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welshman/docs/feeds/compiler.md
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2025-06-10 14:15:45 -07:00

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# Feed Compiler
The `FeedCompiler` class transforms feed definitions into optimized `RequestItem[]` arrays containing filters and relay selections for efficient event fetching.
## Types
```typescript
export type FeedCompilerOptions = {
signer?: ISigner
signal?: AbortSignal
context?: AdapterContext
getPubkeysForScope: (scope: Scope) => string[]
getPubkeysForWOTRange: (minWOT: number, maxWOT: number) => string[]
}
```
## FeedCompiler Class
```typescript
export class FeedCompiler {
constructor(readonly options: FeedCompilerOptions)
// Check if a feed can be compiled
canCompile(feed: Feed): boolean
// Compile a feed into request items
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: [{}]}`
### Time-based Feeds
- **CreatedAt feeds** → Processes `since`/`until` with optional relative timestamps
- **Scope feeds** → Resolves to author filters using `getPubkeysForScope()`
- **WOT feeds** → Resolves to author filters using `getPubkeysForWOTRange()`
- **Search feeds** → `{filters: [{search: "term"}]}`
### Complex Feed Types
- **DVM feeds** → Requests DVM responses and converts result tags to feeds
- **List feeds** → Fetches list events and converts their tags to feeds
- **Label feeds** → Fetches label events (kind 1985) and converts tags to feeds
### Set Operations
- **Union feeds** → Merges all sub-feed results, optimizing by relay
- **Intersection feeds** → Finds overlapping filters and relays across sub-feeds
## Usage
```typescript
import { FeedCompiler, makeAuthorFeed, makeKindFeed } from '@welshman/feeds'
const compiler = new FeedCompiler({
getPubkeysForScope: (scope) => [...], // Your scope resolution logic
getPubkeysForWOTRange: (min, max) => [...], // Your WOT logic
context: adapterContext,
signal: abortSignal
})
// Compile a simple feed
const feed = makeAuthorFeed("pubkey1", "pubkey2")
const requests = await compiler.compile(feed)
// => [{filters: [{authors: ["pubkey1", "pubkey2"]}]}]
// Check if feed can be compiled
if (compiler.canCompile(feed)) {
const requests = await compiler.compile(feed)
}
```