Variable Scoping with identifier_scope

JavaScript pattern

Default Grit patterns are not generally aware of variable scoping, but you can use the identifier_scope pattern to find (or exclude) scopes where an identifier has been locally defined.

This is most often used when you want to target an import from a shared module but exclude scopes where the identifier is shadowed locally.

For example, this pattern would rename t from the translation library to translate unless t is shadowed locally:

GRIT 
language js

`t` as $t => `translate` where {
  $t <: imported_from(from=`"translation"`),
  $t <: not within identifier_scope(name=`t`)
}

Here is a simple example file where t is shadowed locally:

JS 
import { t } from 'translation';

console.log(t('hello world'));

function normal() {
  console.log(t('hello world'));
}

// t is an argument to this function, so the global t is not used and we should *not* rename it here.
function shadowed(t) {
  console.log(t('hello world'));
}

When we rewrite it, the shadowed t is not renamed:

JS 
import { translate } from 'translation';

console.log(translate('hello world'));

function normal() {
  console.log(translate('hello world'));
}

// t is an argument to this function, so the global t is not used and we should *not* rename it here.
function shadowed(t) {
  console.log(t('hello world'));
}