AvoidEscapedUnicodeCharactersCheck.java

////////////////////////////////////////////////////////////////////////////////

// checkstyle: Checks Java source code for adherence to a set of rules.

// Copyright (C) 2001-2017 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;

import java.util.List;

import java.util.Map;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import com.puppycrawl.tools.checkstyle.api.AbstractCheck;

import com.puppycrawl.tools.checkstyle.api.DetailAST;

import com.puppycrawl.tools.checkstyle.api.TextBlock;

import com.puppycrawl.tools.checkstyle.api.TokenTypes;

import com.puppycrawl.tools.checkstyle.utils.CommonUtils;

/**

 * <p>

 * Restrict using <a href =

 * "http://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.3">

 * Unicode escapes</a> (such as {@code &#92;u221e}).

 * It is possible to allow using escapes for

 * <a href="https://en.wiktionary.org/wiki/Appendix:Control_characters">

 * non-printable(control) characters</a>.

 * Also, this check can be configured to allow using escapes

 * if trail comment is present. By the option it is possible to

 * allow using escapes if literal contains only them. By the option it

 * is possible to allow using escapes for space literals.

 * </p>

 * <p>

 * Examples of using Unicode:</p>

 * <pre>

 * String unitAbbrev = "μs";      // Best: perfectly clear even without a comment.

 * String unitAbbrev = "\u03bcs"; // Poor: the reader has no idea what this is.

 * </pre>

 * <p>

 * An example of how to configure the check is:

 * </p>

 * <pre>

 * <module name="AvoidEscapedUnicodeCharacters"/>

 * </pre>

 * <p>

 * An example of non-printable(control) characters.

 * </p>

 * <pre>

 * return '\ufeff' + content; // byte order mark

 * </pre>

 * <p>

 * An example of how to configure the check to allow using escapes

 * for non-printable(control) characters:

 * </p>

 * <pre>

 * <module name="AvoidEscapedUnicodeCharacters">

 *     <property name="allowEscapesForControlCharacters" value="true"/>

 * </module>

 * </pre>

 * <p>

 * Example of using escapes with trail comment:

 * </p>

 * <pre>

 * String unitAbbrev = "\u03bcs"; // Greek letter mu, "s"

 * </pre>

 * <p>An example of how to configure the check to allow using escapes

 * if trail comment is present:

 * </p>

 * <pre>

 * <module name="AvoidEscapedUnicodeCharacters">

 *     <property name="allowByTailComment" value="true"/>

 * </module>

 * </pre>

 * <p>Example of using escapes if literal contains only them:

 * </p>

 * <pre>

 * String unitAbbrev = "\u03bc\u03bc\u03bc";

 * </pre>

 * <p>An example of how to configure the check to allow escapes

 * if literal contains only them:

 * </p>

 * <pre>

 * <module name="AvoidEscapedUnicodeCharacters">

 *    <property name="allowIfAllCharactersEscaped" value="true"/>

 * </module>

 * </pre>

 * <p>An example of how to configure the check to allow non-printable escapes:

 * </p>

 * <pre>

 * <module name="AvoidEscapedUnicodeCharacters">

 *    <property name="allowNonPrintableEscapes" value="true"/>

 * </module>

 * </pre>

 *

 * @author maxvetrenko

 *

 */

    extends AbstractCheck {

    /**

     * A key is pointing to the warning message text in "messages.properties"

     * file.

     */

    public static final String MSG_KEY = "forbid.escaped.unicode.char";

    /** Regular expression for Unicode chars. */

    /**

     * Regular expression Unicode control characters.

     *

     * @see <a href="https://en.wiktionary.org/wiki/Appendix:Control_characters">

     *     Appendix:Control characters</a>

     */

            + "(00[0-1][0-9A-Fa-f]|00[8-9][0-9A-Fa-f]|00(a|A)(d|D)|034(f|F)|070(f|F)"

            + "|180(e|E)|200[b-fB-F]|202[a-eA-E]|206[0-4a-fA-F]"

            + "|[fF]{3}[9a-bA-B]|[fF][eE][fF]{2})");

    /** Regular expression for all escaped chars. */

                    + "||\\\\b|\\\\t|\\\\n|\\\\f|\\\\r|\\\\|\"|\')+$");

    /** Regular expression for escaped backslash. */

    /** Regular expression for non-printable unicode chars. */

            + "|\\\\u2029|\\\\u205(f|F)|\\\\u3000|\\\\u2007|\\\\u2000|\\\\u200(a|A)"

            + "|\\\\u007(F|f)|\\\\u009(f|F)|\\\\u(f|F){4}|\\\\u007(F|f)|\\\\u00(a|A)(d|D)"

            + "|\\\\u0600|\\\\u061(c|C)|\\\\u06(d|D){2}|\\\\u070(f|F)|\\\\u1680|\\\\u180(e|E)"

            + "|\\\\u2000|\\\\u2028|\\\\u205(f|F)|\\\\u2066|\\\\u2067|\\\\u2068|\\\\u2069"

            + "|\\\\u206(a|A)|\\\\u(d|D)800|\\\\u(f|F)(e|E)(f|F){2}|\\\\u(f|F){3}9"

