createParseTreeStore()

Factory function that creates a ParseTreeStore — a bridge between the @ngaf/partial-json parser and Angular's signal-based Spec rendering. It materializes the parse tree into a Spec signal with structural sharing on each push.

Import:

import { createParseTreeStore } from '@ngaf/chat';
import type { ParseTreeStore, ElementAccumulationState } from '@ngaf/chat';

Signature

function createParseTreeStore(parser: PartialJsonParser): ParseTreeStore

Parameter	Type	Description
`parser`	`PartialJsonParser`	A parser instance from `createPartialJsonParser()` in `@ngaf/partial-json`

Returns: ParseTreeStore — must be called within an Angular injection context.

ParseTreeStore Interface

interface ParseTreeStore {
  /** Push characters to the parser and update signals. */
  push(chunk: string): void;
 
  /** Current materialized spec (structurally shared between updates). */
  readonly spec: Signal<Spec | null>;
 
  /** Per-element accumulation tracking. */
  readonly elementStates: Signal<Map<string, ElementAccumulationState>>;
}

ElementAccumulationState

interface ElementAccumulationState {
  hasType: boolean;      // /elements/{key}/type received
  hasProps: boolean;     // /elements/{key}/props received
  hasChildren: boolean;  // /elements/{key}/children received
  streaming: boolean;    // still receiving data for this element
}

Usage

import { createPartialJsonParser } from '@ngaf/partial-json';
import { createParseTreeStore } from '@ngaf/chat';
 
const parser = createPartialJsonParser();
const store = createParseTreeStore(parser);
 
store.push('{"root":"r1","elements":{"r1":{"type":"Text"');
store.spec();  // partial Spec — r1 has type "Text" but no props yet
 
store.push(',"props":{"label":"Hello"}}}}');
store.spec();  // complete Spec
 
// Element tracking
store.elementStates().get('r1');
// { hasType: true, hasProps: true, hasChildren: false, streaming: false }

Structural sharing

The spec signal uses structural sharing. When a new token updates one element, sibling elements keep the same object reference. Angular's computed() with Object.is equality skips re-evaluation for unchanged elements.