dev/core/src/com/google/gwt/dev/jjs/impl/JsniRestrictionChecker.java

/*
 * 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.jjs.impl;

import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.dev.jjs.InternalCompilerException;
import com.google.gwt.dev.jjs.ast.Context;
import com.google.gwt.dev.jjs.ast.JDeclaredType;
import com.google.gwt.dev.jjs.ast.JMethod;
import com.google.gwt.dev.jjs.ast.JProgram;
import com.google.gwt.dev.jjs.ast.JVisitor;
import com.google.gwt.dev.jjs.ast.js.JsniMethodBody;
import com.google.gwt.dev.jjs.ast.js.JsniMethodRef;

/**
 * Checks and throws errors for invalid JSNI constructs.
 */
public class JsniRestrictionChecker extends JVisitor {

  public static void exec(TreeLogger logger, JProgram jprogram) throws UnableToCompleteException {
    JsniRestrictionChecker jsniRestrictionChecker = new JsniRestrictionChecker(logger, jprogram);
    try {
      jsniRestrictionChecker.accept(jprogram);
    } catch (InternalCompilerException e) {
      // Already logged.
      throw new UnableToCompleteException();
    }
  }

  private JMethod currentJsniMethod;
  private final JProgram jprogram;
  private final TreeLogger logger;

  public JsniRestrictionChecker(TreeLogger logger, JProgram jprogram) {
    this.logger = logger;
    this.jprogram = jprogram;
  }

  @Override
  public boolean visit(JsniMethodBody x, Context ctx) {
    currentJsniMethod = x.getMethod();
    return super.visit(x, ctx);
  }

  @Override
  public boolean visit(JsniMethodRef x, Context ctx) {
    JMethod calledMethod = x.getTarget();
    JDeclaredType enclosingTypeOfCalledMethod = calledMethod.getEnclosingType();

    if (isNonStaticJsoClassDispatch(calledMethod, enclosingTypeOfCalledMethod)) {
      logger.log(TreeLogger.ERROR, "JSNI method " + getSignature(currentJsniMethod)
          + " attempts to call non-static method " + getSignature(calledMethod)
          + " on an instance which is a subclass of JavaScriptObject. "
          + "Only static method calls on JavaScriptObject subclasses are allowed in JSNI.");
      throw new UnsupportedOperationException();
    } else if (isJsoInterface(enclosingTypeOfCalledMethod)) {
      logger.log(TreeLogger.ERROR, "JSNI method " + getSignature(currentJsniMethod)
          + " attempts to call method " + getSignature(calledMethod)
          + " on an instance which might be a JavaScriptObject. "
          + "Such a method call is only allowed in pure Java (non-JSNI) functions.");
      throw new UnsupportedOperationException();
    }
    return super.visit(x, ctx);
  }

  private String getSignature(JMethod method) {
    return method.getEnclosingType().getShortName() + "." + method.getSignature();
  }

  private boolean isJsoInterface(JDeclaredType type) {
    return jprogram.typeOracle.isSingleJsoImpl(type)
        || jprogram.typeOracle.isDualJsoInterface(type);
  }

  private boolean isNonStaticJsoClassDispatch(JMethod method, JDeclaredType enclosingType) {
    return !method.isStatic() && jprogram.typeOracle.isJavaScriptObject(enclosingType);
  }
}