All files / lib/internal/streams operators.js

97.77% Statements 396/405
97.27% Branches 143/147
95.83% Functions 23/24
97.77% Lines 396/405

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 40619x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 166x 166x 2x 2x 2x 166x 33x 33x 166x 16x 16x 166x 166x 166x 14x 14x 166x 166x 166x 166x 145x 145x 145x 145x 145x 145x 145x 145x 4x 4x 145x 145x 145x 145x 145x 145x 145x 145x 23x 23x 145x 145x 140x 140x 712x 35x 35x 712x 712x 8x 8x 712x 712x 712x 712x 1x 1x 712x 712x     669x 712x 621x 621x 669x 669x 711x 663x 663x 663x 669x 712x 663x 663x 663x 663x 712x 140x 140x 15x 15x 15x 140x 140x 140x 98x 98x 98x 140x 140x 140x 145x 145x 145x 145x 145x 901x 765x 743x 765x 85x 85x 658x 765x 2x 2x 765x 765x 475x 475x 765x 765x 765x 623x 623x 623x 765x 901x 901x 761x 901x 901x 145x 140x 140x 140x 140x 40x 40x 40x 140x 166x 166x 19x 11x 11x 4x 4x 11x 3x 3x 11x 11x 9x 9x 17x 2x 2x 17x 13x 11x 11x 19x 39x 39x 39x 13x 13x 39x 39x 19x 20x 20x 1x 1x 1x 19x 19x 41x 20x 20x 19x 21x 21x 7x 7x 21x 21x 19x 13x 13x 1x 1x 1x 12x 42x 42x 42x 12x 13x 13x 19x 77x 77x 3x 3x 3x 74x 203x 56x 56x 203x 203x 74x 77x 19x 19x 19x 19x 19x       19x 19x 25x 25x 2x 2x 2x 25x 5x 5x 25x 4x 4x 25x 25x 25x 2x 2x 2x 2x 2x 19x 19x 25x 1x 1x 1x 25x 25x 25x 242x 242x 1x 1x 242x 1x 1x 242x 240x 239x 242x 25x     25x 19x 19x 17x 25x 19x 62x 62x 3x 3x 62x 2x 2x 60x 60x 62x 339x 1x 1x 338x 338x 62x 62x 19x 15x 15x 15x 11x 35x 35x 15x 15x 19x 40x 40x 40x 40x 40x 1x 1x 40x 4x 4x 40x 40x 19x 19x 19x 3x 3x 19x 2x 2x 19x 19x 19x 15x     15x 51x 1x 1x 51x 27x 27x 51x 19x 19x 19x 25x 25x 4x 4x 25x 3x 3x 25x 25x 25x 20x 1x 1x 20x 42x 1x 1x 42x 26x 42x 15x 15x 42x 25x 25x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x  
'use strict';
 
const { AbortController } = require('internal/abort_controller');
 
const {
  codes: {
    ERR_INVALID_ARG_TYPE,
    ERR_MISSING_ARGS,
    ERR_OUT_OF_RANGE,
  },
  AbortError,
} = require('internal/errors');
const {
  validateAbortSignal,
  validateInteger,
  validateObject,
} = require('internal/validators');
const { kWeakHandler } = require('internal/event_target');
const { finished } = require('internal/streams/end-of-stream');
 
const {
  ArrayPrototypePush,
  MathFloor,
  Number,
  NumberIsNaN,
  Promise,
  PromiseReject,
  PromisePrototypeCatch,
  Symbol,
} = primordials;
 
const kEmpty = Symbol('kEmpty');
const kEof = Symbol('kEof');
 
function map(fn, options) {
  if (typeof fn !== 'function') {
    throw new ERR_INVALID_ARG_TYPE(
      'fn', ['Function', 'AsyncFunction'], fn);
  }
  if (options != null) {
    validateObject(options, 'options');
  }
  if (options?.signal != null) {
    validateAbortSignal(options.signal, 'options.signal');
  }
 
  let concurrency = 1;
  if (options?.concurrency != null) {
    concurrency = MathFloor(options.concurrency);
  }
 
