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transform-commonjs.js
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transform-commonjs.js
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/* eslint-disable no-param-reassign, no-shadow, no-underscore-dangle, no-continue */
import { dirname } from 'path';
import { attachScopes, extractAssignedNames, makeLegalIdentifier } from '@rollup/pluginutils';
import { walk } from 'estree-walker';
import MagicString from 'magic-string';
import {
getKeypath,
isDefineCompiledEsm,
isFalsy,
isReference,
isTruthy,
KEY_COMPILED_ESM
} from './ast-utils';
import { rewriteExportsAndGetExportsBlock, wrapCode } from './generate-exports';
import {
getRequireHandlers,
getRequireStringArg,
hasDynamicModuleForPath,
isIgnoredRequireStatement,
isModuleRequire,
isNodeRequirePropertyAccess,
isRequireStatement,
isStaticRequireStatement
} from './generate-imports';
import { DYNAMIC_JSON_PREFIX, DYNAMIC_REGISTER_PREFIX } from './helpers';
import { tryParse } from './parse';
import { deconflict, getName, getVirtualPathForDynamicRequirePath } from './utils';
const exportsPattern = /^(?:module\.)?exports(?:\.([a-zA-Z_$][a-zA-Z_$0-9]*))?$/;
const functionType = /^(?:FunctionDeclaration|FunctionExpression|ArrowFunctionExpression)$/;
export default function transformCommonjs(
parse,
code,
id,
isEsModule,
ignoreGlobal,
ignoreRequire,
sourceMap,
isDynamicRequireModulesEnabled,
dynamicRequireModuleSet,
disableWrap,
commonDir,
astCache
) {
const ast = astCache || tryParse(parse, code, id);
const magicString = new MagicString(code);
const uses = {
module: false,
exports: false,
global: false,
require: false,
commonjsHelpers: false
};
const virtualDynamicRequirePath =
isDynamicRequireModulesEnabled && getVirtualPathForDynamicRequirePath(dirname(id), commonDir);
let scope = attachScopes(ast, 'scope');
let lexicalDepth = 0;
let programDepth = 0;
let shouldWrap = false;
const globals = new Set();
// TODO technically wrong since globals isn't populated yet, but ¯\_(ツ)_/¯
const HELPERS_NAME = deconflict(scope, globals, 'commonjsHelpers');
const namedExports = {};
const dynamicRegisterSources = new Set();
const {
addRequireStatement,
requiredSources,
rewriteRequireExpressionsAndGetImportBlock
} = getRequireHandlers();
// See which names are assigned to. This is necessary to prevent
// illegally replacing `var foo = require('foo')` with `import foo from 'foo'`,
// where `foo` is later reassigned. (This happens in the wild. CommonJS, sigh)
const reassignedNames = new Set();
const topLevelDeclarations = [];
const topLevelRequireDeclarators = new Set();
const skippedNodes = new Set();
const topLevelModuleExportsAssignments = [];
const topLevelExportsAssignmentsByName = new Map();
const defineCompiledEsmExpressions = [];
walk(ast, {
enter(node, parent) {
if (skippedNodes.has(node)) {
this.skip();
return;
}
programDepth += 1;
if (node.scope) ({ scope } = node);
if (functionType.test(node.type)) lexicalDepth += 1;
if (sourceMap) {
magicString.addSourcemapLocation(node.start);
magicString.addSourcemapLocation(node.end);
}
// eslint-disable-next-line default-case
switch (node.type) {
case 'AssignmentExpression':
if (node.left.type === 'MemberExpression') {
const flattened = getKeypath(node.left);
if (!flattened || scope.contains(flattened.name)) return;
const exportsPatternMatch = exportsPattern.exec(flattened.keypath);
if (!exportsPatternMatch || flattened.keypath === 'exports') return;
const [, exportName] = exportsPatternMatch;
uses[flattened.name] = true;
// we're dealing with `module.exports = ...` or `[module.]exports.foo = ...` –
if (programDepth > 3) {
