Speed up new_tibble()

[mgirlich]

Relates to #726.

Some minor code changes give a nice speed up for new_tibble()

library(tibble)

# empty
y <- list()
y_nrow <- 0L

bench::mark(
  tbl = new_tibble(y, nrow = y_nrow),
  iterations = 100000
)
# master
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl          8.66µs   10.5µs    88253.    35.4KB     19.4

# replace `setdiff()`
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl          5.92µs    7.7µs   115497.      36KB     17.3

# this PR
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl          5.29µs   6.56µs   133027.    32.3KB     18.6

x <- unclass(mtcars)
nrow <- 32L

bench::mark(
  tbl = new_tibble(x, nrow = nrow),
  iterations = 100000
)
# master
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl           8.1µs   9.95µs    93560.        0B     22.5

# replace `setdiff()`
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl          5.48µs   7.07µs   128840.        0B     20.6

# this PR
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl             5µs   6.01µs   143254.        0B     20.1


bench::mark(
  tbl = new_tibble(x, nrow = nrow, foo = "bar", foo2 = 1, foo3 = "x"),
  iterations = 100000
)
# master
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl          10.3µs   12.1µs    77771.        0B     24.1

# replace `setdiff()`
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl          7.21µs   9.05µs   103539.        0B     23.8

# this PR
#> # A tibble: 1 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 tbl           6.3µs   8.06µs   112465.        0B     22.5

^{Created on 2021-07-05 by the reprex package (v2.0.0)}

[krlmlr]

Thanks!