# untested, just pseudo code

my @tokens;
local $_ = $value;

while ( !/\G$/gc ) { # while not at end of string
   push @tokens, 
     /\G\./gc ? [ 'DOT', '.' ] :
     /\G(\$\w+)/gc ? [ 'VAR', $1 ] :
     /\G(\w+)\((.*?)\)/gc ? [ 'METHOD', $1, [ split /\s*,\s*/, $2 ] :
     /\G(\w+)/gc ? [ 'METHOD', $1, [] ] :
     ...
     last
}