问题
I'd like to create additional regular expressions for use with etags, but I'd like them to be based upon what's already there (in particular, I'd like to add [ \t]* to the current set of regular expressions that etags uses). What are the default set of regular expressions that etags uses for .lisp files?
回答1:
etags doesn't generally use regular expressions to implement the languages that are built-in. Instead, it has custom parser code for each built-in language.
That said, it seems for Lisp to look for just a few forms, that could be handled by regular expressions:
- It looks for "(" in the first column
- It skips defvar
- It ignores a "cl-" or "CL-" appearing after the "("
- Then, "def" and "DEF" match
- It also checks for "(package::def" as a lead-in
I found this by reading lib-src/etags.c in the Emacs source tree. Search for "Lisp_functions".
来源：https://stackoverflow.com/questions/25290531/default-regular-expression-for-etags