/
concat.js
358 lines (303 loc) Β· 10.3 KB
/
concat.js
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const {relative} = require('path');
const template = require('babel-template');
const t = require('@babel/types');
const traverse = require('@babel/traverse').default;
const generate = require('@babel/generator').default;
const treeShake = require('./shake');
const mangleScope = require('./mangler');
const {getName, getIdentifier} = require('./utils');
const EXPORTS_RE = /^\$([^$]+)\$exports$/;
const DEFAULT_INTEROP_TEMPLATE = template(
'var NAME = $parcel$interopDefault(MODULE)'
);
const THROW_TEMPLATE = template('$parcel$missingModule(MODULE)');
const REQUIRE_TEMPLATE = template('require(ID)');
module.exports = (packager, ast) => {
let {assets} = packager;
let replacements = new Map();
let imports = new Map();
let referenced = new Set();
// Build a mapping of all imported identifiers to replace.
for (let asset of assets.values()) {
for (let name in asset.cacheData.imports) {
let imp = asset.cacheData.imports[name];
imports.set(name, [packager.resolveModule(asset.id, imp[0]), imp[1]]);
}
}
function replaceExportNode(module, originalName, path) {
let {identifier, name, id} = packager.findExportModule(
module.id,
originalName,
replacements
);
let mod = assets.get(id);
let node;
if (identifier) {
node = findSymbol(path, identifier);
}
// If the module is not in this bundle, create a `require` call for it.
if (!node && !mod) {
node = REQUIRE_TEMPLATE({ID: t.stringLiteral(id)}).expression;
return interop(module, name, path, node);
}
// If this is an ES6 module, throw an error if we cannot resolve the module
if (!node && !mod.cacheData.isCommonJS && mod.cacheData.isES6Module) {
let relativePath = relative(packager.options.rootDir, mod.name);
throw new Error(`${relativePath} does not export '${name}'`);
}
// If it is CommonJS, look for an exports object.
if (!node && mod.cacheData.isCommonJS) {
node = findSymbol(path, getName(mod, 'exports'));
if (!node) {
return null;
}
return interop(mod, name, path, node);
}
return node;
}
function findSymbol(path, symbol) {
if (replacements.has(symbol)) {
symbol = replacements.get(symbol);
}
// if the symbol is in the scope there is not need to remap it
if (path.scope.getProgramParent().hasBinding(symbol)) {
return t.identifier(symbol);
}
return null;
}
function interop(mod, originalName, path, node) {
// Handle interop for default imports of CommonJS modules.
if (mod.cacheData.isCommonJS && originalName === 'default') {
let name = getName(mod, '$interop$default');
if (!path.scope.getBinding(name)) {
let [decl] = path.getStatementParent().insertBefore(
DEFAULT_INTEROP_TEMPLATE({
NAME: t.identifier(name),
MODULE: node
})
);
let binding = path.scope.getBinding(getName(mod, 'exports'));
if (binding) {
binding.reference(decl.get('declarations.0.init'));
}
path.scope.registerDeclaration(decl);
}
return t.memberExpression(t.identifier(name), t.identifier('d'));
}
// if there is a CommonJS export return $id$exports.name
if (originalName !== '*') {
return t.memberExpression(node, t.identifier(originalName));
}
return node;
}
function isUnusedValue(path) {
return (
path.parentPath.isExpressionStatement() ||
(path.parentPath.isSequenceExpression() &&
(path.key !== path.container.length - 1 ||
isUnusedValue(path.parentPath)))
);
}
traverse(ast, {
CallExpression(path) {
let {arguments: args, callee} = path.node;
if (!t.isIdentifier(callee)) {
return;
}
// each require('module') call gets replaced with $parcel$require(id, 'module')
if (callee.name === '$parcel$require') {
let [id, source] = args;
if (
args.length !== 2 ||
!t.isStringLiteral(id) ||
!t.isStringLiteral(source)
) {
throw new Error(
'invariant: invalid signature, expected : $parcel$require(number, string)'
);
}
let mod = packager.resolveModule(id.value, source.value);
if (!mod) {
if (assets.get(id.value).dependencies.get(source.value).optional) {
path.replaceWith(
THROW_TEMPLATE({MODULE: t.stringLiteral(source.value)})
);
} else {
throw new Error(
`Cannot find module "${source.value}" in asset ${id.value}`
);
}
} else {
let node;
if (assets.get(mod.id)) {
// Replace with nothing if the require call's result is not used.
