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<?php
// $Id: decorator.inc.php,v 1.8 2007/04/05 11:09:38 mr-russ Exp $
// This group of functions and classes provides support for
// resolving values in a lazy manner (ie, as and when required)
// using the Decorator pattern.
###TODO: Better documentation!!!
// Compatibility functions:
if (!function_exists('is_a')) {
function is_a($object, $class) {
return is_object($object) && get_class($object) == strtolower($class) || is_subclass_of($object, $class);
}
}
// Construction functions:
function field($fieldName, $default = null) {
return new FieldDecorator($fieldName, $default);
}
function merge(/* ... */) {
return new ArrayMergeDecorator(func_get_args());
}
function concat(/* ... */) {
return new ConcatDecorator(func_get_args());
}
function callback($callback, $params = null) {
return new CallbackDecorator($callback, $params);
}
function ifempty($value, $empty, $full = null) {
return new IfEmptyDecorator($value, $empty, $full);
}
function url($base, $vars = null /* ... */) {
// If more than one array of vars is given,
// use an ArrayMergeDecorator to have them merged
// at value evaluation time.
if (func_num_args() > 2) {
$v = func_get_args();
array_shift($v);
return new UrlDecorator($base, new ArrayMergeDecorator($v));
}
return new UrlDecorator($base, $vars);
}
function noEscape($value) {
if (is_a($value, 'Decorator')) {
$value->esc = false;
return $value;
}
return new Decorator($value, false);
}
function replace($str, $params) {
return new replaceDecorator($str, $params);
}
// Resolving functions:
function value(&$var, &$fields, $esc = null) {
if (is_a($var, 'Decorator')) {
$val = $var->value($fields);
if (!$var->esc) $esc = null;
} else {
$val =& $var;
}
if (is_string($val)) {
switch($esc) {
case 'xml':
return strtr($val, array(
'&' => '&',
"'" => ''', '"' => '"',
'<' => '<', '>' => '>'
));
case 'html':
return htmlspecialchars($val);
case 'url':
return urlencode($val);
}
}
return $val;
}
function value_xml(&$var, &$fields) {
return value($var, $fields, 'xml');
}
function value_xml_attr($attr, &$var, &$fields) {
$val = value($var, $fields, 'xml');
if (!empty($val))
return " {$attr}=\"{$val}\"";
else
return '';
}
function value_url(&$var, &$fields) {
return value($var, $fields, 'url');
}
// Underlying classes:
class Decorator
{
var $esc = true;
function Decorator($value, $esc = true) {
$this->v = $value;
$this->esc = $esc;
}
function value($fields) {
return $this->v;
}
}
class FieldDecorator extends Decorator
{
function FieldDecorator($fieldName, $default = null) {
$this->f = $fieldName;
if ($default !== null) $this->d = $default;
}
function value($fields) {
return isset($fields[$this->f]) ? $fields[$this->f] : (isset($this->d) ? $this->d : null);
}
}
class ArrayMergeDecorator extends Decorator
{
function ArrayMergeDecorator($arrays) {
$this->m = $arrays;
}
function value($fields) {
$accum = array();
foreach($this->m as $var) {
$accum = array_merge($accum, value($var, $fields));
}
return $accum;
}
}
class ConcatDecorator extends Decorator
{
function ConcatDecorator($values) {
$this->c = $values;
}
function value($fields) {
$accum = '';
foreach($this->c as $var) {
$accum .= value($var, $fields);
}
return trim($accum);
}
}
class CallbackDecorator extends Decorator
{
function CallbackDecorator($callback, $param = null) {
$this->fn = $callback;
$this->p = $param;
}
function value($fields) {
return call_user_func($this->fn, $fields, $this->p);
}
}
class IfEmptyDecorator extends Decorator
{
function IfEmptyDecorator($value, $empty, $full = null) {
$this->v = $value;
$this->e = $empty;
if ($full !== null) $this->f = $full;
}
function value($fields) {
$val = value($this->v, $fields);
if (empty($val))
return value($this->e, $fields);
else
return isset($this->f) ? value($this->f, $fields) : $val;
}
}
class UrlDecorator extends Decorator
{
function UrlDecorator($base, $queryVars = null) {
$this->b = $base;
if ($queryVars !== null)
$this->q = $queryVars;
}
function value($fields) {
$url = value($this->b, $fields);
if ($url === false) return '';
if (!empty($this->q)) {
$queryVars = value($this->q, $fields);
$sep = '?';
foreach ($queryVars as $var => $value) {
$url .= $sep . value_url($var, $fields) . '=' . value_url($value, $fields);
$sep = '&';
}
}
return $url;
}
}
class replaceDecorator extends Decorator
{
function replaceDecorator($str, $params) {
$this->s = $str;
$this->p = $params;
}
function value($fields) {
$str = $this->s;
foreach ($this->p as $k => $v) {
$str = str_replace($k, value($v, $fields), $str);
}
return $str;
}
}
?>
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