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Improve output when re-exporting #15709

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Improve output when re-exporting #15709

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2a96dc5
improve
liuxingbaoyu Jun 17, 2023
a4dedb1
fix
liuxingbaoyu Jun 25, 2023
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196 changes: 130 additions & 66 deletions packages/babel-helper-module-transforms/src/index.ts
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Expand Up @@ -3,9 +3,11 @@ import {
booleanLiteral,
callExpression,
cloneNode,
continueStatement,
directive,
directiveLiteral,
expressionStatement,
functionDeclaration,
identifier,
isIdentifier,
memberExpression,
Expand Down Expand Up @@ -64,9 +66,9 @@ export interface RewriteModuleStatementsAndPrepareHeaderOptions {
lazy?: Lazy;
esNamespaceOnly?: boolean;
filename: string | undefined;
constantReexports?: boolean | void;
enumerableModuleMeta?: boolean | void;
noIncompleteNsImportDetection?: boolean | void;
constantReexports?: boolean;
enumerableModuleMeta?: boolean;
noIncompleteNsImportDetection?: boolean;
}

/**
Expand Down Expand Up @@ -207,7 +209,8 @@ export function wrapInterop(
export function buildNamespaceInitStatements(
metadata: ModuleMetadata,
sourceMetadata: SourceModuleMetadata,
constantReexports: boolean | void = false,
constantReexports: boolean = false,
buildInteropWrap?: Parameters<typeof buildNamespaceReexport>[3],
) {
const statements = [];

Expand All @@ -233,17 +236,23 @@ export function buildNamespaceInitStatements(
statements.push(
(sourceMetadata.lazy
? template.statement`
Object.defineProperty(EXPORTS, "NAME", {
enumerable: true,
get: function() {
return NAMESPACE;
}
EXPORT_GETTER("NAME", function() {
return NAMESPACE;
});
`
: template.statement`EXPORTS.NAME = NAMESPACE;`)({
EXPORTS: metadata.exportName,
NAME: exportName,
NAMESPACE: cloneNode(srcNamespace),
...(sourceMetadata.lazy
? {
EXPORT_GETTER: buildExportGetter(
metadata.programPath,
metadata.exportName,
),
}
: {
EXPORTS: metadata.exportName,
}),
}),
);
}
Expand All @@ -252,6 +261,7 @@ export function buildNamespaceInitStatements(
metadata,
cloneNode(srcNamespace),
constantReexports,
buildInteropWrap,
);
statement.loc = sourceMetadata.reexportAll.loc;

Expand All @@ -265,11 +275,8 @@ const ReexportTemplate = {
constant: template.statement`EXPORTS.EXPORT_NAME = NAMESPACE_IMPORT;`,
constantComputed: template.statement`EXPORTS["EXPORT_NAME"] = NAMESPACE_IMPORT;`,
spec: template.statement`
Object.defineProperty(EXPORTS, "EXPORT_NAME", {
enumerable: true,
get: function() {
return NAMESPACE_IMPORT;
},
EXPORT_GETTER("EXPORT_NAME", function () {
return NAMESPACE_IMPORT;
});
`,
};
Expand Down Expand Up @@ -312,7 +319,11 @@ function buildReexportsFromMeta(
return ReexportTemplate.constant(astNodes);
}
} else {
return ReexportTemplate.spec(astNodes);
return ReexportTemplate.spec({
EXPORT_NAME: exportName,
NAMESPACE_IMPORT,
EXPORT_GETTER: buildExportGetter(meta.programPath, meta.exportName),
});
}
});
}
Expand All @@ -337,54 +348,106 @@ function buildESModuleHeader(
)({ EXPORTS: metadata.exportName });
}

function addPrivateHelper(
path: NodePath<t.Program>,
name: string,
fn: t.FunctionExpression,
) {
const { scope } = path;
const key = PACKAGE_JSON.name + "." + name;
let id = path.getData(key);
if (id) {
return cloneNode(id);
}
id = scope.generateUidIdentifier("_" + name);
path.setData(key, id);

const [fnPath] = path.unshiftContainer(
"body",
functionDeclaration(id, fn.params, fn.body),
);
path.scope.registerBinding("hoisted", fnPath);

return cloneNode(id);
}

function buildExportGetter(path: NodePath<t.Program>, exportName: string) {
return addPrivateHelper(
path,
"export",
template.expression`
function (name, fn) {
Object.defineProperty(EXPORTS, name, {
enumerable: true,
get: fn
});
}
`({
EXPORTS: identifier(exportName),
}) as t.FunctionExpression,
);
}

