///////////////////////////////////////////////////////////////////////////////////////////////
   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
   // Copyright (C) 2001-2024 the original author or authors.
   //
   // This library is free software; you can redistribute it and/or
   // modify it under the terms of the GNU Lesser General Public
   // License as published by the Free Software Foundation; either
   // version 2.1 of the License, or (at your option) any later version.
   //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ///////////////////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle.checks.javadoc;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  import java.util.ListIterator;
  import java.util.Set;
  import java.util.regex.MatchResult;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.FileContents;
  import com.puppycrawl.tools.checkstyle.api.FullIdent;
  import com.puppycrawl.tools.checkstyle.api.TextBlock;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.checks.naming.AccessModifierOption;
  import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
  import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  import com.puppycrawl.tools.checkstyle.utils.UnmodifiableCollectionUtil;
  
  /**
   * <div>
   * Checks the Javadoc of a method or constructor.
   * </div>
   *
   * <p>
   * Violates parameters and type parameters for which no param tags are present can
   * be suppressed by defining property {@code allowMissingParamTags}.
   * </p>
   *
   * <p>
   * Violates methods which return non-void but for which no return tag is present can
   * be suppressed by defining property {@code allowMissingReturnTag}.
   * </p>
   *
   * <p>
   * Violates exceptions which are declared to be thrown (by {@code throws} in the method
   * signature or by {@code throw new} in the method body), but for which no throws tag is
   * present by activation of property {@code validateThrows}.
   * Note that {@code throw new} is not checked in the following places:
   * </p>
   * <ul>
   * <li>
   * Inside a try block (with catch). It is not possible to determine if the thrown
   * exception can be caught by the catch block as there is no knowledge of the
   * inheritance hierarchy, so the try block is ignored entirely. However, catch
   * and finally blocks, as well as try blocks without catch, are still checked.
   * </li>
   * <li>
   * Local classes, anonymous classes and lambda expressions. It is not known when the
   * throw statements inside such classes are going to be evaluated, so they are ignored.
   * </li>
   * </ul>
   *
   * <p>
   * ATTENTION: Checkstyle does not have information about hierarchy of exception types
   * so usage of base class is considered as separate exception type.
   * As workaround, you need to specify both types in javadoc (parent and exact type).
   * </p>
   *
   * <p>
   * Javadoc is not required on a method that is tagged with the {@code @Override}
   * annotation. However, under Java 5 it is not possible to mark a method required
   * for an interface (this was <i>corrected</i> under Java 6). Hence, Checkstyle
   * supports using the convention of using a single {@code {@inheritDoc}} tag
   * instead of all the other tags.
   * </p>
   *
   * <p>
   * Note that only inheritable items will allow the {@code {@inheritDoc}}
   * tag to be used in place of comments. Static methods at all visibilities,
   * private non-static methods and constructors are not inheritable.
   * </p>
   *
  * <p>
  * For example, if the following method is implementing a method required by
  * an interface, then the Javadoc could be done as:
  * </p>
  * <pre>
  * &#47;** {&#64;inheritDoc} *&#47;
  * public int checkReturnTag(final int aTagIndex,
  *                           JavadocTag[] aTags,
  *                           int aLineNo)
  * </pre>
  * <ul>
  * <li>
  * Property {@code accessModifiers} - Specify the access modifiers where Javadoc comments are
  * checked.
  * Type is {@code com.puppycrawl.tools.checkstyle.checks.naming.AccessModifierOption[]}.
  * Default value is {@code public, protected, package, private}.
  * </li>
  * <li>
  * Property {@code allowMissingParamTags} - Control whether to ignore violations
  * when a method has parameters but does not have matching {@code param} tags in the javadoc.
  * Type is {@code boolean}.
  * Default value is {@code false}.
  * </li>
  * <li>
  * Property {@code allowMissingReturnTag} - Control whether to ignore violations
  * when a method returns non-void type and does not have a {@code return} tag in the javadoc.
  * Type is {@code boolean}.
  * Default value is {@code false}.
  * </li>
  * <li>
  * Property {@code allowedAnnotations} - Specify annotations that allow missed documentation.
  * Type is {@code java.lang.String[]}.
  * Default value is {@code Override}.
  * </li>
  * <li>
  * Property {@code validateThrows} - Control whether to validate {@code throws} tags.
  * Type is {@code boolean}.
  * Default value is {@code false}.
  * </li>
  * <li>
  * Property {@code tokens} - tokens to check
  * Type is {@code java.lang.String[]}.
  * Validation type is {@code tokenSet}.
  * Default value is:
  * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#METHOD_DEF">
  * METHOD_DEF</a>,
  * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#CTOR_DEF">
  * CTOR_DEF</a>,
  * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ANNOTATION_FIELD_DEF">
  * ANNOTATION_FIELD_DEF</a>,
  * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#COMPACT_CTOR_DEF">
  * COMPACT_CTOR_DEF</a>.
  * </li>
  * </ul>
  *
  * <p>
  * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
  * </p>
  *
  * <p>
  * Violation Message Keys:
  * </p>
  * <ul>
  * <li>
  * {@code javadoc.classInfo}
  * </li>
  * <li>
  * {@code javadoc.duplicateTag}
  * </li>
  * <li>
  * {@code javadoc.expectedTag}
  * </li>
  * <li>
  * {@code javadoc.invalidInheritDoc}
  * </li>
  * <li>
  * {@code javadoc.return.expected}
  * </li>
  * <li>
  * {@code javadoc.unusedTag}
  * </li>
  * <li>
  * {@code javadoc.unusedTagGeneral}
  * </li>
  * </ul>
  *
  * @since 3.0
  */
 @StatelessCheck
 public class JavadocMethodCheck extends AbstractCheck {
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_CLASS_INFO = "javadoc.classInfo";
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_UNUSED_TAG_GENERAL = "javadoc.unusedTagGeneral";
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_INVALID_INHERIT_DOC = "javadoc.invalidInheritDoc";
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_UNUSED_TAG = "javadoc.unusedTag";
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_EXPECTED_TAG = "javadoc.expectedTag";
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_RETURN_EXPECTED = "javadoc.return.expected";
 
