checked in initial customized verison for Archlinux32HEADmaster

1 files changed, 171 insertions, 0 deletions

diff --git a/include/utf8/utils/position.php b/include/utf8/utils/position.php
new file mode 100644
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+++ b/include/utf8/utils/position.php
@@ -0,0 +1,171 @@
+<?php
+
+/**
+* Locate a byte index given a UTF-8 character index
+* @version $Id: position.php,v 1.1 2006/10/01 00:01:31 harryf Exp $
+* @package utf8
+* @subpackage position
+*/
+
+/**
+* Given a string and a character index in the string, in
+* terms of the UTF-8 character position, returns the byte
+* index of that character. Can be useful when you want to
+* PHP's native string functions but we warned, locating
+* the byte can be expensive
+* Takes variable number of parameters - first must be
+* the search string then 1 to n UTF-8 character positions
+* to obtain byte indexes for - it is more efficient to search
+* the string for multiple characters at once, than make
+* repeated calls to this function
+*
+* @author Chris Smith<chris@jalakai.co.uk>
+* @param string string to locate index in
+* @param int (n times)
+* @return mixed - int if only one input int, array if more
+* @return boolean TRUE if it's all ASCII
+* @package utf8
+* @subpackage position
+*/
+function utf8_byte_position()
+{
+	$args = func_get_args();
+	$str =& array_shift($args);
+
+	if (!is_string($str))
+		return false;
+
+	$result = array();
+	$prev = array(0, 0); // Trivial byte index, character offset pair
+	$i = utf8_locate_next_chr($str, 300); // Use a short piece of str to estimate bytes per character. $i (& $j) -> byte indexes into $str
+	$c = strlen(utf8_decode(substr($str, 0, $i))); // $c -> character offset into $str
+
+	// Deal with arguments from lowest to highest
+	sort($args);
+
+	foreach ($args as $offset)
+	{
+		// Sanity checks FIXME
+
+		// 0 is an easy check
+		if ($offset == 0)
+		{
+			$result[] = 0; continue;
+		}
+
+		// Ensure no endless looping
+		$safety_valve = 50;
+
+		do
+		{
+			if (($c - $prev[1]) == 0)
+			{
+				// Hack: gone past end of string
+				$error = 0;
+				$i = strlen($str);
+				break;
+			}
+
+			$j = $i + (int)(($offset-$c) * ($i - $prev[0]) / ($c - $prev[1]));
+			$j = utf8_locate_next_chr($str, $j); // Correct to utf8 character boundary
+			$prev = array($i,$c); // Save the index, offset for use next iteration
+
+			if ($j > $i)
+				$c += strlen(utf8_decode(substr($str, $i, $j-$i))); // Determine new character offset
+			else
+				$c -= strlen(utf8_decode(substr($str, $j, $i-$j))); // Ditto
+
+			$error = abs($c-$offset);
+			$i = $j; // Ready for next time around
+		}
+		while (($error > 7) && --$safety_valve); // From 7 it is faster to iterate over the string
+
+		if ($error && $error <= 7)
+		{
+			if ($c < $offset)
+			{
+				// Move up
+				while ($error--)
+					$i = utf8_locate_next_chr($str, ++$i);
+			}
+			else
+			{
+				// Move down
+				while ($error--)
+					$i = utf8_locate_current_chr($str, --$i);
+			}
+
+			// Ready for next arg
+			$c = $offset;
+		}
+
+		$result[] = $i;
+	}
+
+	if (count($result) == 1)
+		return $result[0];
+
+	return $result;
+}
+
+/**
+* Given a string and any byte index, returns the byte index
+* of the start of the current UTF-8 character, relative to supplied
+* position. If the current character begins at the same place as the
+* supplied byte index, that byte index will be returned. Otherwise
+* this function will step backwards, looking for the index where
+* curent UTF-8 character begins
+* @author Chris Smith<chris@jalakai.co.uk>
+* @param string
+* @param int byte index in the string
+* @return int byte index of start of next UTF-8 character
+* @package utf8
+* @subpackage position
+*/
+function utf8_locate_current_chr( &$str, $idx )
+{
+	if ($idx <= 0)
+		return 0;
+
+	$limit = strlen($str);
+	if ($idx >= $limit)
+		return $limit;
+
+	// Binary value for any byte after the first in a multi-byte UTF-8 character
+	// will be like 10xxxxxx so & 0xC0 can be used to detect this kind
+	// of byte - assuming well formed UTF-8
+	while ($idx && ((ord($str[$idx]) & 0xC0) == 0x80))
+		$idx--;
+
+	return $idx;
+}
+
+/**
+* Given a string and any byte index, returns the byte index
+* of the start of the next UTF-8 character, relative to supplied
+* position. If the next character begins at the same place as the
+* supplied byte index, that byte index will be returned.
+* @author Chris Smith<chris@jalakai.co.uk>
+* @param string
+* @param int byte index in the string
+* @return int byte index of start of next UTF-8 character
+* @package utf8
+* @subpackage position
+*/
+function utf8_locate_next_chr(&$str, $idx)
+{
+	if ($idx <= 0)
+		return 0;
+
+	$limit = strlen($str);
+	if ($idx >= $limit)
+		return $limit;
+
+	// Binary value for any byte after the first in a multi-byte UTF-8 character
+	// will be like 10xxxxxx so & 0xC0 can be used to detect this kind
+	// of byte - assuming well formed UTF-8
+	while (($idx < $limit) && ((ord($str[$idx]) & 0xC0) == 0x80))
+		$idx++;
+
+	return $idx;
+}