Invalid output when indexing anonymous table

[fnuecke]

I'm not sure if there's a special term for this, but I'm talking about this pattern: ({...})[key].

For example: luamin.minify("print(({})[1])") will output
print({}[1]) which is invalid. It should remain as print(({})[1]).

Tested with luaparse 0.1.4 and luamin 0.2.7.

[mathiasbynens]

Good catch!

Looks like an IndexExpression of which the base is a TableConstructorExpression must be wrapped in parentheses. I suppose the same goes for MemberExpressions.

[fnuecke]

Awesome, thanks for the quick response and fix!

[mathiasbynens]

@fnuecke Thanks for the helpful bug report with a reduced test case!

---

Perhaps the fix was a bit naive / incomplete.

E.g. print(('a'..'b')[0]) → print('a'..'b'[0]), which is not the same.

After giving it some more thought, I think the base of a MemberExpression should always be wrapped in parens except when it’s an identifier.

Update: Ah, that is another oversimplification. Following that logic, e.g. print(a.b.c) → print((a.b).c) which is unneeded. The best way to fix this is probably by extending PRECEDENCE.

[fnuecke]

Good point. It probably should. Another testcase: (function()end)() becomes function()end() but should remain as is.

[yihuang]

What's the status of the bug with anonymous function?

[ghost]

Well I just took a look and decided to fix this. I think this project has probably been abandoned since the fix was so easy.

Just change this

result = formatExpression(expression.base) + '(';

https://github.com/mathiasbynens/luamin/blob/master/luamin.js#L331

if(expression.base.inParens && expression.base.type == 'FunctionDeclaration')
        result = '(' + formatExpression(expression.base) + ')('
else
        result = formatExpression(expression.base) + '(';

If you have any future issues you can easily debug them by running luaparse and looking at what the AST looks like

./luaparse -b -c '(function()end)()'
{
  "type": "Chunk",
  "body": [
    {
      "type": "CallStatement",
      "expression": {
        "type": "CallExpression",
        "base": {
          "type": "FunctionDeclaration",
          "identifier": null,
          "isLocal": false,
          "parameters": [],
          "body": [],
          "inParens": true
        },
        "arguments": []
      }
    }
  ],
  "comments": []
}

[mathiasbynens]

@EdanPyx Care to submit a pull request?

[ghost]

Done #36

[mathiasbynens]

575a4bb