Compile intersections

packages/feeds/compiler.ts

@@ -1,6 +1,6 @@
 import {uniq, tryCatch, now, isNil} from '@welshman/lib'
 import type {Rumor, Filter} from '@welshman/util'
-import {Tags, getIdFilters, mergeFilters} from '@welshman/util'
+import {Tags, intersectFilters, BOGUS_RELAY_URL, getIdFilters, unionFilters} from '@welshman/util'
 import type {RequestItem, DVMItem, Scope, Feed, DynamicFilter, FeedOptions} from './core'
 import {FeedType, getSubFeeds} from './core'
 
@@ -19,6 +19,7 @@ export class FeedCompiler<E extends Rumor> {
     switch(type) {
       case FeedType.Relay:
       case FeedType.Union:
+      case FeedType.Intersection:
         return getSubFeeds([type, ...feed] as Feed).every(this.canCompile)
       case FeedType.Filter:
       case FeedType.List:
@@ -33,6 +34,8 @@ export class FeedCompiler<E extends Rumor> {
     switch(type) {
       case FeedType.Union:
         return await this._compileUnion(feed as Feed[])
+      case FeedType.Intersection:
+        return await this._compileIntersection(feed as Feed[])
       case FeedType.Relay:
         /* eslint no-case-declarations: 0 */
         const {relays, filters} = await this._compileUnion(feed.slice(1) as Feed[])
@@ -72,10 +75,30 @@ export class FeedCompiler<E extends Rumor> {
 
     return {
       relays: uniq(relays),
-      filters: mergeFilters(filters),
+      filters: unionFilters(filters),
     }
   }
 
+  async _compileIntersection(feeds: Feed[]): Promise<RequestItem> {
+    const items = await Promise.all(feeds.map(this.compile))
+    const filters = intersectFilters(items.map(item => item.filters))
+
+    let relays = uniq(items.flatMap(item => item.relays))
+    let hasRelays = relays.length > 0
+
+    items.forEach((item, i) => {
+      if (item.relays.length > 0) {
+        relays = relays.filter(relay => item.relays.includes(relay))
+      }
+    })
+
+    if (hasRelays && relays.length === 0) {
+      relays.push(BOGUS_RELAY_URL)
+    }
+
+    return {relays, filters}
+  }
+
   async _compileLists(addresses: string[]): Promise<RequestItem> {
     const events: E[] = []
 

packages/feeds/package.json

@@ -31,6 +31,6 @@
     "typescript": "~5.1.6"
   },
   "dependencies": {
-    "@welshman/util": "0.0.2"
+    "@welshman/util": "0.0.3"
   }
 }

packages/net/Subscribe.ts

@@ -1,7 +1,7 @@
 import type {Event} from 'nostr-tools'
 import {Emitter, randomId, groupBy, batch, defer, uniq, uniqBy} from '@welshman/lib'
 import type {Deferred} from '@welshman/lib'
-import {matchFilters, mergeFilters} from '@welshman/util'
+import {matchFilters, unionFilters} from '@welshman/util'
 import type {Filter} from '@welshman/util'
 import {Tracker} from "./Tracker"
 import {Connection} from './Connection'
@@ -83,7 +83,7 @@ export const mergeSubscriptions = (subs: Subscription[]) => {
       const mergedSub = makeSubscription({
         relays: [relay],
         timeout: callerSubs[0].request.timeout,
-        filters: mergeFilters(callerSubs.flatMap((sub: Subscription) => sub.request.filters)),
+        filters: unionFilters(callerSubs.flatMap((sub: Subscription) => sub.request.filters)),
       })
 
       for (const {id, emitter} of callerSubs) {

packages/net/package.json

@@ -33,7 +33,7 @@
   },
   "dependencies": {
     "@welshman/lib": "0.0.2",
-    "@welshman/util": "0.0.2",
+    "@welshman/util": "0.0.3",
     "isomorphic-ws": "^5.0.0",
     "ws": "^8.16.0"
   }

packages/util/Filters.ts

@@ -76,7 +76,7 @@ export const calculateFilterGroup = ({since, until, limit, search, ...filter}: F
   return group.sort().join("-")
 }
 
-export const mergeFilters = (filters: Filter[]) => {
+export const unionFilters = (filters: Filter[]) => {
   const result = []
 
   for (const group of Object.values(groupBy(calculateFilterGroup, filters))) {
@@ -96,6 +96,38 @@ export const mergeFilters = (filters: Filter[]) => {
   return result
 }
 
+export const intersectFilters = (groups: Filter[][]) => {
+  let result = groups[0]
+
+  for (const filters of groups.slice(1)) {
+    result = result.flatMap(f1 => {
+      return filters.map(f2 => {
+        const f3: Filter = {}
+
+        for (const k of uniq([...Object.keys(f1), ...Object.keys(f2)]) as (keyof Filter)[]) {
+          if (k === 'since' || k === 'limit') {
+            f3[k] = Math.max(f1[k] || 0, f2[k] || 0)
+          } else if (k === 'until') {
+            f3[k] = Math.min(f1[k] || f2[k] || 0, f2[k] || f1[k] || 0)
+          } else if (k === 'search') {
+            if (f1[k] && f2[k] && f1[k] !== f2[k]) {
+              f3[k] = [f1[k], f2[k]].join(' ')
+            } else {
+              f3[k] = f1[k] || f2[k]
+            }
+          } else {
+            f3[k] = uniq([...(f1[k] || []), ...(f2[k] || [])]) as any[]
+          }
+        }
+
+        return f3
+      })
+    })
+  }
+
+  return unionFilters(result)
+}
+
 export const getIdFilters = (idsOrAddresses: Iterable<string>) => {
   const ids = []
   const aFilters = []
@@ -114,7 +146,7 @@ export const getIdFilters = (idsOrAddresses: Iterable<string>) => {
     }
   }
 
-  const filters = mergeFilters(aFilters)
+  const filters = unionFilters(aFilters)
 
   if (ids.length > 0) {
     filters.push({ids})

packages/util/Relays.ts

@@ -1,5 +1,9 @@
 import {normalizeUrl, stripProtocol} from '@welshman/lib'
 
+export const LOCAL_RELAY_URL = "local://welshman.relay"
+
+export const BOGUS_RELAY_URL = "bogus://welshman.relay"
+
 export const isShareableRelayUrl = (url: string) =>
   Boolean(
     typeof url === 'string' &&

packages/util/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@welshman/util",
-  "version": "0.0.2",
+  "version": "0.0.3",
   "author": "hodlbod",
   "license": "MIT",
   "description": "A collection of nostr-related utilities.",