CloneExpressionVisitor.java example

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/*
 * 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.jjs.impl;

import com.google.gwt.dev.jjs.InternalCompilerException;
import com.google.gwt.dev.jjs.ast.Context;
import com.google.gwt.dev.jjs.ast.JArrayLength;
import com.google.gwt.dev.jjs.ast.JArrayRef;
import com.google.gwt.dev.jjs.ast.JBinaryOperation;
import com.google.gwt.dev.jjs.ast.JBooleanLiteral;
import com.google.gwt.dev.jjs.ast.JCastOperation;
import com.google.gwt.dev.jjs.ast.JCharLiteral;
import com.google.gwt.dev.jjs.ast.JClassLiteral;
import com.google.gwt.dev.jjs.ast.JClassType;
import com.google.gwt.dev.jjs.ast.JConditional;
import com.google.gwt.dev.jjs.ast.JDoubleLiteral;
import com.google.gwt.dev.jjs.ast.JExpression;
import com.google.gwt.dev.jjs.ast.JFieldRef;
import com.google.gwt.dev.jjs.ast.JFloatLiteral;
import com.google.gwt.dev.jjs.ast.JInstanceOf;
import com.google.gwt.dev.jjs.ast.JIntLiteral;
import com.google.gwt.dev.jjs.ast.JLocalRef;
import com.google.gwt.dev.jjs.ast.JLongLiteral;
import com.google.gwt.dev.jjs.ast.JMethodCall;
import com.google.gwt.dev.jjs.ast.JNameOf;
import com.google.gwt.dev.jjs.ast.JNewArray;
import com.google.gwt.dev.jjs.ast.JNewInstance;
import com.google.gwt.dev.jjs.ast.JNullLiteral;
import com.google.gwt.dev.jjs.ast.JNumericEntry;
import com.google.gwt.dev.jjs.ast.JParameterRef;
import com.google.gwt.dev.jjs.ast.JPermutationDependentValue;
import com.google.gwt.dev.jjs.ast.JPostfixOperation;
import com.google.gwt.dev.jjs.ast.JPrefixOperation;
import com.google.gwt.dev.jjs.ast.JRunAsync;
import com.google.gwt.dev.jjs.ast.JStringLiteral;
import com.google.gwt.dev.jjs.ast.JThisRef;
import com.google.gwt.dev.jjs.ast.JUnsafeTypeCoercion;
import com.google.gwt.dev.jjs.ast.JVisitor;
import com.google.gwt.dev.jjs.ast.js.JMultiExpression;
import com.google.gwt.dev.jjs.ast.js.JsniFieldRef;
import com.google.gwt.dev.jjs.ast.js.JsniMethodRef;

import java.util.ArrayList;
import java.util.List;

/**
 * A general purpose expression cloner.
 */
public class CloneExpressionVisitor extends JVisitor {
  private JExpression expression;

  public CloneExpressionVisitor() {
  }

  @SuppressWarnings("unchecked")
  public <T extends JExpression> T cloneExpression(T expr) {
    if (expr == null) {
      return null;
    }

    // double check that the expression is successfully cloned
    expression = null;

    this.accept(expr);

    if (expression == null) {
      throw new InternalCompilerException(expr, "Unable to clone expression", null);
    }

    Class<T> originalClass = (Class<T>) expr.getClass();
    return originalClass.cast(expression);
  }

  public ArrayList<JExpression> cloneExpressions(List<JExpression> exprs) {
    if (exprs == null) {
      return null;
    }
    ArrayList<JExpression> result = new ArrayList<JExpression>();
    for (JExpression expr : exprs) {
      result.add(cloneExpression(expr));
    }
    return result;
  }

  @Override
  public boolean visit(JArrayLength x, Context ctx) {
    expression = new JArrayLength(x.getSourceInfo(), cloneExpression(x.getInstance()));
    return false;
  }

  @Override
  public boolean visit(JArrayRef x, Context ctx) {
    expression =
        new JArrayRef(x.getSourceInfo(), cloneExpression(x.getInstance()), cloneExpression(x
            .getIndexExpr()));
    return false;
  }

  @Override
  public boolean visit(JBinaryOperation x, Context ctx) {
    expression =
        new JBinaryOperation(x.getSourceInfo(), x.getType(), x.getOp(),
            cloneExpression(x.getLhs()), cloneExpression(x.getRhs()));
    return false;
  }

