Allow multiple adjacent string literals in lark grammar

[benber86]

What I did

Python and Vyper allow multiple adjacent string literals like b: String[4] = "aa" "bb" or b: String[4] = "aa"'bb'.

I updated the lark grammar to handle parsing such statements which are currently unsupported.

How I did it

Added a ?strings: STRING+ rule and changed STRING to strings in the ?literal rule.

How to verify it

The following Vyper code:

b: constant(String[4]) = 'aa'"bb"

can now be parsed as:

[Node(constant_def, [Node(constant_private, [Leaf(NAME, 'b'), Leaf(COLON, ':'), Node(constant, [Leaf(CONSTANT, 'constant'), Leaf(LPAR, '('), Node(type, [Node(array_def, [Leaf(NAME, 'String'), Leaf(LSQB, '['), Leaf(DEC_NUMBER, '4'), Leaf(RSQB, ']')])]), Leaf(RPAR, ')')])]), Leaf(EQUAL, '='), Node(strings, [Leaf(STRING, "'aa'"), Leaf(STRING, '"bb"')])]), Leaf(_NEWLINE, '\n\n')]

Commit message

Allow multiple adjacent string literals in lark grammar

Description for the changelog

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[codecov-commenter]

Codecov Report

Merging #3143 (3936ead) into master (5d10ea0) will decrease coverage by 1.02%.
Report is 1 commits behind head on master.
The diff coverage is n/a.

❗ Current head 3936ead differs from pull request most recent head f53fef2. Consider uploading reports for the commit f53fef2 to get more accurate results

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@@            Coverage Diff             @@
##           master    #3143      +/-   ##
==========================================
- Coverage   89.50%   88.49%   -1.02%     
==========================================
  Files          80       95      +15     
  Lines       11342    10760     -582     
  Branches     2553     2266     -287     
==========================================
- Hits        10152     9522     -630     
+ Misses        797      796       -1     
- Partials      393      442      +49     

see 113 files with indirect coverage changes

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[charles-cooper]

on second thought, i think this results in harder to read code, and we shouldn't officially support it in the vyper grammar.