StrictModeCheck.java
/*
* Copyright 2009 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.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.TypeI;
import java.util.HashSet;
import java.util.Set;
/**
* Checks that the code obeys the static restrictions of strict mode:
* <ol>
* <li> No use of "with".
* <li> No deleting variables, functions, or arguments.
* <li> No re-declarations or assignments of "eval" or arguments.
* <li> No use of arguments.callee
* <li> No use of arguments.caller
* <li> Class: Always under strict mode
* <li> In addition, no duplicate class method names
* </ol>
*
*/
class StrictModeCheck extends AbstractPostOrderCallback
implements CompilerPass {
static final DiagnosticType USE_OF_WITH = DiagnosticType.warning(
"JSC_USE_OF_WITH",
"The 'with' statement cannot be used in strict mode.");
static final DiagnosticType EVAL_DECLARATION = DiagnosticType.warning(
"JSC_EVAL_DECLARATION",
"\"eval\" cannot be redeclared in strict mode");
static final DiagnosticType EVAL_ASSIGNMENT = DiagnosticType.warning(
"JSC_EVAL_ASSIGNMENT",
"the \"eval\" object cannot be reassigned in strict mode");
static final DiagnosticType ARGUMENTS_DECLARATION = DiagnosticType.warning(
"JSC_ARGUMENTS_DECLARATION",
"\"arguments\" cannot be redeclared in strict mode");
static final DiagnosticType ARGUMENTS_ASSIGNMENT = DiagnosticType.warning(
"JSC_ARGUMENTS_ASSIGNMENT",
"the \"arguments\" object cannot be reassigned in strict mode");
static final DiagnosticType ARGUMENTS_CALLEE_FORBIDDEN = DiagnosticType.warning(
"JSC_ARGUMENTS_CALLEE_FORBIDDEN",
"\"arguments.callee\" cannot be used in strict mode");
static final DiagnosticType ARGUMENTS_CALLER_FORBIDDEN = DiagnosticType.warning(
"JSC_ARGUMENTS_CALLER_FORBIDDEN",
"\"arguments.caller\" cannot be used in strict mode");
static final DiagnosticType FUNCTION_CALLER_FORBIDDEN = DiagnosticType.warning(
"JSC_FUNCTION_CALLER_FORBIDDEN",
"A function''s \"caller\" property cannot be used in strict mode");
static final DiagnosticType FUNCTION_ARGUMENTS_PROP_FORBIDDEN = DiagnosticType.warning(
"JSC_FUNCTION_ARGUMENTS_PROP_FORBIDDEN",
"A function''s \"arguments\" property cannot be used in strict mode");
static final DiagnosticType BAD_FUNCTION_DECLARATION = DiagnosticType.warning(
"JSC_BAD_FUNCTION_DECLARATION",
"functions can only be declared at top level or immediately within"
+ " another function in ES5 strict mode");
static final DiagnosticType DELETE_VARIABLE = DiagnosticType.warning(
"JSC_DELETE_VARIABLE",
"variables, functions, and arguments cannot be deleted in strict mode");
static final DiagnosticType DUPLICATE_OBJECT_KEY = DiagnosticType.error(
"JSC_DUPLICATE_OBJECT_KEY",
"Object literal contains illegal duplicate key \"{0}\", disallowed in strict mode");
static final DiagnosticType DUPLICATE_CLASS_METHODS = DiagnosticType.error(
"JSC_DUPLICATE_CLASS_METHODS",
"Class contains duplicate method name \"{0}\"");
private final AbstractCompiler compiler;
StrictModeCheck(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override public void process(Node externs, Node root) {
NodeTraversal.traverseRootsEs6(compiler, this, externs, root);
NodeTraversal.traverseEs6(compiler, root, new NonExternChecks());
}
@Override public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isAssign()) {
checkAssignment(t, n);
} else if (n.isDelProp()) {
checkDelete(t, n);
} else if (n.isObjectLit()) {
checkObjectLiteralOrClass(t, n);
} else if (n.isClass()) {
checkObjectLiteralOrClass(t, n.getLastChild());
} else if (n.isWith()) {
checkWith(t, n);
}
}
/** Reports a warning for with statements. */
private static void checkWith(NodeTraversal t, Node n) {
JSDocInfo info = n.getJSDocInfo();
boolean allowWith =
info != null && info.getSuppressions().contains("with");
if (!allowWith) {
t.report(n, USE_OF_WITH);
}
}
/**
* Determines if the given name is a declaration, which can be a declaration
* of a variable, function, or argument.