     /**
      * A key is pointing to the warning message text in "messages.properties"
      * file.
      */
     public static final String MSG_DUPLICATE_TAG = "javadoc.duplicateTag";
 
     /** Html element start symbol. */
     private static final String ELEMENT_START = "<";
 
     /** Html element end symbol. */
     private static final String ELEMENT_END = ">";
 
     /** Compiled regexp to match Javadoc tags that take an argument. */
     private static final Pattern MATCH_JAVADOC_ARG = CommonUtil.createPattern(
             "^\\s*(?>\\*|\\/\\*\\*)?\\s*@(throws|exception|param)\\s+(\\S+)\\s+\\S*");
     /** Compiled regexp to match Javadoc tags with argument but with missing description. */
     private static final Pattern MATCH_JAVADOC_ARG_MISSING_DESCRIPTION =
         CommonUtil.createPattern("^\\s*(?>\\*|\\/\\*\\*)?\\s*@(throws|exception|param)\\s+"
             + "(\\S[^*]*)(?:(\\s+|\\*\\/))?");
 
     /** Compiled regexp to look for a continuation of the comment. */
     private static final Pattern MATCH_JAVADOC_MULTILINE_CONT =
             CommonUtil.createPattern("(\\*\\/|@|[^\\s\\*])");
 
     /** Multiline finished at end of comment. */
     private static final String END_JAVADOC = "*/";
     /** Multiline finished at next Javadoc. */
     private static final String NEXT_TAG = "@";
 
     /** Compiled regexp to match Javadoc tags with no argument. */
     private static final Pattern MATCH_JAVADOC_NOARG =
             CommonUtil.createPattern("^\\s*(?>\\*|\\/\\*\\*)?\\s*@(return|see)\\s+\\S");
     /** Compiled regexp to match first part of multilineJavadoc tags. */
     private static final Pattern MATCH_JAVADOC_NOARG_MULTILINE_START =
             CommonUtil.createPattern("^\\s*(?>\\*|\\/\\*\\*)?\\s*@(return|see)\\s*$");
     /** Compiled regexp to match Javadoc tags with no argument and {}. */
     private static final Pattern MATCH_JAVADOC_NOARG_CURLY =
             CommonUtil.createPattern("\\{\\s*@(inheritDoc)\\s*\\}");
 
     /** Specify the access modifiers where Javadoc comments are checked. */
     private AccessModifierOption[] accessModifiers = {
         AccessModifierOption.PUBLIC,
         AccessModifierOption.PROTECTED,
         AccessModifierOption.PACKAGE,
         AccessModifierOption.PRIVATE,
     };
 
     /**
      * Control whether to validate {@code throws} tags.
      */
     private boolean validateThrows;
 
     /**
      * Control whether to ignore violations when a method has parameters but does
      * not have matching {@code param} tags in the javadoc.
      */
     private boolean allowMissingParamTags;
 
