mirror of
https://github.com/swc-project/swc.git
synced 2024-12-26 07:02:28 +03:00
60 lines
2.6 KiB
TypeScript
60 lines
2.6 KiB
TypeScript
// Loaded from https://deno.land/x/ramda@v0.27.2/source/transduce.js
|
|
|
|
|
|
import _reduce from './internal/_reduce.js';
|
|
import _xwrap from './internal/_xwrap.js';
|
|
import curryN from './curryN.js';
|
|
|
|
|
|
/**
|
|
* Initializes a transducer using supplied iterator function. Returns a single
|
|
* item by iterating through the list, successively calling the transformed
|
|
* iterator function and passing it an accumulator value and the current value
|
|
* from the array, and then passing the result to the next call.
|
|
*
|
|
* The iterator function receives two values: *(acc, value)*. It will be
|
|
* wrapped as a transformer to initialize the transducer. A transformer can be
|
|
* passed directly in place of an iterator function. In both cases, iteration
|
|
* may be stopped early with the [`R.reduced`](#reduced) function.
|
|
*
|
|
* A transducer is a function that accepts a transformer and returns a
|
|
* transformer and can be composed directly.
|
|
*
|
|
* A transformer is an object that provides a 2-arity reducing iterator
|
|
* function, step, 0-arity initial value function, init, and 1-arity result
|
|
* extraction function, result. The step function is used as the iterator
|
|
* function in reduce. The result function is used to convert the final
|
|
* accumulator into the return type and in most cases is
|
|
* [`R.identity`](#identity). The init function can be used to provide an
|
|
* initial accumulator, but is ignored by transduce.
|
|
*
|
|
* The iteration is performed with [`R.reduce`](#reduce) after initializing the transducer.
|
|
*
|
|
* @func
|
|
* @memberOf R
|
|
* @since v0.12.0
|
|
* @category List
|
|
* @sig (c -> c) -> ((a, b) -> a) -> a -> [b] -> a
|
|
* @param {Function} xf The transducer function. Receives a transformer and returns a transformer.
|
|
* @param {Function} fn The iterator function. Receives two values, the accumulator and the
|
|
* current element from the array. Wrapped as transformer, if necessary, and used to
|
|
* initialize the transducer
|
|
* @param {*} acc The initial accumulator value.
|
|
* @param {Array} list The list to iterate over.
|
|
* @return {*} The final, accumulated value.
|
|
* @see R.reduce, R.reduced, R.into
|
|
* @example
|
|
*
|
|
* const numbers = [1, 2, 3, 4];
|
|
* const transducer = R.compose(R.map(R.add(1)), R.take(2));
|
|
* R.transduce(transducer, R.flip(R.append), [], numbers); //=> [2, 3]
|
|
*
|
|
* const isOdd = (x) => x % 2 === 1;
|
|
* const firstOddTransducer = R.compose(R.filter(isOdd), R.take(1));
|
|
* R.transduce(firstOddTransducer, R.flip(R.append), [], R.range(0, 100)); //=> [1]
|
|
*/
|
|
var transduce = curryN(4, function transduce(xf, fn, acc, list) {
|
|
return _reduce(xf(typeof fn === 'function' ? _xwrap(fn) : fn), acc, list);
|
|
});
|
|
export default transduce;
|