@Override
public int length(ListModule list) {
return list.size() == 0
? 0
: 1
+ (new ListLengthCalculator() {
@Override
public int length(ListModule list) {
return list.size() == 0 ? 0 : 1 + Eternity.length(list.cdr());
}
})
.length(list.cdr());
}
@Override
public int length(ListModule list) {
// in this definition we recognize a common structure: we ask
// something about the size of the list and then delegate to a
// function (constructed dynamically) to do so work. This function
// asks the same question about the size of the list and then
// delegate to a new function...
return list.size() == 0
? 0
: 1
+ (new ListLengthCalculator() {
@Override
public int length(ListModule list) { // label:*
return list.size() == 0
? 0
: 1
+ (new ListLengthCalculator() {
@Override
public int length(ListModule list) { // label:**
// observe that here we fix the finish of
// the chain because we hard-code the use of
// Eternity. In this way if we want to
// extend the chain, we're forced to make a
// copy of the same code because this is a
// fixed structure (is something like
// enumerating all our knowledge)
return list.size() == 0
? 0
: 1 + Eternity.length(list.cdr());
}
})
.length(list.cdr()); // this invocation executes
// label:**
}
})
.length(list.cdr()); // this invocation executes label:*
}
@Override
public int length(ListModule list) {
return list.size() == 0 ? 0 : 1 + this.length(list.cdr());
}