Add support for arrow functions

[jannisborgers]

Adds support for arrow functions inside filters, which makes formatting |filter(), |map() and |reduce() filters possible, resolving #19.

Includes a new test file for three scenarios:

• Arrow function with one argument:

  {{ someArray|filter(item => item.amount > 5) }}

• Arrow function with multiple arguments:

  {{ someArray|map((value, key) => "key #{key} with value #{value}") }}

• Arrow function with multiple arguments and second filter argument:

  {{ numbers|reduce((carry, v, k) => carry + v * k, 10) }}

I also tested with a variety of other combinations, including named parameters, which all seem to work. I will post my notes in the corresponding issue, in case someone is interested.

[zackad]

Hi @jannisborgers, thanks for your awesome work (and notes).

There's a couple things that need to be fixed:

• try to run prettier to fix code formatting node_modules/.bin/prettier --write src/
• fix linter error
• commit updated snapshot file

Running test on my dev environment yield this errors

 FAIL  tests/Statements/jsfmt.spec.js [ tests/Statements/jsfmt.spec.js ]
 FAIL  .direnv/flake-inputs/vf031scinzsn9fsxqrxbggnaq13pazll-source/tests/Statements/jsfmt.spec.js [ .direnv/flake-inputs/vf031scinzsn9fsxqrxbggnaq13pazll-source/tests/Statements/jsfmt.spec.js ]
Error: ERROR: Invalid Token
  22 | {% macro partner(groupId, value) %}
  23 |     {# 80 is the groupid of specific hotel websites that may not have a correct partner name #}
> 24 |     {{ groupId == 80 ? 'book_hotel_website_test' | translate : value }}
     |                ^
  25 | {% endmacro %}
  26 | 
  27 | 

Expected expression end "}}" but found = instead.
 ❯ TokenStream.error src/melody/melody-parser/TokenStream.js:129:24
 ❯ TokenStream.expect src/melody/melody-parser/TokenStream.js:103:14
 ❯ Parser.parse src/melody/melody-parser/Parser.js:162:45
 ❯ Object.parse src/melody/melody-extension-core/parser/macro.js:54:29
 ❯ Parser.matchTag src/melody/melody-parser/Parser.js:494:31
 ❯ Parser.parse src/melody/melody-parser/Parser.js:173:32
 ❯ Object.parse src/parser.js:82:24
 ❯ parse4 node_modules/prettier/index.mjs:22117:24
 ❯ coreFormat node_modules/prettier/index.mjs:22607:7
 ❯ formatWithCursor node_modules/prettier/index.mjs:22809:14

your patch seems to break comparison operator.

[zackad]

Everything seems to be working as expected. Would like to have some feedback from other people though.