All files / lib/internal/streams from.js

100% Statements 113/113
97.87% Branches 46/47
100% Functions 6/6
100% Lines 113/113

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 11420x 20x 20x 20x 20x 20x 20x 20x 20x 20x 20x 20x 20x 20x 41x 41x 41x 2x 2x 2x 2x 2x 2x 2x 2x 2x 39x 39x 41x 21x 21x 41x 17x 17x 18x 1x 1x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 38x 76x 71x 71x 71x 38x 38x 38x 32x 32x 32x 32x 32x 38x 38x 38x 32x 32x 32x 10x 3x 3x 3x 3x 10x 25x 16x 15x 15x 32x 38x 38x 71x 91x 91x 91x 91x 91x 91x 20x 90x 68x 68x 68x 68x 68x 1x 1x 68x 20x 66x 46x 46x 68x 91x 5x 5x 71x 71x 71x 38x 41x 20x 20x  
'use strict';
 
const {
  PromisePrototypeThen,
  SymbolAsyncIterator,
  SymbolIterator,
} = primordials;
const { Buffer } = require('buffer');
 
const {
  ERR_INVALID_ARG_TYPE,
  ERR_STREAM_NULL_VALUES
} = require('internal/errors').codes;
 
function from(Readable, iterable, opts) {
  let iterator;
  if (typeof iterable === 'string' || iterable instanceof Buffer) {
    return new Readable({
      objectMode: true,
      ...opts,
      read() {
        this.push(iterable);
        this.push(null);
      }
    });
  }
 
  let isAsync = false;
  if (iterable && iterable[SymbolAsyncIterator]) {
    isAsync = true;
    iterator = iterable[SymbolAsyncIterator]();
  } else if (iterable && iterable[SymbolIterator]) {
    isAsync = false;
    iterator = iterable[SymbolIterator]();
  } else {
    throw new ERR_INVALID_ARG_TYPE('iterable', ['Iterable'], iterable);
  }
 
  const readable = new Readable({
    objectMode: true,
    highWaterMark: 1,
    // TODO(ronag): What options should be allowed?
    ...opts,
  });
 
  // Flag to protect against _read
  // being called before last iteration completion.
  let reading = false;
 
  readable._read = function() {
    if (!reading) {
      reading = true;
      next();
    }
  };
 
  readable._destroy = function(error, cb) {
    PromisePrototypeThen(
      close(error),
      () => process.nextTick(cb, error), // nextTick is here in case cb throws
      (e) => process.nextTick(cb, e || error),
    );
  };
 
  async function close(error) {
    const hadError = (error !== undefined) && (error !== null);
    const hasThrow = typeof iterator.throw === 'function';
    if (hadError && hasThrow) {
      const { value, done } = await iterator.throw(error);
      await value;
      if (done) {
        return;
      }
    }
    if (typeof iterator.return === 'function') {
      const { value } = await iterator.return();
      await value;
    }
  }
 
  async function next() {
    for (;;) {
      try {
        const { value, done } = isAsync ?
          await iterator.next() :
          iterator.next();
 
        if (done) {
          readable.push(null);
        } else {
          const res = (value &&
            typeof value.then === 'function') ?
            await value :
            value;
          if (res === null) {
            reading = false;
            throw new ERR_STREAM_NULL_VALUES();
          } else if (readable.push(res)) {
            continue;
          } else {
            reading = false;
          }
        }
      } catch (err) {
        readable.destroy(err);
      }
      break;
    }
  }
  return readable;
}
 
module.exports = from;