Ruby: introduce mixin field

[masatake]

See #2476.

@AmaiKinono, plesae look at 205052c. It is a test case showing how new code dealing with "include" mixin.

You may be interested in c4711e8 ..205052c.
c4711e8 and 7af2181 are preparation for 0912d1e.

[masatake]

I thought nestingLevel was not needed because we have cork.
I find it is wrong. To manage information which is not suitable to attach to a tagEntryInfo, nestingLevel is still useful.

[masatake]

I didn't implement reference tags for X and Y because I'm not sure whether it is needed or not.

[coveralls]

Coverage increased (+0.009%) to 86.709% when pulling f9a77b5 on masatake:ruby-mixin-include into 71529ec on universal-ctags:master.

[codecov]

Codecov Report

Merging #2478 into master will decrease coverage by 0.13%.
The diff coverage is 94.91%.

@@            Coverage Diff             @@
##           master    #2478      +/-   ##
==========================================
- Coverage   86.73%   86.60%   -0.14%     
==========================================
  Files         177      177              
  Lines       36621    36759     +138     
==========================================
+ Hits        31764    31835      +71     
- Misses       4857     4924      +67     

Impacted Files	Coverage Δ
main/entry_p.h	100.00% <ø> (ø)
main/nestlevel.c	87.75% <90.90%> (+0.25%)	⬆️
parsers/ruby.c	98.00% <95.00%> (-0.58%)	⬇️
main/entry.c	87.88% <100.00%> (ø)
main/field.c	95.85% <100.00%> (ø)
main/fmt.c	85.62% <100.00%> (ø)
main/writer-ctags.c	98.70% <100.00%> (ø)
main/writer-json.c	93.67% <100.00%> (ø)
readtags-cmd/readtags-cmd.c	44.94% <0.00%> (-26.11%)	⬇️
dsl/qualifier.c	70.23% <0.00%> (+3.20%)	⬆️

---

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[AmaiKinono]

I think I've done the right changes, but now I don't know how to push it to this branch. Maybe you need to open some "push access" for me? Not sure if it can be done on a per branch basis.

Edit: Oh I just got it. I can create a PR on your fork :D Is that the right way?

[masatake]

I think I've done the right changes, but now I don't know how to push it to this branch. Maybe you need to open some "push access" for me? Not sure if it can be done on a per branch basis.

Edit: Oh I just got it. I can create a PR on your fork :D Is that the right way?
Merge state

I will merge this one first. Then you can open your pull request to this repo.

Before merging this, I would like to think about following case:

class A
  def hi
     include X
    p "Calling 'hi' in A."
  end
end

[AmaiKinono]

The code you given actually doesn't work on my side. A working code should look like:

• Use instance method:

class A
  def hi
    self.class.prepend X
    p "Calling 'hi' in A."
  end
end

# a = A.new
# a.hi
# => "Calling 'hi' in A."
# a.hi
# => "Calling 'hi' in X."

• Or use class method:

class A
  def self.hi
    self.include X
  end
end

# a = A.new
# a.hi
# => (undefined method error)
# A.hi
# a.hi
# => "Calling 'hi' in X."

I think we could just not bother with this, because it can actually happen anywhere:

class A
end
a = A.new

# a.hi
# => (undefined method error)
# A.prepend X
# a.hi
# => "Calling 'hi' in X."

[masatake]

@AmaiKinono , thank you for the explanation.

I found a pattern I would like to support:

module X
  def hi
    p "Calling 'hi' in X."
  end
end

class A
  def self.prep
    include X
  end
  def hi
    p "Calling 'hi' in A."
  end

end

a = A.new
A.prep
p A.ancestors

Recognizing include in the singleton method is not hard.

[masatake]

@AmaiKinono, give me an ack if you think it is ready to merge.
Tell me if you think the last commit should be removed.

[AmaiKinono]

Yes I think this is ready to merge.

About include in a singleton method: I can see this is useful. I like it. Currently I can't think about similar cases (as I said I am new to ruby), which might be better to add now. But maybe we could extend it in the future when these cases actually come up.

[masatake]

@AmaiKinono, thank you for reviewing.

Feel free to ask me questions about the changes here.

About include in a singleton method: I can see this is useful. I like it. Currently I can't think about similar cases (as I said I am new to ruby), which might be better to add now. But maybe we could extend it in the future when these cases actually come up.

I agree with you.