[EMAIL PROTECTED] wrote:
I'll show you. Here are some of the generators. This is very dense, functional code. Read at your own risk (but I'm certainly not writing it to be executed!).
Quite. ;)
For the regexp /a aa aaa aaaa aaaaa aaaaaa/, this would sequentially search through all possible ways to decompose 21 until it hit 1+2+3+4+5+6; then it'd return "a"x21 as the single result. This... might take a while.
Since programming in Theoretic Perl6 (Terl6?) /is/ fun, here's my take:
# compositions2($length, @listoflists) gives all possible ways to depompose # $length into the sum of the form a1+a2+a3+...+an so that a[i] is contained # in @listoflists[i]
multi generate(Rule::Group $group: Int $length) {
# For each assignent of lengths to each of $groups children
# such that they sum to $length...
compositions2($length, map(&possible_lengths, $group.children)) ==> map -> @comp {
@comp  $group.children ==> map -> $n, $pat {
# Generate every string of length $n that the subpattern
# matches
[ $pat.generate($n) ]
} ==>
# Join our results together
outer ==> join ''
}
}use IntegerIntervalArithmetics << add_lists, mult_lists >>;
# add_lists(@list1, @list2) returns the list of sums of all possible # elements of the lists. However, it should take .. and ... operators # into account. This generally requires range tree datastructure of some # sort. # mult_lists(@list1, @list2) returns the list of all products
multi possible_lengths(Rule::Group $group) {
[ reduce(&add_lists, map(&possible_lengths, $group.children)) ];
}multi possible_lengths(Rule::Plus $plus) {
[ mult_lists($plus.expression, 1... ];
}
multi possible_lengths(Rule::Constant $const) {
[ length($const.chars) ];
}
I'm still not claiming that this is something one should use, but it /was/ fun to tinker with. :)
Miro