  @Override
  public boolean visit(JBooleanLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JCastOperation x, Context ctx) {
    expression =
        new JCastOperation(x.getSourceInfo(), x.getCastType(), cloneExpression(x.getExpr()));
    return false;
  }

  @Override
  public boolean visit(JCharLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JClassLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JConditional x, Context ctx) {
    expression =
        new JConditional(x.getSourceInfo(), x.getType(), cloneExpression(x.getIfTest()),
            cloneExpression(x.getThenExpr()), cloneExpression(x.getElseExpr()));
    return false;
  }

  @Override
  public boolean visit(JDoubleLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JFieldRef x, Context ctx) {
    expression =
        new JFieldRef(x.getSourceInfo(), cloneExpression(x.getInstance()), x.getField(), x
            .getEnclosingType());
    return false;
  }

  @Override
  public boolean visit(JFloatLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JInstanceOf x, Context ctx) {
    expression = new JInstanceOf(x.getSourceInfo(), x.getTestType(), cloneExpression(x.getExpr()));
    return false;
  }

  @Override
  public boolean visit(JIntLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JLocalRef x, Context ctx) {
    expression = x.getLocal().makeRef(x.getSourceInfo());
    return false;
  }

  @Override
  public boolean visit(JLongLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JMethodCall x, Context ctx) {
    JMethodCall newMethodCall = new JMethodCall(x, cloneExpression(x.getInstance()));
    newMethodCall.addArgs(cloneExpressions(x.getArgs()));
    expression = newMethodCall;
    return false;
  }

  @Override
  public boolean visit(JMultiExpression x, Context ctx) {
    expression = new JMultiExpression(x.getSourceInfo(), cloneExpressions(x.getExpressions()));
    return false;
  }

  @Override
  public boolean visit(JNameOf x, Context ctx) {
    expression =
        new JNameOf(x.getSourceInfo(), (JClassType) x.getType().getUnderlyingType(), x.getNode());
    return false;
  }

  @Override
  public boolean visit(JNewArray x, Context ctx) {
    expression = new JNewArray(x.getSourceInfo(), x.getArrayType(),
        cloneExpressions(x.getDimensionExpressions()), cloneExpressions(x.getInitializers()),
        cloneExpression(x.getLeafTypeClassLiteral()));
    return false;
  }

  @Override
  public boolean visit(JNewInstance x, Context ctx) {
    JNewInstance newInstance = new JNewInstance(x);
    newInstance.addArgs(cloneExpressions(x.getArgs()));
    expression = newInstance;
    return false;
  }

  @Override
  public boolean visit(JNumericEntry x, Context ctx) {
    expression = new JNumericEntry(x.getSourceInfo(), x.getKey(), x.getValue());
    return false;
  }

  @Override
  public boolean visit(JNullLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JParameterRef x, Context ctx) {
    expression = x.getParameter().makeRef(x.getSourceInfo());
    return false;
  }

  @Override
  public void endVisit(JPermutationDependentValue x, Context ctx) {
    throw new IllegalStateException("AST should not contain permutation dependent values at " +
        "this point but contains " + x);
  }

  @Override
  public boolean visit(JPostfixOperation x, Context ctx) {
    expression = new JPostfixOperation(x.getSourceInfo(), x.getOp(), cloneExpression(x.getArg()));
    return false;
  }

  @Override
  public boolean visit(JPrefixOperation x, Context ctx) {
    expression = new JPrefixOperation(x.getSourceInfo(), x.getOp(), cloneExpression(x.getArg()));
    return false;
  }

  @Override
  public boolean visit(JRunAsync x, Context ctx) {
    // Only the runAsync call itself needs cloning, the onSuccess can be shared.
    JExpression runAsyncCall = cloneExpression(x.getRunAsyncCall());
    expression =
        new JRunAsync(x.getSourceInfo(), x.getRunAsyncId(), x.getName(),
            x.hasExplicitClassLiteral(), runAsyncCall, x.getOnSuccessCall());
    return false;
  }

  @Override
  public boolean visit(JsniFieldRef x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JsniMethodRef x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JStringLiteral x, Context ctx) {
    expression = x;
    return false;
  }

  @Override
  public boolean visit(JThisRef x, Context ctx) {
    expression = new JThisRef(x.getSourceInfo(), x.getClassType());
    return false;
  }

  @Override
  public boolean visit(JUnsafeTypeCoercion x, Context ctx) {
    expression = new JUnsafeTypeCoercion(
        x.getSourceInfo(), x.getCoercionType(), cloneExpression(x.getExpression()));
    return false;
  }
}