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API16

JString/valid

From Joomla! Documentation

< API16:JString
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Contents

Description

Tests a string as to whether it's valid UTF-8 and supported by the Unicode standard Note: this function has been modified to simple return true or false <hsivonen@iki.fi>


[Edit Descripton]

Description:JString/valid

Syntax

static valid($str)
Parameter Name Default Value Description
$str UTF-8 encoded string

Returns

boolean true if valid

Defined in

libraries/joomla/utilities/string.php

Importing

jimport( 'joomla.utilities.string' );

Source Body

public static function valid($str)
{
        $mState = 0;    // cached expected number of octets after the current octet
                                        // until the beginning of the next UTF8 character sequence
        $mUcs4  = 0;    // cached Unicode character
        $mBytes = 1;    // cached expected number of octets in the current sequence
 
        $len = strlen($str);
 
        for ($i = 0; $i < $len; $i++)
        {
                $in = ord($str{$i});
 
                if ($mState == 0)
                {
                        // When mState is zero we expect either a US-ASCII character or a
                        // multi-octet sequence.
                        if (0 == (0x80 & ($in))) {
                                // US-ASCII, pass straight through.
                                $mBytes = 1;
                        } else if (0xC0 == (0xE0 & ($in))) {
                                // First octet of 2 octet sequence
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x1F) << 6;
                                $mState = 1;
                                $mBytes = 2;
                        } else if (0xE0 == (0xF0 & ($in))) {
                                // First octet of 3 octet sequence
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x0F) << 12;
                                $mState = 2;
                                $mBytes = 3;
                        } else if (0xF0 == (0xF8 & ($in))) {
                                // First octet of 4 octet sequence
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x07) << 18;
                                $mState = 3;
                                $mBytes = 4;
                        } else if (0xF8 == (0xFC & ($in))) {
                                /* First octet of 5 octet sequence.
                                 *
                                 * This is illegal because the encoded codepoint must be either
                                 * (a) not the shortest form or
                                 * (b) outside the Unicode range of 0-0x10FFFF.
                                 * Rather than trying to resynchronize, we will carry on until the end
                                 * of the sequence and let the later error handling code catch it.
                                 */
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x03) << 24;
                                $mState = 4;
                                $mBytes = 5;
                        } else if (0xFC == (0xFE & ($in))) {
                                // First octet of 6 octet sequence, see comments for 5 octet sequence.
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 1) << 30;
                                $mState = 5;
                                $mBytes = 6;
 
                        } else {
                                /* Current octet is neither in the US-ASCII range nor a legal first
                                 * octet of a multi-octet sequence.
                                 */
                                return FALSE;
                        }
                }
                else
                {
                        // When mState is non-zero, we expect a continuation of the multi-octet
                        // sequence
                        if (0x80 == (0xC0 & ($in)))
                        {
                                // Legal continuation.
                                $shift = ($mState - 1) * 6;
                                $tmp = $in;
                                $tmp = ($tmp & 0x0000003F) << $shift;
                                $mUcs4 |= $tmp;
 
                                if (0 == --$mState)
                                {
                                        /*
                                         * Check for illegal sequences and codepoints.
                                         */
                                        // From Unicode 3.1, non-shortest form is illegal
                                        if (((2 == $mBytes) && ($mUcs4 < 0x0080)) ||
                                                ((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
                                                ((4 == $mBytes) && ($mUcs4 < 0x10000)) ||
                                                (4 < $mBytes) ||
                                                // From Unicode 3.2, surrogate characters are illegal
                                                (($mUcs4 & 0xFFFFF800) == 0xD800) ||
                                                // Codepoints outside the Unicode range are illegal
                                                ($mUcs4 > 0x10FFFF)) {
                                                        return FALSE;
                                                }
 
                                        // Initialize UTF8 cache.
                                        $mState = 0;
                                        $mUcs4  = 0;
                                        $mBytes = 1;
                                }
                        }
                        else
                        {
                                return FALSE;
                        }
                }
        }
        return TRUE;
}

[Edit See Also] SeeAlso:JString/valid

Examples

<CodeExamplesForm />