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Convert proposal-object-rest-spread to TS (#13948)
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* chore: add typings to object-rest-spread

* chore: bundle object-rest-spread package

* improve type inference

* address review comments
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@JLHwung
JLHwung committed Nov 24, 2021
1 parent ad1798e commit 55f020e
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Showing 6 changed files with 105 additions and 56 deletions.
1 change: 1 addition & 0 deletions Gulpfile.mjs
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Expand Up @@ -461,6 +461,7 @@ function copyDts(packages) {

const libBundles = [
"packages/babel-parser",
"packages/babel-plugin-proposal-object-rest-spread",
"packages/babel-plugin-proposal-optional-chaining",
"packages/babel-preset-react",
"packages/babel-preset-typescript",
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133 changes: 84 additions & 49 deletions ...-proposal-object-rest-spread/src/index.js → ...-proposal-object-rest-spread/src/index.ts
View file
@@ -1,21 +1,24 @@
import { declare } from "@babel/helper-plugin-utils";
import syntaxObjectRestSpread from "@babel/plugin-syntax-object-rest-spread";
import { types as t } from "@babel/core";
import type { PluginPass } from "@babel/core";
import type { NodePath, Visitor, Scope } from "@babel/traverse";
import { convertFunctionParams } from "@babel/plugin-transform-parameters";
import { isRequired } from "@babel/helper-compilation-targets";
import compatData from "@babel/compat-data/corejs2-built-ins";
import shouldStoreRHSInTemporaryVariable from "./shouldStoreRHSInTemporaryVariable";

// TODO: Remove in Babel 8
const { isAssignmentPattern, isObjectProperty } = t;
// @babel/types <=7.3.3 counts FOO as referenced in var { x: FOO }.
// We need to detect this bug to know if "unused" means 0 or 1 references.
const ZERO_REFS = (() => {
if (!process.env.BABEL_8_BREAKING) {
const node = t.identifier("a");
const property = t.objectProperty(t.identifier("key"), node);
const pattern = t.objectPattern([property]);

return t.isReferenced(node, property, pattern) ? 1 : 0;
})();
// eslint-disable-next-line no-var
var ZERO_REFS = t.isReferenced(node, property, pattern) ? 1 : 0;
}

export default declare((api, opts) => {
api.assertVersion(7);
Expand All @@ -36,7 +39,9 @@ export default declare((api, opts) => {
const pureGetters = api.assumption("pureGetters") ?? loose;
const setSpreadProperties = api.assumption("setSpreadProperties") ?? loose;

function getExtendsHelper(file) {
function getExtendsHelper(
file: PluginPass,
): t.MemberExpression | t.Identifier {
return useBuiltIns
? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
: file.addHelper("extends");
Expand All @@ -51,7 +56,7 @@ export default declare((api, opts) => {
return foundRestElement;
}

function hasObjectPatternRestElement(path) {
function hasObjectPatternRestElement(path: NodePath): boolean {
let foundRestElement = false;
visitRestElements(path, restElement => {
if (restElement.parentPath.isObjectPattern()) {
Expand All @@ -62,15 +67,16 @@ export default declare((api, opts) => {
return foundRestElement;
}

function visitRestElements(path, visitor) {
function visitRestElements(
path: NodePath,
visitor: (path: NodePath<t.RestElement>) => any,
) {
path.traverse({
Expression(path) {
const parentType = path.parent.type;
const { parent, key } = path;
if (
(parentType === "AssignmentPattern" && path.key === "right") ||
(parentType === "ObjectProperty" &&
path.parent.computed &&
path.key === "key")
(isAssignmentPattern(parent) && key === "right") ||
(isObjectProperty(parent) && parent.computed && key === "key")
) {
path.skip();
}
Expand All @@ -79,7 +85,7 @@ export default declare((api, opts) => {
});
}

function hasSpread(node) {
function hasSpread(node: t.ObjectExpression): boolean {
for (const prop of node.properties) {
if (t.isSpreadElement(prop)) {
return true;
Expand All @@ -92,9 +98,10 @@ export default declare((api, opts) => {
// were converted to stringLiterals or not
// e.g. extracts {keys: ["a", "b", "3", ++x], allLiteral: false }
// from ast of {a: "foo", b, 3: "bar", [++x]: "baz"}
function extractNormalizedKeys(path) {
const props = path.node.properties;
const keys = [];
function extractNormalizedKeys(node: t.ObjectPattern) {
// RestElement has been removed in createObjectRest
const props = node.properties as t.ObjectProperty[];
const keys: t.Expression[] = [];
let allLiteral = true;
let hasTemplateLiteral = false;

Expand All @@ -106,7 +113,14 @@ export default declare((api, opts) => {
keys.push(t.cloneNode(prop.key));
hasTemplateLiteral = true;
} else if (t.isLiteral(prop.key)) {
keys.push(t.stringLiteral(String(prop.key.value)));
keys.push(
t.stringLiteral(
String(
//@ts-ignore prop.key can not be a NullLiteral
prop.key.value,
),
),
);
} else {
keys.push(t.cloneNode(prop.key));
allLiteral = false;
Expand All @@ -118,8 +132,11 @@ export default declare((api, opts) => {

