Skip to content

Handle side effects correctly in rest params index expressions (#4348) #4674

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
danez merged 1 commit into from
Oct 5, 2016
Merged

Handle side effects correctly in rest params index expressions (#4348) #4674

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 19 additions & 4 deletions packages/babel-plugin-transform-es2015-parameters/src/rest.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,10 @@ let restIndex = template(`
ARGUMENTS.length <= INDEX ? undefined : ARGUMENTS[INDEX]
`);

let restIndexImpure = template(`
REF = INDEX, ARGUMENTS.length <= REF ? undefined : ARGUMENTS[REF]
`);

let restLength = template(`
ARGUMENTS.length <= OFFSET ? 0 : ARGUMENTS.length - OFFSET
`);
Expand Down Expand Up @@ -161,10 +165,21 @@ function optimiseIndexGetter(path, argsId, offset) {
index = t.binaryExpression("+", path.parent.property, t.numericLiteral(offset));
}

path.parentPath.replaceWith(restIndex({
ARGUMENTS: argsId,
INDEX: index,
}));
const { scope } = path;
if (!scope.isPure(index)) {
let temp = scope.generateUidIdentifierBasedOnNode(index);
scope.push({id: temp, kind: "var"});
path.parentPath.replaceWith(restIndexImpure({
ARGUMENTS: argsId,
INDEX: index,
REF: temp
}));
} else {
path.parentPath.replaceWith(restIndex({
ARGUMENTS: argsId,
INDEX: index,
}));
}
}

function optimiseLengthGetter(path, argsId, offset) {
Expand Down
4 changes: 4 additions & 0 deletions ...bel-plugin-transform-es2015-parameters/test/fixtures/parameters/regression-4348/actual.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
function first(...values) {
var index = 0;
return values[index++];
}
6 changes: 6 additions & 0 deletions ...l-plugin-transform-es2015-parameters/test/fixtures/parameters/regression-4348/expected.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
function first() {
var _ref;

var index = 0;
return _ref = index++ + 0, arguments.length <= _ref ? undefined : arguments[_ref];
Copy link
Copy Markdown
Member

@hzoo hzoo Oct 5, 2016

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

looks good? wondering where index++ + 0 is coming from (not part of this particular change)

Copy link
Copy Markdown

@mariusschulz mariusschulz Oct 6, 2016 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It's the index of the rest parameter in the parameter list. If the function signature were e.g. function(a, b, ...values), it would be index++ + 2 instead.

Copy link
Copy Markdown
Member

@hzoo hzoo Oct 6, 2016 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I see, so we could make a change so that if it's 0 then don't add the + 0

#4692

Copy link
Copy Markdown

@mariusschulz mariusschulz Oct 6, 2016

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yeah, that would be a good idea.

}
6 changes: 4 additions & 2 deletions ...babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-length/expected.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
var t = function (f) {
var _ref;

arguments.length <= 1 ? undefined : arguments[1];
arguments.length <= (arguments.length <= 1 ? 0 : arguments.length - 1) - 1 + 1 ? undefined : arguments[(arguments.length <= 1 ? 0 : arguments.length - 1) - 1 + 1];
_ref = (arguments.length <= 1 ? 0 : arguments.length - 1) - 1 + 1, arguments.length <= _ref ? undefined : arguments[_ref];
};

function t(f) {
Expand All @@ -11,4 +13,4 @@ function t(f) {
items;
items[0];
items[items.length - 1];
}
}