XpathElement.php

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<?php
 
namespace Depage\XmlDb;
 
use Depage\XmlDb\Exceptions\XmlDbException;

class XpathElement
{
    // Raw selector parts
    public readonly string $divider;
    public readonly string $namespace;
    public readonly string $name;
    public readonly string $condition;
 
    // Pre-computed parsed conditions (set in __construct)
    public readonly mixed $position;        // false or ['op', 'value']
    public readonly mixed $attributes;      // array of condition-rows or false
    public readonly bool $attributesValid; // true when condition matched attribute regex

    public function __construct(string $divider, string $namespace, string $name, string $condition)
    {
        $this->divider      = $divider;
        $this->namespace    = $namespace;
        $this->name         = $name;
        $this->condition    = $condition;
 
        // Derive position from condition
        if (is_string($condition)) {
            $this->position = $this->parsePosition($condition);
        } else {
            $this->position = false;
        }
 
        // Derive attributes from condition
        $attributesValid = false;
        $attributes       = false;
        if ($condition !== '') {
            $cleanString = $this->removeLiteralStrings($condition, $strings);
            $validMatch = preg_match('/^[\w\d@=: -<>\*]*$/', $cleanString);
            if ((bool) $validMatch) {
                $attributesValid = true;
                try {
                    $attributes = $this->getConditionAttributes($cleanString, $strings);
                } catch (XmlDbException $e) {
                    $attributesValid = false;
                    $attributes       = false;
                }
            }
        }
 
        $this->attributes = $attributes;
        $this->attributesValid = $attributesValid;
    }

    protected function parsePosition($condition): array|false
    {
        $positionArray = [];
        $matches = [];
        $pOperator = '(=|!=|<|>|<=|>=)';
        $pPosition = '([0-9]+)';
 
        if (preg_match("/^\s*(?:(?:position\‍(\‍))\s*$pOperator)?\s*$pPosition\s*$/", $condition, $matches)) {
            $positionArray[] = ($matches[1] == '') ? '=' : $matches[1];
            $positionArray[] = $matches[2];
            return $positionArray;
        }
        return false;
    }

    protected function getConditionAttributes($conditionString, $strings)
    {
        $conditionArray = [];
        $pAttr     = '@(\w[\w\d:]*)';
        $pOperator = '(=|!=|<|>|<=|>=)';
        $pBool     = '(and|or|AND|OR)';
        $pString   = '\$(\d*)';
 
        preg_match_all("/$pBool?\s*$pAttr\s*(?:$pOperator\s*$pString)?/", $conditionString, $conditions, PREG_SET_ORDER);
 
        $first = true;
        foreach ($conditions as $condition) {
            $bool = $condition[1] ?? null;
 
            if ($first === $bool) {
                throw new XmlDbException('Invalid XPath syntax');
            }
            if ($first) {
                $first = false;
            }
 
            $conditionArray[] = [
                $condition[2],
                $condition[3] ?? null,
                (isset($condition[4]) && $condition[4] != '') ? $strings[$condition[4]] : null,
                $bool,
            ];
        }
        return $conditionArray;
    }

    protected function removeLiteralStrings($text, &$strings): string
    {
        $n     = 0;
        $newText = '';
        $strings = [];
 
        $p = "/([^\"']*)|(?:\"([^\"]*)\"|'([^']*)')/";
        preg_match_all($p, $text, $parts);
 
        for ($i = 0; $i < count($parts[0]); $i++) {
            if ($parts[1][$i] == '' && ($parts[2][$i] != '' || $parts[3][$i] != '')) {
                $strings[$n] = $parts[2][$i] . $parts[3][$i];
                $newText .= "\$$n";
                $n++;
            } else {
                $newText .= $parts[1][$i];
            }
        }
        return $newText;
    }
}
 
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