shouldWrap = true;
} else if (exportName === KEY_COMPILED_ESM) {
defineCompiledEsmExpressions.push(node);
} else if (flattened.keypath === 'module.exports') {
topLevelModuleExportsAssignments.push(node);
} else if (!topLevelExportsAssignmentsByName.has(exportName)) {
topLevelExportsAssignmentsByName.set(exportName, node);
} else {
shouldWrap = true;
}
skippedNodes.add(node.left);
if (flattened.keypath === 'module.exports' && node.right.type === 'ObjectExpression') {
node.right.properties.forEach((prop) => {
if (prop.computed || !('key' in prop) || prop.key.type !== 'Identifier') return;
const { name } = prop.key;
if (name === makeLegalIdentifier(name)) namedExports[name] = true;
});
return;
}
if (exportsPatternMatch[1]) namedExports[exportsPatternMatch[1]] = true;
} else {
for (const name of extractAssignedNames(node.left)) {
reassignedNames.add(name);
}
}
return;
case 'CallExpression': {
if (isDefineCompiledEsm(node)) {
if (programDepth === 3 && parent.type === 'ExpressionStatement') {
// skip special handling for [module.]exports until we know we render this
skippedNodes.add(node.arguments[0]);
defineCompiledEsmExpressions.push(node);
} else {
shouldWrap = true;
}
return;
}
if (!isStaticRequireStatement(node, scope)) return;
if (!isDynamicRequireModulesEnabled) {
skippedNodes.add(node.callee);
}
if (!isIgnoredRequireStatement(node, ignoreRequire)) {
skippedNodes.add(node.callee);
const usesReturnValue = parent.type !== 'ExpressionStatement';
let sourceId = getRequireStringArg(node);
const isDynamicRegister = sourceId.startsWith(DYNAMIC_REGISTER_PREFIX);
if (isDynamicRegister) {
sourceId = sourceId.substr(DYNAMIC_REGISTER_PREFIX.length);
if (sourceId.endsWith('.json')) {
sourceId = DYNAMIC_JSON_PREFIX + sourceId;
}
dynamicRegisterSources.add(sourceId);
} else {
if (
!sourceId.endsWith('.json') &&
hasDynamicModuleForPath(sourceId, id, dynamicRequireModuleSet)
) {
magicString.overwrite(
node.start,
node.end,
`${HELPERS_NAME}.commonjsRequire(${JSON.stringify(
getVirtualPathForDynamicRequirePath(sourceId, commonDir)
)}, ${JSON.stringify(
dirname(id) === '.' ? null /* default behavior */ : virtualDynamicRequirePath
)})`
);
uses.commonjsHelpers = true;
return;
}
addRequireStatement(sourceId, node, scope, usesReturnValue);
}
if (usesReturnValue) {
if (
parent.type === 'VariableDeclarator' &&
!scope.parent &&
parent.id.type === 'Identifier'
) {
// This will allow us to reuse this variable name as the imported variable if it is not reassigned
// and does not conflict with variables in other places where this is imported
topLevelRequireDeclarators.add(parent);
}
} else {
// This is a bare import, e.g. `require('foo');`
magicString.remove(parent.start, parent.end);
}
}
return;
}
case 'ConditionalExpression':
case 'IfStatement':
// skip dead branches
if (isFalsy(node.test)) {
skippedNodes.add(node.consequent);
} else if (node.alternate && isTruthy(node.test)) {
skippedNodes.add(node.alternate);
}
return;
case 'Identifier': {
const { name } = node;
if (!(isReference(node, parent) && !scope.contains(name))) return;
switch (name) {
case 'require':
if (isNodeRequirePropertyAccess(parent)) return;
if (isDynamicRequireModulesEnabled && isRequireStatement(parent, scope)) {
magicString.appendLeft(
parent.end - 1,
`,${JSON.stringify(
dirname(id) === '.' ? null /* default behavior */ : virtualDynamicRequirePath
)}`
);
}
magicString.overwrite(node.start, node.end, `${HELPERS_NAME}.commonjsRequire`, {
storeName: true
});
uses.commonjsHelpers = true;
return;
case 'module':
case 'exports':
shouldWrap = true;
uses[name] = true;
return;
case 'global':
uses.global = true;
if (!ignoreGlobal) {
