i am trying to learn more about compilers and programming languages, unfortunately my university doesnt offer a course about compilers and so i have to do myself (thank you internet).
At the moment im tryin to understand and to implement a lexer for my language and i need regular expressions.
I am used to script perl regex pretty quickly and i thought that i could embed Perl in my C++ lexer. Now the questions are:
- Will it cause Heavy overhead?
- Should i try to make peace with BOOST (or any other c++ library good gor regex) ?
Thank you for reading this :)
No reason you can't, part of being a good programmer is using the right tool for the job, and perl is VERY good at text processing.
However, instead of thinking about stuffing a perl-based lexer into your C++ compiler (written in C++, not compiling C++, I hope), you should think about writing a perl module in C++, and letting the compiler driver be written in perl, do the lexing, fill in data structures, and then call the C++ module's functions to finish the compile.
Embedding Perl in your project just to do regular expressions would be like trying to stuff an elephant into a Miata to get more trunk space. (Badump!)
Boost would be one way to handle regular expressions, or if you're writing in an environment that supports POSIX.2, look into the regcomp(), regexec() and regfree() functions.
After you've written your own lexer, investigate a tool called lex which is pretty much the gold standard for developing lexical analyzers. It has a partner called YACC for developing parsers. Both are time tested and generate tight, bug-free code. (GNU-ish environments call these programs flex and bison.)
If all you really want is Perl-style regular expressions, look into the libpcre library. It's very well tested, very portable, and in my experience easy to work with. Recommended software. (And probably already on your machine. :)
See the bottom of the "What good is \G in a regular expression?" section of perlfaq6. It describes how //gc can be used to create a tokeniser aka lexer.
来源：https://stackoverflow.com/questions/5372532/writing-part-of-a-compiler-written-in-c-in-perl