  validateInteger(concurrency, 'concurrency', 1);
 
  return async function* map() {
    const ac = new AbortController();
    const stream = this;
    const queue = [];
    const signal = ac.signal;
    const signalOpt = { signal };
 
    const abort = () => ac.abort();
    if (options?.signal?.aborted) {
      abort();
    }
 
    options?.signal?.addEventListener('abort', abort);
 
    let next;
    let resume;
    let done = false;
 
    function onDone() {
      done = true;
    }
 
    async function pump() {
      try {
        for await (let val of stream) {
          if (done) {
            return;
          }
 
          if (signal.aborted) {
            throw new AbortError();
          }
 
          try {
            val = fn(val, signalOpt);
          } catch (err) {
            val = PromiseReject(err);
          }
 
          if (val === kEmpty) {
            continue;
          }
 
          if (typeof val?.catch === 'function') {
            val.catch(onDone);
          }
 
          queue.push(val);
          if (next) {
            next();
            next = null;
          }
 
          if (!done && queue.length && queue.length >= concurrency) {
            await new Promise((resolve) => {
              resume = resolve;
            });
          }
        }
        queue.push(kEof);
      } catch (err) {
        const val = PromiseReject(err);
        PromisePrototypeCatch(val, onDone);
        queue.push(val);
      } finally {
        done = true;
        if (next) {
          next();
          next = null;
        }
        options?.signal?.removeEventListener('abort', abort);
      }
    }
 
    pump();
 
    try {
      while (true) {
        while (queue.length > 0) {
          const val = await queue[0];
 
          if (val === kEof) {
            return;
          }
 
          if (signal.aborted) {
            throw new AbortError();
          }
 
          if (val !== kEmpty) {
            yield val;
          }
 
          queue.shift();
          if (resume) {
            resume();
            resume = null;
          }
        }
 
        await new Promise((resolve) => {
          next = resolve;
        });
      }
    } finally {
      ac.abort();
 
      done = true;
      if (resume) {
        resume();
        resume = null;
      }
    }
  }.call(this);
}
 
function asIndexedPairs(options = undefined) {
  if (options != null) {
    validateObject(options, 'options');
  }
  if (options?.signal != null) {
    validateAbortSignal(options.signal, 'options.signal');
  }
 
  return async function* asIndexedPairs() {
    let index = 0;
    for await (const val of this) {
      if (options?.signal?.aborted) {
        throw new AbortError({ cause: options.signal.reason });
      }
      yield [index++, val];
    }
  }.call(this);
}
 
async function some(fn, options) {
  // eslint-disable-next-line no-unused-vars
  for await (const unused of filter.call(this, fn, options)) {
    return true;
  }
  return false;
}
 
async function every(fn, options) {
  if (typeof fn !== 'function') {
    throw new ERR_INVALID_ARG_TYPE(
      'fn', ['Function', 'AsyncFunction'], fn);
  }
  // https://en.wikipedia.org/wiki/De_Morgan%27s_laws
  return !(await some.call(this, async (...args) => {
    return !(await fn(...args));
  }, options));
}
 
async function find(fn, options) {
  for await (const result of filter.call(this, fn, options)) {
    return result;
  }
  return undefined;
}
 
async function forEach(fn, options) {
  if (typeof fn !== 'function') {
    throw new ERR_INVALID_ARG_TYPE(
      'fn', ['Function', 'AsyncFunction'], fn);
  }
  async function forEachFn(value, options) {
    await fn(value, options);
    return kEmpty;
  }
  // eslint-disable-next-line no-unused-vars
  for await (const unused of map.call(this, forEachFn, options));
}
 
function filter(fn, options) {
  if (typeof fn !== 'function') {
    throw new ERR_INVALID_ARG_TYPE(
      'fn', ['Function', 'AsyncFunction'], fn);
  }
  async function filterFn(value, options) {
    if (await fn(value, options)) {
      return value;
    }
    return kEmpty;
  }
  return map.call(this, filterFn, options);
}
 