/**
* Create a re-export initialization loop for a specific imported namespace.
*/
function buildNamespaceReexport(
metadata: ModuleMetadata,
namespace: t.Identifier | t.CallExpression,
constantReexports: boolean | void,
constantReexports: boolean,
buildInteropWrap?: (reexportsStmts: t.CallExpression) => t.CallExpression,
) {
return (
constantReexports
? template.statement`
Object.keys(NAMESPACE).forEach(function(key) {
if (key === "default" || key === "__esModule") return;
VERIFY_NAME_LIST;
if (key in EXPORTS && EXPORTS[key] === NAMESPACE[key]) return;

EXPORTS[key] = NAMESPACE[key];
});
`
: // Also skip already assigned bindings if they are strictly equal
// to be somewhat more spec-compliant when a file has multiple
// namespace re-exports that would cause a binding to be exported
// multiple times. However, multiple bindings of the same name that
// export the same primitive value are silently skipped
// (the spec requires an "ambiguous bindings" early error here).
template.statement`
Object.keys(NAMESPACE).forEach(function(key) {
if (key === "default" || key === "__esModule") return;
VERIFY_NAME_LIST;
if (key in EXPORTS && EXPORTS[key] === NAMESPACE[key]) return;

Object.defineProperty(EXPORTS, key, {
enumerable: true,
get: function() {
return NAMESPACE[key];
const { programPath, exportNameListName } = metadata;

// Also skip already assigned bindings if they are strictly equal
// to be somewhat more spec-compliant when a file has multiple
// namespace re-exports that would cause a binding to be exported
// multiple times. However, multiple bindings of the same name that
// export the same primitive value are silently skipped
// (the spec requires an "ambiguous bindings" early error here).
const fn = template.expression`
function (exports, mod, exportNames) {
for (const k in mod) {
VERIFY_NAME;
(k in exports && exports[k] === mod[k]) || SET_PROPERTY;
}
}`({
VERIFY_NAME: exportNameListName
? template.statement.ast`
if (k === "default" || k === "__esModule" || exportNames.indexOf(k) >= 0) ${continueStatement()}
`
: template.statement.ast`
if (k === "default" || k === "__esModule") ${continueStatement()}
`,
SET_PROPERTY: constantReexports
? template.expression.ast`exports[k] = mod[k]`
: template.expression.ast`
Object.defineProperty(exports, k, {
get: function () {
return mod[k];
},
});
});
`
)({
NAMESPACE: namespace,
EXPORTS: metadata.exportName,
VERIFY_NAME_LIST: metadata.exportNameListName
? template`
if (Object.prototype.hasOwnProperty.call(EXPORTS_LIST, key)) return;
`({ EXPORTS_LIST: metadata.exportNameListName })
: null,
});
enumerable: true
})
`,
}) as t.FunctionExpression;

if (!exportNameListName) fn.params.pop();

const fnId = addPrivateHelper(
programPath,
constantReexports ? "reexports" : "reexports2",
fn,
);
const args = [identifier(metadata.exportName), namespace];
if (exportNameListName) {
args.push(identifier(exportNameListName));
}

if (!buildInteropWrap) {
return expressionStatement(callExpression(fnId, args));
}

return expressionStatement(buildInteropWrap(callExpression(fnId, args)));
}

/**
Expand All @@ -396,35 +459,36 @@ function buildExportNameListDeclaration(
programPath: NodePath,
metadata: ModuleMetadata,
) {
const exportedVars = Object.create(null);
const exportedVars = new Set<string>();
for (const data of metadata.local.values()) {
for (const name of data.names) {
exportedVars[name] = true;
exportedVars.add(name);
}
}

