Support large opds result listings without an OOM

lib/OpdsParser/OpdsParser.cpp

@@ -146,7 +146,6 @@ void OpdsParser::flush() {
 bool OpdsParser::error() const { return errorOccured; }
 
 void OpdsParser::clear() {
-  entries.clear();
   searchTemplate.clear();
   osdUrl.clear();
   nextPageUrl.clear();
@@ -156,14 +155,6 @@ void OpdsParser::clear() {
   inEntry = inTitle = inAuthor = inAuthorName = inId = false;
 }
 
-std::vector<OpdsEntry> OpdsParser::getBooks() const {
-  std::vector<OpdsEntry> books;
-  for (const auto& entry : entries) {
-    if (entry.type == OpdsEntryType::BOOK) books.push_back(entry);
-  }
-  return books;
-}
-
 const char* OpdsParser::findAttribute(const XML_Char** atts, const char* name) {
   for (int i = 0; atts[i]; i += 2) {
     if (strcmp(atts[i], name) == 0) return atts[i + 1];
@@ -243,7 +234,7 @@ void XMLCALL OpdsParser::endElement(void* userData, const XML_Char* name) {
 
   if (strcmp(name, "entry") == 0 || strstr(name, ":entry") != nullptr) {
     if (!self->currentEntry.title.empty() && !self->currentEntry.href.empty()) {
-      self->entries.push_back(self->currentEntry);
+      if (self->onEntryParsed) self->onEntryParsed(self->currentEntry);
     }
     self->inEntry = false;
   } else if (self->inEntry) {

lib/OpdsParser/OpdsParser.h

@@ -2,6 +2,7 @@
 #include <Print.h>
 #include <expat.h>
 
+#include <functional>
 #include <string>
 #include <vector>
 
@@ -73,24 +74,13 @@ class OpdsParser final : public Print {
 
   operator bool() { return !error(); }
 
-  /**
-   * Get the parsed entries (both navigation and book entries).
-   * @return Vector of OpdsEntry entries
-   */
-  const std::vector<OpdsEntry>& getEntries() const& { return entries; }
-  std::vector<OpdsEntry> getEntries() && { return std::move(entries); }
-
-  /**
-   * Get only book entries (legacy compatibility).
-   * @return Vector of book entries
-   */
-  std::vector<OpdsEntry> getBooks() const;
-
   /**
    * Clear all parsed entries.
    */
   void clear();
 
+  std::function<void(OpdsEntry)> onEntryParsed;
+
  private:
   // Expat callbacks
   static void XMLCALL startElement(void* userData, const XML_Char* name, const XML_Char** atts);
@@ -105,7 +95,6 @@ class OpdsParser final : public Print {
   static const char* findAttribute(const XML_Char** atts, const char* name);
 
   XML_Parser parser = nullptr;
-  std::vector<OpdsEntry> entries;
   OpdsEntry currentEntry;
   std::string currentText;