     /**
      * Control whether to ignore violations when a method returns non-void type
      * and does not have a {@code return} tag in the javadoc.
      */
     private boolean allowMissingReturnTag;
 
     /** Specify annotations that allow missed documentation. */
     private Set<String> allowedAnnotations = Set.of("Override");
 
     /**
      * Setter to control whether to validate {@code throws} tags.
      *
      * @param value user's value.
      * @since 6.0
      */
     public void setValidateThrows(boolean value) {
         validateThrows = value;
     }
 
     /**
      * Setter to specify annotations that allow missed documentation.
      *
      * @param userAnnotations user's value.
      * @since 6.0
      */
     public void setAllowedAnnotations(String... userAnnotations) {
         allowedAnnotations = Set.of(userAnnotations);
     }
 
     /**
      * Setter to specify the access modifiers where Javadoc comments are checked.
      *
      * @param accessModifiers access modifiers.
      * @since 8.42
      */
     public void setAccessModifiers(AccessModifierOption... accessModifiers) {
         this.accessModifiers =
             UnmodifiableCollectionUtil.copyOfArray(accessModifiers, accessModifiers.length);
     }
 
     /**
      * Setter to control whether to ignore violations when a method has parameters
      * but does not have matching {@code param} tags in the javadoc.
      *
      * @param flag a {@code Boolean} value
      * @since 3.1
      */
     public void setAllowMissingParamTags(boolean flag) {
         allowMissingParamTags = flag;
     }
 
     /**
      * Setter to control whether to ignore violations when a method returns non-void type
      * and does not have a {@code return} tag in the javadoc.
      *
      * @param flag a {@code Boolean} value
      * @since 3.1
      */
     public void setAllowMissingReturnTag(boolean flag) {
         allowMissingReturnTag = flag;
     }
 
     @Override
     public final int[] getRequiredTokens() {
         return CommonUtil.EMPTY_INT_ARRAY;
     }
 
     @Override
     public int[] getDefaultTokens() {
         return getAcceptableTokens();
     }
 
     @Override
     public int[] getAcceptableTokens() {
         return new int[] {
             TokenTypes.METHOD_DEF,
             TokenTypes.CTOR_DEF,
             TokenTypes.ANNOTATION_FIELD_DEF,
             TokenTypes.COMPACT_CTOR_DEF,
         };
     }
 
     @Override
     public final void visitToken(DetailAST ast) {
         processAST(ast);
     }
 
     /**
      * Called to process an AST when visiting it.
      *
      * @param ast the AST to process. Guaranteed to not be PACKAGE_DEF or
      *             IMPORT tokens.
      */
     // suppress deprecation until https://github.com/checkstyle/checkstyle/issues/11166
     @SuppressWarnings("deprecation")
     private void processAST(DetailAST ast) {
         if (shouldCheck(ast)) {
             final FileContents contents = getFileContents();
             final TextBlock textBlock = contents.getJavadocBefore(ast.getLineNo());
 
             if (textBlock != null) {
                 checkComment(ast, textBlock);
             }
         }
     }
 
     /**
      * Whether we should check this node.
      *
      * @param ast a given node.
      * @return whether we should check a given node.
      */
     private boolean shouldCheck(final DetailAST ast) {
         final AccessModifierOption surroundingAccessModifier = CheckUtil
                 .getSurroundingAccessModifier(ast);
         final AccessModifierOption accessModifier = CheckUtil
                 .getAccessModifierFromModifiersToken(ast);
         return surroundingAccessModifier != null
                 && Arrays.stream(accessModifiers)
                         .anyMatch(modifier -> modifier == surroundingAccessModifier)
                 && Arrays.stream(accessModifiers).anyMatch(modifier -> modifier == accessModifier);
     }
 
     /**
      * Checks the Javadoc for a method.
      *
      * @param ast the token for the method
      * @param comment the Javadoc comment
      */
     private void checkComment(DetailAST ast, TextBlock comment) {
         final List<JavadocTag> tags = getMethodTags(comment);
 
         if (!hasShortCircuitTag(ast, tags)) {
             if (ast.getType() == TokenTypes.ANNOTATION_FIELD_DEF) {
                 checkReturnTag(tags, ast.getLineNo(), true);
             }
             else {
                 final Iterator<JavadocTag> it = tags.iterator();
                 // Check for inheritDoc
                 boolean hasInheritDocTag = false;
                 while (!hasInheritDocTag && it.hasNext()) {
                     hasInheritDocTag = it.next().isInheritDocTag();
                 }
                 final boolean reportExpectedTags = !hasInheritDocTag
                     && !AnnotationUtil.containsAnnotation(ast, allowedAnnotations);
 
