Add wrappers around XMLReader and SimpleXMLElement to improve error handling

src/Spout/Reader/Wrapper/XMLInternalErrorsHelper.php

@@ -0,0 +1,82 @@
+<?php
+
+namespace Box\Spout\Reader\Wrapper;
+
+use Box\Spout\Reader\Exception\XMLProcessingException;
+
+/**
+ * Trait XMLInternalErrorsHelper
+ *
+ * @package Box\Spout\Reader\Wrapper
+ */
+trait XMLInternalErrorsHelper
+{
+    /** @var bool Stores whether XML errors were initially stored internally - used to reset */
+    protected $initialUseInternalErrorsValue;
+
+    /**
+     * To avoid displaying lots of warning/error messages on screen,
+     * stores errors internally instead.
+     *
+     * @return void
+     */
+    protected function useXMLInternalErrors()
+    {
+        libxml_clear_errors();
+        $this->initialUseInternalErrorsValue = libxml_use_internal_errors(true);
+    }
+
+    /**
+     * Throws an XMLProcessingException if an error occured.
+     * It also always resets the "libxml_use_internal_errors" setting back to its initial value.
+     *
+     * @return void
+     * @throws \Box\Spout\Reader\Exception\XMLProcessingException
+     */
+    protected function resetXMLInternalErrorsSettingAndThrowIfXMLErrorOccured()
+    {
+        if ($this->hasXMLErrorOccured()) {
+            $this->resetXMLInternalErrorsSetting();
+            throw new XMLProcessingException($this->getLastXMLErrorMessage());
+        }
+
+        $this->resetXMLInternalErrorsSetting();
+    }
+
+    /**
+     * Returns whether the a XML error has occured since the last time errors were cleared.
+     *
+     * @return bool TRUE if an error occured, FALSE otherwise
+     */
+    private function hasXMLErrorOccured()
+    {
+        return (libxml_get_last_error() !== false);
+    }
+
+    /**
+     * Returns the error message for the last XML error that occured.
+     * @see libxml_get_last_error
+     *
+     * @return String|null Last XML error message or null if no error
+     */
+    private function getLastXMLErrorMessage()
+    {
+        $errorMessage = null;
+        $error = libxml_get_last_error();
+
+        if ($error !== false) {
+            $errorMessage = trim($error->message);
+        }
+
+        return $errorMessage;
+    }
+
+    /**
+     * @return void
+     */
+    protected function resetXMLInternalErrorsSetting()
+    {
+        libxml_use_internal_errors($this->initialUseInternalErrorsValue);
+    }
+
+}