@jplorg/jpl/src/program/ops/opIf.js

JPL interpreter

import { call } from './utils';

export default {
  /** { ifs: [{ if: [op], then: [op] }], else: [op] } */
  op(runtime, input, params, scope, next) {
    const iter = async (from) => {
      // Call stack decoupling - This is necessary as some browsers (i.e. Safari) have very limited call stack sizes which result in stack overflow exceptions in certain situations.
      await undefined;

      scope.signal.checkHealth();

      if (from >= (params.ifs?.length ?? 0)) {
        return runtime.executeInstructions(params.else ?? [], [input], scope, (output) =>
          next(output, scope),
        );
      }

      const condition = params.ifs[from];

      return runtime.executeInstructions(condition.if ?? [], [input], scope, (result) => {
        if (runtime.truthy(result)) {
          return runtime.executeInstructions(condition.then ?? [], [input], scope, (output) =>
            next(output, scope),
          );
        }

        return iter(from + 1);
      });
    };

    return iter(0);
  },

  /** { ifs: [{ if: function, then: function }], else: function } */
  map(runtime, params) {
    return {
      ifs: runtime.muxOne([params.ifs], (entry) => ({
        if: call(entry.if),
        then: call(entry.then),
      })),
      else: call(params.else),
    };
  },
};