I'm building a custom expression parser and evaluator for production enviroment
to provide a limited DSL
to the users. The parser itself as the DSL, need
to be simple. The parser is going
to be built in an exotic language that doesn't support dynamic expression parsing nor has any parser generator tools available.
My decision is
to go for recursive descent approach with LL(1) grammar, so that even programmers with no previous experience in evaluating expression could quickly learn how the code works.
It has
to handle mixed expressions made up of several data types: decimals, percentages, strings and dates. And dates in the format of dd/mm/yyyy are easy
to confuse with a
string of devision ops.
Is where a good solution
to this problem?
My own solution that is aimed at keeping the parser simple involves prefixing dates with a special symbol, let's say apostrophe:
<date> ::= <apostr><digit><digit>/<digit><digit>/<digit><digit><digit><digit>
<apostr> ::= '
<digit> ::= '0'..'9'
