@bernierllc/nevar-condition-tree

Condition tree data structure for the Nevar rules engine. Validate, walk, and extract fields from condition trees. No evaluation logic.

Installation

npm install @bernierllc/nevar-condition-tree

Usage

import { validateTree, walkTree, extractFields } from '@bernierllc/nevar-condition-tree';

const tree = {
  operator: 'AND' as const,
  conditions: [
    { field: 'age', op: 'gte', value: 18 },
    { field: 'country', op: 'eq', value: 'US' }
  ]
};

// Validate
const result = validateTree(tree);
// { valid: true, errors: [] }

// Walk
walkTree(tree, (node, depth, parent) => {
  console.log(`depth=${depth}`, node);
});

// Extract fields
const fields = extractFields(tree);
// ['age', 'country']

API

validateTree(tree)

Validates a condition tree structure. Checks for valid operators (AND/OR/NOT), non-empty condition arrays, and correct leaf node shape.

Returns: { valid: boolean, errors: string[] }

walkTree(tree, visitor)

Depth-first traversal of a condition tree. Calls the visitor function for every node (both groups and leaf conditions) with the current node, depth, and parent group.

Parameters:

• tree: ConditionGroup - The root condition group
• visitor: (node, depth, parent?) => void - Callback invoked for each node

extractFields(tree)

Extracts all unique field paths referenced by leaf conditions in the tree. Useful for determining which context providers need to be invoked before evaluation.

Returns: string[] - Deduplicated array of field paths

Integration Documentation

Logger Integration

This package does not integrate with @bernierllc/logger. As a core package, logger integration is optional and not included by default. Consumers should handle logging at the service layer.

NeverHub Integration

This package does not integrate with @bernierllc/neverhub-adapter. As a core package, NeverHub integration is not applicable. NeverHub registration should be handled by service-layer packages that compose this package.

License

Copyright (c) 2025 Bernier LLC. All rights reserved.