diff --git a/lib/AbstractException.php b/lib/AbstractException.php
index 73a17076..5a575c34 100644
--- a/lib/AbstractException.php
+++ b/lib/AbstractException.php
@@ -100,6 +100,7 @@ abstract class AbstractException extends \Exception {
         "ImportExport/Exception.invalidFolderName"    => 10613,
         "ImportExport/Exception.invalidFolderCopy"    => 10614,
         "ImportExport/Exception.invalidTagName"       => 10615,
+        "Rule/Exception.invalidPattern"               => 10701,
     ];
 
     public function __construct(string $msgID = "", $vars = null, \Throwable $e = null) {
diff --git a/lib/Feed.php b/lib/Feed.php
index 81256a63..da01d2f0 100644
--- a/lib/Feed.php
+++ b/lib/Feed.php
@@ -79,10 +79,14 @@ class Feed {
             // we only really care if articles have been modified; if there are no new articles, act as if the feed is unchanged
             if (!sizeof($this->newItems) && !sizeof($this->changedItems)) {
                 $this->modified = false;
-            }
-            // if requested, scrape full content for any new and changed items
-            if ($scrape) {
-                $this->scrape();
+            } else {
+                if ($feedID) {
+                    $this->computeFilterRules($feedID);
+                }
+                // if requested, scrape full content for any new and changed items
+                if ($scrape) {
+                    $this->scrape();
+                }
             }
         }
         // compute the time at which the feed should next be fetched
@@ -119,7 +123,7 @@ class Feed {
         }
     }
 
-    protected function parse(): bool {
+    protected function parse(): void {
         try {
             $feed = $this->resource->reader->getParser(
                 $this->resource->getUrl(),
@@ -222,7 +226,6 @@ class Feed {
             sort($f->categories);
         }
         $this->data = $feed;
-        return true;
     }
 
     protected function deduplicateItems(array $items): array {
@@ -269,13 +272,13 @@ class Feed {
         return $out;
     }
 
-    protected function matchToDatabase(int $feedID = null): bool {
+    protected function matchToDatabase(int $feedID = null): void {
         // first perform deduplication on items
         $items = $this->deduplicateItems($this->data->items);
         // if we haven't been given a database feed ID to check against, all items are new
         if (is_null($feedID)) {
             $this->newItems = $items;
-            return true;
+            return;
         }
         // get as many of the latest articles in the database as there are in the feed
         $articles = Arsse::$db->feedMatchLatest($feedID, sizeof($items))->getAll();
@@ -303,7 +306,6 @@ class Feed {
             // merge the two change-lists, preserving keys
             $this->changedItems = array_combine(array_merge(array_keys($this->changedItems), array_keys($changed)), array_merge($this->changedItems, $changed));
         }
-        return true;
     }
 
     protected function matchItems(array $items, array $articles): array {
@@ -438,7 +440,7 @@ class Feed {
         return $dates;
     }
 
