see that lines 4 through 6
are simply indented two spaces to the right of line 3.  But perhaps we'd
like @code{cc-mode} to be a little more intelligent so that it lines up
all the @samp{<<} symbols in lines 3 through 6.  To do this, we have
to write a custom indentation function which finds the column of first
stream operator on the first line of the statement.  Here is the lisp
code (from the @file{cc-mode.el} source file) that implements this:
@example
@group

(defun c-lineup-streamop (langelem)
  ;; lineup stream operators
  (save-excursion
    (let* ((relpos (cdr langelem))
           (curcol (progn (goto-char relpos)
                          (current-column))))
      (re-search-forward "<<\\|>>" (c-point 'eol) 'move)
      (goto-char (match-beginning 0))
      (- (current-column) curcol))))

@end group
@end example
@noindent
Custom indent functions take a single argument, which is a syntactic
component cons cell (see @ref{Syntactic Analysis}).  The
function returns an integer offset value that will be added to the
running total indentation for the line.  Note that what actually gets
returned is the difference between the column that the first stream
operator is on, and the column of the buffer relative position passed in
the function's argument.  Remember that @code{cc-mode} automatically
adds in the column of the component's relative buffer position and we
don't want that value added into the final total twice.

@cindex stream-op syntactic symbol
@findex c-lineup-streamop
@findex lineup-streamop (c-)
Now, to associate the function @code{c-lineup-streamop} with the
@code{stream-op} syntactic symbol, we can add something like the
following to our @code{c++-mode-hook}@footnote{It probably makes more
sense to add this to @code{c++-mode-hook} than @code{c-mode-common-hook}
since stream operators are only relevent for C++.}:
@example

(c-set-offset 'stream-op 'c-lineup-streamop)

@end example

@kindex C-c C-q
Now the function looks like this after re-indenting (using @kbd{C-c
C-q}):
@example
@group

1: void main(int argc, char**)
2: @{
3:   cout << "There were "
4:        << argc
5:        << "arguments passed to the program"
6:        << endl;
7: @}

@end group
@end example

@vindex c-offsets-alist
@vindex offsets-alist (c-)
Custom indentation functions can be as simple or as complex as you like,
and any syntactic symbol that appears in @code{c-offsets-alist} can have
a custom indentation function associated with it.  @code{cc-mode} comes
with several standard custom indentation functions, not all of which are
used by the default styles.

@itemize @bullet
@item
@findex c-lineup-arglist
@findex lineup-arglist (c-)
@code{c-lineup-arglist} --- lines up function argument lines under the
argument on the previous line.

@item
@findex c-lineup-arglist-intro-after-paren
@findex lineup-arglist-intro-after-paren (c-)
@code{c-lineup-arglist-intro-after-paren} --- similar to
@code{c-lineup-arglist}, but works for argument lists that begin with an
open parenthesis followed by a newline.

@item
@findex c-lineup-arglist-close-under-paren
@findex lineup-arglist-close-under-paren (c-)
@code{c-lineup-arglist-close-under-paren} --- set your
@code{arglist-close} syntactic symbol to this line-up function so that
parentheses that close argument lists will line up under the parenthesis
that opened the argument list.

@item
@findex c-lineup-streamop
@findex lineup-streamop (c-)
@code{c-lineup-streamop} --- lines up C++ stream operators
(e.g. @samp{<<} and @samp{>>}).

@item
@findex c-lineup-multi-inher
@findex lineup-multi-inher (c-)
@code{c-lineup-multi-inher} --- lines up multiple inheritance lines.

@item
@findex c-lineup-C-comments
@findex lineup-C-comments (c-)
@code{c-lineup-C-comments} --- lines up C block comment continuation
lines.

@item
@findex c-lineup-comment
@findex lineup-comment (c-)
@vindex c-comment-only-line-offset
@vindex comment-only-line-offset (c-)
@code{c-lineup-comment} --- implements the old comment line up behavior
specified by the variable @code{c-comment-only-line-offset}.

@item
@findex c-lineup-runin-statements
@findex lineup-runin-statements (c-)
@code{c-lineup-runin-statements} --- lines up @code{statement}s for coding
standards which place the first statement in a block on the same line as
the block opening brace.

@item
@findex c-lineup-math
@findex lineup-math (c-)
@code{c-lineup-math} --- lines up math @code{statement-cont} lines under
the previous line after the equals sign.

@item
@findex c-lineup-ObjC-method-call
@findex lineup-ObjC-method-call (c-)
@code{c-lineup-ObjC-method-call} --- for Objective-C code, lines up
selector arguments just after the message receiver.

@item
@findex c-lineup-ObjC-method-args
@findex lineup-ObjC-method-args (c-)
@code{c-lineup-ObjC-method-args} --- for Objective-C code, lines up the
colons that separate arguments by aligning colons vertically.

@item
@findex c-lineup-ObjC-method-args-2
@findex lineup-ObjC-method-args-2 (c-)
@code{c-lineup-ObjC-method-args-2} --- similar to
@code{c-lineup-ObjC-method-args} but lines up the colon on the current
line with the colon on the previous line.

@end itemize

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Custom Brace and Colon Hanging, Customizing Semi-colons and Commas, Custom Indentation Functions, Advanced Customizations
@comment  node-name,              next,                    previous,up

@subsection  Custom Brace and Colon Hanging
@cindex   Custom Brace and Colon Hanging
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-hanging-braces-alist
@vindex hanging-braces-alist (c-)
Syntactic symbols aren't the only place where you can customize
@code{cc-mode} with the lisp equivalent of callback functions.  Brace
``hanginess'' can also be determined by custom functions associated with
syntactic symbols on the @code{c-hanging-braces-alist} variable.
Remember that @var{ACTION}'s are typically a list containing some
combination of the symbols @code{before} and @code{after} (see
@ref{Hanging Braces}).  However, an @var{ACTION} can also be a function
symbol which gets called when a brace matching that syntactic symbol is
typed.

