Re: Decomposition of grammars

[Patrick Donnelly <batrick@...>]

On Fri, Jan 6, 2012 at 10:51 AM, Gavin Wraith <gavin@wra1th.plus.com> wrote:
> Purely as an exercise I have been writing a small Lua 5.2
> script using lpeg 0.10 to remove comments from scripts. This
> has started me thinking about aspects of syntax, and I suspect
> that on the list there may be those who can point me toward
> useful material.

Take a look at the Lua Parser on [1]. Using that, it should be trivial
to modify to remove comments/unnecessary whitespace. [Someone looking
to modify it should probably change most (all?) of the instances of
calls to lpeg.P to some local function so it can be easily changed to,
say, lpeg.C. That would allow for changing the subject string code to
something else more easily.]

Some other changes you can do to make the code as compact as possible:

o Change local names to one or two characters.
o Remove redundant parenthesis. e.g. if (foo) then <block> end  OR
foo("bar") --> foo"bar"
o Change numbers to a more compact format. e.g. 0x00000 --> 0
o Change strings to a more compact format. e.g. "\000" --> "\0" (where
permissible)

I'm sure there are many more...

[1] http://lua-users.org/wiki/LpegRecipes

-- 
- Patrick Donnelly