// Specific to provide better error to reduce since the argument is only
// missing if the stream has no items in it - but the code is still appropriate
class ReduceAwareErrMissingArgs extends ERR_MISSING_ARGS {
  constructor() {
    super('reduce');
    this.message = 'Reduce of an empty stream requires an initial value';
  }
}
 
async function reduce(reducer, initialValue, options) {
  if (typeof reducer !== 'function') {
    throw new ERR_INVALID_ARG_TYPE(
      'reducer', ['Function', 'AsyncFunction'], reducer);
  }
  if (options != null) {
    validateObject(options, 'options');
  }
  if (options?.signal != null) {
    validateAbortSignal(options.signal, 'options.signal');
  }
 
  let hasInitialValue = arguments.length > 1;
  if (options?.signal?.aborted) {
    const err = new AbortError(undefined, { cause: options.signal.reason });
    this.once('error', () => {}); // The error is already propagated
    await finished(this.destroy(err));
    throw err;
  }
  const ac = new AbortController();
  const signal = ac.signal;
  if (options?.signal) {
    const opts = { once: true, [kWeakHandler]: this };
    options.signal.addEventListener('abort', () => ac.abort(), opts);
  }
  let gotAnyItemFromStream = false;
  try {
    for await (const value of this) {
      gotAnyItemFromStream = true;
      if (options?.signal?.aborted) {
        throw new AbortError();
      }
      if (!hasInitialValue) {
        initialValue = value;
        hasInitialValue = true;
      } else {
        initialValue = await reducer(initialValue, value, { signal });
      }
    }
    if (!gotAnyItemFromStream && !hasInitialValue) {
      throw new ReduceAwareErrMissingArgs();
    }
  } finally {
    ac.abort();
  }
  return initialValue;
}
 
async function toArray(options) {
  if (options != null) {
    validateObject(options, 'options');
  }
  if (options?.signal != null) {
    validateAbortSignal(options.signal, 'options.signal');
  }
 
  const result = [];
  for await (const val of this) {
    if (options?.signal?.aborted) {
      throw new AbortError(undefined, { cause: options.signal.reason });
    }
    ArrayPrototypePush(result, val);
  }
  return result;
}
 
function flatMap(fn, options) {
  const values = map.call(this, fn, options);
  return async function* flatMap() {
    for await (const val of values) {
      yield* val;
    }
  }.call(this);
}
 
function toIntegerOrInfinity(number) {
  // We coerce here to align with the spec
  // https://github.com/tc39/proposal-iterator-helpers/issues/169
  number = Number(number);
  if (NumberIsNaN(number)) {
    return 0;
  }
  if (number < 0) {
    throw new ERR_OUT_OF_RANGE('number', '>= 0', number);
  }
  return number;
}
 
function drop(number, options = undefined) {
  if (options != null) {
    validateObject(options, 'options');
  }
  if (options?.signal != null) {
    validateAbortSignal(options.signal, 'options.signal');
  }
 
  number = toIntegerOrInfinity(number);
  return async function* drop() {
    if (options?.signal?.aborted) {
      throw new AbortError();
    }
    for await (const val of this) {
      if (options?.signal?.aborted) {
        throw new AbortError();
      }
      if (number-- <= 0) {
        yield val;
      }
    }
  }.call(this);
}
 
function take(number, options = undefined) {
  if (options != null) {
    validateObject(options, 'options');
  }
  if (options?.signal != null) {
    validateAbortSignal(options.signal, 'options.signal');
  }
 
  number = toIntegerOrInfinity(number);
  return async function* take() {
    if (options?.signal?.aborted) {
      throw new AbortError();
    }
    for await (const val of this) {
      if (options?.signal?.aborted) {
        throw new AbortError();
      }
      if (number-- > 0) {
        yield val;
      } else {
        return;
      }
    }
  }.call(this);
}
 
module.exports.streamReturningOperators = {
  asIndexedPairs,
  drop,
  filter,
  flatMap,
  map,
  take,
};
 
module.exports.promiseReturningOperators = {
  every,
  forEach,
  reduce,
  toArray,
  some,
  find,
};