@cindex customizing brace hanging
These @var{ACTION} functions are called with two arguments: the
syntactic symbol for the brace, and the buffer position at which the
brace was inserted.  The @var{ACTION} function is expected to return a
list containing some combination of @code{before} and @code{after}.  The
function can also return @code{nil}.  This return value has the normal
brace hanging semantics.

As an example, @code{cc-mode} itself uses this feature to dynamically
determine the hanginess of braces which close ``do-while''
constructs:
@example
@group

void do_list( int count, char** atleast_one_string )
@{
    int i=0;
    do @{
        handle_string( atleast_one_string[i] );
        i++;
    @} while( i < count );
@}

@end group
@end example

@findex c-snug-do-while
@findex snug-do-while (c-)
@code{cc-mode} assigns the @code{block-close} syntactic symbol to the
brace that closes the @code{do} construct, and normally we'd like the
line that follows a @code{block-close} brace to begin on a separate
line.  However, with ``do-while'' constructs, we want the
@code{while} clause to follow the closing brace.  To do this, we
associate the @code{block-close} symbol with the @var{ACTION} function
@code{c-snug-do-while}:
@example

(defun c-snug-do-while (syntax pos)
  "Dynamically calculate brace hanginess for do-while statements.
Using this function, `while' clauses that end a `do-while' block will
remain on the same line as the brace that closes that block.

See `c-hanging-braces-alist' for how to utilize this function as an
ACTION associated with `block-close' syntax."
  (save-excursion
    (let (langelem)
      (if (and (eq syntax 'block-close)
               (setq langelem (assq 'block-close c-syntactic-context))
               (progn (goto-char (cdr langelem))
                      (if (= (following-char) ?@{)
                          (forward-sexp -1))
                      (looking-at "\\<do\\>[^_]")))
          '(before)
        '(before after)))))

@end example

This function simply looks to see if the brace closes a ``do-while''
clause and if so, returns the list @samp{(before)} indicating
that a newline should be inserted before the brace, but not after it.
In all other cases, it returns the list @samp{(before after)} so
that the brace appears on a line by itself.

@vindex c-syntactic-context
@vindex syntactic-context (c-)
During the call to the brace hanging @var{ACTION} function, the variable
@code{c-syntactic-context} is bound to the full syntactic analysis list.

@cindex customizing colon hanging
@vindex c-hanging-colon-alist
@vindex hanging-colon-alist (c-)
Note that for symmetry, colon hanginess should be customizable by
allowing function symbols as @var{ACTION}s on the
@code{c-hanging-colon-alist} variable.  Since no use has actually been
found for this feature, it isn't currently implemented.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Customizing Semi-colons and Commas, Other Special Indentations, Custom Brace and Colon Hanging, Advanced Customizations
@comment  node-name,              next,                    previous,up

@subsection  Customizing Semi-colons and Commas
@cindex   Customizing Semi-colons and Commas
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@cindex customizing semi-colons and commas
@vindex c-hanging-semi&comma-criteria
@vindex hanging-semi&comma-criteria (c-)
You can also customize the insertion of newlines after semi-colons and
commas, when the auto-newline minor mode is enabled (see @ref{Minor
Modes}).  This is controlled by the variable
@code{c-hanging-semi&comma-criteria}, which contains a list of functions
that are called in the order they appear.  Each function is called with
zero arguments, and is expected to return one of the following values:

@itemize @bullet
@item
non-@code{nil} --- A newline is inserted, and no more functions from the
list are called.

@item
@code{stop} --- No more functions from the list are called, but no
newline is inserted.

@item
@code{nil} --- No determination is made, and the next function in the
list is called.

@end itemize

If every function in the list is called without a determination being
made, then no newline is added. The default value for this variable is a
list containing a single function which inserts newlines only after
semi-colons which do not appear inside parenthesis lists (i.e. those
that separate @code{for}-clause statements).

Here's an example of a criteria function that will prevent newlines from
being inserted after semicolons when there is a non-blank following
line.  Otherwise, it makes no determination:

@example
@group

(defun my-semicolon-criteria ()
  (save-excursion
    (if (and (= last-command-char ?\;)
             (zerop (forward-line 1))
             (not (looking-at "^[ \t]*$")))
        'stop
      nil)))

@end group
@end example


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node     Other Special Indentations, , Customizing Semi-colons and Commas, Advanced Customizations
@comment  node-name,              next,                    previous,up

@subsection  Other Special Indentations
@cindex   Customizing Semi-colons and Commas
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-label-minimum-indentation
@vindex label-minimum-indentation (c-)
In @samp{gnu} style (see @ref{Built-in Styles}), a minimum indentation
is imposed on lines with @code{label} or @code{case-label} syntax.  This
minimum indentation is controlled by the variable
@code{c-label-minimum-indentation}.  The default value for this variable
is 1.

@vindex c-special-indent-hook
@vindex special-indent-hook (c-)
One other customization variable is available in @code{cc-mode}:
@code{c-special-indent-hook}.  This is a standard hook variable that is
called after every line is indented by @code{cc-mode}.  You can use it
to do any special indentation or line adjustments your style dictates,
such as adding extra indentation to constructors or destructor
declarations in a class definition, etc.  Note however, that you should
not change Point or Mark inside your @code{c-special-indent-hook}
functions (i.e. you'll probably want to wrap your function in a
@code{save-excursion}).