                 // COMPACT_CTOR_DEF has no parameters
                 if (ast.getType() != TokenTypes.COMPACT_CTOR_DEF) {
                     checkParamTags(tags, ast, reportExpectedTags);
                 }
                 final List<ExceptionInfo> throwed =
                     combineExceptionInfo(getThrows(ast), getThrowed(ast));
                 checkThrowsTags(tags, throwed, reportExpectedTags);
                 if (CheckUtil.isNonVoidMethod(ast)) {
                     checkReturnTag(tags, ast.getLineNo(), reportExpectedTags);
                 }
 
             }
 
             // Dump out all unused tags
             tags.stream().filter(javadocTag -> !javadocTag.isSeeOrInheritDocTag())
                 .forEach(javadocTag -> log(javadocTag.getLineNo(), MSG_UNUSED_TAG_GENERAL));
         }
     }
 
     /**
      * Validates whether the Javadoc has a short circuit tag. Currently, this is
      * the inheritTag. Any violations are logged.
      *
      * @param ast the construct being checked
      * @param tags the list of Javadoc tags associated with the construct
      * @return true if the construct has a short circuit tag.
      */
     private boolean hasShortCircuitTag(final DetailAST ast, final List<JavadocTag> tags) {
         boolean result = true;
         // Check if it contains {@inheritDoc} tag
         if (tags.size() == 1
                 && tags.get(0).isInheritDocTag()) {
             // Invalid if private, a constructor, or a static method
             if (!JavadocTagInfo.INHERIT_DOC.isValidOn(ast)) {
                 log(ast, MSG_INVALID_INHERIT_DOC);
             }
         }
         else {
             result = false;
         }
         return result;
     }
 
     /**
      * Returns the tags in a javadoc comment. Only finds throws, exception,
      * param, return and see tags.
      *
      * @param comment the Javadoc comment
      * @return the tags found
      */
     private static List<JavadocTag> getMethodTags(TextBlock comment) {
         final String[] lines = comment.getText();
         final List<JavadocTag> tags = new ArrayList<>();
         int currentLine = comment.getStartLineNo() - 1;
         final int startColumnNumber = comment.getStartColNo();
 
         for (int i = 0; i < lines.length; i++) {
             currentLine++;
             final Matcher javadocArgMatcher =
                 MATCH_JAVADOC_ARG.matcher(lines[i]);
             final Matcher javadocArgMissingDescriptionMatcher =
                 MATCH_JAVADOC_ARG_MISSING_DESCRIPTION.matcher(lines[i]);
             final Matcher javadocNoargMatcher =
                 MATCH_JAVADOC_NOARG.matcher(lines[i]);
             final Matcher noargCurlyMatcher =
                 MATCH_JAVADOC_NOARG_CURLY.matcher(lines[i]);
             final Matcher noargMultilineStart =
                 MATCH_JAVADOC_NOARG_MULTILINE_START.matcher(lines[i]);
 
             if (javadocArgMatcher.find()) {
                 final int col = calculateTagColumn(javadocArgMatcher, i, startColumnNumber);
                 tags.add(new JavadocTag(currentLine, col, javadocArgMatcher.group(1),
                         javadocArgMatcher.group(2)));
             }
             else if (javadocArgMissingDescriptionMatcher.find()) {
                 final int col = calculateTagColumn(javadocArgMissingDescriptionMatcher, i,
                     startColumnNumber);
                 tags.add(new JavadocTag(currentLine, col,
                     javadocArgMissingDescriptionMatcher.group(1),
                     javadocArgMissingDescriptionMatcher.group(2)));
             }
             else if (javadocNoargMatcher.find()) {
                 final int col = calculateTagColumn(javadocNoargMatcher, i, startColumnNumber);
                 tags.add(new JavadocTag(currentLine, col, javadocNoargMatcher.group(1)));
             }
             else if (noargCurlyMatcher.find()) {
                 tags.add(new JavadocTag(currentLine, 0, noargCurlyMatcher.group(1)));
             }
             else if (noargMultilineStart.find()) {
                 tags.addAll(getMultilineNoArgTags(noargMultilineStart, lines, i, currentLine));
             }
         }
         return tags;
     }
 
