The parser-generator yacc is one of the oldest examples of a
domain-specific language, providing significant enhancements over
hand-coded parsers in the area of speed, efficiency and
maintainability.  Despite its widespread use, often in highly complex
systems such as compilers or program analysis tools, there is
relatively little written about the integration of parsing, and
yacc-based parsers in particular, into the software engineering
process.

We exploit software metrics as an aid toward estimating the
complexity of preparing a grammar for the ISO C++
programming language for input to yacc.
Our metrics provide a means of assessing the
relative merits of the trade-off between preserving the
grammar's structure and rearranging it to ease
implementation of the resulting parser.
We see this work as part of a
larger process of designing well-engineered, re-usable and reliable
program processors, which themselves will play an important role in
the future design of code-based software-engineering tools.