Setting @code{c-special-indent-hook} in your style definition is handled
slightly differently than other variables.  In your style definition,
you should set the value for
@code{c-special-indent-hook} to a function or list of functions, which
will be appended to @code{c-special-indent-hook} using @code{add-hook}.
That way, the current setting for the buffer local value of
@code{c-special-indent-hook} won't be overridden.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Syntactic Symbols, Performance Issues, Customizing Indentation, Top
@comment  node-name,              next,                    previous,up

@chapter  Syntactic Symbols
@cindex   Syntactic Symbols
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@vindex c-offsets-alist
@vindex offsets-alist (c-)

Here is a complete list of the recognized syntactic symbols as described
in the @code{c-offsets-alist} variable, along with a brief description.
More detailed descriptions follow below.

@itemize @bullet
@item
@code{string} --- inside multi-line string
@item
@code{c} --- inside a multi-line C style block comment
@item
@code{defun-open} --- brace that opens a function definition
@item
@code{defun-close} --- brace that closes a function definition
@item
@code{defun-block-intro} --- the first line in a top-level defun
@item
@code{class-open} --- brace that opens a class definition
@item
@code{class-close} --- brace that closes a class definition
@item
@code{inline-open} --- brace that opens an in-class inline method
@item
@code{inline-close} --- brace that closes an in-class inline method
@item
@code{ansi-funcdecl-cont} --- the nether region between an ANSI function
declaration and the defun opening brace
@item
@code{knr-argdecl-intro} --- first line of a K&R C argument declaration
@item
@code{knr-argdecl} --- subsequent lines in a K&R C argument declaration
@item
@code{topmost-intro} --- the first line in a topmost construct definition
@item
@code{topmost-intro-cont} --- topmost definition continuation lines
@item
@code{member-init-intro} --- first line in a member initialization list
@item
@code{member-init-cont} --- subsequent member initialization list lines
@item
@code{inher-intro} --- first line of a multiple inheritance list
@item
@code{inher-cont} --- subsequent multiple inheritance lines
@item
@code{block-open} --- statement block open brace
@item
@code{block-close} --- statement block close brace
@item
@code{brace-list-open} --- open brace of an enum or static array list
@item
@code{brace-list-close} --- close brace of an enum or static array list
@item
@code{brace-list-intro} --- first line in an enum or static array list
@item
@code{brace-list-entry} --- subsequent lines in an enum or static array list
@item
@code{statement} --- a C (or like) statement
@item
@code{statement-cont} --- a continuation of a C (or like) statement
@item
@code{statement-block-intro} --- the first line in a new statement block
@item
@code{statement-case-intro} --- the first line in a case `block'
@item
@code{statement-case-open} --- the first line in a case block starting
with brace
@item
@code{substatement} --- the first line after an if/while/for/do/else
@item
@code{substatement-open} --- the brace that opens a substatement block
@item
@code{case-label} --- a case or default label
@item
@code{access-label} --- C++ private/protected/public access label
@item
@code{label} --- any non-special C (or like) label
@item
@code{do-while-closure} --- the `while' that ends a do/while construct
@item
@code{else-clause} --- the `else' of an if/else construct
@item
@code{comment-intro} --- a line containing only a comment introduction
@item
@code{arglist-intro} --- the first line in an argument list
@item
@code{arglist-cont} --- subsequent argument list lines when no arguments
follow on the same line as the the arglist opening paren
@item
@code{arglist-cont-nonempty} --- subsequent argument list lines when at
least one argument follows on the same line as the arglist opening paren
@item
@code{arglist-close} --- the solo close paren of an argument list
@item
@code{stream-op} --- lines continuing a stream operator construct
@item
@code{inclass} --- the construct is nested inside a class definition
@item
@code{cpp-macro} --- the start of a cpp macro
@item
@code{friend} --- a C++ friend declaration
@item
@code{objc-method-intro} --- the first line of an Objective-C method definition
@item
@code{objc-method-args-cont} --- lines continuing an Objective-C method
definition 
@item
@code{objc-method-call-cont} --- lines continuing an Objective-C method call
@item
@code{extern-lang-open} --- brace that opens an external language block
@item
@code{extern-lang-close} --- brace that closes an external language block
@item
@code{inextern-lang} --- analogous to `inclass' syntactic symbol
@end itemize

@cindex -open syntactic symbols
@cindex -close syntactic symbols
Most syntactic symbol names follow a general naming convention.  When a
line begins with an open or close brace, the syntactic symbol will
contain the suffix @code{-open} or @code{-close} respectively.

@cindex -intro syntactic symbols
@cindex -cont syntactic symbols
@cindex -block-intro syntactic symbols
Usually, a distinction is made between the first line that introduces a
construct and lines that continue a construct, and the syntactic symbols
that represent these lines will contain the suffix @code{-intro} or
@code{-cont} respectively.  As a sub-classification of this scheme, a
line which is the first of a particular brace block construct will
contain the suffix @code{-block-intro}.

@kindex C-c C-s
Let's look at some examples to understand how this works.  Remember that
you can check the syntax of any line by using @kbd{C-c C-s}.
@example
@group

  1: void
  2: swap( int& a, int& b )
  3: @{
  4:     int tmp = a;
  5:     a = b;
  6:     b = tmp;
  7:     int ignored =
  8:         a + b;
  9: @}

@end group
@end example

@cindex topmost-intro syntactic symbol
@cindex topmost-intro-cont syntactic symbol
@cindex defun-open syntactic symbol
@cindex defun-close syntactic symbol
@cindex defun-block-intro syntactic symbol
Line 1 shows a @code{topmost-intro} since it is the first line that
introduces a top-level construct.  Line 2 is a continuation of the
top-level construct introduction so it has the syntax
@code{topmost-intro-cont}.  Line 3 shows a @code{defun-open} since it is
the brace that opens a top-level function definition.  Line 9 is a
@code{defun-close} since it contains the brace that closes the top-level
function definition.  Line 4 is a @code{defun-block-intro}, i.e. it is
the first line of a brace-block, which happens to be enclosed in a
top-level function definition.