     /**
      * Calculates column number using Javadoc tag matcher.
      *
      * @param javadocTagMatchResult found javadoc tag match result
      * @param lineNumber line number of Javadoc tag in comment
      * @param startColumnNumber column number of Javadoc comment beginning
      * @return column number
      */
     private static int calculateTagColumn(MatchResult javadocTagMatchResult,
             int lineNumber, int startColumnNumber) {
         int col = javadocTagMatchResult.start(1) - 1;
         if (lineNumber == 0) {
             col += startColumnNumber;
         }
         return col;
     }
 
     /**
      * Gets multiline Javadoc tags with no arguments.
      *
      * @param noargMultilineStart javadoc tag Matcher
      * @param lines comment text lines
      * @param lineIndex line number that contains the javadoc tag
      * @param tagLine javadoc tag line number in file
      * @return javadoc tags with no arguments
      */
     private static List<JavadocTag> getMultilineNoArgTags(final Matcher noargMultilineStart,
             final String[] lines, final int lineIndex, final int tagLine) {
         int remIndex = lineIndex;
         Matcher multilineCont;
 
         do {
             remIndex++;
             multilineCont = MATCH_JAVADOC_MULTILINE_CONT.matcher(lines[remIndex]);
         } while (!multilineCont.find());
 
         final List<JavadocTag> tags = new ArrayList<>();
         final String lFin = multilineCont.group(1);
         if (!NEXT_TAG.equals(lFin)
             && !END_JAVADOC.equals(lFin)) {
             final String param1 = noargMultilineStart.group(1);
             final int col = noargMultilineStart.start(1) - 1;
 
             tags.add(new JavadocTag(tagLine, col, param1));
         }
 
         return tags;
     }
 
     /**
      * Computes the parameter nodes for a method.
      *
      * @param ast the method node.
      * @return the list of parameter nodes for ast.
      */
     private static List<DetailAST> getParameters(DetailAST ast) {
         final DetailAST params = ast.findFirstToken(TokenTypes.PARAMETERS);
         final List<DetailAST> returnValue = new ArrayList<>();
 
         DetailAST child = params.getFirstChild();
         while (child != null) {
             final DetailAST ident = child.findFirstToken(TokenTypes.IDENT);
             if (ident != null) {
                 returnValue.add(ident);
             }
             child = child.getNextSibling();
         }
         return returnValue;
     }
 
     /**
      * Computes the exception nodes for a method.
      *
      * @param ast the method node.
      * @return the list of exception nodes for ast.
      */
     private static List<ExceptionInfo> getThrows(DetailAST ast) {
         final List<ExceptionInfo> returnValue = new ArrayList<>();
         final DetailAST throwsAST = ast
                 .findFirstToken(TokenTypes.LITERAL_THROWS);
         if (throwsAST != null) {
             DetailAST child = throwsAST.getFirstChild();
             while (child != null) {
                 if (child.getType() == TokenTypes.IDENT
                         || child.getType() == TokenTypes.DOT) {
                     returnValue.add(getExceptionInfo(child));
                 }
                 child = child.getNextSibling();
             }
         }
         return returnValue;
     }
 
     /**
      * Get ExceptionInfo for all exceptions that throws in method code by 'throw new'.
      *
      * @param methodAst method DetailAST object where to find exceptions
      * @return list of ExceptionInfo
      */
     private static List<ExceptionInfo> getThrowed(DetailAST methodAst) {
         final List<ExceptionInfo> returnValue = new ArrayList<>();
         final DetailAST blockAst = methodAst.findFirstToken(TokenTypes.SLIST);
         if (blockAst != null) {
             final List<DetailAST> throwLiterals = findTokensInAstByType(blockAst,
                     TokenTypes.LITERAL_THROW);
             for (DetailAST throwAst : throwLiterals) {
                 if (!isInIgnoreBlock(blockAst, throwAst)) {
                     final DetailAST newAst = throwAst.getFirstChild().getFirstChild();
                     if (newAst.getType() == TokenTypes.LITERAL_NEW) {
                         final DetailAST child = newAst.getFirstChild();
                         returnValue.add(getExceptionInfo(child));
                     }
                 }
             }
         }
         return returnValue;
     }
 
     /**
      * Get ExceptionInfo instance.
      *
      * @param ast DetailAST object where to find exceptions node;
      * @return ExceptionInfo
      */
     private static ExceptionInfo getExceptionInfo(DetailAST ast) {
         final FullIdent ident = FullIdent.createFullIdent(ast);
         final DetailAST firstClassNameNode = getFirstClassNameNode(ast);
         return new ExceptionInfo(firstClassNameNode,
                 new ClassInfo(new Token(ident)));
     }
 
