/* Jackson JSON-processor.
 *
 * Copyright (c) 2007- Tatu Saloranta, tatu.saloranta@iki.fi
 */
package com.fasterxml.jackson.core;

Container for commonly used Base64 variants:

 MIME 
 MIME_NO_LINEFEEDS 
 PEM 
 MODIFIED_FOR_URL 
Author:
Tatu Saloranta/**
 * Container for commonly used Base64 variants:
 *<ul>
 * <li> {@link #MIME}
 * <li> {@link #MIME_NO_LINEFEEDS}
 * <li> {@link #PEM}
 * <li> {@link #MODIFIED_FOR_URL}
 * </ul>
 * 
 * @author Tatu Saloranta
 */
public final class Base64Variants
{
    final static String STD_BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    
This variant is what most people would think of "the standard"
Base64 encoding.

See wikipedia Base64 entry for details.

Note that although this can be thought of as the standard variant,
it is not the default for Jackson: no-linefeeds alternative
is because of JSON requirement of escaping all linefeeds.
/**
     * This variant is what most people would think of "the standard"
     * Base64 encoding.
     *<p>
     * See <a href="http://en.wikipedia.org/wiki/Base64">wikipedia Base64 entry</a> for details.
     *<p>
     * Note that although this can be thought of as the standard variant,
     * it is <b>not</b> the default for Jackson: no-linefeeds alternative
     * is because of JSON requirement of escaping all linefeeds.
     */
    public final static Base64Variant MIME;
    static {
        MIME = new Base64Variant("MIME", STD_BASE64_ALPHABET, true, '=', 76);
    }

    
Slightly non-standard modification of MIME which does not use linefeeds (max line length set to infinite). Useful when linefeeds wouldn't work well (possibly in attributes), or for minor space savings (save 1 linefeed per 76 data chars, ie. ~1.4% savings). /**
     * Slightly non-standard modification of {@link #MIME} which does not
     * use linefeeds (max line length set to infinite). Useful when linefeeds
     * wouldn't work well (possibly in attributes), or for minor space savings
     * (save 1 linefeed per 76 data chars, ie. ~1.4% savings).
     */
    public final static Base64Variant MIME_NO_LINEFEEDS;
    static {
        MIME_NO_LINEFEEDS = new Base64Variant(MIME, "MIME-NO-LINEFEEDS", Integer.MAX_VALUE);
    }

    
This variant is the one that predates MIME: it is otherwise identical, except that it mandates shorter line length. /**
     * This variant is the one that predates {@link #MIME}: it is otherwise
     * identical, except that it mandates shorter line length.
     */
    public final static Base64Variant PEM = new Base64Variant(MIME, "PEM", true, '=', 64);

    
This non-standard variant is usually used when encoded data needs to be passed via URLs (such as part of GET request). It differs from the base MIME variant in multiple ways. First, no padding is used: this also means that it generally can not be written in multiple separate but adjacent chunks (which would not be the usual use case in any case). Also, no linefeeds are used (max line length set to infinite). And finally, two characters (plus and slash) that would need quoting in URLs are replaced with more optimal alternatives (hyphen and underscore, respectively). /**
     * This non-standard variant is usually used when encoded data needs to be
     * passed via URLs (such as part of GET request). It differs from the
     * base {@link #MIME} variant in multiple ways.
     * First, no padding is used: this also means that it generally can not
     * be written in multiple separate but adjacent chunks (which would not
     * be the usual use case in any case). Also, no linefeeds are used (max
     * line length set to infinite). And finally, two characters (plus and
     * slash) that would need quoting in URLs are replaced with more
     * optimal alternatives (hyphen and underscore, respectively).
     */
    public final static Base64Variant MODIFIED_FOR_URL;
    static {
        StringBuilder sb = new StringBuilder(STD_BASE64_ALPHABET);
        // Replace plus with hyphen, slash with underscore (and no padding)
        sb.setCharAt(sb.indexOf("+"), '-');
        sb.setCharAt(sb.indexOf("/"), '_');
        // And finally, let's not split lines either, wouldn't work too well with URLs
        MODIFIED_FOR_URL = new Base64Variant("MODIFIED-FOR-URL", sb.toString(), false, Base64Variant.PADDING_CHAR_NONE, Integer.MAX_VALUE);
    }

    
Method used to get the default variant ("MIME_NO_LINEFEEDS") for cases
where caller does not explicitly specify the variant.
We will prefer no-linefeed version because linefeeds in JSON values
must be escaped, making linefeed-containing variants sub-optimal.
/**
     * Method used to get the default variant ("MIME_NO_LINEFEEDS") for cases
     * where caller does not explicitly specify the variant.
     * We will prefer no-linefeed version because linefeeds in JSON values
     * must be escaped, making linefeed-containing variants sub-optimal.
     */
    public static Base64Variant getDefaultVariant() {
        return MIME_NO_LINEFEEDS;
    }

    
Since:
2.1/**
     * @since 2.1
     */
    public static Base64Variant valueOf(String name) throws IllegalArgumentException
    {
        if (MIME._name.equals(name)) {
            return MIME;
        }
        if (MIME_NO_LINEFEEDS._name.equals(name)) {
            return MIME_NO_LINEFEEDS;
        }
        if (PEM._name.equals(name)) {
            return PEM;
        }
        if (MODIFIED_FOR_URL._name.equals(name)) {
            return MODIFIED_FOR_URL;
        }
        if (name == null) {
            name = "<null>";
        } else {
            name = "'"+name+"'";
        }
        throw new IllegalArgumentException("No Base64Variant with name "+name);
    }
}