@cindex statement syntactic symbol
@cindex statement-cont syntactic symbol
Lines 5, 6, and 7 are all given @code{statement} syntax since there
isn't much special about them.  Note however that line 8 is given
@code{statement-cont} syntax since it continues the statement begun
on the previous line.

Here's another example, which illustrates some C++ class syntactic
symbols:
@example
@group

   1: class Bass
   2:     : public Guitar,
   3:       public Amplifiable
   4: @{
   5: public:
   6:     Bass()
   7:         : eString( new BassString( 0.105 )),
   8:           aString( new BassString( 0.085 )),
   9:           dString( new BassString( 0.065 )),
  10:           gString( new BassString( 0.045 ))
  11:     @{
  12:         eString.tune( 'E' );
  13:         aString.tune( 'A' );
  14:         dString.tune( 'D' );
  15:         gString.tune( 'G' );
  16:     @}
  17:     friend class Luthier;
  18: @}

@end group
@end example

@cindex class-open syntactic symbol
@cindex class-close syntactic symbol
As in the previous example, line 1 has the @code{topmost-intro} syntax.
Here however, the brace that opens a C++ class definition on line 4 is
assigned the @code{class-open} syntax.  Note that in C++, classes,
structs, and unions are essentially equivalent syntactically (and are
very similar semantically), so replacing the @code{class} keyword in the
example above with @code{struct} or @code{union} would still result in a
syntax of @code{class-open} for line 4 @footnote{This is the case even
for C and Objective-C.  For consistency, structs in all supported
languages are syntactically equivalent to classes.  Note however that
the keyword @code{class} is meaningless in C and Objective-C.}.
Similarly, line 18 is assigned @code{class-close} syntax.

@cindex inher-intro syntactic symbol
@cindex inher-cont syntactic symbol
Line 2 introduces the inheritance list for the class so it is assigned
the @code{inher-intro} syntax, and line 3, which continues the
inheritance list is given @code{inher-cont} syntax.

@cindex access-label syntactic symbol
@cindex inclass syntactic symbol
Hitting @kbd{C-c C-s} on line 5 shows the following analysis:

@example
@group

@code{((inclass . 1) (access-label . 67))}

@end group
@end example

@noindent
The primary syntactic symbol for this line is @code{access-label} as
this a label keyword that specifies access protection in C++.  However,
because this line is also a top-level construct inside a class
definition, the analysis actually shows two syntactic symbols.  The
other syntactic symbol assigned to this line is @code{inclass}.
Similarly, line 6 is given both @code{inclass} and @code{topmost-intro}
syntax:

@example
@group

@code{((inclass . 58) (topmost-intro . 60))}

@end group
@end example

@cindex member-init-intro syntactic symbol
@cindex member-init-cont syntactic symbol
Line 7 introduces a C++ member initialization list and as such is given
@code{member-init-intro} syntax.  Note that in this case it is
@emph{not} assigned @code{inclass} since this is not considered a
top-level construct.  Lines 8 through 10 are all assigned
@code{member-init-cont} since they continue the member initialization
list started on line 7.

@cindex in-class inline methods
@cindex inline-open syntactic symbol
@cindex inline-close syntactic symbol
But the line 11's analysis is a bit more complicated:

@example
@group

@code{((inclass . 1) (inline-open))}

@end group
@end example

This line is assigned a syntax of both @code{inline-open} and
@code{inclass} because it opens an @dfn{in-class} C++ inline method
definition.  This is distinct from, but related to, the C++ notion of an
inline function in that its definition occurs inside an enclosing class
definition, which in C++ implies that the function should be inlined.
For example, if the definition of the @code{Bass} constructor appeared
outside the class definition, line 11 would be given the
@code{defun-open} syntax, even if the keyword @code{inline} appeared
before the method name, as in:
@example
@group

class Bass
    : public Guitar,
      public Amplifiable
@{
public:
    Bass();
@}

inline
Bass::Bass()
    : eString( new BassString( 0.105 )),
      aString( new BassString( 0.085 )),
      dString( new BassString( 0.065 )),
      gString( new BassString( 0.045 ))
@{
    eString.tune( 'E' );
    aString.tune( 'A' );
    dString.tune( 'D' );
    gString.tune( 'G' );
@}

@end group
@end example

@cindex friend syntactic symbol
Returning to the previous example, line 16 is given @code{inline-close}
syntax, while line 12 is given @code{defun-block-open} syntax, and lines
13 through 15 are all given @code{statement} syntax.  Line 17 is
interesting in that it's syntactic analysis list contains three
elements:

@example

@code{((friend) (inclass . 58) (topmost-intro . 380))}

@end example

The @code{friend} syntactic symbol is a modifier that typically does not
have a relative buffer position.

Here is another (totally contrived) example which illustrates how syntax
is assigned to various conditional constructs:
@example
@group

   1: void spam( int index )
   2: @{
   3:     for( int i=0; i<index; i++ )
   4:     @{
   5:         if( i == 10 )
   6:         @{
   7:             do_something_special();
   8:         @}
   9:         else
  10:             do_something( i );
  11:     @}
  12:     do @{
  13:         another_thing( i-- );
  14:     @}
  15:     while( i > 0 );
  16: @}


@end group
@end example

@noindent
Only the lines that illustrate new syntactic symbols will be discussed.

