com.google.javascript.jscomp.ProcessEs6Modules Maven / Gradle / Ivy
/*
* Copyright 2014 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import com.google.common.base.Preconditions;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.deps.ModuleLoader;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.JSDocInfoBuilder;
import com.google.javascript.rhino.JSTypeExpression;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Rewrites a ES6 module into a form that can be safely concatenated.
* Note that we treat a file as an ES6 module if it has at least one import or
* export statement.
*
* @author [email protected] (Michael Zhou)
*/
public final class ProcessEs6Modules extends AbstractPostOrderCallback {
private static final String DEFAULT_EXPORT_NAME = "$jscompDefaultExport";
static final DiagnosticType LHS_OF_GOOG_REQUIRE_MUST_BE_CONST =
DiagnosticType.error(
"JSC_LHS_OF_GOOG_REQUIRE_MUST_BE_CONST",
"The left side of a goog.require() must use ''const'' (not ''let'' or ''var'')");
static final DiagnosticType NAMESPACE_IMPORT_CANNOT_USE_STAR =
DiagnosticType.error(
"JSC_NAMESPACE_IMPORT_CANNOT_USE_STAR",
"Namespace imports ('goog:some.Namespace') cannot use import * as. "
+ "Did you mean to import {0} from ''{1}'';?");
private final Compiler compiler;
private int scriptNodeCount = 0;
/**
* Maps exported names to their names in current module.
*/
private Map exportMap = new LinkedHashMap<>();
/**
* Maps symbol names to a pair of (moduleName, originalName). The original
* name is the name of the symbol exported by the module. This is required
* because we want to be able to update the original property on the module
* object. Eg: "import {foo as f} from 'm'" maps 'f' to the pair ('m', 'foo').
* In the entry for "import * as ns", the originalName will be the empty string.
*/
private Map importMap = new HashMap<>();
private Set classes = new HashSet<>();
private Set typedefs = new HashSet<>();
private Set alreadyRequired = new HashSet<>();
private boolean isEs6Module;
private boolean forceRewrite;
private Node googRequireInsertSpot;
/**
* Creates a new ProcessEs6Modules instance which can be used to rewrite
* ES6 modules to a concatenable form.
*/
public ProcessEs6Modules(Compiler compiler) {
this.compiler = compiler;
}
/**
* If a file contains an ES6 "import" or "export" statement, or the forceRewrite
* option is true, rewrite the source as a module.
*/
public void processFile(Node root, boolean forceRewrite) {
FindGoogProvideOrGoogModule finder = new FindGoogProvideOrGoogModule();
NodeTraversal.traverseEs6(compiler, root, finder);
if (finder.isFound()) {
return;
}
this.forceRewrite = forceRewrite;
isEs6Module = forceRewrite;
NodeTraversal.traverseEs6(compiler, root, this);
}
/**
* Avoid processing if we find the appearance of goog.provide or goog.module.
*
* TODO(moz): Let ES6, CommonJS and goog.provide live happily together.
*/
static class FindGoogProvideOrGoogModule extends NodeTraversal.AbstractPreOrderCallback {
private boolean found;
boolean isFound() {
return found;
}
@Override
public boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node parent) {
if (found) {
return false;
}
// Shallow traversal, since we don't need to inspect within functions or expressions.
if (parent == null
|| NodeUtil.isControlStructure(parent)
|| NodeUtil.isStatementBlock(parent)) {
if (n.isExprResult()) {
Node maybeGetProp = n.getFirstFirstChild();
if (maybeGetProp != null
&& (maybeGetProp.matchesQualifiedName("goog.provide")
|| maybeGetProp.matchesQualifiedName("goog.module"))) {
found = true;
return false;
}
}
return true;
}
return false;
}
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isImport()) {
isEs6Module = true;
visitImport(t, n, parent);
} else if (n.isExport()) {
isEs6Module = true;
visitExport(t, n, parent);
} else if (n.isScript()) {
scriptNodeCount++;
visitScript(t, n);
}
}
private void visitImport(NodeTraversal t, Node importDecl, Node parent) {
String moduleName;
String importName = importDecl.getLastChild().getString();
boolean isNamespaceImport = importName.startsWith("goog:");
if (isNamespaceImport) {
// Allow importing Closure namespace objects (e.g. from goog.provide or goog.module) as
// import ... from 'goog:my.ns.Object'.
// These are rewritten to plain namespace object accesses.
moduleName = importName.substring("goog:".length());
} else {
moduleName = t.getInput().getPath().resolveEs6Module(importName).toModuleName();
}
for (Node child : importDecl.children()) {
if (child.isEmpty() || child.isString()) {
continue;
} else if (child.isName()) { // import a from "mod"
// Namespace imports' default export is the namespace itself.
