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/*
 * =============================================================================
 * 
 *   Copyright (c) 2014-2017, The UNBESCAPE team (http://www.unbescape.org)
 * 
 *   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 org.unbescape.css;

/**
 * 
 *   Levels defined for escape/unescape operations of CSS identifiers:
 * 
 *
 * 
 *     Level 1: Escape only the basic escape set. Note the result of a level-1 escape
 *         operation might still contain non-ASCII characters if they existed in input, and therefore you
 *         will still need to correctly manage your input/output character encoding settings. Such
 *         basic set consists of:
 *         
 *           The Backslash Escapes:
 *               \  (U+0020),
 *               \! (U+0021),
 *               \" (U+0022),
 *               \# (U+0023),
 *               \$ (U+0024),
 *               \% (U+0025),
 *               \& (U+0026),
 *               \' (U+0027),
 *               \( (U+0028),
 *               \) (U+0029),
 *               \* (U+002A),
 *               \+ (U+002B),
 *               \, (U+002C),
 *               \. (U+002E),
 *               \/ (U+002F),
 *               \; (U+003B),
 *               \< (U+003C),
 *               \= (U+003D),
 *               \> (U+003E),
 *               \? (U+003F),
 *               \@ (U+0040),
 *               \[ (U+005B),
 *               \\ (U+005C),
 *               \] (U+005D),
 *               \^ (U+005E),
 *               \` (U+0060),
 *               \{ (U+007B),
 *               \| (U+007C),
 *               \} (U+007D) and
 *               \~ (U+007E).
 *               Note that the \- (U+002D) escape sequence exists, but will only be used
 *               when an identifier starts with two hypens or hyphen + digit. Also, the \_
 *               (U+005F) escape will only be used at the beginning of an identifier to avoid
 *               problems with Internet Explorer 6. In the same sense, note that the \:
 *               (U+003A) escape sequence is also defined in the standard, but will not be
 *               used for escaping as Internet Explorer < 8 does not recognize it.
 *           
 *           
 *               Two ranges of non-displayable, control characters: U+0000 to U+001F
 *               and U+007F to U+009F.
 *           
 *         
 *     
 *     Level 2: Escape the basic escape set (as defined in level 1), plus all
 *         non-ASCII characters. The result of a level-2 escape operation is therefore always ASCII-only text, and
 *         safer to use in complex scenarios with mixed input/output character encodings.
 *     Level 3: Escape all non-alphanumeric characters, this is, all but those in the
 *         A-Z, a-z and 0-9 ranges. This level
 *         can be safely used for completely escaping texts, including whitespace, line feeds, punctuation, etc. in
 *         scenarios where this adds an extra level of safety.
 *     Level 4: Escape all characters, even alphanumeric ones.
 * 
 *
 * 
 *   For further information, see the Glossary and the References sections at the
 *   documentation for the {@link CssEscape} class.
 * 
 *
 * @author Daniel Fernández
 * 
 * @since 1.0.0
 *
 */
public enum CssIdentifierEscapeLevel {

    /**
     * Level 1 escape: escape only the basic escape set: Backslash Escape plus non-displayable control chars.
     */
    LEVEL_1_BASIC_ESCAPE_SET(1),

    /**
     * Level 2 escape: escape the basic escape set plus all non-ASCII characters (result will always be ASCII).
     */
    LEVEL_2_ALL_NON_ASCII_PLUS_BASIC_ESCAPE_SET(2),

    /**
     * Level 3 escape: escape all non-alphanumeric characteres (escape all but those in the
     * A-Z, a-z and 0-9 ranges).
     */
    LEVEL_3_ALL_NON_ALPHANUMERIC(3),

    /**
     * Level 4 escape: escape all characters, including alphanumeric.
     */
    LEVEL_4_ALL_CHARACTERS(4);




    private final int escapeLevel;


    /**
     * 
     *   Utility method for obtaining an enum value from its corresponding int level value.
     * 
     *
     * @param level the level
     * @return the escape level enum constant, or IllegalArgumentException if level does not exist.
     */
    public static CssIdentifierEscapeLevel forLevel(final int level) {
        switch (level) {
            case 1: return LEVEL_1_BASIC_ESCAPE_SET;
            case 2: return LEVEL_2_ALL_NON_ASCII_PLUS_BASIC_ESCAPE_SET;
            case 3: return LEVEL_3_ALL_NON_ALPHANUMERIC;
            case 4: return LEVEL_4_ALL_CHARACTERS;
            default:
                throw new IllegalArgumentException("No escape level enum constant defined for level: " + level);
        }
    }


    CssIdentifierEscapeLevel(final int escapeLevel) {
        this.escapeLevel = escapeLevel;
    }

    /**
     * Return the int escape level.
     *
     * @return the escape level.
     */
    public int getEscapeLevel() {
        return this.escapeLevel;
    }

}