if (!isUnusedValue(path)) {
let name = getName(mod, 'exports');
node = t.identifier(replacements.get(name) || name);
}
// We need to wrap the module in a function when a require
// call happens inside a non top-level scope, e.g. in a
// function, if statement, or conditional expression.
if (mod.cacheData.shouldWrap) {
let call = t.callExpression(getIdentifier(mod, 'init'), []);
node = node ? t.sequenceExpression([call, node]) : call;
}
} else {
node = REQUIRE_TEMPLATE({ID: t.stringLiteral(mod.id)}).expression;
}
if (node) {
path.replaceWith(node);
} else {
path.remove();
}
}
} else if (callee.name === '$parcel$require$resolve') {
let [id, source] = args;
if (
args.length !== 2 ||
!t.isStringLiteral(id) ||
!t.isStringLiteral(source)
) {
throw new Error(
'invariant: invalid signature, expected : $parcel$require$resolve(number, string)'
);
}
let mapped = assets.get(id.value);
let dep = mapped.dependencies.get(source.value);
let mod = mapped.depAssets.get(dep);
let bundles = mod.id;
if (dep.dynamic && packager.bundle.childBundles.has(mod.parentBundle)) {
bundles = [];
for (let child of mod.parentBundle.siblingBundles) {
if (!child.isEmpty && packager.options.bundleLoaders[child.type]) {
bundles.push(packager.getBundleSpecifier(child));
}
}
bundles.push(packager.getBundleSpecifier(mod.parentBundle));
bundles.push(mod.id);
}
path.replaceWith(t.valueToNode(bundles));
}
},
VariableDeclarator: {
exit(path) {
// Replace references to declarations like `var x = require('x')`
// with the final export identifier instead.
// This allows us to potentially replace accesses to e.g. `x.foo` with
// a variable like `$id$export$foo` later, avoiding the exports object altogether.
let {id, init} = path.node;
if (!t.isIdentifier(init)) {
return;
}
let match = init.name.match(EXPORTS_RE);
if (!match) {
return;
}
// Replace patterns like `var {x} = require('y')` with e.g. `$id$export$x`.
if (t.isObjectPattern(id)) {
for (let p of path.get('id.properties')) {
let {computed, key, value} = p.node;
if (computed || !t.isIdentifier(key) || !t.isIdentifier(value)) {
continue;
}
let {identifier} = packager.findExportModule(
match[1],
key.name,
replacements
);
if (identifier) {
replace(value.name, identifier, p);
}
}
if (id.properties.length === 0) {
path.remove();
}
} else if (t.isIdentifier(id)) {
replace(id.name, init.name, path);
}
function replace(id, init, path) {
let binding = path.scope.getBinding(id);
if (!binding.constant) {
return;
}
for (let ref of binding.referencePaths) {
ref.replaceWith(t.identifier(init));
}
replacements.set(id, init);
path.remove();
}
}
},
MemberExpression: {
exit(path) {
if (!path.isReferenced()) {
return;
}
let {object, property, computed} = path.node;
if (
!(
t.isIdentifier(object) &&
((t.isIdentifier(property) && !computed) ||
t.isStringLiteral(property))
)
) {
return;
}
let match = object.name.match(EXPORTS_RE);
// If it's a $id$exports.name expression.
if (match) {
let name = t.isIdentifier(property) ? property.name : property.value;
let {identifier} = packager.findExportModule(
match[1],
name,
replacements
);
// Check if $id$export$name exists and if so, replace the node by it.
if (identifier) {
path.replaceWith(t.identifier(identifier));
}
}
}
},
ReferencedIdentifier(path) {
let {name} = path.node;
if (typeof name !== 'string') {
return;
}
if (imports.has(name)) {
let imp = imports.get(name);
let node = replaceExportNode(imp[0], imp[1], path);
// If the export does not exist, replace with an empty object.
if (!node) {
node = t.objectExpression([]);
}
path.replaceWith(node);
return;
}
let match = name.match(EXPORTS_RE);
if (match) {
referenced.add(name);
}
// If it's an undefined $id$exports identifier.
if (match && !path.scope.hasBinding(name)) {
path.replaceWith(t.objectExpression([]));
}
},
Program: {
// A small optimization to remove unused CommonJS exports as sometimes Uglify doesn't remove them.
exit(path) {
treeShake(path.scope);
if (packager.options.minify) {
mangleScope(path.scope);
}
}
}
});
let opts = {
sourceMaps: packager.options.sourceMaps,
sourceFileName: packager.bundle.name,
minified: packager.options.minify,
comments: !packager.options.minify
};
return generate(ast, opts);
};