2 files changed, 65 insertions, 0 deletions
diff --git a/src/parse/lex.cpp b/src/parse/lex.cpp
index a3e8c0d0..0e928bf2 100644
--- a/src/parse/lex.cpp
+++ b/src/parse/lex.cpp
@@ -1205,6 +1205,53 @@ Position TTStream::getPosition() const
     return Position("TTStream", 0,0);
 }
 
+
+TTStreamO::TTStreamO(TokenTree input_tt):
+    m_input_tt( mv$(input_tt) )
+{
+    m_stack.push_back( ::std::make_pair(0, nullptr) );
+}
+TTStreamO::~TTStreamO()
+{
+}
+Token TTStreamO::realGetToken()
+{
+    while(m_stack.size() > 0)
+    {
+        // If current index is above TT size, go up
+        unsigned int& idx = m_stack.back().first;
+        const TokenTree& tree = *( m_stack.back().second ? m_stack.back().second : &m_input_tt );
+
+        if(idx == 0 && tree.is_token()) {
+            idx ++;
+            m_last_pos = tree.tok().get_pos();
+            return tree.tok();
+        }
+
+        if(idx < tree.size())
+        {
+            const TokenTree&    subtree = tree[idx];
+            idx ++;
+            if( subtree.size() == 0 ) {
+                m_last_pos = subtree.tok().get_pos();
+                return subtree.tok();
+            }
+            else {
+                m_stack.push_back( ::std::make_pair(0, &subtree ) );
+            }
+        }
+        else {
+            m_stack.pop_back();
+        }
+    }
+    return Token(TOK_EOF);
+}
+Position TTStreamO::getPosition() const
+{
+    return m_last_pos;
+}
+
+
 TokenStream::TokenStream():
     m_cache_valid(false)
 {
diff --git a/src/parse/tokentree.hpp b/src/parse/tokentree.hpp
index 6b54e66e..257bd6ad 100644
--- a/src/parse/tokentree.hpp
+++ b/src/parse/tokentree.hpp
@@ -60,6 +60,24 @@ protected:
     virtual Token realGetToken() override;
 };
 
+class TTStreamO:
+    public TokenStream
+{
+    Position    m_last_pos;
+    const TokenTree m_input_tt;
+    ::std::vector< ::std::pair<unsigned int, const TokenTree*> > m_stack;
+public:
+    TTStreamO(const TokenTree input_tt);
+    ~TTStreamO();
+
+    TTStreamO& operator=(const TTStreamO& x) { m_stack = x.m_stack; return *this; }
+    
+    virtual Position getPosition() const override;
+
+protected:
+    virtual Token realGetToken() override;
+};
+
 // unwrapped = Exclude the enclosing brackets (used by macro parse code)
 extern TokenTree Parse_TT(TokenStream& lex, bool unwrapped);
 extern TokenTree Parse_TT_Pattern(TokenStream& lex);