            + "|\\\\u(f|F){3}(a|A)|\\\\u0020|\\\\u00(a|A)0|\\\\u00(a|A)(d|D)|\\\\u0604"

            + "|\\\\u061(c|C)|\\\\u06(d|D){2}|\\\\u070(f|F)|\\\\u1680|\\\\u180(e|E)|\\\\u200(f|F)"

            + "|\\\\u202(f|F)|\\\\u2064|\\\\u2066|\\\\u2067|\\\\u2068|\\\\u2069|\\\\u206(f|F)"

            + "|\\\\u(f|F)8(f|F){2}|\\\\u(f|F)(e|E)(f|F){2}|\\\\u(f|F){3}9|\\\\u(f|F){3}(b|B)"

            + "|\\\\u05(d|D)0|\\\\u05(f|F)3|\\\\u0600|\\\\u0750|\\\\u0(e|E)00|\\\\u1(e|E)00"

            + "|\\\\u2100|\\\\u(f|F)(b|B)50|\\\\u(f|F)(e|E)70|\\\\u(F|f){2}61|\\\\u04(f|F)9"

            + "|\\\\u05(b|B)(e|E)|\\\\u05(e|E)(a|A)|\\\\u05(f|F)4|\\\\u06(f|F){2}"

            + "|\\\\u077(f|F)|\\\\u0(e|E)7(f|F)|\\\\u20(a|A)(f|F)|\\\\u213(a|A)|\\\\u0000"

            + "|\\\\u(f|F)(d|D)(f|F){2}|\\\\u(f|F)(e|E)(f|F){2}|\\\\u(f|F){2}(d|D)(c|C)"

            + "|\\\\u2002|\\\\u0085|\\\\u200(a|A)|\\\\u2005|\\\\u2000|\\\\u2029|\\\\u000(B|b)"

            + "|\\\\u2008|\\\\u2003|\\\\u205(f|F)|\\\\u1680|\\\\u0009|\\\\u0020|\\\\u2006"

            + "|\\\\u2001|\\\\u202(f|F)|\\\\u00(a|A)0|\\\\u000(c|C)|\\\\u2009|\\\\u2004|\\\\u2028"

            + "|\\\\u2028|\\\\u2007|\\\\u2004|\\\\u2028|\\\\u2007|\\\\u2025"

            + "|\\\\u(f|F){2}0(e|E)|\\\\u(f|F){2}61");

    /** Cpp style comments. */

    private Map<Integer, TextBlock> singlelineComments;

    /** C style comments. */

    private Map<Integer, List<TextBlock>> blockComments;

    /** Allow use escapes for non-printable(control) characters.  */

    private boolean allowEscapesForControlCharacters;

    /** Allow use escapes if trail comment is present. */

    private boolean allowByTailComment;

    /** Allow if all characters in literal are escaped. */

    private boolean allowIfAllCharactersEscaped;

    /** Allow escapes for space literals. */

    private boolean allowNonPrintableEscapes;

    /**

     * Set allowIfAllCharactersEscaped.

     * @param allow user's value.

     */

    public final void setAllowEscapesForControlCharacters(boolean allow) {

    /**

     * Set allowByTailComment.

     * @param allow user's value.

     */

    public final void setAllowByTailComment(boolean allow) {

    /**

     * Set allowIfAllCharactersEscaped.

     * @param allow user's value.

     */

    public final void setAllowIfAllCharactersEscaped(boolean allow) {

    /**

     * Set allowSpaceEscapes.

     * @param allow user's value.

     */

    public final void setAllowNonPrintableEscapes(boolean allow) {

    @Override

    public int[] getDefaultTokens() {

    }

    @Override

    public int[] getAcceptableTokens() {

    }

    @Override

    public int[] getRequiredTokens() {

    }

    @Override

    public void beginTree(DetailAST rootAST) {

    @Override

    public void visitToken(DetailAST ast) {

                || allowEscapesForControlCharacters

                || allowNonPrintableEscapes

        }

    /**

     * Checks if literal has Unicode chars.

     * @param literal String literal.

     * @return true if literal has Unicode chars.

     */

    private static boolean hasUnicodeChar(String literal) {

    }

    /**

     * Check if String literal contains Unicode control chars.

     * @param literal String literal.

     * @param pattern RegExp for valid characters.

     * @return true, if String literal contains Unicode control chars.

     */

    private static boolean isOnlyUnicodeValidChars(String literal, Pattern pattern) {

    }

    /**

     * Check if trail comment is present after ast token.

     * @param ast current token.

     * @return true if trail comment is present after ast token.

     */

    private boolean hasTrailComment(DetailAST ast) {

        }

        else {

            }

        }

    }

    /**

     * Whether the C style comment is trailing.

     * @param comment the comment to check.

     * @param line the line where the comment starts.

     * @return true if the comment is trailing.

     */

    private static boolean isTrailingBlockComment(TextBlock comment, String line) {

    }

    /**

     * Count regexp matches into String literal.

     * @param pattern pattern.

     * @param target String literal.

     * @return count of regexp matches.

     */

    private static int countMatches(Pattern pattern, String target) {

        }

    }

    /**

     * Checks if all characters in String literal is escaped.

     * @param literal current literal.

     * @return true if all characters in String literal is escaped.

     */

    private boolean isAllCharactersEscaped(String literal) {

    }

}

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