2. Installation and Basic Configuration

Semantic should be installed as a part of the CEDET distribution. See the cedet/INSTALL file in the cedet distribution for basic installation instructions.

2.1 Canned Configuration

As described briefly in the cedet/INSTALL file, there are several canned configurations you can use. These configuration files just turn different semantic modes on and off, but don't change intrinsic semantic parsing behaviors.

Command: semantic-load-enable-minimum-features

Enable the minimum number of semantic features for basic usage. This includes:

semantic-idle-scheduler-mode

Keeps a buffer's parse tree up to date. (@xref{(semantic-user)Idle Scheduler}.)

semanticdb-minor-mode

Stores tags when a buffer is not in memory. (@xref{(semantic-user)semanticdb}.)

semanticdb-load-system-caches

Loads any systemdbs created earlier. (@xref{(semantic-user)semanticdb}.)

semanticdb-load-ebrowse-caches

Loads any ebrowse dbs created earlier. (@xref{(semantic-user)Create System Databases}.)

Command: semantic-load-enable-code-helpers

Enable some semantic features that provide coding assistance. This includes semantic-load-enable-minimum-features plus:

imenu

Lists Semantic generated tags in the menubar.

semantic-idle-summary-mode

Show a summary for the tag indicated by code under point. (intellisense) (@xref{(semantic-user)Idle Summary Mode}.)

senator-minor-mode

Semantic Navigator, and global menu for all features semantic. (@xref{(semantic-user)senator}.)

semantic-mru-bookmark-mode

Provides a `switch-to-buffer' like keybinding for tag names. (@xref{(semantic-user)MRU Bookmarks Mode}.)

Command: semantic-load-enable-gaudy-code-helpers

Enable semantic features that provide gaudy coding assistance. This includes semantic-load-enable-code-helpers.

semantic-stickyfunc-mode

Tracks current function in header-line (when available). (@xref{(semantic-user)Sticky Function Mode}.)

semantic-idle-completions-mode

Provide smart symbol completion automatically at idle time. (@xref{(semantic-user)Idle Completions Mode}.)

semantic-decoration-mode

Decorate tags based on various attributes. (@xref{(semantic-user)Tag Decoration Mode}.)

Compatibility: semantic-load-enable-gaudy-code-helpers introduced in semantic version 2.0 supercedes semantic-load-enable-guady-code-helpers which is now obsolete.

Command: semantic-load-enable-excessive-code-helpers

Enable all semantic features that provide coding assistance. This includes all features of semantic-load-enable-code-helpers plus:

which-func-mode

Display the current function in the mode line.

Command: semantic-load-enable-semantic-debugging-helpers

Enable all semantic features that assist with debugging semantic. These modes include:

semantic-highlight-edits-mode

Highlight text that has been edited since the last parse step. (@xref{(semantic-user)Highlight Edits Mode}.)

semantic-show-unmatched-syntax-mode

Highlight lexical tokens which failed to be parsed. (@xref{(semantic-user)Unmatched Syntax Highlighting}.)

semantic-show-parser-state-mode

Show the current buffer state via small indicators in the mode line. (@xref{(semantic-user)Parser State}.)

2.2 Search Optimization

A common use of semantic is for smart completion and tag browsing. These operations involve searching through the tags of your files. For complete documentation on configuring your searches, @xref{(semantic-user)Semanticdb Search Configuration}.

The default configuration is for fast searches that may not find your symbols all the time.

Searching is controlled with semanticdb-find-default-throttle. To force the search to find and read and tag files not yet in memory, you might add code like this for C mode.

(setq-mode-local c-mode
		 semanticdb-find-default-throttle
		 '(project unloaded system recursive))

Finding unloaded databases requires knowing the search path. You can find headers on a system or project level search path. @xref{(semantic-user)Include paths}.

If using the above tactic doesn't work for your language (something other than C/C++), it may be that your language isn't configured properly for finding include files. You would need to refer to the @xref{(semantic-langdev)} for details.

If you were to be working on a linux kernel, you might opt to configure your search path in your `.emacs' file with code like this:

(semantic-reset-system-include 'c-mode)
(semantic-add-system-include "/usr/src/linux-2.4/include" 'c-mode)

It is also useful to find and install extra search engine back-ends, such @xref{(semantic-user)Create System Databases}. Ebrowse is one such back-end for C and C++ code.

You might create an ebrowse database for your C include files like this:

M-x semanticdb-create-ebrowse-database RET /usr/include/ RET

This will create the database, save it, and add it to the database search list for your C and C++ based projects. These databases will be created in your `~/.semanticdb' directory to be reloaded in future Emacs sessions.

2.3 Parsing Optimization

The semantic parsers generate the tags that form the basis of all the semantic based tools, such as browsers and completion. Keeping those tags up to date can have performance implications.

Here are some common tasks you may be interested in:

2.3.1 Don't parse certain buffers

You can inhibit parsing using the semantic-inhibit-functions variable.

Variable: semantic-inhibit-functions

List of functions to call with no arguments before to setup Semantic. If any of these functions returns non-nil, the current buffer is not setup to use Semantic.

You could have this inihibit parsing in very large files, or files which case particular problems to semantic.

2.3.2 Parsing in idle time

Tags are usually kept up to date when Emacs is idle @xref{(semantic-user)Idle Scheduler}. The semantic's idle-scheduler automatically updates the tags in various buffers before executing specific idle modes, such as summary mode.

You might choose to tune the scheduler with some code like this in your `.emacs' file:

;; Increase the delay before activation
(setq semantic-idle-scheduler-idle-time 10)
;; Don't reparse really big buffers.
(setq semantic-idle-scheduler-max-buffer-size 100000)

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