Simplify feed entries filtering

- Rename processor package to filter
- Remove boilerplate code

reader/filter/filter.go

@@ -0,0 +1,36 @@
+// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package filter
+
+import (
+	"miniflux.app/logger"
+	"miniflux.app/model"
+	"miniflux.app/reader/rewrite"
+	"miniflux.app/reader/sanitizer"
+	"miniflux.app/reader/scraper"
+	"miniflux.app/storage"
+)
+
+// Apply executes all entry filters.
+func Apply(store *storage.Storage, feed *model.Feed) {
+	for _, entry := range feed.Entries {
+		if feed.Crawler {
+			if !store.EntryURLExists(feed.UserID, entry.URL) {
+				content, err := scraper.Fetch(entry.URL, feed.ScraperRules, feed.UserAgent)
+				if err != nil {
+					logger.Error("Unable to crawl this entry: %q => %v", entry.URL, err)
+				} else {
+					// We replace the entry content only if the scraper doesn't return any error.
+					entry.Content = content
+				}
+			}
+		}
+
+		entry.Content = rewrite.Rewriter(entry.URL, entry.Content, feed.RewriteRules)
+
+		// The sanitizer should always run at the end of the process to make sure unsafe HTML is filtered.
+		entry.Content = sanitizer.Sanitize(entry.URL, entry.Content)
+	}
+}