fn size_hint(&self) -> (usize, Option<usize>) {
        let max_size = self
            .query_state
            .matched_archetypes
            .ones()
            .map(|index| self.world.archetypes[ArchetypeId::new(index)].len())
            .sum();

        (0, Some(max_size))
    }
// NOTE: For unfiltered Queries this should actually return a exact size hint,
// to fulfil the ExactSizeIterator invariant, but this isn't practical without specialization.
// For more information see Issue #1686.
For unfiltered Queries this should actually return a exact size hint,
to fulfil the ExactSizeIterator invariant, but this isn't practical without specialization.
For more information see Issue #1686.
For unfiltered Queries this should actually return a exact size hint to fulfil the ExactSizeIterator invariant but this isn ' t practical without specialization . For more information see Issue #1686 .
fn size_hint(&self) -> (usize, Option<usize>) {
        let max_size = self
            .query_state
            .matched_archetypes
            .ones()
            .map(|index| self.world.archetypes[ArchetypeId::new(index)].len())
            .sum();
        (0, Some(max_size))
    }
fn size_hint ( & self ) -> ( usize , Option < usize > ) { let max_size = self . query_state . matched_archetypes . ones ( ) . map ( | index | self . world . archetypes [ ArchetypeId :: new ( index ) ] . len ( ) ) . sum ( ) ; ( 0 , Some ( max_size ) ) }
NOTE: For unfiltered Queries this should actually return a exact size hint,
to fulfil the ExactSizeIterator invariant, but this isn't practical without specialization.
NOTE : For unfiltered Queries this should actually return a exact size hint to fulfil the ExactSizeIterator invariant but this isn ' t practical without specialization .
&self
&self