Improve readability with null coalescing.

themes/bootstrap3/templates/search/searchbox.phtml

@@ -7,8 +7,7 @@
     // Load search actions and settings (if any):
     $options = $this->searchOptions($this->searchClassId);
     $handlers = $this->searchbox()->getHandlers(
-        $this->searchClassId,
-        isset($this->searchIndex) ? $this->searchIndex : null
+        $this->searchClassId, $this->searchIndex ?? null
     );
     $handlerCount = count($handlers);
     $basicSearch = $this->searchbox()->combinedHandlersActive() ? 'combined-searchbox' : $options->getSearchAction();
@@ -16,8 +15,8 @@
     $advSearch = $options->getAdvancedSearchAction();
     $lastSort = $this->searchMemory()->getLastSort($this->searchClassId);
     $lastLimit = $this->searchMemory()->getLastLimit($this->searchClassId);
-    $ignoreHiddenFilterMemory = isset($this->ignoreHiddenFilterMemory) && $this->ignoreHiddenFilterMemory;
-    $ignoreHiddenFiltersInRequest = isset($this->ignoreHiddenFiltersInRequest) && $this->ignoreHiddenFiltersInRequest;
+    $ignoreHiddenFilterMemory = $this->ignoreHiddenFilterMemory ?? false;
+    $ignoreHiddenFiltersInRequest = $this->ignoreHiddenFiltersInRequest ?? false;
     $hiddenFilters = $this->searchTabs()->getHiddenFilters($this->searchClassId, $ignoreHiddenFilterMemory, $ignoreHiddenFiltersInRequest);
     if (empty($hiddenFilters) && !$ignoreHiddenFilterMemory) {
         $hiddenFilters = $this->searchMemory()->getLastHiddenFilters($this->searchClassId);
@@ -74,7 +73,7 @@
     <?php endif; ?>
     <button type="submit" class="btn btn-primary"><i class="fa fa-search" aria-hidden="true"></i> <?=$this->transEsc("Find")?></button>
     <?php if ($advSearch): ?>
-      <a href="<?=$this->url($advSearch) . ((isset($this->searchId) && $this->searchId) ? '?edit=' . $this->escapeHtmlAttr($this->searchId) : $hiddenFilterParams) ?>" class="btn btn-link" rel="nofollow"><?=$this->transEsc("Advanced")?></a>
+      <a href="<?=$this->url($advSearch) . (($this->searchId ?? false) ? '?edit=' . $this->escapeHtmlAttr($this->searchId) : $hiddenFilterParams) ?>" class="btn btn-link" rel="nofollow"><?=$this->transEsc("Advanced")?></a>
     <?php endif; ?>
     <?php if ($geoUrl = $this->geocoords()->getSearchUrl($options)) : ?>
         <a href="<?=$geoUrl ?>" class="btn btn-link"><?=$this->transEsc('Geographic Search')?></a>
@@ -93,11 +92,11 @@
     <?php endif; ?>
     <?php
       $filterDetails = $this->searchbox()->getFilterDetails(
-          isset($this->filterList) && is_array($this->filterList) ? $this->filterList : [],
-          isset($this->checkboxFilters) && is_array($this->checkboxFilters) ? $this->checkboxFilters : []
+          is_array($this->filterList ?? null) ? $this->filterList : [],
+          is_array($this->checkboxFilters ?? null) ? $this->checkboxFilters : []
       );
     ?>
-    <?php if ((isset($hasDefaultsApplied) && $hasDefaultsApplied) || !empty($filterDetails)): ?>
+    <?php if (($hasDefaultsApplied ?? false) || !empty($filterDetails)): ?>
       <?php $defaultFilterState = $options->getRetainFilterSetting() ? ' checked="checked"' : ''; ?>
       <div class="checkbox">
         <label>
@@ -110,7 +109,7 @@
           <input class="applied-filter" id="<?=$this->escapeHtmlAttr($current['id'])?>" type="checkbox"<?=$defaultFilterState?> name="filter[]" value="<?=$this->escapeHtmlAttr($current['value'])?>" />
           <label for="<?=$this->escapeHtmlAttr($current['id'])?>"><?=$this->escapeHtml($current['value'])?></label>
         <?php endforeach; ?>
-        <?php if (isset($hasDefaultsApplied) && $hasDefaultsApplied): ?>
+        <?php if ($hasDefaultsApplied ?? false): ?>
           <!-- this is a hidden element that flags whether or not default filters have been applied;
                it is intentionally unlabeled, as users are not meant to manipulate it directly. -->
           <input class="applied-filter" id="dfApplied" type="checkbox" name="dfApplied" value="1"<?=$defaultFilterState?> />