Domain Specific Languages

Chapter 29. Nested Operator Expression

An operator expression that can recursively contain the same form of expression (for example, arithmetic and Boolean expressions).

2 * (4 + 5)

Calling Nested Operator Expression a pattern is a bit of a stretch, since it isn’t so much a solution as it is a common problem in parsing. This is particularly the case with bottom-up parsers where you need to avoid left recursion.

29.1 How It Works

Nested Operator Expressions have two aspects that can make them a bit tricky—their recursive nature (the rule appears in its own body) and sorting out precedence. Exactly how to deal with these depends in part on the particular Parser Generator you are using, but there are some useful general principles that apply. ...