/build/charset.php

<?php

require_once '../autoloader.php';

function normalize_character_set($charset)
{
	return strtolower(preg_replace('/(?:[^a-zA-Z0-9]+|([^0-9])0+)/', '\1', $charset));
}

function build_character_set_list()
{
	$file = new SimplePie_File('http://www.iana.org/assignments/character-sets');
	if (!$file->success && !($file->method & SIMPLEPIE_FILE_SOURCE_REMOTE === 0 || ($file->status_code === 200 || $file->status_code > 206 && $file->status_code < 300)))
	{
		return false;
	}

	$data = explode("\n", $file->body);
	unset($file);

	foreach ($data as $line)
	{
		// New character set
		if (preg_match('/^Name:\s+(\S+)/', $line, $match))
		{
			// If we already have one, push it on to the array
			if (isset($aliases))
			{
				foreach ($aliases as &$alias)
				{
					$alias = normalize_character_set($alias);
				}
				$charsets[$preferred] = array_unique($aliases);
				natsort($charsets[$preferred]);
			}

			$aliases = array($match[1]);
			$preferred = $match[1];
		}
		// Another alias
		elseif (preg_match('/^Alias:\s+(\S+)(\s+\(preferred MIME name\))?\s*$/', $line, $match))
		{
			if ($match[1] !== 'None')
			{
				$aliases[] = $match[1];
				if (isset($match[2]))
				{
					$preferred = $match[1];
				}
			}
		}
	}

	// Compatibility replacements
	// From http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#misinterpreted-for-compatibility
	$compat = array(
		'EUC-KR' => 'windows-949',
		'GB2312' => 'GBK',
		'GB_2312-80' => 'GBK',
		'ISO-8859-1' => 'windows-1252',
		'ISO-8859-9' => 'windows-1254',
		'ISO-8859-11' => 'windows-874',
		'KS_C_5601-1987' => 'windows-949',
		'Shift_JIS' => 'Windows-31J',
		'TIS-620' => 'windows-874',
		//'US-ASCII' => 'windows-1252',
	);

	foreach ($compat as $real => $replace)
	{
		if (isset($charsets[$real]) && isset($charsets[$replace]))
		{
			$charsets[$replace] = array_merge($charsets[$replace], $charsets[$real]);
			unset($charsets[$real]);
		}
		elseif (isset($charsets[$real]))
		{
			$charsets[$replace] = $charsets[$real];
			$charsets[$replace][] = normalize_character_set($replace);
			unset($charsets[$real]);
		}
		else
		{
			$charsets[$replace][] = normalize_character_set($real);
		}
		$charsets[$replace] = array_unique($charsets[$replace]);
		natsort($charsets[$replace]);
	}

	// Sort it
	uksort($charsets, 'strnatcasecmp');

	// Check that nothing matches more than one
	$all = call_user_func_array('array_merge', $charsets);
	$all_count = array_count_values($all);
	if (max($all_count) > 1)
	{
		echo "Duplicated charsets:\n";
		foreach ($all_count as $charset => $count)
		{
			if ($count > 1)
			{
				echo "$charset\n";
			}
		}
	}

	// And we're done!
	return $charsets;
}

function charset($charset)
{
	$normalized_charset = normalize_character_set($charset);
	if ($charsets = build_character_set_list())
	{
		foreach ($charsets as $preferred => $aliases)
		{
			if (in_array($normalized_charset, $aliases))
			{
				return $preferred;
			}
		}
		return $charset;
	}

	return false;
}

function build_function()
{
	if ($charsets = build_character_set_list())
	{
		$return = <<<EOF
public static function encoding(\$charset)
{
	// Normalization from UTS #22
	switch (strtolower(preg_replace('/(?:[^a-zA-Z0-9]+|([^0-9])0+)/', '\\1', \$charset)))
	{

EOF;
		foreach ($charsets as $preferred => $aliases)
		{
			foreach ($aliases as $alias)
			{
				$return .= "\t\tcase " . var_export($alias, true) . ":\n";
			}
			$return .= "\t\t\treturn " . var_export($preferred, true) . ";\n\n";
		}
		$return .= <<<EOF
		default:
			return \$charset;
	}
}
EOF;
		return $return;
	}

	return false;
}

if (php_sapi_name() === 'cli' && realpath($_SERVER['argv'][0]) === __FILE__)
{
	echo build_function();
}

?>