content: /*
   * Copyright 2015 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.googlejavaformat;
  
  import com.google.common.base.MoreObjects;
  import java.util.ArrayDeque;
  import java.util.List;
  
  /** A {@code DocBuilder} converts a sequence of {@link Op}s into a {@link Doc}. */
  public final class DocBuilder {
    private final Doc.Level base = Doc.Level.make(Indent.Const.ZERO);
    private final ArrayDeque<Doc.Level> stack = new ArrayDeque<>();
  
    /**
     * A possibly earlier {@link Doc.Level} for appending text, à la Philip Wadler.
     *
     * <p>Processing {@link Doc}s presents a subtle problem. Suppose we have a {@link Doc} for to an
     * assignment node, {@code a = b}, with an optional {@link Doc.Break} following the {@code =}.
     * Suppose we have 5 characters to write it, so that we think we don't need the break.
     * Unfortunately, this {@link Doc} lies in an expression statement {@link Doc} for the statement
     * {@code a = b;} and this statement does not fit in 3 characters. This is why many formatters
     * sometimes emit lines that are too long, or cheat by using a narrower line length to avoid such
     * problems.
     *
     * <p>One solution to this problem is not to decide whether a {@link Doc.Level} should be broken
     * until later (in this case, after the semicolon has been seen). A simpler approach is to rewrite
     * the {@link Doc} as here, so that the semicolon moves inside the inner {@link Doc}, and we can
     * decide whether to break that {@link Doc} without seeing later text.
     */
    private Doc.Level appendLevel = base;
  
    /** Start to build a {@code DocBuilder}. */
    public DocBuilder() {
      stack.addLast(base);
    }
  
    /**
     * Add a list of {@link Op}s to the {@link OpsBuilder}.
     *
     * @param ops the {@link Op}s
     * @return the {@link OpsBuilder}
     */
    public DocBuilder withOps(List<Op> ops) {
      for (Op op : ops) {
        op.add(this); // These operations call the operations below to build the doc.
      }
      return this;
    }
  
    /**
     * Open a new {@link Doc.Level}.
     *
     * @param plusIndent the extra indent for the {@link Doc.Level}
     */
    void open(Indent plusIndent) {
      Doc.Level level = Doc.Level.make(plusIndent);
      stack.addLast(level);
    }
  
    /** Close the current {@link Doc.Level}. */
    void close() {
      Doc.Level top = stack.removeLast();
      stack.peekLast().add(top);
    }
  
    /**
     * Add a {@link Doc} to the current {@link Doc.Level}.
     *
     * @param doc the {@link Doc}
     */
    void add(Doc doc) {
      appendLevel.add(doc);
    }
  
    /**
     * Add a {@link Doc.Break} to the current {@link Doc.Level}.
     *
     * @param breakDoc the {@link Doc.Break}
     */
    void breakDoc(Doc.Break breakDoc) {
      appendLevel = stack.peekLast();
      appendLevel.add(breakDoc);
    }
  
    /**
     * Return the {@link Doc}.
     *
     * @return the {@link Doc}
     */
    public Doc build() {
      return base;
    }
  
    @Override
    public String toString() {
      return MoreObjects.toStringHelper(this)
          .add("base", base)
          .add("stack", stack)
          .add("appendLevel", appendLevel)
          .toString();
    }
  }
  