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Transform exported functions correctly #225

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merged 4 commits into from
Dec 3, 2020
Merged

Transform exported functions correctly #225

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f32f599
transform exported functions correctly - fixes #224
Rich-Harris Dec 3, 2020
bc8562c
add changeset
Rich-Harris Dec 3, 2020
41baacf
lint
Rich-Harris Dec 3, 2020
05d93f0
fix daft mistakes
Rich-Harris Dec 3, 2020
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5 changes: 5 additions & 0 deletions .changeset/tasty-donkeys-wait.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@sveltejs/kit': patch
---

Transform exported functions correctly
144 changes: 10 additions & 134 deletions packages/kit/src/api/dev/loader.js
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Original file line number Diff line number Diff line change
@@ -1,9 +1,6 @@
import { URL } from 'url';
import { resolve, relative } from 'path';
import * as meriyah from 'meriyah';
import MagicString from 'magic-string';
import { extract_names } from 'periscopic';
import { walk } from 'estree-walker';
import { transform } from './transform';

// This function makes it possible to load modules from the 'server'
// snowpack server, for the sake of SSR
Expand Down Expand Up @@ -47,7 +44,6 @@ export default function loader(snowpack, config) {
});

async function load(url, url_stack) {
// TODO: meriyah (JS parser) doesn't support `import.meta.hot = ...` used in HMR setup code.
if (url.endsWith('.css.proxy.js')) {
return null;
}
Expand Down Expand Up @@ -75,133 +71,7 @@ export default function loader(snowpack, config) {
}

async function initialize_module(url, data, url_stack) {
const code = new MagicString(data);
const ast = meriyah.parseModule(data, {
ranges: true,
next: true
});

const imports = [];

const export_from_identifiers = new Map();
let uid = 1;

ast.body.forEach((node) => {
if (node.type === 'ImportDeclaration') {
imports.push(node);
code.remove(node.start, node.end);
}

if (node.type === 'ExportAllDeclaration') {
if (!export_from_identifiers.has(node.source)) {
export_from_identifiers.set(node.source, `__import${uid++}`);
}

code.overwrite(
node.start,
node.end,
`Object.assign(exports, ${export_from_identifiers.get(node.source)})`
);
imports.push(node);
}

if (node.type === 'ExportDefaultDeclaration') {
code.overwrite(node.start, node.declaration.start, 'exports.default = ');
}

if (node.type === 'ExportNamedDeclaration') {
if (node.source) {
imports.push(node);

if (!export_from_identifiers.has(node.source)) {
export_from_identifiers.set(node.source, `__import${uid++}`);
}
}

if (node.specifiers && node.specifiers.length > 0) {
code.remove(node.start, node.specifiers[0].start);

node.specifiers.forEach((specifier) => {
const lhs = `exports.${specifier.exported.name}`;
const rhs = node.source
? `${export_from_identifiers.get(node.source)}.${specifier.local.name}`
: specifier.local.name;

code.overwrite(specifier.start, specifier.end, `${lhs} = ${rhs}`);
});

code.remove(node.specifiers[node.specifiers.length - 1].end, node.end);
} else {
// `export const foo = ...` or `export function foo() {...}`
if (node.declaration.type === 'VariableDeclaration') {
code.remove(node.start, node.declaration.start);

const names = [];
node.declaration.declarations.forEach((declarator) => {
names.push(...extract_names(declarator.id));
});

code.appendLeft(node.end, names.map((name) => ` exports.${name} = ${name};`).join(''));
} else {
code.overwrite(
node.start,
node.declaration.start,
`exports.${node.declaration.id.name} = `
);
}
}
}
});

// replace import.meta and import(dynamic)
if (/import\s*\.\s*meta/.test(data) || /import\s*\(/.test(data)) {
walk(ast.body, {
enter(node) {
if (node.type === 'MetaProperty' && node.meta.name === 'import') {
code.overwrite(node.start, node.end, '__importmeta__');
} else if (node.type === 'ImportExpression') {
code.overwrite(node.start, node.start + 6, '__import__');
}
}
});
}

const deps = [];
imports.forEach((node) => {
const promise = get_module(url, node.source.value, url_stack);

if (node.type === 'ExportAllDeclaration' || node.type === 'ExportNamedDeclaration') {
// `export * from './other.js'` or `export { foo } from './other.js'`
deps.push({
name: export_from_identifiers.get(node.source),
promise
});
} else if (node.specifiers.length === 0) {
// bare import
deps.push({
name: null,
promise
});
} else if (node.specifiers[0].type === 'ImportNamespaceSpecifier') {
deps.push({
name: node.specifiers[0].local.name,
promise
});
} else {
deps.push(
...node.specifiers.map((specifier) => ({
name: specifier.local.name,
promise: promise.then(
(exports) => exports[specifier.imported ? specifier.imported.name : 'default']
)
}))
);
}
});

deps.sort((a, b) => (!!a.name !== !!b.name ? (a.name ? -1 : 1) : 0));

code.append(`\n//# sourceURL=${url}`);
const { code, deps } = transform(data);

const fn = new Function(
'exports',
Expand All @@ -210,9 +80,15 @@ export default function loader(snowpack, config) {
'__import__',
'__importmeta__',
...deps.map((d) => d.name).filter(Boolean),
code.toString()
`${code}\n//# sourceURL=${url}`
);
const values = await Promise.all(deps.map((d) => d.promise));

const promises = deps.map(async (dep) => {
const mod = await get_module(url, dep.source, url_stack);
return dep.prop ? mod[dep.prop] : mod;
});

const values = await Promise.all(promises);

const exports = {};