String name = isNamespaceImport ? "" : "default";
importMap.put(child.getString(), new ModuleOriginalNamePair(moduleName, name));
} else if (child.getToken() == Token.IMPORT_SPECS) {
for (Node grandChild : child.children()) {
String origName = grandChild.getFirstChild().getString();
if (grandChild.hasTwoChildren()) { // import {a as foo} from "mod"
importMap.put(
grandChild.getLastChild().getString(),
new ModuleOriginalNamePair(moduleName, origName));
} else { // import {a} from "mod"
importMap.put(
origName,
new ModuleOriginalNamePair(moduleName, origName));
}
}
} else {
// import * as ns from "mod"
Preconditions.checkState(
child.getToken() == Token.IMPORT_STAR,
"Expected an IMPORT_STAR node, but was: %s",
child);
// Namespace imports cannot be imported "as *".
if (isNamespaceImport) {
compiler.report(t.makeError(importDecl, NAMESPACE_IMPORT_CANNOT_USE_STAR,
child.getString(), moduleName));
}
importMap.put(
child.getString(),
new ModuleOriginalNamePair(moduleName, ""));
}
}
Node script = NodeUtil.getEnclosingScript(parent);
// Emit goog.require call for the module.
if (alreadyRequired.add(moduleName)) {
Node require = IR.exprResult(
IR.call(NodeUtil.newQName(compiler, "goog.require"), IR.string(moduleName)));
require.useSourceInfoIfMissingFromForTree(importDecl);
script.addChildAfter(require, googRequireInsertSpot);
googRequireInsertSpot = require;
t.getInput().addRequire(moduleName);
}
parent.removeChild(importDecl);
compiler.reportCodeChange();
}
private void visitExport(NodeTraversal t, Node export, Node parent) {
if (export.getBooleanProp(Node.EXPORT_DEFAULT)) {
// export default
// If the thing being exported is a class or function that has a name,
// extract it from the export statement, so that it can be referenced
// from within the module.
//
// export default class X {} -> class X {}; ... moduleName.default = X;
// export default function X() {} -> function X() {}; ... moduleName.default = X;
//
// Otherwise, create a local variable for it and export that.
//
// export default 'someExpression'
// ->
// var $jscompDefaultExport = 'someExpression';
// ...
// moduleName.default = $jscompDefaultExport;
Node child = export.getFirstChild();
String name = null;
if (child.isFunction() || child.isClass()) {
name = NodeUtil.getName(child);
}
if (name != null) {
Node decl = child.cloneTree();
decl.setJSDocInfo(child.getJSDocInfo());
parent.replaceChild(export, decl);
exportMap.put("default", new NameNodePair(name, child));
} else {
Node var = IR.var(IR.name(DEFAULT_EXPORT_NAME), export.removeFirstChild());
var.setJSDocInfo(child.getJSDocInfo());
child.setJSDocInfo(null);
var.useSourceInfoIfMissingFromForTree(export);
parent.replaceChild(export, var);
exportMap.put("default", new NameNodePair(DEFAULT_EXPORT_NAME, child));
}
} else if (export.getBooleanProp(Node.EXPORT_ALL_FROM)) {
// export * from 'moduleIdentifier';
compiler.report(JSError.make(export, Es6ToEs3Converter.CANNOT_CONVERT_YET,
"Wildcard export"));
} else if (export.hasTwoChildren()) {
// export {x, y as z} from 'moduleIdentifier';
Node moduleIdentifier = export.getLastChild();
Node importNode = new Node(Token.IMPORT, moduleIdentifier.cloneNode());
importNode.useSourceInfoFrom(export);
parent.addChildBefore(importNode, export);
visit(t, importNode, parent);
String moduleName =
t.getInput().getPath().resolveEs6Module(moduleIdentifier.getString()).toModuleName();
for (Node exportSpec : export.getFirstChild().children()) {
String nameFromOtherModule = exportSpec.getFirstChild().getString();
String exportedName = exportSpec.getLastChild().getString();
exportMap.put(exportedName,
new NameNodePair(moduleName + "." + nameFromOtherModule, exportSpec));
}
parent.removeChild(export);
} else {
if (export.getFirstChild().getToken() == Token.EXPORT_SPECS) {
// export {Foo};
for (Node exportSpec : export.getFirstChild().children()) {
Node origName = exportSpec.getFirstChild();
exportMap.put(
exportSpec.hasTwoChildren()
? exportSpec.getLastChild().getString()
: origName.getString(),
new NameNodePair(origName.getString(), exportSpec));
}
parent.removeChild(export);
} else {
// export var Foo;
// export function Foo() {}
// etc.