let hasReexport = false;
for (const data of metadata.source.values()) {
for (const exportName of data.reexports.keys()) {
exportedVars[exportName] = true;
exportedVars.add(exportName);
}
for (const exportName of data.reexportNamespace) {
exportedVars[exportName] = true;
exportedVars.add(exportName);
}

hasReexport = hasReexport || !!data.reexportAll;
}

if (!hasReexport || Object.keys(exportedVars).length === 0) return null;
exportedVars.delete("default");
exportedVars.delete("__esModule");

const name = programPath.scope.generateUidIdentifier("exportNames");
if (!hasReexport || exportedVars.size === 0) return null;

delete exportedVars.default;
const name = programPath.scope.generateUidIdentifier("exportNames");

return {
name: name.name,
statement: variableDeclaration("var", [
variableDeclarator(name, valueToNode(exportedVars)),
variableDeclarator(name, valueToNode(Array.from(exportedVars))),
]),
};
}
Expand All @@ -436,8 +500,8 @@ function buildExportNameListDeclaration(
function buildExportInitializationStatements(
programPath: NodePath,
metadata: ModuleMetadata,
constantReexports: boolean | void = false,
noIncompleteNsImportDetection: boolean | void = false,
constantReexports: boolean = false,
noIncompleteNsImportDetection: boolean = false,
) {
const initStatements: Array<[string, t.Statement | null]> = [];

Expand Down
2 changes: 2 additions & 0 deletions packages/babel-helper-module-transforms/src/normalize-and-load-metadata.ts
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Expand Up @@ -6,6 +6,7 @@ import splitExportDeclaration from "@babel/helper-split-export-declaration";
import type { NodePath } from "@babel/traverse";

export interface ModuleMetadata {
programPath: NodePath<t.Program>;
exportName: string;
// The name of the variable that will reference an object containing export names.
exportNameListName: null | string;
Expand Down Expand Up @@ -176,6 +177,7 @@ export default function normalizeModuleAndLoadMetadata(
}

return {
programPath,
exportName,
exportNameListName: null,
hasExports,
Expand Down
13 changes: 8 additions & 5 deletions packages/babel-plugin-transform-modules-amd/test/fixtures/amd/export-from-2/output.js
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Expand Up @@ -4,10 +4,13 @@ define(["exports", "foo"], function (_exports, _foo) {
Object.defineProperty(_exports, "__esModule", {
value: true
});
Object.defineProperty(_exports, "foo", {
enumerable: true,
get: function () {
return _foo.foo;
}
_export("foo", function () {
return _foo.foo;
});
function _export(name, fn) {
Object.defineProperty(_exports, name, {
enumerable: true,
get: fn
});
}
});
20 changes: 10 additions & 10 deletions packages/babel-plugin-transform-modules-amd/test/fixtures/amd/export-from-3/output.js
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Expand Up @@ -4,16 +4,16 @@ define(["exports", "foo"], function (_exports, _foo) {
Object.defineProperty(_exports, "__esModule", {
value: true
});
Object.defineProperty(_exports, "bar", {
enumerable: true,
get: function () {
return _foo.bar;
}
_export("bar", function () {
return _foo.bar;
});
Object.defineProperty(_exports, "foo", {
enumerable: true,
get: function () {
return _foo.foo;
}
_export("foo", function () {
return _foo.foo;
});
function _export(name, fn) {
Object.defineProperty(_exports, name, {
enumerable: true,
get: fn
});
}
});
13 changes: 8 additions & 5 deletions packages/babel-plugin-transform-modules-amd/test/fixtures/amd/export-from-4/output.js
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Expand Up @@ -4,10 +4,13 @@ define(["exports", "foo"], function (_exports, _foo) {
Object.defineProperty(_exports, "__esModule", {
value: true
});
Object.defineProperty(_exports, "bar", {
enumerable: true,
get: function () {
return _foo.foo;
}
_export("bar", function () {
return _foo.foo;
});
function _export(name, fn) {
Object.defineProperty(_exports, name, {
enumerable: true,
get: fn
});
}
});