@cindex substatement-open syntactic symbol
@cindex substatement-block-intro syntactic symbol
@cindex block-close syntactic symbol
Line 4 has a brace which opens a conditional's substatement block.  It
is thus assigned @code{substatement-open} syntax, and since line 5 is
the first line in the substatement block, it is assigned
@code{substatement-block-intro} syntax.  Lines 6 and 7 are assigned
similar syntax.  Line 8 contains the brace that closes the inner
substatement block.  It is given the syntax @code{block-close},
as are lines 11 and 14.

@cindex else-clause syntactic symbol
@cindex substatement syntactic symbol
Line 9 is a little different --- since it contains the keyword
@code{else} matching the @code{if} statement introduced on line 5, it is
given the @code{else-clause} syntax.  Note also that line 10 is slightly
different too.  Because @code{else} is considered a conditional
introducing keyword @footnote{The list of conditional keywords are (in
C, C++, Objective-C, and Java): @code{for}, @code{if}, @code{do},
@code{else}, @code{while}, and @code{switch}.  C++ and Java have two
additional conditional keywords: @code{try} and @code{catch}.  Java also
has the @code{finally} and @code{synchronized} keywords.}, and because
the following substatement is not a brace block, line 10 is assigned the
@code{substatement} syntax.

@cindex do-while-closure syntactic symbol
One other difference is seen on line 15.  The @code{while} construct
that closes a @code{do} conditional is given the special syntax
@code{do-while-closure} if it appears on a line by itself.  Note that if
the @code{while} appeared on the same line as the preceding close brace,
that line would have been assigned @code{block-close} syntax instead.

Switch statements have their own set of syntactic symbols.  Here's an
example:
@example
@group

   1: void spam( enum Ingredient i )
   2: @{
   3:     switch( i ) @{
   4:     case Ham:
   5:         be_a_pig();
   6:         break;
   7:     case Salt:
   8:         drink_some_water();
   9:         break;
  10:     default:
  11:         @{
  12:             what_is_it();
  13:             break;
  14:         @}
  15:     @}
  14: @}

@end group
@end example

@cindex case-label syntactic symbol
@cindex statement-case-intro syntactic symbol
@cindex statement-case-open syntactic symbol
Here, lines 4, 7, and 10 are all assigned @code{case-label} syntax,
while lines 5 and 8 are assigned @code{statement-case-intro}.  Line 11
is treated slightly differently since it contains a brace that opens a
block --- it is given @code{statement-case-open} syntax.

@cindex brace lists
There are a set of syntactic symbols that are used to recognize
constructs inside of brace lists.  A brace list is defined as an
@code{enum} or aggregate initializer list, such as might statically
initialize an array of structs.  For example:
@example
@group

  1: static char* ingredients[] =
  2: @{
  3:     "Ham",
  4:     "Salt",
  5:     NULL
  6: @}

@end group
@end example

@cindex brace-list-open syntactic symbol
@cindex brace-list-intro syntactic symbol
@cindex brace-list-close syntactic symbol
@cindex brace-list-entry syntactic symbol
Following convention, line 2 in this example is assigned
@code{brace-list-open} syntax, and line 3 is assigned
@code{brace-list-intro} syntax.  Likewise, line 6 is assigned
@code{brace-list-close} syntax.  Lines 4 and 5 however, are assigned
@code{brace-list-entry} syntax, as would all subsequent lines in this
initializer list.

External language definition blocks also have their own syntactic
symbols.  In this example:
@example
@group

   1: extern "C" 
   2: @{
   3:     int thing_one( int );
   4:     int thing_two( double );
   5: @}

@end group
@end example

@cindex extern-lang-open syntactic symbol
@cindex extern-lang-close syntactic symbol
@cindex inextern-lang syntactic symbol
@cindex inclass syntactic symbol
@noindent
line 2 is given the @code{extern-lang-open} syntax while line 5 is given
the @code{extern-lang-close} syntax.  The analysis for line 3 yields:
@code{((inextern-lang) (topmost-intro . 14))}, where
@code{inextern-lang} is a modifier similar in purpose to @code{inclass}.

A number of syntactic symbols are associated with parenthesis lists,
a.k.a argument lists, as found in function declarations and function
calls.  This example illustrates these:
@example
@group

   1: void a_function( int line1,
   2:                  int line2 );
   3: 
   4: void a_longer_function(
   5:     int line1,
   6:     int line2
   7:     );
   8: 
   9: void call_them( int line1, int line2 )
  10: @{
  11:     a_function(
  12:         line1,
  13:         line2
  14:         );
  15: 
  16:     a_longer_function( line1,
  17:                        line2 );
  18: @}

@end group
@end example

@cindex arglist-intro syntactic symbol
@cindex arglist-close syntactic symbol
Lines 5 and 12 are assigned @code{arglist-intro} syntax since they are
the first line following the open parenthesis, and lines 7 and 14 are
assigned @code{arglist-close} syntax since they contain the parenthesis
that closes the argument list.

@cindex arglist-cont-nonempty syntactic symbol
@cindex arglist-cont syntactic symbol
Lines that continue argument lists can be assigned one of two syntactic
symbols.  For example, Lines 2 and 17
are assigned @code{arglist-cont-nonempty} syntax.  What this means
is that they continue an argument list, but that the line containing the
parenthesis that opens the list is @emph{not empty} following the open
parenthesis.  Contrast this against lines 6 and 13 which are assigned
@code{arglist-cont} syntax.  This is because the parenthesis that opens
their argument lists is the last character on that line @footnote{The
need for this somewhat confusing arrangement is that the typical
indentation desired for these lines is calculated differently.
This should be simplified in version 5 of @code{cc-mode}, along with the
added distinction between argument lists in function declarations, and
argument lists in function calls.}.

Note that there is no @code{arglist-open} syntax.  This is because any
parenthesis that opens an argument list, appearing on a separate line,
is assigned the @code{statement-cont} syntax instead.

