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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.
/*
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Rhino code, released
* May 6, 1999.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1997-1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Bob Jervis
* Google Inc.
*
* Alternatively, the contents of this file may be used under the terms of
* the GNU General Public License Version 2 or later (the "GPL"), in which
* case the provisions of the GPL are applicable instead of those above. If
* you wish to allow use of your version of this file only under the terms of
* the GPL and not to allow others to use your version of this file under the
* MPL, indicate your decision by deleting the provisions above and replacing
* them with the notice and other provisions required by the GPL. If you do
* not delete the provisions above, a recipient may use your version of this
* file under either the MPL or the GPL.
*
* ***** END LICENSE BLOCK ***** */
package com.google.javascript.rhino.jstype;
import com.google.javascript.rhino.ErrorReporter;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
/**
* The bottom Object type, representing the subclass of all objects.
*
* Although JavaScript programmers can't explicitly denote the bottom
* Object type, it comes up in static analysis. For example, if we have:
*
* var x = function() {};
* if (x instanceof Array) {
* f(x);
* }
*
* We need to be able to assign {@code x} a type within the {@code f(x)}
* call. It has no possible type, but {@code x} would not be legal if f
* expected a string. So we assign it the {@code NoObjectType}.
*
* @see Bottom types
*/
public class NoObjectType extends FunctionType {
private static final long serialVersionUID = 1L;
NoObjectType(JSTypeRegistry registry) {
super(
registry, null, null, registry.createArrowType(null, null), null, null, true, true, false);
getInternalArrowType().returnType = this;
this.setInstanceType(this);
}
@Override
public boolean isSubtype(JSType that) {
return isSubtype(that, ImplCache.create(), SubtypingMode.NORMAL);
}
@Override
protected boolean isSubtype(JSType that,
ImplCache implicitImplCache, SubtypingMode subtypingMode) {
if (JSType.isSubtypeHelper(this, that, implicitImplCache, subtypingMode)) {
return true;
} else {
return that.isObject() && !that.isNoType() && !that.isNoResolvedType();
}
}
@Override
public FunctionType toMaybeFunctionType() {
return null;
}
@Override
public boolean isNoObjectType() {
return true;
}
@Override
public boolean isConstructor() {
return false;
}
@Override
public ObjectType getImplicitPrototype() {
return null;
}
@Override
public String getReferenceName() {
return null;
}
@Override
public boolean hasReferenceName() {
return false;
}
@Override
public boolean matchesNumberContext() {
return true;
}
@Override
public boolean matchesObjectContext() {
return true;
}
@Override
public boolean matchesStringContext() {
return true;
}
@Override
public int hashCode() {
return System.identityHashCode(this);
}
@Override
boolean defineProperty(String propertyName, JSType type,
boolean inferred, Node propertyNode) {
// nothing, all properties are defined
return true;
}
@Override
public boolean removeProperty(String name) {
return false;
}
@Override
public void setPropertyJSDocInfo(String propertyName, JSDocInfo info) {
// Do nothing, specific properties do not have JSDocInfo.
}
@Override
public T visit(Visitor visitor) {
return visitor.caseNoObjectType();
}
@Override T visit(RelationshipVisitor visitor, JSType that) {
return visitor.caseNoObjectType(that);
}
@Override
StringBuilder appendTo(StringBuilder sb, boolean forAnnotations) {
return sb.append(forAnnotations ? "?" : "NoObject");
}
@Override
public FunctionType getConstructor() {
return null;
}
@Override
JSType resolveInternal(ErrorReporter t, StaticTypedScope scope) {
return this;
}
}