     /**
      * Get node where class name of exception starts.
      *
      * @param ast DetailAST object where to find exceptions node;
      * @return exception node where class name starts
      */
     private static DetailAST getFirstClassNameNode(DetailAST ast) {
         DetailAST startNode = ast;
         while (startNode.getType() == TokenTypes.DOT) {
             startNode = startNode.getFirstChild();
         }
         return startNode;
     }
 
     /**
      * Checks if a 'throw' usage is contained within a block that should be ignored.
      * Such blocks consist of try (with catch) blocks, local classes, anonymous classes,
      * and lambda expressions. Note that a try block without catch is not considered.
      *
      * @param methodBodyAst DetailAST node representing the method body
      * @param throwAst DetailAST node representing the 'throw' literal
      * @return true if throwAst is inside a block that should be ignored
      */
     private static boolean isInIgnoreBlock(DetailAST methodBodyAst, DetailAST throwAst) {
         DetailAST ancestor = throwAst;
         while (ancestor != methodBodyAst) {
             if (ancestor.getType() == TokenTypes.LAMBDA
                     || ancestor.getType() == TokenTypes.OBJBLOCK
                     || ancestor.findFirstToken(TokenTypes.LITERAL_CATCH) != null) {
                 // throw is inside a lambda expression/anonymous class/local class,
                 // or throw is inside a try block, and there is a catch block
                 break;
             }
             if (ancestor.getType() == TokenTypes.LITERAL_CATCH
                     || ancestor.getType() == TokenTypes.LITERAL_FINALLY) {
                 // if the throw is inside a catch or finally block,
                 // skip the immediate ancestor (try token)
                 ancestor = ancestor.getParent();
             }
             ancestor = ancestor.getParent();
         }
         return ancestor != methodBodyAst;
     }
 
     /**
      * Combine ExceptionInfo collections together by matching names.
      *
      * @param first the first collection of ExceptionInfo
      * @param second the second collection of ExceptionInfo
      * @return combined list of ExceptionInfo
      */
     private static List<ExceptionInfo> combineExceptionInfo(Collection<ExceptionInfo> first,
                                                             Iterable<ExceptionInfo> second) {
         final List<ExceptionInfo> result = new ArrayList<>(first);
         for (ExceptionInfo exceptionInfo : second) {
             if (result.stream().noneMatch(item -> isExceptionInfoSame(item, exceptionInfo))) {
                 result.add(exceptionInfo);
             }
         }
         return result;
     }
 
     /**
      * Finds node of specified type among root children, siblings, siblings children
      * on any deep level.
      *
      * @param root    DetailAST
      * @param astType value of TokenType
      * @return {@link List} of {@link DetailAST} nodes which matches the predicate.
      */
     public static List<DetailAST> findTokensInAstByType(DetailAST root, int astType) {
         final List<DetailAST> result = new ArrayList<>();
         // iterative preorder depth-first search
         DetailAST curNode = root;
         do {
             // process curNode
             if (curNode.getType() == astType) {
                 result.add(curNode);
             }
             // process children (if any)
             if (curNode.hasChildren()) {
                 curNode = curNode.getFirstChild();
                 continue;
             }
             // backtrack to parent if last child, stopping at root
             while (curNode != root && curNode.getNextSibling() == null) {
                 curNode = curNode.getParent();
             }
             // explore siblings if not root
             if (curNode != root) {
                 curNode = curNode.getNextSibling();
             }
         } while (curNode != root);
         return result;
     }
 
     /**
      * Checks a set of tags for matching parameters.
      *
      * @param tags the tags to check
      * @param parent the node which takes the parameters
      * @param reportExpectedTags whether we should report if do not find
      *            expected tag
      */
     private void checkParamTags(final List<JavadocTag> tags,
             final DetailAST parent, boolean reportExpectedTags) {
         final List<DetailAST> params = getParameters(parent);
         final List<DetailAST> typeParams = CheckUtil
                 .getTypeParameters(parent);
 
         // Loop over the tags, checking to see they exist in the params.
         final ListIterator<JavadocTag> tagIt = tags.listIterator();
         while (tagIt.hasNext()) {
             final JavadocTag tag = tagIt.next();
 
             if (!tag.isParamTag()) {
                 continue;
             }
 
             tagIt.remove();
 
             final String arg1 = tag.getFirstArg();
             boolean found = removeMatchingParam(params, arg1);
 
             if (arg1.startsWith(ELEMENT_START) && arg1.endsWith(ELEMENT_END)) {
                 found = searchMatchingTypeParameter(typeParams,
                         arg1.substring(1, arg1.length() - 1));
             }
 