Node declaration = export.getFirstChild();
Node first = declaration.getFirstChild();
for (Node maybeName = first; maybeName != null; maybeName = maybeName.getNext()) {
if (!maybeName.isName()) {
break;
}
// Break out on "B" in "class A extends B"
if (declaration.isClass() && maybeName != first) {
break;
}
String name = maybeName.getString();
Var v = t.getScope().getVar(name);
if (v == null || v.isGlobal()) {
exportMap.put(name, new NameNodePair(name, maybeName));
}
// If the declaration declares a new type, create annotations for
// the type checker.
// TODO(moz): Currently we only record ES6 classes and typedefs,
// need to handle other kinds of type declarations too.
if (declaration.isClass()) {
classes.add(name);
}
if (declaration.getJSDocInfo() != null && declaration.getJSDocInfo().hasTypedefType()) {
typedefs.add(name);
}
}
parent.replaceChild(export, declaration.detach());
}
compiler.reportCodeChange();
}
}
private void visitScript(NodeTraversal t, Node script) {
if (!isEs6Module) {
return;
}
ClosureRewriteModule.checkAndSetStrictModeDirective(t, script);
Preconditions.checkArgument(scriptNodeCount == 1,
"ProcessEs6Modules supports only one invocation per "
+ "CompilerInput / script node");
// rewriteRequires is here (rather than being part of the main visit()
// method, because we only want to rewrite the requires if this is an
// ES6 module.
rewriteRequires(script);
String moduleName = t.getInput().getPath().toModuleName();
for (Map.Entry entry : exportMap.entrySet()) {
String exportedName = entry.getKey();
String withSuffix = entry.getValue().name;
Node nodeForSourceInfo = entry.getValue().nodeForSourceInfo;
Node getProp = IR.getprop(IR.name(moduleName), IR.string(exportedName));
if (typedefs.contains(exportedName)) {
// /** @typedef {foo} */
// moduleName.foo;
JSDocInfoBuilder builder = new JSDocInfoBuilder(true);
JSTypeExpression typeExpr = new JSTypeExpression(
IR.string(exportedName), script.getSourceFileName());
builder.recordTypedef(typeExpr);
JSDocInfo info = builder.build();
getProp.setJSDocInfo(info);
Node exprResult = IR.exprResult(getProp)
.useSourceInfoIfMissingFromForTree(nodeForSourceInfo);
script.addChildToBack(exprResult);
} else {
// moduleName.foo = foo;
// with a @const annotation if needed.
Node assign = IR.assign(
getProp,
NodeUtil.newQName(compiler, withSuffix));
Node exprResult = IR.exprResult(assign)
.useSourceInfoIfMissingFromForTree(nodeForSourceInfo);
if (classes.contains(exportedName)) {
JSDocInfoBuilder builder = new JSDocInfoBuilder(true);
builder.recordConstancy();
JSDocInfo info = builder.build();
assign.setJSDocInfo(info);
}
script.addChildToBack(exprResult);
}
}
// Rename vars to not conflict in global scope.
NodeTraversal.traverseEs6(compiler, script, new RenameGlobalVars(moduleName));
if (!exportMap.isEmpty() || forceRewrite) {
// Add goog.provide call.
Node googProvide = IR.exprResult(
IR.call(NodeUtil.newQName(compiler, "goog.provide"),
IR.string(moduleName)));
script.addChildToFront(googProvide.useSourceInfoIfMissingFromForTree(script));
t.getInput().addProvide(moduleName);
}
JSDocInfoBuilder jsDocInfo = script.getJSDocInfo() == null
? new JSDocInfoBuilder(false)
: JSDocInfoBuilder.copyFrom(script.getJSDocInfo());
if (!jsDocInfo.isPopulatedWithFileOverview()) {
jsDocInfo.recordFileOverview("");
}
// Don't check provides and requires, since most of them are auto-generated.
jsDocInfo.recordSuppressions(ImmutableSet.of("missingProvide", "missingRequire"));
script.setJSDocInfo(jsDocInfo.build());
exportMap.clear();
compiler.reportCodeChange();
}
private void rewriteRequires(Node script) {
NodeTraversal.traverseEs6(
compiler,
script,
new NodeTraversal.AbstractShallowCallback() {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isCall()
&& n.getFirstChild().matchesQualifiedName("goog.require")
&& NodeUtil.isNameDeclaration(parent.getParent())) {
visitRequire(n, parent);
}
}
/**
* Rewrites
* const foo = goog.require('bar.foo');
* to
* goog.require('bar.foo');
* const foo = bar.foo;
*/
private void visitRequire(Node requireCall, Node parent) {
String namespace = requireCall.getLastChild().getString();
if (!parent.getParent().isConst()) {
compiler.report(JSError.make(parent.getParent(), LHS_OF_GOOG_REQUIRE_MUST_BE_CONST));
}
// If the LHS is a destructuring pattern with the "shorthand" syntax,
// desugar it because otherwise the renaming will not be done correctly.
