com.google.gwt.dev.js.JsUtils Maven / Gradle / Ivy
/*
* Copyright 2014 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;
import com.google.gwt.dev.js.ast.JsExpression;
import com.google.gwt.dev.js.ast.JsFunction;
import com.google.gwt.dev.js.ast.JsInvocation;
import com.google.gwt.dev.js.ast.JsNameRef;
import com.google.gwt.dev.js.ast.JsNode;
/**
* Utils for JS AST.
*/
public class JsUtils {
/**
* Given a JsInvocation, determine if it is invoking a JsFunction that is
* specified to be executed only once during the program's lifetime.
*/
public static JsFunction isExecuteOnce(JsInvocation invocation) {
JsFunction f = isFunction(invocation.getQualifier());
if (f != null && f.getExecuteOnce()) {
return f;
}
return null;
}
/**
* Given an expression, determine if it is a JsNameRef that refers to a
* statically-defined JsFunction.
*/
public static JsFunction isFunction(JsExpression e) {
if (!(e instanceof JsNameRef)) {
return null;
}
JsNameRef ref = (JsNameRef) e;
// Unravel foo.call(...).
if (!ref.getName().isObfuscatable() && "call".equals(ref.getIdent())) {
if (ref.getQualifier() instanceof JsNameRef) {
ref = (JsNameRef) ref.getQualifier();
}
}
JsNode staticRef = ref.getName().getStaticRef();
if (staticRef instanceof JsFunction) {
return (JsFunction) staticRef;
}
return null;
}
private JsUtils() {
}
}