             // Handle extra JavadocTag
             if (!found) {
                 log(tag.getLineNo(), tag.getColumnNo(), MSG_UNUSED_TAG,
                         "@param", arg1);
             }
         }
 
         // Now dump out all type parameters/parameters without tags :- unless
         // the user has chosen to suppress these problems
         if (!allowMissingParamTags && reportExpectedTags) {
             for (DetailAST param : params) {
                 log(param, MSG_EXPECTED_TAG,
                     JavadocTagInfo.PARAM.getText(), param.getText());
             }
 
             for (DetailAST typeParam : typeParams) {
                 log(typeParam, MSG_EXPECTED_TAG,
                     JavadocTagInfo.PARAM.getText(),
                     ELEMENT_START + typeParam.findFirstToken(TokenTypes.IDENT).getText()
                     + ELEMENT_END);
             }
         }
     }
 
     /**
      * Returns true if required type found in type parameters.
      *
      * @param typeParams
      *            collection of type parameters
      * @param requiredTypeName
      *            name of required type
      * @return true if required type found in type parameters.
      */
     private static boolean searchMatchingTypeParameter(Iterable<DetailAST> typeParams,
             String requiredTypeName) {
         // Loop looking for matching type param
         final Iterator<DetailAST> typeParamsIt = typeParams.iterator();
         boolean found = false;
         while (typeParamsIt.hasNext()) {
             final DetailAST typeParam = typeParamsIt.next();
             if (typeParam.findFirstToken(TokenTypes.IDENT).getText()
                     .equals(requiredTypeName)) {
                 found = true;
                 typeParamsIt.remove();
                 break;
             }
         }
         return found;
     }
 
     /**
      * Remove parameter from params collection by name.
      *
      * @param params collection of DetailAST parameters
      * @param paramName name of parameter
      * @return true if parameter found and removed
      */
     private static boolean removeMatchingParam(Iterable<DetailAST> params, String paramName) {
         boolean found = false;
         final Iterator<DetailAST> paramIt = params.iterator();
         while (paramIt.hasNext()) {
             final DetailAST param = paramIt.next();
             if (param.getText().equals(paramName)) {
                 found = true;
                 paramIt.remove();
                 break;
             }
         }
         return found;
     }
 
     /**
      * Checks for only one return tag. All return tags will be removed from the
      * supplied list.
      *
      * @param tags the tags to check
      * @param lineNo the line number of the expected tag
      * @param reportExpectedTags whether we should report if do not find
      *            expected tag
      */
     private void checkReturnTag(List<JavadocTag> tags, int lineNo,
         boolean reportExpectedTags) {
         // Loop over tags finding return tags. After the first one, report a
         // violation.
         boolean found = false;
         final ListIterator<JavadocTag> it = tags.listIterator();
         while (it.hasNext()) {
             final JavadocTag javadocTag = it.next();
             if (javadocTag.isReturnTag()) {
                 if (found) {
                     log(javadocTag.getLineNo(), javadocTag.getColumnNo(),
                             MSG_DUPLICATE_TAG,
                             JavadocTagInfo.RETURN.getText());
                 }
                 found = true;
                 it.remove();
             }
         }
 
         // Handle there being no @return tags :- unless
         // the user has chosen to suppress these problems
         if (!found && !allowMissingReturnTag && reportExpectedTags) {
             log(lineNo, MSG_RETURN_EXPECTED);
         }
     }
 
     /**
      * Checks a set of tags for matching throws.
      *
      * @param tags the tags to check
      * @param throwsList the throws to check
      * @param reportExpectedTags whether we should report if do not find
      *            expected tag
      */
     private void checkThrowsTags(List<JavadocTag> tags,
             List<ExceptionInfo> throwsList, boolean reportExpectedTags) {
         // Loop over the tags, checking to see they exist in the throws.
         final ListIterator<JavadocTag> tagIt = tags.listIterator();
         while (tagIt.hasNext()) {
             final JavadocTag tag = tagIt.next();
 
             if (!tag.isThrowsTag()) {
                 continue;
             }
             tagIt.remove();
 
             // Loop looking for matching throw
             processThrows(throwsList, tag.getFirstArg());
         }
         // Now dump out all throws without tags :- unless
         // the user has chosen to suppress these problems
         if (validateThrows && reportExpectedTags) {
             throwsList.stream().filter(exceptionInfo -> !exceptionInfo.isFound())
                 .forEach(exceptionInfo -> {
                     final Token token = exceptionInfo.getName();
                     log(exceptionInfo.getAst(),
                         MSG_EXPECTED_TAG,
                         JavadocTagInfo.THROWS.getText(), token.getText());
                 });
         }
     }
 
