////////////////////////////////////////////////////////////////////////////////
   // checkstyle: Checks Java source code for adherence to a set of rules.
   // Copyright (C) 2001-2019 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.naming;
  
  import java.util.regex.Pattern;
  
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
  
  /**
   * <p>
   * Checks that local, non-{@code final} variable names conform to a format specified
   * by the format property. A catch parameter is considered to be
   * a local variable.
   * </p>
   * <ul>
   * <li>
   * Property {@code format} - Specifies valid identifiers. Default value is
   * {@code "^[a-z][a-zA-Z0-9]*$"}.
   * </li>
   * <li>
   * Property {@code allowOneCharVarInForLoop} - Allow one character variable name in
   * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">initialization expressions</a>
   * in FOR loop. For example:
   * <pre>
   * for (int i = 1; i &lt; 10; i++) {}
   * </pre>
   * Default value is {@code false}.
   * </li>
   * </ul>
   * <p>
   * An example of how to configure the check is:
   * </p>
   * <pre>
   * &lt;module name="LocalVariableName"/&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   void MyMethod() {
   *     for (int var = 1; var &lt; 10; var++) {} // OK
   *     for (int VAR = 1; VAR &lt; 10; VAR++) {} // violation, name 'VAR' must match
   *                                           // pattern '^[a-z][a-zA-Z0-9]*$'
   *     for (int i = 1; i &lt; 10; i++) {} // OK
   *     for (int var_1 = 0; var_1 &lt; 10; var_1++) {} // violation, name 'var_1' must match
   *                                                    // pattern '^[a-z][a-zA-Z0-9]*$'
   *   }
   * }
   * </pre>
   * <p>
   * An example of how to configure the check for names that begin with a lower
   * case letter, followed by letters, digits, and underscores is:
   * </p>
   * <pre>
   * &lt;module name="LocalVariableName"&gt;
   *   &lt;property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Code Example:</p>
   * <pre>
   * class MyClass {
   *   void MyMethod() {
   *     for (int var = 1; var &lt; 10; var++) {} // OK
   *     for (int VAR = 1; VAR &lt; 10; VAR++) {} // violation, name 'VAR' must match
   *                                              // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
   *     for (int i = 1; i &lt; 10; i++) {} // OK
   *     for (int var_1 = 0; var_1 &lt; 10; var_1++) {} // OK
   *   }
   * }
   * </pre>
   * <p>
   * An example of one character variable name in
   * initialization expression(like "i") in FOR loop:
   * </p>
   * <pre>
   * for(int i = 1; i &lt; 10; i++) {}
   * </pre>
   * <p>
   * An example of how to configure the check to allow one character variable name in
   * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
   * initialization expressions</a> in FOR loop:
  * </p>
  * <pre>
  * &lt;module name="LocalVariableName"&gt;
  *   &lt;property name="allowOneCharVarInForLoop" value="true"/&gt;
  * &lt;/module&gt;
  * </pre>
  *
  * @since 3.0
  */
 public class LocalVariableNameCheck
     extends AbstractNameCheck {
 
     /** Regexp for one-char loop variables. */
     private static final Pattern SINGLE_CHAR = Pattern.compile("^[a-z]$");
 
     /**
      * Allow one character variable name in
      * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">initialization expressions</a>
      * in FOR loop. For example:
      * <pre>
      * for (int i = 1; i &lt; 10; i++) {}
      * </pre>
      */
     private boolean allowOneCharVarInForLoop;
 
     /** Creates a new {@code LocalVariableNameCheck} instance. */
     public LocalVariableNameCheck() {
         super("^[a-z][a-zA-Z0-9]*$");
     }
 
     /**
      * Setter to allow one character variable name in
      * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">initialization expressions</a>
      * in FOR loop. For example:
      * <pre>
      * for (int i = 1; i &lt; 10; i++) {}
      * </pre>
      *
      * @param allow Flag for allowing or not one character name in FOR loop.
      */
     public final void setAllowOneCharVarInForLoop(boolean allow) {
         allowOneCharVarInForLoop = allow;
     }
 
     @Override
     public int[] getDefaultTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public int[] getAcceptableTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public int[] getRequiredTokens() {
         return new int[] {
             TokenTypes.VARIABLE_DEF,
         };
     }
 
     @Override
     protected final boolean mustCheckName(DetailAST ast) {
         final boolean result;
         if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
             final String variableName = ast.findFirstToken(TokenTypes.IDENT).getText();
             result = !SINGLE_CHAR.matcher(variableName).find();
         }
         else {
             final DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
             final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
             result = !isFinal && ScopeUtil.isLocalVariableDef(ast);
         }
         return result;
     }
 
     /**
      * Checks if a variable is the loop's one.
      * @param variableDef variable definition.
      * @return true if a variable is the loop's one.
      */
     private static boolean isForLoopVariable(DetailAST variableDef) {
         final int parentType = variableDef.getParent().getType();
         return parentType == TokenTypes.FOR_INIT
                 || parentType == TokenTypes.FOR_EACH_CLAUSE;
     }
 
 }