Add filter_result_iterator_t::contains_atleast_one.

include/filter.h

@@ -2,6 +2,7 @@
 
 #include <string>
 #include <map>
+#include "posting_list.h"
 #include "index.h"
 
 class filter_result_iterator_t {
@@ -92,4 +93,6 @@ public:
     /// Advances the iterator until the doc value reaches or just overshoots id. The iterator may become invalid during
     /// this operation.
     void skip_to(uint32_t id);
+
+    bool contains_atleast_one(const void* obj);
 };

src/filter.cpp

@@ -502,3 +502,45 @@ Option<bool> filter_result_iterator_t::init_status() {
 
     return status;
 }
+
+bool filter_result_iterator_t::contains_atleast_one(const void *obj) {
+    if(IS_COMPACT_POSTING(obj)) {
+        compact_posting_list_t* list = COMPACT_POSTING_PTR(obj);
+
+        size_t i = 0;
+        while(i < list->length && valid()) {
+            size_t num_existing_offsets = list->id_offsets[i];
+            size_t existing_id = list->id_offsets[i + num_existing_offsets + 1];
+
+            if (existing_id == seq_id) {
+                return true;
+            }
+
+            // advance smallest value
+            if (existing_id < seq_id) {
+                i += num_existing_offsets + 2;
+            } else {
+                skip_to(existing_id);
+            }
+        }
+    } else {
+        auto list = (posting_list_t*)(obj);
+        posting_list_t::iterator_t it = list->new_iterator();
+
+        while(it.valid() && valid()) {
+            uint32_t id = it.id();
+
+            if(id == seq_id) {
+                return true;
+            }
+
+            if(id < seq_id) {
+                it.skip_to(seq_id);
+            } else {
+                skip_to(id);
+            }
+        }
+    }
+
+    return false;
+}