     /**
      * Verifies that documented exception is in throws.
      *
      * @param throwsIterable collection of throws
      * @param documentedClassName documented exception class name
      */
     private static void processThrows(Iterable<ExceptionInfo> throwsIterable,
                                       String documentedClassName) {
         for (ExceptionInfo exceptionInfo : throwsIterable) {
             if (isClassNamesSame(exceptionInfo.getName().getText(),
                     documentedClassName)) {
                 exceptionInfo.setFound();
                 break;
             }
         }
     }
 
     /**
      * Check that ExceptionInfo objects are same by name.
      *
      * @param info1 ExceptionInfo object
      * @param info2 ExceptionInfo object
      * @return true is ExceptionInfo object have the same name
      */
     private static boolean isExceptionInfoSame(ExceptionInfo info1, ExceptionInfo info2) {
         return isClassNamesSame(info1.getName().getText(),
                                     info2.getName().getText());
     }
 
     /**
      * Check that class names are same by short name of class. If some class name is fully
      * qualified it is cut to short name.
      *
      * @param class1 class name
      * @param class2 class name
      * @return true is ExceptionInfo object have the same name
      */
     private static boolean isClassNamesSame(String class1, String class2) {
         boolean result = false;
         if (class1.equals(class2)) {
             result = true;
         }
         else {
             final String separator = ".";
             if (class1.contains(separator) || class2.contains(separator)) {
                 final String class1ShortName = class1
                         .substring(class1.lastIndexOf('.') + 1);
                 final String class2ShortName = class2
                         .substring(class2.lastIndexOf('.') + 1);
                 result = class1ShortName.equals(class2ShortName);
             }
         }
         return result;
     }
 
     /**
      * Contains class's {@code Token}.
      */
     private static class ClassInfo {
 
         /** {@code FullIdent} associated with this class. */
         private final Token name;
 
         /**
          * Creates new instance of class information object.
          *
          * @param className token which represents class name.
          * @throws IllegalArgumentException when className is nulls
          */
         protected ClassInfo(final Token className) {
             name = className;
         }
 
         /**
          * Gets class name.
          *
          * @return class name
          */
         public final Token getName() {
             return name;
         }
 
     }
 
     /**
      * Represents text element with location in the text.
      */
     private static final class Token {
 
         /** Token's column number. */
         private final int columnNo;
         /** Token's line number. */
         private final int lineNo;
         /** Token's text. */
         private final String text;
 
         /**
          * Creates token.
          *
          * @param text token's text
          * @param lineNo token's line number
          * @param columnNo token's column number
          */
         private Token(String text, int lineNo, int columnNo) {
             this.text = text;
             this.lineNo = lineNo;
             this.columnNo = columnNo;
         }
 
         /**
          * Converts FullIdent to Token.
          *
          * @param fullIdent full ident to convert.
          */
         private Token(FullIdent fullIdent) {
             text = fullIdent.getText();
             lineNo = fullIdent.getLineNo();
             columnNo = fullIdent.getColumnNo();
         }
 
         /**
          * Gets text of the token.
          *
          * @return text of the token
          */
         public String getText() {
             return text;
         }
 
         @Override
         public String toString() {
             return "Token[" + text + "(" + lineNo
                 + "x" + columnNo + ")]";
         }
 
     }
 
     /** Stores useful information about declared exception. */
     private static final class ExceptionInfo {
 
         /** AST node representing this exception. */
         private final DetailAST ast;
 
         /** Class information associated with this exception. */
         private final ClassInfo classInfo;
         /** Does the exception have throws tag associated with. */
         private boolean found;
 
         /**
          * Creates new instance for {@code FullIdent}.
          *
          * @param ast AST node representing this exception
          * @param classInfo class info
          */
         private ExceptionInfo(DetailAST ast, ClassInfo classInfo) {
             this.ast = ast;
             this.classInfo = classInfo;
         }
 
         /**
          * Gets the AST node representing this exception.
          *
          * @return the AST node representing this exception
          */
         private DetailAST getAst() {
             return ast;
         }
 
         /** Mark that the exception has associated throws tag. */
         private void setFound() {
             found = true;
         }
 
         /**
          * Checks that the exception has throws tag associated with it.
          *
          * @return whether the exception has throws tag associated with
          */
         private boolean isFound() {
             return found;
         }
 
         /**
          * Gets exception name.
          *
          * @return exception's name
          */
         private Token getName() {
             return classInfo.getName();
         }
 
     }
 
 }