src/Configuration/adapters/XmlAdapter.php

<?php
/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Apache\Log4php\Configuration\Adapters;

use Apache\Log4php\LoggerException;

/**
 * Converts XML configuration files to a PHP array.
 * @license http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
 * @since 2.2
 */
class XmlAdapter implements AdapterInterface
{
    /** Path to the XML schema used for validation. */
    const SCHEMA_PATH = '/../xml/log4php.xsd';

    private $config = array(
        'appenders' => array(),
        'loggers' => array(),
        'renderers' => array(),
    );

    public function convert($url)
    {
        $xml = $this->loadXML($url);

        $this->parseConfiguration($xml);

        // Parse the <root> node
        if (isset($xml->root)) {
            $this->parseRootLogger($xml->root);
        }

        // Process <logger> nodes
        foreach ($xml->logger as $logger) {
            $this->parseLogger($logger);
        }

        // Process <appender> nodes
        foreach ($xml->appender as $appender) {
            $this->parseAppender($appender);
        }

        // Process <renderer> nodes
        foreach ($xml->renderer as $rendererNode) {
            $this->parseRenderer($rendererNode);
        }

        // Process <defaultRenderer> node
        foreach ($xml->defaultRenderer as $rendererNode) {
            $this->parseDefaultRenderer($rendererNode);
        }

        return $this->config;
    }

    /**
     * Loads and validates the XML.
     * @param string $url Input XML.
     */
    private function loadXML($url)
    {
        if (!file_exists($url)) {
            throw new LoggerException("File [$url] does not exist.");
        }

        libxml_clear_errors();
        $oldValue = libxml_use_internal_errors(true);

        // Load XML
        $xml = @simplexml_load_file($url);
        if ($xml === false) {

            $errorStr = "";
            foreach (libxml_get_errors() as $error) {
                $errorStr .= $error->message;
            }

            throw new LoggerException("Error loading configuration file: " . trim($errorStr));
        }

        libxml_clear_errors();
        libxml_use_internal_errors($oldValue);

        return $xml;
    }

    /**
     * Parses the <configuration> node.
     */
    private function parseConfiguration(\SimpleXMLElement $xml)
    {
        $attributes = $xml->attributes();
        if (isset($attributes['threshold'])) {
            $this->config['threshold'] = (string) $attributes['threshold'];
        }
    }

    /** Parses an <appender> node. */
    private function parseAppender(\SimpleXMLElement $node)
    {
        $name = $this->getAttributeValue($node, 'name');
        if (empty($name)) {
            $this->warn("An <appender> node is missing the required 'name' attribute. Skipping appender definition.");

            return;
        }

        $appender = array();
        $appender['class'] = $this->getAttributeValue($node, 'class');

        if (isset($node['threshold'])) {
            $appender['threshold'] = $this->getAttributeValue($node, 'threshold');
        }

        if (isset($node->layout)) {
            $appender['layout']= $this->parseLayout($node->layout, $name);
        }

        if (count($node->param) > 0) {
            $appender['params'] = $this->parseParameters($node);
        }

        foreach ($node->filter as $filterNode) {
            $appender['filters'][] = $this->parseFilter($filterNode);
        }

        $this->config['appenders'][$name] = $appender;
    }

    /** Parses a <layout> node. */
    private function parseLayout(\SimpleXMLElement $node, $appenderName)
    {
        $layout = array();
        $layout['class'] = $this->getAttributeValue($node, 'class');

        if (count($node->param) > 0) {
            $layout['params'] = $this->parseParameters($node);
        }

        return $layout;
    }

    /** Parses any <param> child nodes returning them in an array. */
    private function parseParameters($paramsNode)
    {
        $params = array();

        foreach ($paramsNode->param as $paramNode) {
            if (empty($paramNode['name'])) {
                $this->warn("A <param> node is missing the required 'name' attribute. Skipping parameter.");
                continue;
            }

            $name = $this->getAttributeValue($paramNode, 'name');
            $value = $this->getAttributeValue($paramNode, 'value');

            $params[$name] = $value;
        }

        return $params;
    }

    /** Parses a <root> node. */
    private function parseRootLogger(\SimpleXMLElement $node)
    {
        $logger = array();

        if (isset($node->level)) {
            $logger['level'] = $this->getAttributeValue($node->level, 'value');
        }

        $logger['appenders'] = $this->parseAppenderReferences($node);

        $this->config['rootLogger'] = $logger;
    }

    /** Parses a <logger> node. */
    private function parseLogger(\SimpleXMLElement $node)
    {
        $logger = array();

        $name = $this->getAttributeValue($node, 'name');
        if (empty($name)) {
            $this->warn("A <logger> node is missing the required 'name' attribute. Skipping logger definition.");

            return;
        }

        if (isset($node->level)) {
            $logger['level'] = $this->getAttributeValue($node->level, 'value');
        }

        if (isset($node['additivity'])) {
            $logger['additivity'] = $this->getAttributeValue($node, 'additivity');
        }

        $logger['appenders'] = $this->parseAppenderReferences($node);

        // Check for duplicate loggers
        if (isset($this->config['loggers'][$name])) {
            $this->warn("Duplicate logger definition [$name]. Overwriting.");
        }

        $this->config['loggers'][$name] = $logger;
    }

    /**
     * Parses a <logger> node for appender references and returns them in an array.
     *
     * Previous versions supported appender-ref, as well as appender_ref so both
     * are parsed for backward compatibility.
     */
    private function parseAppenderReferences(\SimpleXMLElement $node)
    {
        $refs = array();
        foreach ($node->appender_ref as $ref) {
            $refs[] = $this->getAttributeValue($ref, 'ref');
        }

        foreach ($node->{'appender-ref'} as $ref) {
            $refs[] = $this->getAttributeValue($ref, 'ref');
        }

        return $refs;
    }

    /** Parses a <filter> node. */
    private function parseFilter($filterNode)
    {
        $filter = array();
        $filter['class'] = $this->getAttributeValue($filterNode, 'class');

        if (count($filterNode->param) > 0) {
            $filter['params'] = $this->parseParameters($filterNode);
        }

        return $filter;
    }

    /** Parses a <renderer> node. */
    private function parseRenderer(\SimpleXMLElement $node)
    {
        $renderedClass = $this->getAttributeValue($node, 'renderedClass');
        $renderingClass = $this->getAttributeValue($node, 'renderingClass');

        $this->config['renderers'][] = compact('renderedClass', 'renderingClass');
    }

    /** Parses a <defaultRenderer> node. */
    private function parseDefaultRenderer(\SimpleXMLElement $node)
    {
        $renderingClass = $this->getAttributeValue($node, 'renderingClass');

        // Warn on duplicates
        if (isset($this->config['defaultRenderer'])) {
            $this->warn("Duplicate <defaultRenderer> node. Overwriting.");
        }

        $this->config['defaultRenderer'] = $renderingClass;
    }

    // ******************************************
    // ** Helper methods                       **
    // ******************************************

    private function getAttributeValue(\SimpleXMLElement $node, $name)
    {
        return isset($node[$name]) ? (string) $node[$name] : null;
    }

    private function warn($message)
    {
        trigger_error("log4php: " . $message, E_USER_WARNING);
    }
}