A few miscellaneous syntactic symbols that haven't been previously
covered are illustrated by this example:
@example
@group

   1: void Bass::play( int volume )
   2: const
   3: @{
   4:     /* this line starts a multi-line
   5:      * comment.  This line should get `c' syntax */
   6: 
   7:     char* a_long_multiline_string = "This line starts a multi-line \
   8: string.  This line should get `string' syntax.";
   9: 
  10:   note:
  11:     @{
  12: #ifdef LOCK
  13:         Lock acquire();
  14: #endif // LOCK
  15:         slap_pop();
  16:         cout << "I played "
  17:              << "a note\n";
  18:     @}
  19: @}

@end group
@end example

@cindex modifier syntactic symbol
The lines to note in this example include:

@itemize @bullet

@cindex ansi-funcdecl-cont syntactic symbol
@item
line 2, assigned the @code{ansi-funcdecl-cont} syntax;

@cindex comment-intro syntactic symbol
@item
line 4, assigned both @code{defun-block-intro} @emph{and}
@code{comment-intro} syntax @footnote{The @code{comment-intro} syntactic
symbol is is another example of a @dfn{modifier} since it always appears
on a syntactic analysis list with other symbols, and rarely has an
associated relative buffer position.};

@cindex c syntactic symbol
@item
line 5, assigned @code{c} syntax;

@item
@cindex syntactic whitespace
line 6 which, even though it contains nothing but whitespace, is
assigned @code{defun-block-intro}.  Note that the appearance of the
comment on lines 4 and 5 do not cause line 6 to be assigned
@code{statement} syntax because comments are considered to be
@dfn{syntactic whitespace}, which are ignored when analyzing
code;

@cindex string syntactic symbol
@item
line 8, assigned @code{string} syntax;

@cindex label syntactic symbol
@item
line 10, assigned @code{label} syntax;

@cindex block-open syntactic symbol
@item
line 11, assigned @code{block-open} syntax;

@cindex cpp-macro syntactic symbol
@item
lines 12 and 14, assigned @code{cpp-macro} syntax;

@cindex stream-op syntactic symbol
@item
line 17, assigned @code{stream-op} syntax @footnote{In C++ only.}.

@end itemize

In Objective-C buffers, there are three additional syntactic symbols
assigned to various message calling constructs.  Here's an example
illustrating these:
@example
@group

  1: - (void)setDelegate:anObject
  2:           withStuff:stuff
  3: @{
  4:     [delegate masterWillRebind:self
  5:               toDelegate:anObject
  6:               withExtraStuff:stuff];
  7: @}

@end group
@end example

@cindex objc-method-intro syntactic symbol
@cindex objc-method-args-cont syntactic symbol
@cindex objc-method-call-cont syntactic symbol
Here, line 1 is assigned @code{objc-method-intro} syntax, and line 2 is
assigned @code{objc-method-args-cont} syntax.  Lines 5 and 6 are both
assigned @code{objc-method-call-cont} syntax.

@cindex knr-argdecl-intro
@cindex knr-argdecl
Two other syntactic symbols can appear in old style, non-prototyped C
code @footnote{a.k.a. K&R C, or Kernighan & Ritchie C}:
@example
@group

  1: int add_three_integers(a, b, c)
  2:      int a;
  3:      int b;
  4:      int c;
  5: @{
  6:     return a + b + c;
  7: @}

@end group
@end example

Here, line 2 is the first line in an argument declaration list and so is
given the @code{knr-argdecl-intro} syntactic symbol.  Subsequent lines
(i.e. lines 3 and 4 in this example), are given @code{knr-argdecl}
syntax.

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Performance Issues, Frequently Asked Questions, Syntactic Symbols, Top
@comment  node-name,              next,                    previous,up

@chapter  Performance Issues
@cindex   Performance Issues
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

C and it's derivative languages are highly complex creatures.  Often,
ambiguous code situations arise that require @code{cc-mode} to scan
large portions of the buffer to determine syntactic context.  Such
pathological code@footnote{such as the output of @code{lex(1)}!}
can cause @code{cc-mode} to perform fairly badly.
This section identifies some of the coding styles to watch out for, and
suggests some workarounds that you can use to improve performance.

Note that this is an area that will get a lot of attention in
@code{cc-mode} version 5.  The mode should end up being much faster, at
the expense of dropping Emacs 18 support, owing to the implementation of
syntactic analysis caching.

Because @code{cc-mode} has to scan the buffer backwards from the current
insertion point, and because C's syntax is fairly difficult to parse in
the backwards direction, @code{cc-mode} often tries to find the nearest
position higher up in the buffer from which to begin a forward scan.
The farther this position is from the current insertion point, the
slower the mode gets.  Some coding styles can even force @code{cc-mode}
to scan from the beginning of the buffer!

@findex beginning-of-defun
@findex defun-prompt-regexp
One of the simplest things you can do to reduce scan time, is make sure
any brace that opens a top-level block construct always appears in the
leftmost column.  This is actually an Emacs constraint, as embodied in
the @code{beginning-of-defun} function which @code{cc-mode} uses
heavily.  If you insist on hanging top-level open braces on the right
side of the line, then you should set the variable
@code{defun-prompt-regexp} to something reasonable @footnote{Note that
this variable is only defined in Emacs 19.}, however that ``something
reasonable'' is difficult to define, so @code{cc-mode} doesn't do it
for you.

You will probably notice pathological behavior from @code{cc-mode} when
working in files containing large amounts of cpp macros.  This is
because @code{cc-mode} cannot quickly skip backwards over these lines.

