Feature #15771
Updated by sawa (Tsuyoshi Sawada) over 4 years ago
When `String#split`'s separator is a single space character, it executes under `split_type: awk`.
When you want to split literally by a single space `" "`, and not a sequence of space characters, you need to take special care. For example, the CSV library detours this behavior like [this](https://github.com/ruby/csv/blob/7ff57a50e81c368029fa9b664700bec4a456b81b/lib/csv/parser.rb#L508-L512):
```ruby
if @column_separator == " ".encode(@encoding)
@split_column_separator = Regexp.new(@escaped_column_separator)
else
@split_column_separator = @column_separator
end
```
Unfortunately, using a regexp here makes it slower than using a string. [The following result](https://github.com/284km/benchmarks_no_yatu#stringsplitstring-or-regexp) shows it is about nine times slower.
```sh
$ be benchmark-driver string_split_string-regexp.yml --rbenv '2.6.2'
Comparison:
string: 3161117.6 i/s
regexp: 344448.0 i/s - 9.18x slower
```
I want to add a `:literal` option to execute the method under `split_type: string` as follows: string`.
### Implementation
- https://github.com/284km/ruby/tree/split_space
- test code: https://github.com/284km/ruby/blob/split_space/test/ruby/test_string.rb#L1708-L1713
This change will result in the following:
```ruby
" a b c ".split(" ")
# => ["a", "b", "c"]
" a b c ".split(" ", literal: true) -1)
# => ["", "a", "", ["a", "b", "", "", "c"] "c", ""]
" a b c ".split(" ", -1) literal: true)
# => ["a", ["", "a", "", "b", "c", ""] "", "", "c"]
" a b c ".split(" ", -1, literal: true)
# => ["", "a", "", "b", "", "", "c", "", "", "", ""]
```
### Implementation
- https://github.com/284km/ruby/tree/split_space
- test code: https://github.com/284km/ruby/blob/split_space/test/ruby/test_string.rb#L1708-L1713