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Semantic is a package that provides language-aware editing commands
based on source code parsers
. This section provides a brief
description of Semantic; for full details,
see Semantic.
Most of the language-aware features in Emacs, such as Font Lock mode (see Font Lock), rely on rules of thumb1 that usually give good results but are never completely exact. In contrast, the parsers used by Semantic have an exact understanding of programming language syntax. This allows Semantic to provide search, navigation, and completion commands that are powerful and precise.
To begin using Semantic, type M-x semantic-mode or click on the menu item named ‘Source Code Parsers (Semantic)’ in the ‘Tools’ menu. This enables Semantic mode, a global minor mode.
When Semantic mode is enabled, Emacs automatically attempts to parse each file you visit. Currently, Semantic understands C, C++, HTML, Java, Javascript, Make, Python, Scheme, SRecode, and Texinfo. Within each parsed buffer, the following commands are available:
semantic-complete-jump-local
).
semantic-complete-jump
).
semantic-complete-analyze-inline
). This also activates a set
of special key bindings for choosing a completion: <RET>
accepts the current completion, M-n and M-p cycle through
possible completions, <TAB> completes as far as possible and
then cycles, and C-g or any other key aborts completion.
semantic-analyze-possible-completions
).
In addition to the above commands, the Semantic package provides a variety of other ways to make use of parser information. For instance, you can use it to display a list of completions when Emacs is idle. See Semantic, for details.