Module: SimpleCov::Combine::LinesCombiner

Extended by:
LinesCombiner
Included in:
LinesCombiner
Defined in:
lib/simplecov/combine/lines_combiner.rb

Instance Method Summary collapse

Instance Method Details

#merge_into(target, source) ⇒ Object

Folds source into target rather than building a third array, so only for a target the caller owns outright: a caller still holding a reference would see it change. source is never touched.

Two runs of the same source file should agree on which lines are coverage-relevant (nil for comments, 0+ for executable). When they don't, "relevant on either side" wins rather than masking a real 0 as nil, which would drop an uncovered line from the denominator:

nil + nil = nil
nil + int = int (preserves a relevant-but-uncovered 0)
int + int = int (sum)



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# File 'lib/simplecov/combine/lines_combiner.rb', line 20

def merge_into(target, source)
  return target unless source
  return source.dup unless target

  size = source.size
  target.fill(nil, target.size, size - target.size)
  sum_into(target, source, size)
end

#sum_into(target, source, size) ⇒ Object

The loop is written out rather than dispatching a block per element because this is the innermost loop of a merge: a 160-worker run over ~1,800 files folds tens of millions of line counts through it.

Both sides go through to_i, which is what keeps the merge total over external input: a count a hand-edited or foreign resultset wrote as "3" or as a JSON float merges to a wrong answer instead of raising out of the middle of a merge. On the accumulated side it doubles as the nil arm.



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# File 'lib/simplecov/combine/lines_combiner.rb', line 37

def sum_into(target, source, size)
  index = 0
  while index < size
    if (value = source[index])
      target[index] = target.at(index).to_i + value.to_i
    end
    index += 1
  end
  target
end