* Fix path.popContext() to not try to load "-1" from contexts array.
The current implement of popContext does
```js
this.setContext(this.contexts[this.contexts.length - 1]);
```
even if `this.contexts` can be empty, which causes it to lookup the
property `"-1"`, which is not found on the array itself and obviously
also not in the `Object.prototype` and the `Array.prototype`. However
since `"-1"` is not a valid array index, but has a valid integer
representation, this is a very expensive lookup in V8 (and probably
other engines too, but that is probably less relevant, since Babel
most often runs on Node nowadays).
* Make zero check explicit (for readability).
This prevents a requeued path from inheriting a totally wrong scope later on. I can't find exactly where this is happening, but either way a path should only inherit scope from it's ancestors.
* Path#ensureBlock keeps path context
This ensures that if you're inside an ArrowFunction with an expression body (say, you're on the BooleanLiteral in `() => true`), you don't suddenly lose your path context after inserting a variable.
This is because of 82d8aded8e (diff-9e0668ad44535be897b934e7077ecea5R14). Basically, an innocent `Scope#push` caused my visitor to suddenly stop working. Now, we mutate the Path so it's still in the tree.
* Tests
* Return inserted/replaced paths
This gives `Path`’s replacement and insertion methods a consistent
return value: the inserted/replaced paths.
Before, they could return `undefined`, a `node`, or a the current path
inside an array. It was kinda pointless. But now they always return an
array of paths, which is useful for solving
https://github.com/babel/babel/pull/4935#discussion_r96151368.
* Return inserted nodes and not BlockStatement
Addded test for bug #4363
* Cleanups
- `#replaceWith` will now return the current path if it's the same node
- `#insertAfter` and `#insertBefore` use public Path APIs now
- Makes container insertion faster (single splice call)
- Use public APIs in container insertion
- Replacing a statement with an expression returns the expression's path
- Replacing an expression with multiple statements returns the inserted
closure's body's paths.
* Fix bad Scope#parent caching
Now, we traverse the path until we find a parent scope.
Fixes#6057.
* Fix bad merge
* Remove cached data
* I need to stop using Github editor
* Fix infinite loops due to scopable paths being moved up
This reverts the former fix done in #5743 and always requeues
BlockStatements when they get created.
This also fixes a bug in babel-generator which would indent code
even though no comments are present.
So, I was reading the new Flow type strictness and noticed
https://flow.org/blog/2017/05/07/Strict-Function-Call-Arity/
Specifically, I wondered whether the `sum_all` example would copy the
arguments into an array, then loop over. Sadly, it does.
```js
function sum_all(...rest) {
let ret = 0;
for (let i = 0; i < rest.length; i++) { ret += rest[i]; }
return ret;
}
// output
function sum_all() {
var ret = 0;
for (var _len = arguments.length, rest = Array(_len), _key = 0; _key < _len; _key++) {
rest[_key] = arguments[_key];
}
for (var i = 0; i < rest.length; i++) { ret += rest[i]; }
return ret;
}
```
But then I noticed if I changed `let i = 0` to `let i: number = 0`, it
worked directly on `arguments`. That lead me down a rabbit hole to
`Path#_guessExecutionStatusRelativeTo`. When tracing through, the last
comparison made no sense to me. It was trying to find the index of
`"init"` in a list of `["declarations"]` and `"body"` in `["directives",
"body"]`. Red flags and such.
But it makes sense when you're trying to compare the visitor order of
the common ancestor path. Then we're trying to find `"init"` in a list
of `["init", "test", "update", "body"]`. Oh, and there's `"body"` in
there too! And now we know the `ForStatement`'s `init` is executed
before the `body`.
* Additional testcase and require->import refactorings
* Removed duplicated getStatementParent function. Refactored all babel-traverse tests to use ESmodules
* Handle arrow function processing via shared API rather than default plugin.
* Fix a few small PR comments.
* Preserve existing spec arrow 'this' rewrites, and support spec in subclass constructors.
Remove imports to lodash/assign and replace assign with Object.assign.
The lodash/assign is unnecessary for babel 7 as node >4 has the same
functionality built-in with Object.assign as used here.
This resolve the [issue 5353](https://github.com/babel/babel/issues/5353)
The PathHoister ignored member references on "this", causing it
to potentially hoist an expression above its function scope.
This patch tells the hoister to watch for "this", and if seen,
mark the nearest non-arrow function scope as the upper limit
for hoistng.
This fixes#4397 and is an alternative to #4787.
