@atomic-ehr/fhirpath/src/operations/allFalse-function.ts

A TypeScript implementation of FHIRPath

import type { FunctionDefinition, FunctionEvaluator } from '../types';
import { Errors } from '../errors';
import { box, unbox } from '../boxing';

export const evaluate: FunctionEvaluator = async (input, context, args, evaluator) => {
  // If the input is empty, the result is true
  if (input.length === 0) {
    return { value: [box(true, { type: 'Boolean', singleton: true })], context };
  }
  
  // Verify all inputs are booleans (unbox first)
  for (let i = 0; i < input.length; i++) {
    const unboxedValue = unbox(input[i]!);
    if (typeof unboxedValue !== 'boolean') {
      throw Errors.booleanOperationOnNonBoolean('allFalse', i, `${typeof unboxedValue}`);
    }
  }
  
  // Return true if all items are false, false if any item is true
  const result = input.every(item => unbox(item) === false);
  
  return { value: [box(result, { type: 'Boolean', singleton: true })], context };
};

export const allFalseFunction: FunctionDefinition & { evaluate: FunctionEvaluator } = {
  name: 'allFalse',
  category: ['existence'],
  description: 'Takes a collection of Boolean values and returns true if all the items are false. If any items are true, the result is false. If the input is empty, the result is true.',
  examples: [
    "Observation.select(component.value > 90 'mm[Hg]').allFalse()"
  ],
  signatures: [{

    name: 'allFalse',
    input: { type: 'Boolean', singleton: false },
    parameters: [],
    result: { type: 'Boolean', singleton: true }
  }],
  evaluate
};