magicString.overwrite(node.start, node.end, `${HELPERS_NAME}.commonjsGlobal`, {
storeName: true
});
uses.commonjsHelpers = true;
}
return;
case 'define':
magicString.overwrite(node.start, node.end, 'undefined', { storeName: true });
return;
default:
globals.add(name);
return;
}
}
case 'MemberExpression':
if (!isDynamicRequireModulesEnabled && isModuleRequire(node, scope)) {
magicString.overwrite(node.start, node.end, `${HELPERS_NAME}.commonjsRequire`, {
storeName: true
});
uses.commonjsHelpers = true;
skippedNodes.add(node.object);
skippedNodes.add(node.property);
}
return;
case 'ReturnStatement':
// if top-level return, we need to wrap it
if (lexicalDepth === 0) {
shouldWrap = true;
}
return;
case 'ThisExpression':
// rewrite top-level `this` as `commonjsHelpers.commonjsGlobal`
if (lexicalDepth === 0) {
uses.global = true;
if (!ignoreGlobal) {
magicString.overwrite(node.start, node.end, `${HELPERS_NAME}.commonjsGlobal`, {
storeName: true
});
uses.commonjsHelpers = true;
}
}
return;
case 'UnaryExpression':
// rewrite `typeof module`, `typeof module.exports` and `typeof exports` (https://github.com/rollup/rollup-plugin-commonjs/issues/151)
if (node.operator === 'typeof') {
const flattened = getKeypath(node.argument);
if (!flattened) return;
if (scope.contains(flattened.name)) return;
if (
flattened.keypath === 'module.exports' ||
flattened.keypath === 'module' ||
flattened.keypath === 'exports'
) {
magicString.overwrite(node.start, node.end, `'object'`, { storeName: false });
}
}
return;
case 'VariableDeclaration':
if (!scope.parent) {
topLevelDeclarations.push(node);
}
}
},
leave(node) {
programDepth -= 1;
if (node.scope) scope = scope.parent;
if (functionType.test(node.type)) lexicalDepth -= 1;
}
});
// TODO Lukas we do not need this for ES modules
const moduleName = deconflict(scope, globals, getName(id));
// We cannot wrap ES/mixed modules
shouldWrap = shouldWrap && !disableWrap && !isEsModule;
uses.commonjsHelpers = uses.commonjsHelpers || shouldWrap;
if (
!(
requiredSources.length ||
dynamicRegisterSources.size ||
uses.module ||
uses.exports ||
uses.require ||
uses.commonjsHelpers
) &&
(ignoreGlobal || !uses.global)
) {
return { meta: { commonjs: { isCommonJS: false } } };
}
let leadingComment = '';
if (code.startsWith('/*')) {
const commentEnd = code.indexOf('*/', 2) + 2;
leadingComment = `${code.slice(0, commentEnd)}\n`;
magicString.remove(0, commentEnd).trim();
}
// TODO Lukas test all cases
const replacesModuleExports =
!shouldWrap &&
topLevelExportsAssignmentsByName.size === 0 &&
defineCompiledEsmExpressions.length === 0;
const importBlock = rewriteRequireExpressionsAndGetImportBlock(
magicString,
topLevelDeclarations,
topLevelRequireDeclarators,
reassignedNames,
uses.commonjsHelpers && HELPERS_NAME,
dynamicRegisterSources,
moduleName,
id,
replacesModuleExports
);
const exportBlock = isEsModule
? ''
: rewriteExportsAndGetExportsBlock(
magicString,
moduleName,
shouldWrap,
topLevelModuleExportsAssignments,
topLevelExportsAssignmentsByName,
defineCompiledEsmExpressions,
(name) => deconflict(scope, globals, name),
code,
uses,
HELPERS_NAME,
id,
replacesModuleExports
);
if (shouldWrap) {
wrapCode(magicString, uses, moduleName, HELPERS_NAME, virtualDynamicRequirePath);
}
magicString
.trim()
.prepend(leadingComment + importBlock)
.append(exportBlock);
// TODO Lukas remove
// console.log('<===', id);
// console.log(magicString.toString());
// console.log();
return {
code: magicString.toString(),
map: sourceMap ? magicString.generateMap() : null,
syntheticNamedExports: isEsModule ? false : '__moduleExports',
meta: { commonjs: { isCommonJS: !isEsModule } }
};
}