Function evaluateReduce

packages/graph/src/Steps.ts:2070–2104

* Evaluate a reduce expression over a list. * Folds the list into a single value using an accumulator.

(
  path: TraversalPath<any, any, any>,
  reduce: {
    accumulator: string;
    variable: string;
    expression: ConditionValue;
  },
  initialValue: any,
  list: any[],
  context?: QueryContext,
)

 * Folds the list into a single value using an accumulator.
 */
function evaluateReduce(
  path: TraversalPath<any, any, any>,
  reduce: {
    accumulator: string;
    variable: string;
    expression: ConditionValue;
  },
  initialValue: any,
  list: any[],
  context?: QueryContext,
): any {
  let accumulator = initialValue;

  for (const element of list) {
    // Create bindings for both the accumulator and the iteration variable
    // First, create a binding for the accumulator
    const accumulatorBinding = {
      label: "ComprehensionElement",
      value: accumulator,
    };
    const pathWithAcc = new TraversalPath(path, accumulatorBinding as any, [reduce.accumulator]);

    // Then, create a binding for the iteration variable
    const iterationBinding = {
      label: "ComprehensionElement",
      value: element,
    };
    const boundPath = new TraversalPath(pathWithAcc, iterationBinding as any, [reduce.variable]);

    // Evaluate the expression to get the new accumulator value
    accumulator = resolveConditionValue(boundPath, reduce.expression, context);
  }

  return accumulator;
}

/**
 * Compare two values using the given operator.