// replaces impure computed keys with new identifiers
// and returns variable declarators of these new identifiers
function replaceImpureComputedKeys(properties, scope) {
const impureComputedPropertyDeclarators = [];
function replaceImpureComputedKeys(
properties: NodePath<t.ObjectProperty>[],
scope: Scope,
) {
const impureComputedPropertyDeclarators: t.VariableDeclarator[] = [];
for (const propPath of properties) {
const key = propPath.get("key");
if (propPath.node.computed && !key.isPure()) {
Expand All @@ -132,13 +149,14 @@ export default declare((api, opts) => {
return impureComputedPropertyDeclarators;
}

function removeUnusedExcludedKeys(path) {
function removeUnusedExcludedKeys(path: NodePath<t.ObjectPattern>): void {
const bindings = path.getOuterBindingIdentifierPaths();

Object.keys(bindings).forEach(bindingName => {
const bindingParentPath = bindings[bindingName].parentPath;
if (
path.scope.getBinding(bindingName).references > ZERO_REFS ||
path.scope.getBinding(bindingName).references >
(process.env.BABEL_8_BREAKING ? 0 : ZERO_REFS) ||
!bindingParentPath.isObjectProperty()
) {
return;
Expand All @@ -148,19 +166,24 @@ export default declare((api, opts) => {
}

//expects path to an object pattern
function createObjectRest(path, file, objRef) {
function createObjectRest(
path: NodePath<t.ObjectPattern>,
file: PluginPass,
objRef: t.Identifier | t.MemberExpression,
): [t.VariableDeclarator[], t.LVal, t.CallExpression] {
const props = path.get("properties");
const last = props[props.length - 1];
t.assertRestElement(last.node);
const restElement = t.cloneNode(last.node);
last.remove();

const impureComputedPropertyDeclarators = replaceImpureComputedKeys(
path.get("properties"),
path.get("properties") as NodePath<t.ObjectProperty>[],
path.scope,
);
const { keys, allLiteral, hasTemplateLiteral } =
extractNormalizedKeys(path);
const { keys, allLiteral, hasTemplateLiteral } = extractNormalizedKeys(
path.node,
);

if (keys.length === 0) {
return [
Expand Down Expand Up @@ -210,7 +233,11 @@ export default declare((api, opts) => {
];
}

function replaceRestElement(parentPath, paramPath, container) {
function replaceRestElement(
parentPath: NodePath<t.Function | t.CatchClause>,
paramPath: NodePath,
container?: t.VariableDeclaration[],
): void {
if (paramPath.isAssignmentPattern()) {
replaceRestElement(parentPath, paramPath.get("left"), container);
return;
Expand Down Expand Up @@ -299,7 +326,7 @@ export default declare((api, opts) => {
for (let i = 0; i < params.length; ++i) {
const param = params[i];
if (paramsWithRestElement.has(i)) {
replaceRestElement(param.parentPath, param);
replaceRestElement(path, param);
}
}
} else {
Expand Down Expand Up @@ -360,14 +387,15 @@ export default declare((api, opts) => {
}

let ref = originalPath.node.init;
const refPropertyPath = [];
const refPropertyPath: NodePath<t.ObjectProperty>[] = [];
let kind;

path.findParent(path => {
path.findParent((path: NodePath): boolean => {
if (path.isObjectProperty()) {
refPropertyPath.unshift(path);
} else if (path.isVariableDeclarator()) {
kind = path.parentPath.node.kind;
kind = (path.parentPath as NodePath<t.VariableDeclaration>).node
.kind;
return true;
}
});
Expand All @@ -385,12 +413,17 @@ export default declare((api, opts) => {
);
});

const objectPatternPath = path.findParent(path =>
path.isObjectPattern(),
//@ts-expect-error: findParent can not apply assertions on result shape
const objectPatternPath: NodePath<t.ObjectPattern> = path.findParent(
path => path.isObjectPattern(),
);

const [impureComputedPropertyDeclarators, argument, callExpression] =
createObjectRest(objectPatternPath, file, ref);
createObjectRest(
objectPatternPath,
file,
ref as t.MemberExpression,
);

if (pureGetters) {
removeUnusedExcludedKeys(objectPatternPath);
Expand All @@ -402,11 +435,9 @@ export default declare((api, opts) => {

insertionPath.insertBefore(impureObjRefComputedDeclarators);

insertionPath.insertAfter(
insertionPath = insertionPath.insertAfter(
t.variableDeclarator(argument, callExpression),
);

insertionPath = insertionPath.getSibling(insertionPath.key + 1);
)[0] as NodePath<t.VariableDeclarator>;

path.scope.registerBinding(kind, insertionPath);

