Hi Everybody and Sean !
I noticed something odd ( I am following the design decisions I have previously learnt from Sean Conner).
When using lpeg.Cc with lpeg.Cmt, for whatever reason if you create a object with lpeg.Cc expect the object to be
deleted or garbage collected by lpeg internals.
Here is a concrete simplified example:
local fin = { }
local add = function(all, pos, constant)
table.insert(fin, constant)
print(fin)
return pos
end
local test_constant = { 'hello', 'world'}
local gram = Cmt (((Cc(test_constant)) * P('a')), add)
local patt = gram ^ 1
return patt:match('aa')
------<| CONSOLE OUTPUT START |>--------
{
{"hello", "world"}
}
{
{"hello", "world"}, nil -- nil should be {"hello", "world"}, why is the constant being garbage collected.
}
------<| CONSOLE OUTPUT END |>--------
My temporary solution is to deep clone the constant:
add = function(all, pos, constant)
local copy _.extend({},constant) -- from underscore.lua library
table.insert(fin,copy)
print (fin)
return pos
end
In situations like this are we expected to assume the object created with lpeg.Cc will be deleted and make copies ? Or is my usage of Cmt with Cc unjustified ?
best wishes,
Joy