@vindex c-recognize-knr-p
@vindex recognize-knr-p (c-)
Previous versions of @code{cc-mode} had potential performance problems
when recognizing ``K&R'' style function argument declarations.  This was
because there are ambiguities in the C syntax when K&R style argument
lists are used (it is hard to distinguish them from top-level
declarations).  @code{cc-mode} has adopted BOCM's convention for
limiting the search: it assumes that argdecls are indented at least one
space, and that the function headers are not indented at all.  With
current versions of @code{cc-mode},
@code{c-recognize-knr-p} is deprecated.

@cindex @file{cc-lobotomy.el} file
@vindex cc-lobotomy-pith-list
You might want to investigate some of the
speed-ups contained in the file @file{cc-lobotomy.el}, which
is part of the canonical @code{cc-mode} distribution.  As mentioned
previous, @code{cc-mode} always trades accuracy for speed, however it is
recognized that sometimes you need speed and can sacrifice some accuracy
in indentation.  The file @file{cc-lobotomy.el} contains hacks that
will ``dumb down'' @code{cc-mode} in some specific ways, making that
trade-off of speed for accuracy.  I won't go into details of its use
here; you should read the comments at the top of the file, and look at
the variable @code{cc-lobotomy-pith-list} for details.


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Frequently Asked Questions, Getting the latest cc-mode release, Performance Issues, Top
@comment  node-name,              next,                    previous,up

@chapter  Frequently Asked Questions
@cindex   Frequently Asked Questions
@comment FAQ
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@kindex C-x h
@kindex ESC C-\
@kindex ESC C-x
@kindex C-c C-q
@kindex ESC C-q
@kindex ESC C-u
@kindex RET
@kindex LFD
@findex newline-and-indent
@quotation

@strong{Q.} @emph{How do I re-indent the whole file?}

@strong{A.} Visit the file and hit @kbd{C-x h} to mark the whole
buffer. Then hit @kbd{@key{ESC} C-\}.
@sp 1

@strong{Q.} @emph{How do I re-indent the entire function?
@kbd{@key{ESC} C-x} doesn't work.}

@strong{A.} @kbd{@key{ESC} C-x} is reserved for future Emacs use.
To re-indent the entire function hit @kbd{C-c C-q}.
@sp 1

@strong{Q.} @emph{How do I re-indent the current block?}

@strong{A.} First move to the brace which opens the block with
@kbd{@key{ESC} C-u}, then re-indent that expression with
@kbd{@key{ESC} C-q}.
@sp 1

@strong{Q.} @emph{Why doesn't the @key{RET} key indent the line to
where the new text should go after inserting the newline?}

@strong{A.} Emacs' convention is that @key{RET} just adds a newline,
and that @key{LFD} adds a newline and indents it.  You can make
@key{RET} do this too by adding this to your
@code{c-mode-common-hook} (see the sample @file{.emacs} file
@ref{Sample .emacs File}):
@example

(define-key c-mode-map "\C-m" 'newline-and-indent)

@end example

This is a very common question. @code{:-)} If you want this to be the
default behavior, don't lobby me, lobby RMS!
@sp 1

@strong{Q.} @emph{I put @code{(c-set-offset 'substatement-open 0)}
in my @file{.emacs} file but I get an error saying that
@code{c-set-offset}'s function definition is void.}

@strong{A.} This means that @code{cc-mode} wasn't loaded into your
Emacs session by the time the @code{c-set-offset} call was reached,
mostly likely because @code{cc-mode} is being autoloaded.  Instead
of putting the @code{c-set-offset} line in your top-level
@file{.emacs} file, put it in your @code{c-mode-common-hook}, or
simply add the following to the top of your @file{.emacs} file:
@example

(require 'cc-mode)

@end example

See the sample @file{.emacs} file @ref{Sample .emacs File} for
details.

@sp 1
@strong{Q.} @emph{How do I make strings, comments, keywords, and other
constructs appear in different colors, or in bold face, etc.?}

@strong{A.} ``Syntax Colorization'' is an Emacs 19 feature, controlled
by @code{font-lock-mode}.  It is not part of @code{cc-mode}.

@sp 1
@strong{Q.} @emph{I @code{setq} @code{c-basic-offset} to 4 in my
@file{.emacs} file, but why does everything still get indented with only
2 spaces?}

@strong{A.} It's because @code{c-basic-offset} is now a ``buffer local
variable'', meaning its value is unique to each buffer.  The prefered
way to customize this is to change its value in a ``mode hook'' (most
likely @code{c-mode-common-hook}.  Alternatively you can use
@code{setq-default} to change its value globally.

@end quotation


@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Getting the latest cc-mode release, Sample .emacs File, Frequently Asked Questions, Top
@comment  node-name,              next,                    previous,up

@chapter  Getting the latest @code{cc-mode} release
@cindex   Getting the latest @code{cc-mode} release
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@code{cc-mode} is now distributed with both Emacs 19 and XEmacs 19, so
you would typically just use the version that comes with your Emacs.
These may be slightly out of date due to release schedule skew, so you
should always check the canonical site for the latest version.

@example
@group

    World Wide Web:

        @code{http://www.python.org/ftp/emacs/}

    Anonymous FTP:

        @code{ftp://ftp.python.org/pub/emacs/}

@end group
@end example

There are many files under these directories; you can pick up the entire
distribution (named @code{cc-mode.tar.gz}; a gzip'd tar file), or any of
the individual files, including PostScript documentation.

If you do not have anonymous ftp access, you can get the distribution
through an anonymous ftp-to-mail gateway, such as the one run by DEC at
@code{ftpmail@@decwrl.dec.com}.  To get @code{cc-mode} via email, send
the following message in the body of your mail to that address:
@example

reply <a valid net address back to you>
connect ftp.python.org
binary
uuencode
chdir pub/emacs
get cc-mode.tar.gz

@end example
@noindent
or just send the message "help" for more information on ftpmail.
Response times will vary with the number of requests in the queue.  I am
in no way connected to this service, so I make no claims or guarantees
about its availability!

