@livefolio/sdk / evaluateRuleTree

Function: evaluateRuleTree()

evaluateRuleTree(rules, values, state?): object

Defined in: tactical/evaluate-rule-tree.ts:139

Evaluates a RuleNode tree against a resolved set of feature values and returns the target allocation weights together with the updated hysteresis state.

The tree is walked depth-first. At each IfNode the comparison is evaluated (with hysteresis applied when tolerance and id are present) and the walk follows either then or else. Evaluation terminates at an AllocateNode whose weights map is returned verbatim.

Hysteresis: when a Comparison carries a tolerance, the previous outcome in state is used to decide whether to flip the result. The updated outcomes for all visited comparisons are collected in the returned state map.

Throws if a FeatureRef resolves to undefined (the caller should suppress this with a guard or catch-block, as fromSpec does).

Parameters

Parameter	Type	Description
rules	RuleNode	Root of the rule tree to evaluate.
values	ReadonlyMap<string, number>	Resolved feature values, keyed by feature id. Must contain every ref string used in the tree; missing keys throw.
state	RuleTreeState	Prior hysteresis state from the previous evaluation step. Pass an empty Map on the first call.

Returns

object

An object with:

• weights — target portfolio weights as a Map<AssetId, number>.
• state — updated RuleTreeState to pass to the next step.

Name	Type	Defined in
state	RuleTreeState	tactical/evaluate-rule-tree.ts:143
weights	TargetWeights	tactical/evaluate-rule-tree.ts:143

Example

import { evaluateRuleTree } from '@livefolio/sdk';
import type { RuleNode, RuleTreeState } from '@livefolio/sdk';

const rules: RuleNode = {
  op:   'if',
  cond: { op: 'gt', left: { ref: 'price' }, right: { ref: 'sma200' } },
  then: { op: 'allocate', weights: { SPY: 1 } },
  else: { op: 'allocate', weights: { SHY: 1 } },
};

let state: RuleTreeState = new Map();
const values = new Map([['price', 450], ['sma200', 420]]);
const result = evaluateRuleTree(rules, values, state);
// result.weights → Map { 'SPY' => 1 }
state = result.state;