Expand Down
137 changes: 137 additions & 0 deletions packages/kit/src/api/dev/transform.js
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@@ -0,0 +1,137 @@
import * as meriyah from 'meriyah';
import MagicString from 'magic-string';
import { extract_names } from 'periscopic';
import { walk } from 'estree-walker';

export function transform(data) {
const code = new MagicString(data);
const ast = meriyah.parseModule(data, {
ranges: true,
next: true
});

const imports = [];

const export_from_identifiers = new Map();
let uid = 1;

ast.body.forEach((node) => {
if (node.type === 'ImportDeclaration') {
imports.push(node);
code.remove(node.start, node.end);
}

if (node.type === 'ExportAllDeclaration') {
if (!export_from_identifiers.has(node.source)) {
export_from_identifiers.set(node.source, `__import${uid++}`);
}

code.overwrite(
node.start,
node.end,
`Object.assign(exports, ${export_from_identifiers.get(node.source)})`
);
imports.push(node);
}

if (node.type === 'ExportDefaultDeclaration') {
code.overwrite(node.start, node.declaration.start, 'exports.default = ');
}

if (node.type === 'ExportNamedDeclaration') {
if (node.source) {
imports.push(node);

if (!export_from_identifiers.has(node.source)) {
export_from_identifiers.set(node.source, `__import${uid++}`);
}
}

if (node.specifiers && node.specifiers.length > 0) {
code.remove(node.start, node.specifiers[0].start);

node.specifiers.forEach((specifier) => {
const lhs = `exports.${specifier.exported.name}`;
const rhs = node.source
? `${export_from_identifiers.get(node.source)}.${specifier.local.name}`
: specifier.local.name;

code.overwrite(specifier.start, specifier.end, `${lhs} = ${rhs}`);
});

code.remove(node.specifiers[node.specifiers.length - 1].end, node.end);
} else {
// `export const foo = ...` or `export function foo() {...}`
code.remove(node.start, node.declaration.start);

let suffix;

if (node.declaration.type === 'VariableDeclaration') {
const names = [];
node.declaration.declarations.forEach((declarator) => {
names.push(...extract_names(declarator.id));
});

suffix = names.map((name) => ` exports.${name} = ${name};`).join('');
} else {
const { name } = node.declaration.id;
suffix = ` exports.${name} = ${name};`;
}

code.appendLeft(node.end, suffix);
}
}
});

// replace import.meta and import(dynamic)
if (/import\s*\.\s*meta/.test(data) || /import\s*\(/.test(data)) {
walk(ast.body, {
enter(node) {
if (node.type === 'MetaProperty' && node.meta.name === 'import') {
code.overwrite(node.start, node.end, '__importmeta__');
} else if (node.type === 'ImportExpression') {
code.overwrite(node.start, node.start + 6, '__import__');
}
}
});
}

const deps = [];
imports.forEach((node) => {
const source = node.source.value;

if (node.type === 'ExportAllDeclaration' || node.type === 'ExportNamedDeclaration') {
// `export * from './other.js'` or `export { foo } from './other.js'`
deps.push({
name: export_from_identifiers.get(node.source),
prop: null,
source
});
} else if (node.specifiers.length === 0) {
// bare import
deps.push({
name: null,
prop: null,
source
});
} else if (node.specifiers[0].type === 'ImportNamespaceSpecifier') {
deps.push({
name: node.specifiers[0].local.name,
prop: null,
source
});
} else {
deps.push(
...node.specifiers.map((specifier) => ({
name: specifier.local.name,
prop: specifier.imported ? specifier.imported.name : 'default',
source
}))
);
}
});

deps.sort((a, b) => (!!a.name !== !!b.name ? (a.name ? -1 : 1) : 0));

return { code: code.toString(), deps };
}
58 changes: 58 additions & 0 deletions packages/kit/src/api/dev/transform.spec.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,58 @@
import { test } from 'uvu';
import * as assert from 'uvu/assert';
import { transform } from './transform';

function compare(a, b) {
assert.equal(
a.replace(/^\t+/gm, '').trim(),
b.replace(/^\t+/gm, '').trim()
);
}

test('extracts imports', () => {
const { code, deps } = transform(`
import './empty.js';
import foo from './foo.js';
import { bar } from './bar.js';
import * as baz from './baz.js';

console.log(foo, bar, baz);
`);

compare(code, `
console.log(foo, bar, baz);
`);

assert.equal(deps, [
{ name: 'foo', prop: 'default', source: './foo.js' },
{ name: 'bar', prop: 'bar', source: './bar.js' },
{ name: 'baz', prop: null, source: './baz.js' },
{ name: null, prop: null, source: './empty.js' }
]);
});

test('transforms exported functions safely', () => {
const { code, deps } = transform(`
export function foo() {
console.log('foo');
}

export function bar() {
foo();
}
`);

compare(code, `
function foo() {
console.log('foo');
} exports.foo = foo;

function bar() {
foo();
} exports.bar = bar;
`);

assert.equal(deps, []);
});

test.run();