Method substituteDeep

lib/util.js:1321–1354

* Create a new object patterned after substitutionMap, where: * 1. Terminal string values in substitutionMap are used as keys * 2. To look up values in a key-value store, variables * 3. And parent keys are created as necessary to retain the structure of substitutionMap. * * @protected

(substitutionMap, variables)

   *      corresponded to a key in `variables`
   */
  substituteDeep(substitutionMap, variables) {
    const result = {};

    const _substituteVars = (map, vars, pathTo) => {
      for (const prop in map) {
        const value = map[prop];

        if (typeof(value) === 'string') { // We found a leaf variable name
          if (typeof vars[value] !== 'undefined' && vars[value] !== '') { // if the vars provide a value set the value in the result map
            Util.setPath(result, pathTo.concat(prop), vars[value]);
          }
        } else if (Util.isObject(value)) { // work on the subtree, giving it a clone of the pathTo
          if ('__name' in value && '__format' in value && typeof vars[value.__name] !== 'undefined' && vars[value.__name] !== '') {
            let parsedValue;
            try {
              parsedValue = this.parseString(vars[value.__name], value.__format);
            } catch(err) {
              err.message = '__format parser error in ' + value.__name + ': ' + err.message;
              throw err;
            }
            Util.setPath(result, pathTo.concat(prop), parsedValue);
          } else {
            _substituteVars(value, vars, pathTo.concat(prop));
          }
        } else {
          let msg = "Illegal key type for substitution map at " + pathTo.join('.') + ': ' + typeof(value);
          throw Error(msg);
        }
      }
    };

    _substituteVars(substitutionMap, variables, []);
    return result;
  }

  /**
   * Populate a LoadConfig entirely from environment variables.