[d24f17c] | 1 | import _xReduce from "./internal/_xReduce.js";
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| 2 | import _xwrap from "./internal/_xwrap.js";
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| 3 | import curryN from "./curryN.js";
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| 4 | /**
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| 5 | * Initializes a transducer using supplied iterator function. Returns a single
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| 6 | * item by iterating through the list, successively calling the transformed
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| 7 | * iterator function and passing it an accumulator value and the current value
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| 8 | * from the array, and then passing the result to the next call.
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| 9 | *
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| 10 | * The iterator function receives two values: *(acc, value)*. It will be
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| 11 | * wrapped as a transformer to initialize the transducer. A transformer can be
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| 12 | * passed directly in place of an iterator function. In both cases, iteration
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| 13 | * may be stopped early with the [`R.reduced`](#reduced) function.
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| 14 | *
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| 15 | * A transducer is a function that accepts a transformer and returns a
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| 16 | * transformer and can be composed directly.
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| 17 | *
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| 18 | * A transformer is an object that provides a 2-arity reducing iterator
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| 19 | * function, step, 0-arity initial value function, init, and 1-arity result
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| 20 | * extraction function, result. The step function is used as the iterator
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| 21 | * function in reduce. The result function is used to convert the final
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| 22 | * accumulator into the return type and in most cases is
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| 23 | * [`R.identity`](#identity). The init function can be used to provide an
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| 24 | * initial accumulator, but is ignored by transduce.
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| 25 | *
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| 26 | * The iteration is performed with [`R.reduce`](#reduce) after initializing the transducer.
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| 27 | *
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| 28 | * @func
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| 29 | * @memberOf R
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| 30 | * @since v0.12.0
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| 31 | * @category List
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| 32 | * @sig (c -> c) -> ((a, b) -> a) -> a -> [b] -> a
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| 33 | * @param {Function} xf The transducer function. Receives a transformer and returns a transformer.
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| 34 | * @param {Function} fn The iterator function. Receives two values, the accumulator and the
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| 35 | * current element from the array. Wrapped as transformer, if necessary, and used to
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| 36 | * initialize the transducer
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| 37 | * @param {*} acc The initial accumulator value.
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| 38 | * @param {Array} list The list to iterate over.
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| 39 | * @return {*} The final, accumulated value.
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| 40 | * @see R.reduce, R.reduced, R.into
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| 41 | * @example
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| 42 | *
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| 43 | * const numbers = [1, 2, 3, 4];
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| 44 | * const transducer = R.compose(R.map(R.add(1)), R.take(2));
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| 45 | * R.transduce(transducer, R.flip(R.append), [], numbers); //=> [2, 3]
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| 46 | *
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| 47 | * const isOdd = (x) => x % 2 !== 0;
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| 48 | * const firstOddTransducer = R.compose(R.filter(isOdd), R.take(1));
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| 49 | * R.transduce(firstOddTransducer, R.flip(R.append), [], R.range(0, 100)); //=> [1]
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| 50 | */
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| 51 |
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| 52 | var transduce =
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| 53 | /*#__PURE__*/
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| 54 | curryN(4, function transduce(xf, fn, acc, list) {
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| 55 | return _xReduce(xf(typeof fn === 'function' ? _xwrap(fn) : fn), acc, list);
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| 56 | });
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| 57 | export default transduce; |
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