// const {x} = goog.require('y')
// becomes
// const {x: x} = goog.require('y');
if (parent.isObjectPattern()) {
for (Node key = parent.getFirstChild(); key != null; key = key.getNext()) {
if (!key.hasChildren()) {
key.addChildToBack(IR.name(key.getString()).useSourceInfoFrom(key));
}
}
}
Node replacement = NodeUtil.newQName(compiler, namespace).srcrefTree(requireCall);
parent.replaceChild(requireCall, replacement);
Node varNode = parent.getParent();
varNode.getParent().addChildBefore(
IR.exprResult(requireCall).srcrefTree(requireCall),
varNode);
}
});
}
/**
* Traverses a node tree and
*
* - Appends a suffix to all global variable names defined in this module.
*
- Changes references to imported values to be property accesses on the
* imported module object.
*
*/
private class RenameGlobalVars extends AbstractPostOrderCallback {
private final String suffix;
RenameGlobalVars(String suffix) {
this.suffix = suffix;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
JSDocInfo info = n.getJSDocInfo();
if (info != null) {
for (Node typeNode : info.getTypeNodes()) {
fixTypeNode(t, typeNode);
}
}
boolean isShorthandObjLitKey = n.isStringKey() && !n.hasChildren();
if (n.isName() || isShorthandObjLitKey) {
String name = n.getString();
if (suffix.equals(name)) {
// TODO(moz): Investigate whether we need to return early in this unlikely situation.
return;
}
Var var = t.getScope().getVar(name);
if (var != null && var.isGlobal()) {
// Avoid polluting the global namespace.
String newName = name + "$$" + suffix;
if (isShorthandObjLitKey) {
// Change {a} to {a: a$$module$foo}
n.addChildToBack(IR.name(newName).useSourceInfoIfMissingFrom(n));
} else {
n.setString(newName);
n.setOriginalName(name);
}
} else if (var == null && importMap.containsKey(name)) {
// Change to property access on the imported module object.
if (parent.isCall() && parent.getFirstChild() == n) {
parent.putBooleanProp(Node.FREE_CALL, false);
}
ModuleOriginalNamePair pair = importMap.get(name);
Node moduleAccess = NodeUtil.newQName(compiler, pair.module);
if (pair.originalName.isEmpty()) {
n.replaceWith(moduleAccess.useSourceInfoIfMissingFromForTree(n));
} else {
n.replaceWith(
IR.getprop(moduleAccess, IR.string(pair.originalName))
.useSourceInfoIfMissingFromForTree(n));
}
}
}
}
/**
* Replace type name references. Change short names to fully qualified names
* with namespace prefixes. Eg: {Foo} becomes {module$test.Foo}.
*/
private void fixTypeNode(NodeTraversal t, Node typeNode) {
if (typeNode.isString()) {
String name = typeNode.getString();
if (ModuleLoader.isPathIdentifier(name)) {
int lastSlash = name.lastIndexOf('/');
int endIndex = name.indexOf('.', lastSlash);
String localTypeName = null;
if (endIndex == -1) {
endIndex = name.length();
} else {
localTypeName = name.substring(endIndex);
}
String moduleName = name.substring(0, endIndex);
String globalModuleName =
t.getInput().getPath().resolveEs6Module(moduleName).toModuleName();
typeNode.setString(
localTypeName == null ? globalModuleName : globalModuleName + localTypeName);
} else {
List splitted = Splitter.on('.').limit(2).splitToList(name);
String baseName = splitted.get(0);
String rest = "";
if (splitted.size() == 2) {
rest = "." + splitted.get(1);
}
Var var = t.getScope().getVar(baseName);
if (var != null && var.isGlobal()) {
typeNode.setString(baseName + "$$" + suffix + rest);
} else if (var == null && importMap.containsKey(baseName)) {
ModuleOriginalNamePair pair = importMap.get(baseName);
if (pair.originalName.isEmpty()) {
typeNode.setString(pair.module + rest);
} else {
typeNode.setString(baseName + "$$" + pair.module + rest);
}
}
typeNode.setOriginalName(name);
}
}
for (Node child = typeNode.getFirstChild(); child != null;
child = child.getNext()) {
fixTypeNode(t, child);
}
compiler.reportCodeChange();
}
}
private static class ModuleOriginalNamePair {
private String module;
private String originalName;
private ModuleOriginalNamePair(String module, String originalName) {
this.module = module;
this.originalName = originalName;
}
@Override
public String toString() {
return "(" + module + ", " + originalName + ")";
}
}
private static class NameNodePair {
final String name;
final Node nodeForSourceInfo;
private NameNodePair(String name, Node nodeForSourceInfo) {
this.name = name;
this.nodeForSourceInfo = nodeForSourceInfo;
}
@Override
public String toString() {
return "(" + name + ", " + nodeForSourceInfo + ")";
}
}
}