google-java-format-master/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
/*
 * 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.java;

import com.google.common.base.CharMatcher;
import com.google.common.base.Strings;
import com.google.googlejavaformat.CommentsHelper;
import com.google.googlejavaformat.Input.Tok;
import com.google.googlejavaformat.Newlines;
import com.google.googlejavaformat.java.javadoc.JavadocFormatter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/** {@code JavaCommentsHelper} extends {@link CommentsHelper} to rewrite Java comments. */
public final class JavaCommentsHelper implements CommentsHelper {

  private final String lineSeparator;
  private final JavaFormatterOptions options;

  public JavaCommentsHelper(String lineSeparator, JavaFormatterOptions options) {
    this.lineSeparator = lineSeparator;
    this.options = options;
  }

  @Override
  public String rewrite(Tok tok, int maxWidth, int column0) {
    if (!tok.isComment()) {
      return tok.getOriginalText();
    }
    String text = tok.getOriginalText();
    if (tok.isJavadocComment() && options.formatJavadoc()) {
      text = JavadocFormatter.formatJavadoc(text, column0);
    }
    List<String> lines = new ArrayList<>();
    Iterator<String> it = Newlines.lineIterator(text);
    while (it.hasNext()) {
      lines.add(CharMatcher.whitespace().trimTrailingFrom(it.next()));
    }
    if (tok.isSlashSlashComment()) {
      return indentLineComments(lines, column0);
    }
    return CommentsHelper.reformatParameterComment(tok)
        .orElseGet(
            () ->
                javadocShaped(lines)
                    ? indentJavadoc(lines, column0)
                    : preserveIndentation(lines, column0));
  }

  // For non-javadoc-shaped block comments, shift the entire block to the correct
  // column, but do not adjust relative indentation.
  private String preserveIndentation(List<String> lines, int column0) {
    StringBuilder builder = new StringBuilder();

    // find the leftmost non-whitespace character in all trailing lines
    int startCol = -1;
    for (int i = 1; i < lines.size(); i++) {
      int lineIdx = CharMatcher.whitespace().negate().indexIn(lines.get(i));
      if (lineIdx >= 0 && (startCol == -1 || lineIdx < startCol)) {
        startCol = lineIdx;
      }
    }

    // output the first line at the current column
    builder.append(lines.get(0));

    // output all trailing lines with plausible indentation
    for (int i = 1; i < lines.size(); ++i) {
      builder.append(lineSeparator).append(Strings.repeat(" ", column0));
      // check that startCol is valid index, e.g. for blank lines
      if (lines.get(i).length() >= startCol) {
        builder.append(lines.get(i).substring(startCol));
      } else {
        builder.append(lines.get(i));
      }
    }
    return builder.toString();
  }

  // Wraps and re-indents line comments.
  private String indentLineComments(List<String> lines, int column0) {
    lines = wrapLineComments(lines, column0);
    StringBuilder builder = new StringBuilder();
    builder.append(lines.get(0).trim());
    String indentString = Strings.repeat(" ", column0);
    for (int i = 1; i < lines.size(); ++i) {
      builder.append(lineSeparator).append(indentString).append(lines.get(i).trim());
    }
    return builder.toString();
  }

  // Preserve special `//noinspection` and `//$NON-NLS-x$` comments used by IDEs, which cannot
  // contain leading spaces.
  private static final Pattern LINE_COMMENT_MISSING_SPACE_PREFIX =
      Pattern.compile("^(//+)(?!noinspection|\\$NON-NLS-\\d+\\$)[^\\s/]");

  private List<String> wrapLineComments(List<String> lines, int column0) {
    List<String> result = new ArrayList<>();
    for (String line : lines) {
      // Add missing leading spaces to line comments: `//foo` -> `// foo`.
      Matcher matcher = LINE_COMMENT_MISSING_SPACE_PREFIX.matcher(line);
      if (matcher.find()) {
        int length = matcher.group(1).length();
        line = Strings.repeat("/", length) + " " + line.substring(length);
      }
      if (line.startsWith("// MOE:")) {
        // don't wrap comments for https://github.com/google/MOE
        result.add(line);
        continue;
      }
      while (line.length() + column0 > Formatter.MAX_LINE_LENGTH) {
        int idx = Formatter.MAX_LINE_LENGTH - column0;
        // only break on whitespace characters, and ignore the leading `// `
        while (idx >= 2 && !CharMatcher.whitespace().matches(line.charAt(idx))) {
          idx--;
        }
        if (idx <= 2) {
          break;
        }
        result.add(line.substring(0, idx));
        line = "//" + line.substring(idx);
      }
      result.add(line);
    }
    return result;
  }

  // Remove leading whitespace (trailing was already removed), and re-indent.
  // Add a +1 indent before '*', and add the '*' if necessary.
  private String indentJavadoc(List<String> lines, int column0) {
    StringBuilder builder = new StringBuilder();
    builder.append(lines.get(0).trim());
    int indent = column0 + 1;
    String indentString = Strings.repeat(" ", indent);
    for (int i = 1; i < lines.size(); ++i) {
      builder.append(lineSeparator).append(indentString);
      String line = lines.get(i).trim();
      if (!line.startsWith("*")) {
        builder.append("* ");
      }
      builder.append(line);
    }
    return builder.toString();
  }

  // Returns true if the comment looks like javadoc
  private static boolean javadocShaped(List<String> lines) {
    Iterator<String> it = lines.iterator();
    if (!it.hasNext()) {
      return false;
    }
    String first = it.next().trim();
    // if it's actually javadoc, we're done
    if (first.startsWith("/**")) {
      return true;
    }
    // if it's a block comment, check all trailing lines for '*'
    if (!first.startsWith("/*")) {
      return false;
    }
    while (it.hasNext()) {
      if (!it.next().trim().startsWith("*")) {
        return false;
      }
    }
    return true;
  }
}

