Fix comments in REPL - fixes #78

[ncw]

Before this change, entering a comment in the REPL caused the REPL to
read the comment indefinitely effectively breaking it.

After this change the behaviour should be exactly the same as python3/

[ncw]

Can you review this for me @corona10 ?

[codecov-io]

Codecov Report

Merging #79 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #79      +/-   ##
==========================================
+ Coverage   68.65%   68.66%   +<.01%     
==========================================
  Files          59       59              
  Lines       10525    10528       +3     
==========================================
+ Hits         7226     7229       +3     
  Misses       2790     2790              
  Partials      509      509

Impacted Files	Coverage Δ
repl/repl.go	100% <100%> (ø)	⬆️
symtable/symtable.go	94.23% <0%> (ø)	⬆️

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[corona10]

This patch will fix this issue #78 .
But the input of '#' should be handled as same as below code?
Should we update grammar file for this?

[Gpython dev]
- os/arch: darwin/amd64
- go version: go1.10
>>> def a(): pass
>>>

[corona10]

This is the example of pypy and rustpython.

Python 3.6.1 (dab365a465140aa79a5f3ba4db784c4af4d5c195, Feb 18 2019, 10:53:27)
[PyPy 7.0.0-alpha0 with GCC 4.2.1 Compatible Apple LLVM 10.0.0 (clang-1000.11.45.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
And now for something completely different: ``"it's likely temporary until
forever" arigo''
>>>> #
>>>> #
>>>>

Welcome to the magnificent Rust Python 0.1.0 interpreter 😱 🖖
>>>>> #
>>>>>

[corona10]

And it still doesn't work well on my local laptop with branch fix-78-repl bcb3785

Python 3.4.0 (none, unknown)
[Gpython dev]
- os/arch: darwin/amd64
- go version: go1.10
>>> #
... #
...

[ncw]

And it still doesn't work well on my local laptop with branch fix-78-repl bcb3785

Python 3.4.0 (none, unknown)
[Gpython dev]
- os/arch: darwin/amd64
- go version: go1.10
>>> #
... #
...

Ah you are right this is broken :-(

The pypy and rustpython ways of doing it are

• a whole lot more logical in my opinion
• much easier that emulating python3 exactly

Shall I make it work like that?

[corona10]

@ncw
Yes, please.
IMHO, we don't have to follow everything of CPython :)

[ncw]

OK I did that! PTAL

[corona10]

@ncw

gpython/parser/lexer.go

Line 375 in 2609237

func (x *yyLex) Lex(yylval *yySymType) (ret int) {

Can we fix this issue on lexer level approach?

[corona10]

@ncw
This PR is pending for 2 weeks.
Should we merge this PR for this time and later fix it?
Or do you have any ideas?
Thanks!

[ncw]

I think this is good to go now.

I don't think fixing it in the lexer is the right place - this is specifically to do with how the REPL works and in particular how the single input grammar works which is a bit strange but it is how the Python grammar is defined.

I'll merge this now and if there are any problem with it I'm sure we can fix them up :-)