From 306b5db1efaaa64893c9a1321835e72f99691cfc Mon Sep 17 00:00:00 2001 From: Victor Felder Date: Wed, 4 Nov 2015 15:14:41 +0100 Subject: [PATCH] Have es2015 rest transform safely use `arguments` --- .../src/rest.js | 22 +++++++++++++++++-- .../parameters/rest-arrow-functions/actual.js | 2 +- .../rest-arrow-functions/expected.js | 16 +++++++------- .../expected.js | 8 +++---- 4 files changed, 33 insertions(+), 15 deletions(-) diff --git a/packages/babel-plugin-transform-es2015-parameters/src/rest.js b/packages/babel-plugin-transform-es2015-parameters/src/rest.js index 50072a0d04..1563f87ed0 100644 --- a/packages/babel-plugin-transform-es2015-parameters/src/rest.js +++ b/packages/babel-plugin-transform-es2015-parameters/src/rest.js @@ -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 @@ -116,7 +120,15 @@ export let visitor = { // otherwise `arguments` will be remapped in arrow functions argsId._shadowedFunctionLiteral = path; - // support patterns + function optimiseLoadStatement(parent, offset) { + let newExpr = loadRest({ + ARGUMENTS: argsId, + KEY: t.numericLiteral(parent.property.value + offset) + }); + return newExpr; + } + + // support patterns // no test case? if (t.isPattern(rest)) { let pattern = rest; rest = scope.generateUidIdentifier("ref"); @@ -154,7 +166,13 @@ export let visitor = { for (let candidate of (state.candidates: Array)) { candidate.replaceWith(argsId); if (candidate.parentPath.isMemberExpression()) { - optimiseMemberExpression(candidate.parent, state.offset); + if (t.isReturnStatement(candidate.parentPath.parent) + || t.isIdentifier(candidate.parentPath.parent.id)) { + let optimized = optimiseLoadStatement(candidate.parent, state.offset, argsId); + candidate.parentPath.replaceWith(optimized); + } else { + optimiseMemberExpression(candidate.parent, state.offset); + } } } } diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/actual.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/actual.js index 43378f3344..e9d376e92b 100644 --- a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/actual.js +++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/actual.js @@ -14,7 +14,7 @@ var somefun = function () { }; var _d = args1[1]; }; - let get1stArg = (...args) => args[0]; + let get3rdArg = (...args) => args[2]; } function demo1(...args) { diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/expected.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/expected.js index 62c2f6d931..171f1d01a0 100644 --- a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/expected.js +++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-arrow-functions/expected.js @@ -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]; }; }; diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js index dbae1250ad..9a680b3ad4 100644 --- a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js +++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js @@ -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]; }