Compute closure of item sets under symbol expansion

src/lr/item_set.cpp

@@ -1,13 +1,62 @@
 #include "item_set.h"
 
+#include <iostream>
+
+using namespace std;
+
 namespace tree_sitter {
     namespace lr {
-        ItemSet::ItemSet(const Item &item, const Grammar &grammar) {
-
-        }
+        ItemSet::ItemSet(const vector<Item> &items) : contents(items) {}
+        ItemSet::ItemSet(const initializer_list<Item> &items) : contents(items) {}
         
         TransitionMap<ItemSet> ItemSet::transitions() const {
             return TransitionMap<ItemSet>();
         }
+        
+        bool vector_contains(vector<Item> items, lr::Item item) {
+            return (std::find(items.begin(), items.end(), item) != items.end());
+        }
+        
+        void add_item(vector<Item> &vector, const Item &item, Grammar &grammar) {
+            if (!vector_contains(vector, item)) {
+                vector.push_back(item);
+                for (rules::sym_ptr rule : item.next_symbols()) {
+                    Item next_item = Item::at_beginning_of_rule(rule->name, grammar);
+                    add_item(vector, next_item, grammar);
+                }
+            }
+        }
+
+        ItemSet ItemSet::closure_in_grammar(Grammar &grammar) const {
+            vector<Item> items;
+            for (Item item : *this)
+                add_item(items, item, grammar);
+            return ItemSet(items);
+        }
+        
+#pragma mark - container
+        ItemSet::const_iterator ItemSet::begin() const {
+            return contents.begin();
+        }
+
+        ItemSet::const_iterator ItemSet::end() const {
+            return contents.end();
+        }
+
+        size_t ItemSet::size() const {
+            return contents.size();
+        }
+        
+#pragma mark - printing
+        ostream& operator<<(ostream &stream, const ItemSet &item_set) {
+            stream << string("(item_set ");
+            for (Item item : item_set) {
+                stream << item;
+                stream << string(" ");
+            }
+            stream << string(")");
+            return stream;
+        }
+        
     }
-}
+}