semantic: Introduction
1 Introduction
**************
This chapter gives an overview of Semantic and its goals.
Ordinarily, Emacs uses regular expressions (and syntax tables) to
analyze source code for purposes such as syntax highlighting. This
approach, though simple and efficient, has its limitations: roughly
speaking, it only “guesses” the meaning of each piece of source code in
the context of the programming language, instead of rigorously
“understanding” it.
Semantic provides a new infrastructure to analyze source code using
“parsers” instead of regular expressions. It contains two built-in
parser generators (an LL generator named ‘Bovine’ and an LALR generator
named ‘Wisent’, both written in Emacs Lisp), and parsers for several
common programming languages. It can also make use of “external
parsers”—programs such as GNU Global and GNU IDUtils.
Semantic provides a uniform, language-independent API for accessing
the parser output. This output can be used by other Emacs Lisp programs
to implement “syntax-aware” behavior. Semantic itself includes several
such utilities, including user-level Emacs commands for navigating,
searching, and completing source code.
The following diagram illustrates the structure of the Semantic
package:
*Please Note:*
The words in all-capital are those that Semantic itself provides.
Others are current or future languages or applications that are not
distributed along with Semantic.
Applications
and
Utilities
-------
/ \
+---------------+ +--------+ +--------+
C --->| C PARSER |--->| | | |
+---------------+ | | | |
+---------------+ | COMMON | | COMMON |<--- SPEEDBAR
Java --->| JAVA PARSER |--->| PARSE | | |
+---------------+ | TREE | | PARSE |<--- SEMANTICDB
+---------------+ | FORMAT | | API |
Scheme --->| SCHEME PARSER |--->| | | |<--- ecb
+---------------+ | | | |
+---------------+ | | | |
Texinfo --->| TEXI. PARSER |--->| | | |
+---------------+ | | | |
... ... ... ...
+---------------+ | | | |
Lang. Y --->| Y Parser |--->| | | |<--- app. ?
+---------------+ | | | |
+---------------+ | | | |<--- app. ?
Lang. Z --->| Z Parser |--->| | | |
+---------------+ +--------+ +--------+
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