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Sample .emacs File, Limitations and Known Bugs, Getting the latest cc-mode release, Top
@comment  node-name,              next,                    previous,up

@chapter  Sample @file{.emacs} file
@cindex   Sample @file{.emacs} file
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@example
;; Here's a sample .emacs file that might help you along the way.  Just
;; copy this region and paste it into your .emacs file.  You may want to
;; change some of the actual values.

(defconst my-c-style
  '((c-tab-always-indent           . t)
    (c-comment-only-line-offset    . 4)
    (c-hanging-braces-alist        . ((substatement-open after)
                                      (brace-list-open)))
    (c-hanging-colons-alist        . ((member-init-intro before)
                                      (inher-intro)
                                      (case-label after)
                                      (label after)
                                      (access-label after)))
    (c-cleanup-list                . (scope-operator
                                      empty-defun-braces
                                      defun-close-semi))
    (c-offsets-alist               . ((arglist-close     . c-lineup-arglist)
                                      (substatement-open . 0)
                                      (case-label        . 4)
                                      (block-open        . 0)
                                      (knr-argdecl-intro . -)))
    (c-echo-syntactic-information-p . t)
    )
  "My C Programming Style")

;; Customizations for all of c-mode, c++-mode, and objc-mode
(defun my-c-mode-common-hook ()
  ;; add my personal style and set it for the current buffer
  (c-add-style "PERSONAL" my-c-style t)
  ;; offset customizations not in my-c-style
  (c-set-offset 'member-init-intro '++)
  ;; other customizations
  (setq tab-width 8
        ;; this will make sure spaces are used instead of tabs
        indent-tabs-mode nil)
  ;; we like auto-newline and hungry-delete
  (c-toggle-auto-hungry-state 1)
  ;; keybindings for all supported languages.  We can put these in
  ;; c-mode-map because c++-mode-map, objc-mode-map, and java-mode-map
  ;; inherit from it.
  (define-key c-mode-map "\C-m" 'newline-and-indent)
  )

;; the following only works in Emacs 19
;; Emacs 18ers can use (setq c-mode-common-hook 'my-c-mode-common-hook)
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
@end example

@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Limitations and Known Bugs, Mailing Lists and Submitting Bug Reports, Sample .emacs File, Top
@comment  node-name,              next,                    previous,up
@chapter  Limitations and Known Bugs
@cindex   Limitations and Known Bugs
@comment * Limitations and Known Bugs
@comment !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@itemize @bullet
@item
Multi-line macros are not handled properly.

@item
Re-indenting large regions or expressions can be slow.

@item
Use with Emacs 18 can be slow and annoying. You should seriously
consider upgrading to Emacs 19.

@item
There is still some weird behavior when filling C block comments.
My suggestion is to check out separate fill packages such as
@code{filladapt} or @code{adaptive-fill-mode}.  These can do a much
better job of filling comment regions.

@cindex c-indent-exp
@cindex indent-exp (c-)
@item
@code{c-indent-exp} has not been fully optimized.  It essentially
equivalent to hitting @kbd{TAB} (@code{c-indent-command}) on every
line.  Some information is cached from line to line, but such caching
invariable causes inaccuracies in analysis in some bizarre situations.

@end itemize

@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node  Mailing Lists and Submitting Bug Reports, Concept Index, Limitations and Known Bugs, Top
@comment  node-name,              next,                    previous,up
@chapter  Mailing Lists and Submitting Bug Reports
@cindex   Mailing Lists and Submitting Bug Reports
@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@kindex C-c C-b
@findex c-submit-bug-report
@findex submit-bug-report (c-)
@cindex beta testers mailing list
@cindex announcement mailing list
To report bugs, use the @kbd{C-c C-b} (@code{c-submit-bug-report})
command.  This provides vital information I need to reproduce your
problem.  Make sure you include a concise, but complete code example.
Please try to boil your example down to just the essential code needed
to reproduce the problem, and include an exact recipe of steps needed to
expose the bug.  Be especially sure to include any code that appears
@emph{before} your bug example, if you think it might affect my ability
to reproduce it.

Bug reports are now sent to the following email addresses:
@code{cc-mode-help@@python.org} and
@code{bug-gnu-emacs@@prep.ai.mit.edu}; the latter is mirrored on the Usenet
newsgroup @code{gnu.emacs.bug}.  Other questions and suggestions should
be mailed to @code{help-gnu-emacs@@prep.ai.mit.edu} which is mirrored on
@code{gnu.emacs.help}.


@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Concept Index, Command Index,  Mailing Lists and Submitting Bug Reports, Top
@comment node-name,    next,  previous,      up
@unnumbered Concept Index
@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@printindex cp


@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Command Index, Key Index,  Concept Index, Top
@comment node-name,    next,  previous,      up
@unnumbered Command Index
@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ifinfo

@end ifinfo
Since all @code{cc-mode} commands are prepended with the string
@samp{c-}, each appears under its @code{c-@var{<thing>}} name and its
@code{@var{<thing>} (c-)} name.
@iftex
@sp 2
@end iftex
@printindex fn


@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Key Index, Variable Index,  Command Index, Top
@comment node-name,    next,  previous,      up
@unnumbered Key Index
@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@printindex ky


@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@node    Variable Index,    ,  Key Index, Top
@comment node-name,    next,  previous,      up
@unnumbered Variable Index
@c !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@ifinfo

@end ifinfo
Since all @code{cc-mode} variables are prepended with the string
@samp{c-}, each appears under its @code{c-@var{<thing>}} name and its
@code{@var{<thing>} (c-)} name.
@iftex
@sp 2
@end iftex
@printindex vr
@summarycontents
@contents
@bye