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NoObjectType.java
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NoObjectType.java
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/*
*
* ***** 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:
* <code>
* var x = function() {};
* if (x instanceof Array) {
* f(x);
* }
* </code>
* 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 <a href="http://en.wikipedia.org/wiki/Bottom_type">Bottom types</a>
*/
public class NoObjectType extends FunctionType {
private static final long serialVersionUID = 1L;
NoObjectType(JSTypeRegistry registry) {
super(
registry,
/* name= */ null,
/* source= */ null,
registry.createArrowType(null, null),
/* typeOfThis= */ null,
/* templateTypeMap= */ null,
FunctionType.Kind.CONSTRUCTOR,
/* nativeType= */ true,
/* isAbstract= */ 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 final FunctionType toMaybeFunctionType() {
return null;
}
@Override
public boolean isNoObjectType() {
return true;
}
@Override
public final boolean isConstructor() {
return false;
}
@Override
public final ObjectType getImplicitPrototype() {
return null;
}
@Override
public String getReferenceName() {
return null;
}
@Override
public boolean hasReferenceName() {
return false;
}
@Override
public final boolean matchesNumberContext() {
return true;
}
@Override
public final boolean matchesObjectContext() {
return true;
}
@Override
public final boolean matchesStringContext() {
return true;
}
@Override
public final boolean matchesSymbolContext() {
return true;
}
@Override
int recursionUnsafeHashCode() {
return System.identityHashCode(this);
}
@Override
final boolean defineProperty(String propertyName, JSType type,
boolean inferred, Node propertyNode) {
// nothing, all properties are defined
return true;
}
@Override
public final boolean removeProperty(String name) {
return false;
}
@Override
public final void setPropertyJSDocInfo(String propertyName, JSDocInfo info) {
// Do nothing, specific properties do not have JSDocInfo.
}
@Override
public <T> T visit(Visitor<T> visitor) {
return visitor.caseNoObjectType();
}
@Override <T> T visit(RelationshipVisitor<T> visitor, JSType that) {
return visitor.caseNoObjectType(that);
}
@Override
StringBuilder appendTo(StringBuilder sb, boolean forAnnotations) {
return sb.append(forAnnotations ? "?" : "NoObject");
}
@Override
public final FunctionType getConstructor() {
return null;
}
@Override
final JSType resolveInternal(ErrorReporter reporter) {
return this;
}
}