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diff --git a/java/com/google/gerrit/mail/ParserUtil.java b/java/com/google/gerrit/mail/ParserUtil.java
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+++ b/java/com/google/gerrit/mail/ParserUtil.java
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+// Copyright (C) 2016 The Android Open Source Project
+//
+// 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.gerrit.mail;
+
+import com.google.common.base.Splitter;
+import com.google.common.collect.Iterables;
+import com.google.gerrit.reviewdb.client.Comment;
+import java.util.List;
+import java.util.StringJoiner;
+import java.util.regex.Pattern;
+
+public class ParserUtil {
+  private static final Pattern SIMPLE_EMAIL_PATTERN =
+      Pattern.compile(
+          "[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+"
+              + "(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})");
+
+  private ParserUtil() {}
+
+  /**
+   * Trims the quotation that email clients add Example: On Sun, Nov 20, 2016 at 10:33 PM,
+   * <gerrit@gerritcodereview.com> wrote:
+   *
+   * @param comment Comment parsed from an email.
+   * @return Trimmed comment.
+   */
+  public static String trimQuotation(String comment) {
+    StringJoiner j = new StringJoiner("\n");
+    List<String> lines = Splitter.on('\n').splitToList(comment);
+    for (int i = 0; i < lines.size() - 2; i++) {
+      j.add(lines.get(i));
+    }
+
+    // Check if the last line contains the full quotation pattern (date + email)
+    String lastLine = lines.get(lines.size() - 1);
+    if (containsQuotationPattern(lastLine)) {
+      if (lines.size() > 1) {
+        j.add(lines.get(lines.size() - 2));
+      }
+      return j.toString().trim();
+    }
+
+    // Check if the second last line + the last line contain the full quotation pattern. This is
+    // necessary, as the quotation line can be split across the last two lines if it gets too long.
+    if (lines.size() > 1) {
+      String lastLines = lines.get(lines.size() - 2) + lastLine;
+      if (containsQuotationPattern(lastLines)) {
+        return j.toString().trim();
+      }
+    }
+
+    // Add the last two lines
+    if (lines.size() > 1) {
+      j.add(lines.get(lines.size() - 2));
+    }
+    j.add(lines.get(lines.size() - 1));
+
+    return j.toString().trim();
+  }
+
+  /** Check if string is an inline comment url on a patch set or the base */
+  public static boolean isCommentUrl(String str, String changeUrl, Comment comment) {
+    int lineNbr = comment.range == null ? comment.lineNbr : comment.range.startLine;
+    return str.equals(filePath(changeUrl, comment) + "@" + lineNbr)
+        || str.equals(filePath(changeUrl, comment) + "@a" + lineNbr);
+  }
+
+  /** Generate the fully qualified filepath */
+  public static String filePath(String changeUrl, Comment comment) {
+    return changeUrl + "/" + comment.key.patchSetId + "/" + comment.key.filename;
+  }
+
+  /**
+   * When parsing mail content, we need to append comments prematurely since we are parsing
+   * block-by-block and never know what comes next. This can result in a comment being parsed as two
+   * comments when it spans multiple blocks. This method takes care of merging those blocks or
+   * adding a new comment to the list of appropriate.
+   */
+  public static void appendOrAddNewComment(MailComment comment, List<MailComment> comments) {
+    if (comments.isEmpty()) {
+      comments.add(comment);
+      return;
+    }
+    MailComment lastComment = Iterables.getLast(comments);
+
+    if (comment.isSameCommentPath(lastComment)) {
+      // Merge the two comments. Links should just be appended, while regular text that came from
+      // different <div> elements should be separated by a paragraph.
+      lastComment.message += (comment.isLink ? " " : "\n\n") + comment.message;
+      return;
+    }
+
+    comments.add(comment);
+  }
+
+  private static boolean containsQuotationPattern(String s) {
+    // Identifying the quotation line is hard, as it can be in any language.
+    // We identify this line by it's characteristics: It usually contains a
+    // valid email address, some digits for the date in groups of 1-4 in a row
+    // as well as some characters.
+
+    // Count occurrences of digit groups
+    int numConsecutiveDigits = 0;
+    int maxConsecutiveDigits = 0;
+    int numDigitGroups = 0;
+    for (char c : s.toCharArray()) {
+      if (c >= '0' && c <= '9') {
+        numConsecutiveDigits++;
+      } else if (numConsecutiveDigits > 0) {
+        maxConsecutiveDigits = Integer.max(maxConsecutiveDigits, numConsecutiveDigits);
+        numConsecutiveDigits = 0;
+        numDigitGroups++;
+      }
+    }
+    if (numDigitGroups < 4 || maxConsecutiveDigits > 4) {
+      return false;
+    }
+
+    // Check if the string contains an email address
+    return SIMPLE_EMAIL_PATTERN.matcher(s).find();
+  }
+}