Feed Compiler

FeedCompiler turns a feed into RequestItem[], each holding filters, relays, or both.

Types

export type FeedCompilerOptions = {
  router: FeedRouter
  signer?: ISigner
  signal?: AbortSignal
  context?: AdapterContext
  getPubkeysForScope: (scope: Scope) => string[]
  getPubkeysForWOTRange: (minWOT: number, maxWOT: number) => string[]
}

router resolves relay selections for list, label and DVM requests; app.use(Router) implements it. signer signs DVM requests and defaults to an ephemeral key.

FeedCompiler Class

export class FeedCompiler {
  constructor(readonly options: FeedCompilerOptions)

  // False for difference feeds, and for unions and intersections that contain one
  canCompile(feed: Feed): boolean

  async compile(feed: Feed): Promise<RequestItem[]>
}

Compilation Logic

Basic Feed Types

• ID feeds → {filters: [{ids: [...]}]}
• Kind feeds → {filters: [{kinds: [...]}]}
• Author feeds → {filters: [{authors: [...]}]}
• Tag feeds → {filters: [{[key]: [...values]}]}
• Address feeds → Converts to ID filters using getIdFilters()
• Relay feeds → {relays: [...urls]}
• Global feeds → {filters: [{}]}
• Search feeds → {filters: [{search: "term"}]}

Time-based Feeds

• CreatedAt feeds → {filters: [{since, until}]}. A value listed in relative is an offset in seconds before now.

Pubkey Feeds

• Scope feeds → Author filters from getPubkeysForScope()
• WOT feeds → Author filters from getPubkeysForWOTRange(min, max), with min defaulting to 0 and max to 1

Complex Feed Types

• DVM feeds → Publishes a DVM request and converts the tags in each result's content to feeds
• List feeds → Fetches list events and converts their tags to feeds
• Label feeds → Fetches label events (kind 1985) and converts their tags to feeds

Each converts tags with the item's mappings, or defaultTagFeedMappings, and compiles the resulting feeds as a union.

Set Operations

• Union feeds → Groups sub-feed filters by relay and merges them
• Intersection feeds → Intersects the filters and relays of the sub-feeds

Usage

import { FeedCompiler, makeAuthorFeed, makeKindFeed } from '@welshman/feeds'

const compiler = new FeedCompiler({
  router,
  getPubkeysForScope: (scope) => [...],
  getPubkeysForWOTRange: (min, max) => [...],
  context: adapterContext,
  signal: abortSignal
})

const feed = makeAuthorFeed("pubkey1", "pubkey2")

if (compiler.canCompile(feed)) {
  const requests = await compiler.compile(feed)
  // => [{filters: [{authors: ["pubkey1", "pubkey2"]}]}]
}