Expand All @@ -433,7 +464,7 @@ export default declare((api, opts) => {

const specifiers = [];

for (const name of Object.keys(path.getOuterBindingIdentifiers(path))) {
for (const name of Object.keys(path.getOuterBindingIdentifiers(true))) {
specifiers.push(
t.exportSpecifier(t.identifier(name), t.identifier(name)),
);
Expand All @@ -449,7 +480,7 @@ export default declare((api, opts) => {
// try {} catch ({a, ...b}) {}
CatchClause(path) {
const paramPath = path.get("param");
replaceRestElement(paramPath.parentPath, paramPath);
replaceRestElement(path, paramPath);
},

// ({a, ...b} = c);
Expand Down Expand Up @@ -511,14 +542,15 @@ export default declare((api, opts) => {
]);

path.ensureBlock();
const body = node.body as t.BlockStatement;

if (node.body.body.length === 0 && path.isCompletionRecord()) {
node.body.body.unshift(
if (body.body.length === 0 && path.isCompletionRecord()) {
body.body.unshift(
t.expressionStatement(scope.buildUndefinedNode()),
);
}

node.body.body.unshift(
body.body.unshift(
t.expressionStatement(
t.assignmentExpression("=", left, t.cloneNode(temp)),
),
Expand All @@ -533,8 +565,9 @@ export default declare((api, opts) => {
]);

path.ensureBlock();
const body = node.body as t.BlockStatement;

node.body.body.unshift(
body.body.unshift(
t.variableDeclaration(node.left.kind, [
t.variableDeclarator(pattern, t.cloneNode(key)),
]),
Expand Down Expand Up @@ -565,11 +598,13 @@ export default declare((api, opts) => {

if (objectPatterns.length > 0) {
const statementPath = path.getStatementParent();
const statementNode = statementPath.node;
const kind =
statementNode.type === "VariableDeclaration"
? statementNode.kind
: "var";
statementPath.insertAfter(
t.variableDeclaration(
statementPath.node.kind || "var",
objectPatterns,
),
t.variableDeclaration(kind, objectPatterns),
);
}
},
Expand Down Expand Up @@ -627,7 +662,7 @@ export default declare((api, opts) => {
]);
}

for (const prop of (path.node.properties: Array)) {
for (const prop of path.node.properties) {
if (t.isSpreadElement(prop)) {
make();
exp.arguments.push(prop.argument);
Expand All @@ -640,6 +675,6 @@ export default declare((api, opts) => {

path.replaceWith(exp);
},
},
} as Visitor<PluginPass>,
};
});
20 changes: 14 additions & 6 deletions .../src/shouldStoreRHSInTemporaryVariable.js → .../src/shouldStoreRHSInTemporaryVariable.ts
View file
@@ -1,23 +1,31 @@
import { types as t } from "@babel/core";

const { isObjectProperty } = t;
/**
* This is a helper function to determine if we should create an intermediate variable
* such that the RHS of an assignment is not duplicated.
*
* See https://github.com/babel/babel/pull/13711#issuecomment-914388382 for discussion
* on further optimizations.
*/
export default function shouldStoreRHSInTemporaryVariable(node) {
export default function shouldStoreRHSInTemporaryVariable(node: t.LVal) {
if (t.isArrayPattern(node)) {
const nonNullElements = node.elements.filter(element => element !== null);
if (nonNullElements.length > 1) return true;
else return shouldStoreRHSInTemporaryVariable(nonNullElements[0]);
} else if (t.isObjectPattern(node)) {
if (node.properties.length > 1) return true;
else if (node.properties.length === 0) return false;
else return shouldStoreRHSInTemporaryVariable(node.properties[0]);
} else if (t.isObjectProperty(node)) {
return shouldStoreRHSInTemporaryVariable(node.value);
const { properties } = node;
if (properties.length > 1) return true;
else if (properties.length === 0) return false;
else {
const firstProperty = properties[0];
if (isObjectProperty(firstProperty)) {
// the value of the property must be an LVal
return shouldStoreRHSInTemporaryVariable(firstProperty.value as t.LVal);
} else {
return shouldStoreRHSInTemporaryVariable(firstProperty);
}
}
} else if (t.isAssignmentPattern(node)) {
return shouldStoreRHSInTemporaryVariable(node.left);
} else if (t.isRestElement(node)) {
Expand Down
1 change: 1 addition & 0 deletions packages/babel-traverse/src/path/ancestry.ts
View file
Expand Up @@ -12,6 +12,7 @@ import NodePath from "./index";
*/

export function findParent(
this: NodePath,
callback: (path: NodePath) => boolean,
): NodePath | null {
let path = this;
Expand Down
2 changes: 1 addition & 1 deletion packages/babel-traverse/src/scope/index.ts
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Expand Up @@ -983,7 +983,7 @@ export default class Scope {
init?: t.Expression;
unique?: boolean;
_blockHoist?: number | undefined;
kind?: "var" | "let";
kind?: "var" | "let" | "const";
}) {
let path = this.path;

Expand Down

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