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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
This binary checks for style issues such as incorrect or missing JSDoc
usage, and missing goog.require() statements. It does not do more advanced
checks such as typechecking.
/*
* Copyright 2008 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.lint;
import static com.google.common.base.Preconditions.checkArgument;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.AbstractCompiler;
import com.google.javascript.jscomp.DiagnosticType;
import com.google.javascript.jscomp.HotSwapCompilerPass;
import com.google.javascript.jscomp.JSError;
import com.google.javascript.jscomp.NodeTraversal;
import com.google.javascript.jscomp.NodeUtil;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.QualifiedName;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Walks the AST looking for usages of qualified names, and 'goog.require's of those names. Then,
* reconciles the two lists, and reports warning for any unnecessary require statements.
*/
public class CheckExtraRequires extends NodeTraversal.AbstractPostOrderCallback
implements HotSwapCompilerPass {
private final AbstractCompiler compiler;
// Keys are the local name of a required namespace. Values are the goog.require CALL node.
private final Map requires = new HashMap<>();
// Adding an entry to usages indicates that the name (either a fully qualified or local name)
// is used and can be required. Note that since usages are name-based and not scoped, any usage
// that shadows an unused require in that file will cause the extra require warning to be missed.
private final Set usages = new HashSet<>();
public static final DiagnosticType EXTRA_REQUIRE_WARNING =
DiagnosticType.disabled(
"JSC_EXTRA_REQUIRE_WARNING", "extra require: ''{0}'' is never referenced in this file");
// TODO(b/130215517): This should eventually be removed and exceptions supressed
private static final ImmutableSet DEFAULT_EXTRA_NAMESPACES =
ImmutableSet.of(
"goog.testing.asserts", "goog.testing.jsunit", "goog.testing.JsTdTestCaseAdapter");
public CheckExtraRequires(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override
public void process(Node externs, Node root) {
reset();
NodeTraversal.traverse(compiler, root, this);
}
@Override
public void hotSwapScript(Node scriptRoot, Node originalRoot) {
process(null, scriptRoot);
}
private String extractNamespace(Node call, String... primitiveNames) {
Node callee = call.getFirstChild();
if (!callee.isGetProp()) {
return null;
}
for (String primitiveName : primitiveNames) {
if (callee.matchesQualifiedName(primitiveName)) {
Node target = callee.getNext();
if (target != null && target.isString()) {
return target.getString();
}
}
}
return null;
}
private String extractNamespaceIfRequire(Node call) {
return extractNamespace(call, "goog.require", "goog.requireType");
}
private String extractNamespaceIfForwardDeclare(Node call) {
return extractNamespace(call, "goog.forwardDeclare");
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
maybeAddJsDocUsages(n);
switch (n.getToken()) {
case NAME:
if (!NodeUtil.isLValue(n) && !parent.isGetProp() && !parent.isImportSpec()) {
visitQualifiedName(n);
}
break;
case GETPROP:
// If parent is a GETPROP, they will handle all the usages.
if (!parent.isGetProp() && n.isQualifiedName()) {
visitQualifiedName(n);
}
break;
case CALL:
visitCallNode(n, parent);
break;
case SCRIPT:
visitScriptNode();
reset();
break;
case IMPORT:
visitImportNode(n);
break;
default:
break;
}
}
private void reset() {
this.usages.clear();
this.requires.clear();
}
private void visitScriptNode() {
// For every goog.require, check that there is a usage and warn if there is not.
for (Map.Entry entry : requires.entrySet()) {
String require = entry.getKey();
Node call = entry.getValue();
if (!usages.contains(require)) {
reportExtraRequireWarning(call, require);
}
}
}
private void reportExtraRequireWarning(Node call, String require) {
if (DEFAULT_EXTRA_NAMESPACES.contains(require)) {
return;
}
JSDocInfo jsDoc = NodeUtil.getBestJSDocInfo(call);
if (jsDoc != null && jsDoc.getSuppressions().contains("extraRequire")) {
// There is a @suppress {extraRequire} on the call node or its enclosing statement.
// This is one of the acceptable places for a @suppress, per
// https://github.com/google/closure-compiler/wiki/@suppress-annotations
return;
}
compiler.report(JSError.make(call, EXTRA_REQUIRE_WARNING, require));
}
/**
* @param localName The name that should be used in this file.
*
* Require style | localName
* -------------------------------------|----------
* goog.require('foo.bar'); | foo.bar
* var bar = goog.require('foo.bar'); | bar
* var {qux} = goog.require('foo.bar'); | qux
* import {qux} from 'foo.bar'; | qux
*
*/
private void visitRequire(String localName, Node node) {
if (!requires.containsKey(localName)) {
requires.put(localName, node);
}
}
private void visitImportNode(Node importNode) {
Node defaultImport = importNode.getFirstChild();
if (defaultImport.isName()) {
visitRequire(defaultImport.getString(), importNode);
}
Node namedImports = defaultImport.getNext();
if (namedImports.isImportSpecs()) {
for (Node importSpec : namedImports.children()) {
visitRequire(importSpec.getLastChild().getString(), importNode);
}
}
}
private void visitForwardDeclare(String namespace, Node forwardDeclareCall, Node parent) {
visitGoogRequire(namespace, forwardDeclareCall, parent);
}
private void visitGoogRequire(String namespace, Node googRequireCall, Node parent) {
if (parent.isName()) {
visitRequire(parent.getString(), googRequireCall);
} else if (parent.isDestructuringLhs() && parent.getFirstChild().isObjectPattern()) {
if (parent.getFirstChild().hasChildren()) {
for (Node stringKey : parent.getFirstChild().children()) {
Node importName = stringKey.getFirstChild();
if (!importName.isName()) {
// invalid reported elsewhere
continue;
}
visitRequire(importName.getString(), importName);
}
} else {
visitRequire(namespace, googRequireCall);
}
} else {
visitRequire(namespace, googRequireCall);
}
}
private void visitCallNode(Node call, Node parent) {
String required = extractNamespaceIfRequire(call);
if (required != null) {
visitGoogRequire(required, call, parent);
return;
}
String declare = extractNamespaceIfForwardDeclare(call);
if (declare != null) {
visitForwardDeclare(declare, call, parent);
return;
}
Node callee = call.getFirstChild();
if (callee.matchesQualifiedName("goog.module.get") && call.getSecondChild().isString()) {
usages.add(call.getSecondChild().getString());
}
}
private void addUsagesOfAllPrefixes(QualifiedName qualifiedName) {
usages.add(qualifiedName.join());
// For "foo.bar.baz.qux" add usages for "foo.bar.baz.qux", "foo.bar.baz",
// "foo.bar", and "foo" because any of those might be a require that
// we need to include.
while (!qualifiedName.isSimple()) {
qualifiedName = qualifiedName.getOwner();
usages.add(qualifiedName.join());
}
}
private void visitQualifiedName(Node n) {
checkArgument(n.isQualifiedName(), n);
addUsagesOfAllPrefixes(n.getQualifiedNameObject());
}
private void maybeAddJsDocUsages(Node n) {
JSDocInfo info = n.getJSDocInfo();
if (info == null) {
return;
}
info.getTypeExpressions().stream()
.flatMap(e -> e.getAllTypeNames().stream())
.map(QualifiedName::of)
.forEach(this::addUsagesOfAllPrefixes);
}
}