*/
private static boolean isDeclaration(Node n) {
switch (n.getParent().getToken()) {
case LET:
case CONST:
case VAR:
case CATCH:
return true;
case FUNCTION:
return n == n.getParent().getFirstChild();
case PARAM_LIST:
return n.getGrandparent().isFunction();
default:
return false;
}
}
/** Checks that an assignment is not to the "arguments" object. */
private static void checkAssignment(NodeTraversal t, Node n) {
if (n.getFirstChild().isName()) {
if ("arguments".equals(n.getFirstChild().getString())) {
t.report(n, ARGUMENTS_ASSIGNMENT);
} else if ("eval".equals(n.getFirstChild().getString())) {
// Note that assignment to eval is already illegal because any use of
// that name is illegal.
t.report(n, EVAL_ASSIGNMENT);
}
}
}
/** Checks that variables, functions, and arguments are not deleted. */
private static void checkDelete(NodeTraversal t, Node n) {
if (n.getFirstChild().isName()) {
Var v = t.getScope().getVar(n.getFirstChild().getString());
if (v != null) {
t.report(n, DELETE_VARIABLE);
}
}
}
/** Checks that object literal keys or class method names are valid. */
private static void checkObjectLiteralOrClass(NodeTraversal t, Node n) {
Set<String> getters = new HashSet<>();
Set<String> setters = new HashSet<>();
Set<String> staticGetters = new HashSet<>();
Set<String> staticSetters = new HashSet<>();
for (Node key = n.getFirstChild();
key != null;
key = key.getNext()) {
if (key.isEmpty() || key.isComputedProp()) {
continue;
}
if (key.isSpread()) {
continue;
}
String keyName = key.getString();
if (!key.isSetterDef()) {
// normal property and getter cases
Set<String> set = key.isStaticMember() ? staticGetters : getters;
if (!set.add(keyName)) {
if (n.isClassMembers()) {
t.report(key, DUPLICATE_CLASS_METHODS, keyName);
} else {
t.report(key, DUPLICATE_OBJECT_KEY, keyName);
}
}
}
if (!key.isGetterDef()) {
// normal property and setter cases
Set<String> set = key.isStaticMember() ? staticSetters : setters;
if (!set.add(keyName)) {
if (n.isClassMembers()) {
t.report(key, DUPLICATE_CLASS_METHODS, keyName);
} else {
t.report(key, DUPLICATE_OBJECT_KEY, keyName);
}
}
}
}
}
/** Checks that are performed on non-extern code only. */
private static class NonExternChecks extends AbstractPostOrderCallback {
@Override public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isName() && isDeclaration(n)) {
checkDeclaration(t, n);
} else if (n.isGetProp()) {
checkGetProp(t, n);
}
}
/** Checks for illegal declarations. */
private void checkDeclaration(NodeTraversal t, Node n) {
if ("eval".equals(n.getString())) {
t.report(n, EVAL_DECLARATION);
} else if ("arguments".equals(n.getString())) {
t.report(n, ARGUMENTS_DECLARATION);
}
}
/** Checks that the arguments.callee is not used. */
private void checkGetProp(NodeTraversal t, Node n) {
Node target = n.getFirstChild();
Node prop = n.getLastChild();
if (prop.getString().equals("callee")) {
if (target.isName() && target.getString().equals("arguments")) {
t.report(n, ARGUMENTS_CALLEE_FORBIDDEN);
}
} else if (prop.getString().equals("caller")) {
if (target.isName() && target.getString().equals("arguments")) {
t.report(n, ARGUMENTS_CALLER_FORBIDDEN);
} else if (isFunctionType(target)) {
t.report(n, FUNCTION_CALLER_FORBIDDEN);
}
} else if (prop.getString().equals("arguments")
&& isFunctionType(target)) {
t.report(n, FUNCTION_ARGUMENTS_PROP_FORBIDDEN);
}
}
}
private static boolean isFunctionType(Node n) {
TypeI type = n.getTypeI();
return (type != null && type.isFunctionType());
}
}