56 lines
2.6 KiB
Java
56 lines
2.6 KiB
Java
package dev.relism.flash.routing;
|
|
|
|
import dev.relism.flash.models.RequestHandler;
|
|
import dev.relism.flash.models.SimpleHandler;
|
|
|
|
import java.util.*;
|
|
|
|
/** Boot-only DAG compiler for a route's middleware nodes. */
|
|
public final class MiddlewareGraph {
|
|
private MiddlewareGraph() {}
|
|
|
|
public static Middleware[] order(String route, List<MiddlewareNode> nodes) {
|
|
if (nodes.isEmpty()) return new Middleware[0];
|
|
Map<MiddlewareKey, Integer> index = new LinkedHashMap<>();
|
|
for (int i = 0; i < nodes.size(); i++) {
|
|
MiddlewareKey key = nodes.get(i).key();
|
|
if (index.putIfAbsent(key, i) != null)
|
|
throw new IllegalStateException("Duplicate middleware " + key.value() + " on " + route);
|
|
}
|
|
List<Set<Integer>> outgoing = new ArrayList<>(nodes.size());
|
|
int[] incoming = new int[nodes.size()];
|
|
for (int i = 0; i < nodes.size(); i++) outgoing.add(new LinkedHashSet<>());
|
|
for (int source = 0; source < nodes.size(); source++) {
|
|
for (MiddlewareNode.Constraint c : nodes.get(source).constraints()) {
|
|
Integer target = index.get(c.target());
|
|
if (target == null) {
|
|
if (c.required()) throw new IllegalStateException("Middleware " + nodes.get(source).key().value()
|
|
+ " on " + route + " requires " + c.target().value() + " to be present");
|
|
continue;
|
|
}
|
|
int from = c.relation() == MiddlewareNode.Relation.AFTER ? target : source;
|
|
int to = c.relation() == MiddlewareNode.Relation.AFTER ? source : target;
|
|
if (outgoing.get(from).add(to)) incoming[to]++;
|
|
}
|
|
}
|
|
PriorityQueue<Integer> ready = new PriorityQueue<>();
|
|
for (int i = 0; i < incoming.length; i++) if (incoming[i] == 0) ready.add(i);
|
|
Middleware[] ordered = new Middleware[nodes.size()];
|
|
int out = 0;
|
|
while (!ready.isEmpty()) {
|
|
int current = ready.remove();
|
|
ordered[out++] = nodes.get(current).middleware();
|
|
for (int next : outgoing.get(current)) if (--incoming[next] == 0) ready.add(next);
|
|
}
|
|
if (out != nodes.size()) throw new IllegalStateException("Middleware ordering cycle on " + route);
|
|
return ordered;
|
|
}
|
|
|
|
/** Pre-composes a sorted chain once at boot. */
|
|
public static RequestHandler compose(RequestHandler handler, Middleware[] ordered) {
|
|
RequestHandler current = handler;
|
|
for (int i = ordered.length - 1; i >= 0; i--) current = new SimpleHandler(ordered[i].wrap(current));
|
|
return current;
|
|
}
|
|
}
|