L05DOCBST-41 add LoggerTrait trait

this is a copy of the LoggerTrait trait from the wms-api

src/library/LoggerTrait.php

+<?php
+
+namespace Library;
+
+/**
+ * Logger trait to add logging functionality to a class.
+ * If no logger is set all logging methods, error(), info(), etc. do nothing.
+ * The context for a log message can be provided with the ndc_push() and ndc_pop methods.
+ * NDC stands for Nested Diagnostic Context
+ *
+ * To use this trait add
+ *   use \Library\Logger;
+ * at the begin of your class declaration.
+ */
+trait LoggerTrait {
+
+    /**
+     * PSR-3 compatible logger instance, if not set no logging is done
+     * @var \Psr\Log\LoggerInterface
+     */
+    protected $logger;
+
+    /**
+     * nested diagnostic context, used as context for log messages
+     * @var array
+     */
+    protected $ndc_context = [];
+
+    /**
+     * set logger to send log messages to
+     * @param \Psr\Log\LoggerInterface $logger
+     */
+    public function set_logger(\Psr\Log\LoggerInterface $logger) {
+
+        $this->logger = $logger;
+        return $this;
+    }
+
+    /**
+     * debug message
+     * @param string $message
+     * @param array $context if not set the ndc is used
+     * @return type
+     */
+    public function debug(string $message, array $context = null) {
+
+        if (!isset($this->logger)) {
+            return;
+        }
+        $this->logger->debug($message, isset($context) ? $context : $this->ndc_context);
+    }
+
+    /**
+     * info message
+     * @param string $message
+     * @param array $context if not set the ndc is used
+     * @return type
+     */
+    public function info(string $message, array $context = null) {
+
+        if (!isset($this->logger)) {
+            return;
+        }
+        $this->logger->info($message, isset($context) ? $context : $this->ndc_context);
+    }
+
+    /**
+     * warning message
+     * @param string $message
+     * @param array $context if not set the ndc is used
+     * @return type
+     */
+    public function warning(string $message, array $context = null) {
+
+        if (!isset($this->logger)) {
+            return;
+        }
+        $this->logger->warning($message, isset($context) ? $context : $this->ndc_context);
+    }
+
+    /**
+     * error message
+     * @param string $message
+     * @param array $context if not set the ndc is used
+     * @return type
+     */
+    public function error(string $message, array $context = null) {
+
+        if (!isset($this->logger)) {
+            return;
+        }
+        $this->logger->error($message, isset($context) ? $context : $this->ndc_context);
+    }
+
+    /**
+     * add message to the ndc (nested diagnostic context)
+     * @param string $message
+     */
+    public function ndc_push(string $message){
+
+        array_push($this->ndc_context, $message);
+    }
+
+    /**
+     * remove last message from the ndc (nested diagnostic context)
+     */
+    public function ndc_pop(){
+
+        array_pop($this->ndc_context);
+    }
+
+}
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