org.immutables.criteria.expression.DebugExpressionVisitor Maven / Gradle / Ivy

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/*
 * Copyright 2019 Immutables Authors and Contributors
 *
 * 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 org.immutables.criteria.expression;

import java.io.PrintWriter;
import java.util.Collections;
import java.util.Objects;

/**
 * Used to output expression tree as string. Useful for debugging expressions.
 */
public class DebugExpressionVisitor extends AbstractExpressionVisitor {

  private final PrintWriter writer;

  private int depth;

  public DebugExpressionVisitor(PrintWriter writer) {
    super(e -> { throw new UnsupportedOperationException(); });
    this.writer = Objects.requireNonNull(writer, "writer");
  }

  @Override
  public Void visit(Call call) {
    writer.println();
    writer.print(String.join("", Collections.nCopies(depth * 2, " ")));
    writer.print("call op=" + call.operator().name());
    for (Expression expr: call.arguments()) {
      depth++;
      expr.accept(this);
      depth--;
    }
    return null;
  }

  @Override
  public Void visit(Constant constant) {
    writer.print(" constant=");
    writer.print(constant.value());
    return null;
  }

  @Override
  public Void visit(Path path) {
    writer.print(" path=");
    writer.print(path.toStringPath());
    return null;
  }

}