From 6b4448ec8a8fdc059c09df9da4bddfb83be4ac57 Mon Sep 17 00:00:00 2001
From: Paul Beckingham <paul@beckingham.net>
Date: Sun, 27 Dec 2015 11:57:19 -0500
Subject: [PATCH] LR0: Implemented the LR0::Item object

---
 src/LR0.cpp | 26 +++++++++++++++++++++++++-
 src/LR0.h   | 12 +++++++-----
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/src/LR0.cpp b/src/LR0.cpp
index d0f5317b..db1a73d9 100644
--- a/src/LR0.cpp
+++ b/src/LR0.cpp
@@ -57,19 +57,23 @@ void LR0::createParseTables (const Grammar& grammar)
 
   // Add all items from augmented grammar, in initial state:
   //   A --> . B ....
+/*
   LR0::Closure closure;
   for (unsigned int i = 0; i < augmented.size (); ++i)
     closure.push_back (LR0::Item (i, 0));
   LR0::States states;
   states.push_back (closure);
-
+*/
   // Iteratively expand non-terminals until there are no more.
+/*
   int state = 0;
   while (expandNonTerminals (augmented, states, state))
     ;
+*/
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+/*
 bool LR0::expandNonTerminals (
   std::vector <std::vector <std::string>>& augmented,
   LR0::States& states,
@@ -83,6 +87,7 @@ bool LR0::expandNonTerminals (
 
   return false;
 }
+*/
 
 ////////////////////////////////////////////////////////////////////////////////
 void LR0::parse (const std::string& input)
@@ -115,6 +120,7 @@ std::string LR0::dump () const
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+/*
 std::string LR0::dump (std::vector <std::vector <std::string>>& augmented, States& states) const
 {
   std::stringstream out;
@@ -149,5 +155,23 @@ std::string LR0::dump (std::vector <std::vector <std::string>>& augmented, State
   out << "\n";
   return out.str ();
 }
+*/
+
+////////////////////////////////////////////////////////////////////////////////
+LR0::Item::Item (std::vector <std::string>& rule)
+: _rule (rule)
+, _cursor (2)
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////
+bool LR0::Item::advance ()
+{
+  if (_cursor >= _rule.size ())
+    return false;
+
+  ++_cursor;
+  return true;
+}
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/LR0.h b/src/LR0.h
index 95d7aac1..46224bbd 100644
--- a/src/LR0.h
+++ b/src/LR0.h
@@ -44,10 +44,12 @@ protected:
   class Item
   {
   public:
-    Item (int rule, int cursor) : _rule (rule), _cursor (cursor) {}
+    Item (std::vector <std::string>&);
+    bool advance ();
 
-    int _rule;
-    int _cursor;
+  private:
+    std::vector <std::string> _rule;
+    unsigned int _cursor;
   };
 
   class Closure : public std::vector <Item>
@@ -59,8 +61,8 @@ protected:
   };
 
 private:
-  bool expandNonTerminals (std::vector <std::vector <std::string>>&, States&, int);
-  std::string dump (std::vector <std::vector <std::string>>&, States&) const;
+//  bool expandNonTerminals (std::vector <std::vector <std::string>>&, States&, int);
+//  std::string dump (std::vector <std::vector <std::string>>&, States&) const;
 
 private:
   //        state         column        result