cerxes/babel
3
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Merge pull request #2833 from vhf/rest-arguments-use

Browse Source 
Have es2015 rest transform safely use `arguments`
This commit is contained in:
Sebastian McKenzie
2015-12-12 01:35:57 +11:00
parent d8445e0e78 9a97d92217
commit e9fa841ae6
4 changed files with 36 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
packages/babel-plugin-transform-es2015-parameters/src/rest.js
View File

@@ -11,6 +11,10 @@ let buildRest = template(`
}
`);
let loadRest = template(`
ARGUMENTS.length <= KEY || ARGUMENTS[KEY] === undefined ? undefined : ARGUMENTS[KEY]
`);
let memberExpressionOptimisationVisitor = {
Scope(path, state) {
// check if this scope has a local binding that will shadow the rest parameter
@@ -84,21 +88,6 @@ let memberExpressionOptimisationVisitor = {
}
};
function optimiseMemberExpression(parent, offset) {
if (offset === 0) return;
let newExpr;
let prop = parent.property;
if (t.isLiteral(prop)) {
prop.value += offset;
prop.raw = String(prop.value);
} else { // // UnaryExpression, BinaryExpression
newExpr = t.binaryExpression("+", prop, t.numericLiteral(offset));
parent.property = newExpr;
}
}
function hasRest(node) {
return t.isRestElement(node.params[node.params.length - 1]);
}
@@ -116,16 +105,25 @@ export let visitor = {
// otherwise `arguments` will be remapped in arrow functions
argsId._shadowedFunctionLiteral = path;
// support patterns
if (t.isPattern(rest)) {
let pattern = rest;
rest = scope.generateUidIdentifier("ref");
function optimiseCandidate(parent, parentPath, offset) {
if (t.isReturnStatement(parentPath.parent) || t.isIdentifier(parentPath.parent.id)) {
parentPath.replaceWith(loadRest({
ARGUMENTS: argsId,
KEY: t.numericLiteral(parent.property.value + offset)
}));
} else {
if (offset === 0) return;
let newExpr;
let prop = parent.property;
let declar = t.variableDeclaration("let", pattern.elements.map(function (elem, index) {
let accessExpr = t.memberExpression(rest, t.numericLiteral(index), true);
return t.variableDeclarator(elem, accessExpr);
}));
node.body.body.unshift(declar);
if (t.isLiteral(prop)) {
prop.value += offset;
prop.raw = String(prop.value);
} else { // UnaryExpression, BinaryExpression
newExpr = t.binaryExpression("+", prop, t.numericLiteral(offset));
parent.property = newExpr;
}
}
}
// check and optimise for extremely common cases
@@ -153,9 +151,7 @@ export let visitor = {
if (state.candidates.length) {
for (let candidate of (state.candidates: Array)) {
candidate.replaceWith(argsId);
if (candidate.parentPath.isMemberExpression()) {
optimiseMemberExpression(candidate.parent, state.offset);
}
optimiseCandidate(candidate.parent, candidate.parentPath, state.offset);
}
}
return;
@@ -166,8 +162,6 @@ export let visitor = {
// deopt shadowed functions as transforms like regenerator may try touch the allocation loop
state.deopted = state.deopted || !!node.shadow;
//
let start = t.numericLiteral(node.params.length);
let key = scope.generateUidIdentifier("key");
let len = scope.generateUidIdentifier("len");

2
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/actual.js vendored
View File

@@ -14,7 +14,7 @@ var somefun = function () {
};
var _d = args1[1];
};
let get1stArg = (...args) => args[0];
let get3rdArg = (...args) => args[2];
}
function demo1(...args) {

16
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/expected.js vendored
View File

@@ -1,21 +1,21 @@
var concat = function () {
var x = arguments[0];
var y = arguments[1];
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
};
var somefun = function () {
var get2ndArg = function (a, b) {
var _b = arguments[2];
var _b = arguments.length <= 2 || arguments[2] === undefined ? undefined : arguments[2];
var somef = function (x, y, z) {
var _a = arguments[3];
var _a = arguments.length <= 3 || arguments[3] === undefined ? undefined : arguments[3];
};
var somefg = function (c, d, e, f) {
var _a = arguments[4];
var _a = arguments.length <= 4 || arguments[4] === undefined ? undefined : arguments[4];
};
var _d = arguments[3];
var _d = arguments.length <= 3 || arguments[3] === undefined ? undefined : arguments[3];
};
var get1stArg = function () {
return arguments[0];
var get3rdArg = function () {
return arguments.length <= 2 || arguments[2] === undefined ? undefined : arguments[2];
};
};

8
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js vendored
View File

@@ -1,9 +1,9 @@
var t = function () {
var x = arguments[0];
var y = arguments[1];
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
};
function t() {
var x = arguments[0];
var y = arguments[1];
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
}