-    protected function scrape(): bool {
+    protected function scrape(): void {
         $scraper = new Scraper(self::configure());
         foreach (array_merge($this->newItems, $this->changedItems) as $item) {
             $scraper->setUrl($item->url);
@@ -447,6 +449,17 @@ class Feed {
                 $item->content = $scraper->getFilteredContent();
             }
         }
-        return true;
+    }
+
+    protected function computeFilterRules(int $feedID): void {
+        return;
+        $rules = Arsse::$db->feedRulesGet($feedID);
+        foreach ($rules as $r) {
+            $keep = "";
+            $block = "";
+            if (strlen($r['keep'])) {
+                
+            }
+        }
     }
 }
diff --git a/lib/Rule/Exception.php b/lib/Rule/Exception.php
new file mode 100644
index 00000000..e3c66645
--- /dev/null
+++ b/lib/Rule/Exception.php
@@ -0,0 +1,10 @@
+<?php
+/** @license MIT
+ * Copyright 2017 J. King, Dustin Wilson et al.
+ * See LICENSE and AUTHORS files for details */
+
+declare(strict_types=1);
+namespace JKingWeb\Arsse\Rule;
+
+class Exception extends \JKingWeb\Arsse\AbstractException {
+}
\ No newline at end of file
diff --git a/lib/Rule/Rule.php b/lib/Rule/Rule.php
new file mode 100644
index 00000000..90b0bbec
--- /dev/null
+++ b/lib/Rule/Rule.php
@@ -0,0 +1,31 @@
+<?php
+/** @license MIT
+ * Copyright 2017 J. King, Dustin Wilson et al.
+ * See LICENSE and AUTHORS files for details */
+
+declare(strict_types=1);
+namespace JKingWeb\Arsse\Rule;
+
+abstract class Rule {
+    public static function prep(string $pattern): string {
+        if (preg_match_all("<`>", $pattern, $m, \PREG_OFFSET_CAPTURE)) {
+            // where necessary escape our chosen delimiter (backtick) in reverse order
+            foreach (array_reverse($m[0]) as [,$pos]) {
+                // count the number of backslashes preceding the delimiter character
+                $count = 0;
+                $p = $pos;
+                while ($p-- && $pattern[$p] === "\\" && ++$count);
+                // if the number is even (including zero), add a backslash
+                if ($count % 2 === 0) {
+                    $pattern = substr($pattern, 0, $pos)."\\".substr($pattern, $pos);
+                }
+            }
+        }
+        // add the delimiters and test the pattern
+        $pattern = "`$pattern`u";
+        if (@preg_match($pattern, "") === false) {
+            throw new Exception("invalidPattern");
+        }
+        return $pattern;
+    }
+}
\ No newline at end of file
diff --git a/locale/en.php b/locale/en.php
index d67547aa..1927eaf7 100644
--- a/locale/en.php
+++ b/locale/en.php
@@ -194,4 +194,5 @@ return [
     'Exception.JKingWeb/Arsse/ImportExport/Exception.invalidFolderName'    => 'Input data contains an invalid folder name',
     'Exception.JKingWeb/Arsse/ImportExport/Exception.invalidFolderCopy'    => 'Input data contains multiple folders of the same name under the same parent',
     'Exception.JKingWeb/Arsse/ImportExport/Exception.invalidTagName'       => 'Input data contains an invalid tag name',
+    'Exception.JKingWeb/Arsse/Rule/Exception.invalidPattern'               => 'Specified rule pattern is invalid'
 ];
diff --git a/tests/cases/Misc/TestRule.php b/tests/cases/Misc/TestRule.php
new file mode 100644
index 00000000..804b1724
--- /dev/null
+++ b/tests/cases/Misc/TestRule.php
@@ -0,0 +1,22 @@
+<?php
+/** @license MIT
+ * Copyright 2017 J. King, Dustin Wilson et al.
+ * See LICENSE and AUTHORS files for details */
+
+declare(strict_types=1);
+namespace JKingWeb\Arsse\TestCase\Misc;
+
+use JKingWeb\Arsse\Rule\Rule;
+
+/** @covers \JKingWeb\Arsse\Rule\Rule */
+class TestRule extends \JKingWeb\Arsse\Test\AbstractTest {
+    public function testPrepareAPattern(): void {
+        $exp = "`\\`..\\`..\\`..\\\\\\`..`u";
+        $this->assertSame($exp, Rule::prep("`..`..\\`..\\\\`.."));
+    }
+
+    public function testPrepareAnInvalidPattern(): void {
+        $this->assertException("invalidPattern", "Rule");
+        Rule::prep("[");
+    }
+}
\ No newline at end of file
diff --git a/tests/phpunit.dist.xml b/tests/phpunit.dist.xml
index 18486652..0875bf54 100644
--- a/tests/phpunit.dist.xml
+++ b/tests/phpunit.dist.xml
@@ -51,6 +51,7 @@
         <file>cases/Misc/TestContext.php</file>
         <file>cases/Misc/TestURL.php</file>
         <file>cases/Misc/TestHTTP.php</file>
+        <file>cases/Misc/TestRule.php</file>
     </testsuite>
     <testsuite name="User management">
         <file>cases/User/TestInternal.php</file>