com.google.gwt.dev.js.ast.JsScope Maven / Gradle / Ivy
/*
* Copyright 2008 Google Inc.
*
* 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.gwt.dev.js.ast;
import com.google.gwt.dev.js.JsKeywords;
import com.google.gwt.dev.util.StringInterner;
import java.io.Serializable;
import java.util.Iterator;
import java.util.List;
/**
* A scope is a factory for creating and allocating
* {@link com.google.gwt.dev.js.ast.JsName}s. A JavaScript AST is built in terms
* of abstract name objects without worrying about obfuscation,
* keyword/identifier blacklisting, and so on.
*
*
*
* Scopes are associated with {@link com.google.gwt.dev.js.ast.JsFunction}s, but
* the two are not equivalent. Functions have scopes, but a scope does
* not necessarily have an associated Function. Examples of this include the
* {@link com.google.gwt.dev.js.ast.JsRootScope} and synthetic scopes that might
* be created by a client.
*
*
*
* Scopes can have parents to provide constraints when allocating actual
* identifiers for names. Specifically, names in child scopes are chosen such
* that they do not conflict with names in their parent scopes. The ultimate
* parent is usually the global scope (see
* {@link com.google.gwt.dev.js.ast.JsProgram#getGlobalScope()}), but parentless
* scopes are useful for managing names that are always accessed with a
* qualifier and could therefore never be confused with the global scope
* hierarchy.
*/
public abstract class JsScope implements Serializable {
/**
* Prevents the client from programmatically creating an illegal ident.
*/
private static String maybeMangleKeyword(String ident) {
if (JsKeywords.isKeyword(ident)) {
ident = ident + "_$";
}
return StringInterner.get().intern(ident);
}
private final String description;
protected JsScope(String description) {
this.description = StringInterner.get().intern(description);
}
/**
* Gets a name object associated with the specified ident in this scope,
* creating it if necessary.
*
* @param ident An identifier that is unique within this scope.
*/
public final JsName declareName(String ident) {
ident = maybeMangleKeyword(ident);
JsName name = findExistingNameNoRecurse(ident);
if (name != null) {
return name;
}
return doCreateName(ident, ident);
}
/**
* Gets a name object associated with the specified ident in this scope,
* creating it if necessary.
*
* @param ident An identifier that is unique within this scope.
* @param shortIdent A "pretty" name that does not have to be unique.
* @throws IllegalArgumentException if ident already exists in this scope but
* the requested short name does not match the existing short name.
*/
public final JsName declareName(String ident, String shortIdent) {
ident = maybeMangleKeyword(ident);
shortIdent = maybeMangleKeyword(shortIdent);
JsName name = findExistingNameNoRecurse(ident);
if (name != null) {
if (!name.getShortIdent().equals(shortIdent)) {
throw new IllegalArgumentException("Requested short name " + shortIdent
+ " conflicts with preexisting short name " + name.getShortIdent()
+ " for identifier " + ident);
}
return name;
}
return doCreateName(ident, shortIdent);
}
/**
* Attempts to find the name object for the specified ident, searching in this
* scope, and if not found, in the parent scopes.
*
* @return null if the identifier has no associated name
*/
public final JsName findExistingName(String ident) {
ident = maybeMangleKeyword(ident);
JsName name = findExistingNameNoRecurse(ident);
if (name == null && getParent() != null) {
return getParent().findExistingName(ident);
}
return name;
}
/**
* Attempts to find an unobfuscatable name object for the specified ident,
* searching in this scope, and if not found, in the parent scopes.
*
* @return null if the identifier has no associated name
*/
public final JsName findExistingUnobfuscatableName(String ident) {
ident = maybeMangleKeyword(ident);
JsName name = findExistingNameNoRecurse(ident);
if (name != null && name.isObfuscatable()) {
name = null;
}
if (name == null && getParent() != null) {
return getParent().findExistingUnobfuscatableName(ident);
}
return name;
}
/**
* Returns an iterator for all the names defined by this scope.
*/
public abstract Iterator getAllNames();
/**
* Returns a list of this scope's child scopes.
*/
public abstract List getChildren();
/**
* Returns the parent scope of this scope, or null if this is the
* root scope.
*/
public abstract JsScope getParent();
@Override
public final String toString() {
if (getParent() != null) {
return description + "->" + getParent();
} else {
return description;
}
}
protected abstract void addChild(JsScope child);
/**
* Creates a new name in this scope.
*/
protected abstract JsName doCreateName(String ident, String shortIdent);
/**
* Attempts to find the name object for the specified ident, searching in this
* scope only.
*
* @return null if the identifier has no associated name
*/
protected abstract JsName findExistingNameNoRecurse(String ident);
}