Add missing overloads for String#byte_slice

[straight-shoota]

String#byte_slice and #byte_slice have signatures accepting a start index plus count. String#byte_slice also has an overload with only a start index.

There are no overloads accepting a Range argument, which is typically present in similar methods (most prominently Indexable#[]).

This patch adds:

• String#byte_slice(range : Range) - resolves range indices and delegates to #byte_slice(start : Int, count : Int)
• String#byte_slice?(range : Range) - resolves range indices and delegates to #byte_slice?(start : Int, count : Int)
• String#byte_slice?(start : Int) - counterpart to String#byte_slice(start : Int)

[HertzDevil]

This and the two calls above actually return "lo". I don't know why these aren't caught by the routine "fix examples in the docs" PRs

(those lines are due to #8447 so they are fairly old)

[straight-shoota]

@maiha Any idea?

[maiha]

The basic premise is that my checkers cannot handle all EXAMPLES.

• why: https://github.com/maiha/crystal-examples#difficulty

EXAMPLES that cannot be handled are managed as an "exclusion list" and excluded from testing.

• how: https://github.com/maiha/crystal-examples/blob/master/bundled/heuristic.jnl#L295

In this case, the entire code block is excluded because the incorrect comment syntax would interfere with the automatic generation of tests.

"¥hello".byte_slice(0, 1)  # => "\C2" (invalid UTF-8 character)
                                      ^^^^^^^^^^^^^^^^^^^^^^^^^

The following code is generated and fails.

$ cd tmp/string/working && LC_ALL=C /v/crystal/bin/crystal run -D preview_overflow ../all_spec.cr 2>&1
Using compiled compiler at /v/crystal/.build/crystal
In /v/tmp/string/all_spec.cr:509:46

 509 | �[0m�[1m( "¥hello".byte_slice(0, 1) ).should eq( "�" (invalid UTF-8 character) )
                                                    ^
Error: expecting token ')', not '('

I understand. So how many examples of such exclusions do you have?

1979 test
1341 success 43 pending 3 general 147 pseudo 71 macro 9 wrong 44 random 321 failure

[straight-shoota]

Perhaps we could fix a format for such comments on the output value.

My initial idea for this would be to just append another comment:

"¥hello".byte_slice(0, 1)  # => "\C2" # invalid UTF-8 character

This should be fairly readable, unambiguous and easy to parse.

[maiha]

It's good. I think it is the best choice so far. 💯

[maiha]

@straight-shoota
I would like to inspect the excluded EXAMPLES like this one once again.

There are probably about 300 cases, and it takes about a week.
I smell a 1.7 release, will it be ready in time?

[straight-shoota]

There should be time. 1.7.0 is scheduled for January 6.

[straight-shoota]

@HertzDevil Thanks for digging into the examples. I know there were some issues with that and meant to look into using https://github.com/maiha/crystal-examples for checking. But I didn't get anywhere and lost track before publishing the PR.