Return support for plugin-extract-sequence-expressions

[Yesterday17]

For example:

function t() {
  return a, b, c, d;
}

equals

function t() {
  a;b;c;
  return d;
}

[coderaiser]

There was no support of such cases in putout. But it is a good idea :).

traverse should be modified to handle ReturnStatement, same with fix.

[coderaiser]

Added support of ReturnStatement to @putout/plugin-extract-sequence-expressions v1.7.0. Please reinstall putout.

Is it works for you?

[Yesterday17]

It works on many occasions, but on some code it may break, for example, it throws an error after trying to transform the following code(sequenced expression with multiple layers):

const putout = require('putout');

const code = `function t(){return 1,2,(3,4),5,(6,7)}`;

console.log(
  putout(code, {
    plugins: ['extract-sequence-expressions']
  }).code
);

/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/engine-runner/lib/run-fix.js:13
    throw e;
    ^

Error: cannot turn SequenceExpression to a statement
    at toStatement (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@babel/types/lib/converters/toStatement.js:38:13)
    at wrap (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/plugin-extract-sequence-expressions/lib/extract-sequence-expressions.js:21:12)
    at Array.map (<anonymous>)
    at module.exports.fix (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/plugin-extract-sequence-expressions/lib/extract-sequence-expressions.js:53:28)
    at tryCatch (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/try-catch/lib/try-catch.js:7:26)
    at tryToFix (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/engine-runner/lib/run-fix.js:6:17)
    at module.exports (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/engine-runner/lib/run-fix.js:20:5)
    at push (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/engine-runner/lib/merge-visitors.js:63:9)
    at SequenceExpression (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@putout/plugin-extract-sequence-expressions/lib/extract-sequence-expressions.js:71:17)
    at NodePath._call (/home/yesterday17/GitHub/majsoul-source-prettier/node_modules/@babel/traverse/lib/path/context.js:53:20) {
  loc: { line: 1, column: 20 }
}

And on transforming arrow function, it produced a wrong output:

const putout = require('putout');

const code = `() => 1,2,3,4,5,6,7`;

console.log(
  putout(code, {
    plugins: ['extract-sequence-expressions']
  }).code
);

Output:

() => 1;
2;
3;
4;
5;
6;
7;

[coderaiser]

Do you have such code in your codebase? Look every case should be programmed independently (ArrowFunctions, nested SequenceExpressions etc) to get things works. I think that only code from a real codebase should be used as example.

Possible cases to break things is countless 🙂. But if you think that it's important you can always send a pull request.

[coderaiser]

OK, multiple layers worth fixing, it is landed in @putout/plugin-extract-sequence-expressions v1.8.0, but transforming this:

() => 1,2,3,4,5,6,7

into this:

() => 1;
2;
3;
4;
5;
6;
7;

Is absolutely correct because () => 1 is one of sequence expressions.

If you want to put all numbers into body of an arrow function you need to add brackets:

() => (1,2,3,4,5,6,7)

And it will be:

() => {
  1;
  2;
  3;
  4;
  5;
  6;
  return 7;
}