1 files changed, 50 insertions, 7 deletions

diff --git a/src/tools/parser.cpp b/src/tools/parser.cpp
index e4fc95f..76d4a72 100644
--- a/src/tools/parser.cpp
+++ b/src/tools/parser.cpp
@@ -157,15 +157,44 @@ void redPrint( Bu::Parser &p )
 {
 }
 
+/* Basic grammer example:
+ *
+ * input: expr '='
+ *      ;
+ *
+ * expr: expr '+' expr
+ *     | '(' expr ')'
+ *     | NUMBER
+ *     ;
+ *
+ * The problem is, that we can't actually make something left hand recursive,
+ * so we break it into two exprs:
+ *
+ * expr': '(' expr ')'
+ *      | NUMBER
+ *      ;
+ *
+ * expr: expr' expr''
+ *     ;
+ *
+ * expr'': '+' expr
+ *       |
+ *       ;
+ *
+ * 5 + 5 + 5 =
+ */
+
 int main( int argc, char *argv[] )
 {
         File fIn( argv[1], File::Read );
 
         Parser p;
 
+        p.addNonTerminal("expr");
+        p.addNonTerminal("expr'");
+        p.addNonTerminal("expr''");
         {
                 Parser::NonTerminal nt;
-                int iSelf = p.addNonTerminal("expr");
                 nt.addProduction(
                         Parser::Production(
                                 Parser::State(
@@ -175,7 +204,7 @@ int main( int argc, char *argv[] )
                                 ).append(
                                 Parser::State(
                                         Parser::State::typeNonTerminal,
-                                        iSelf
+                                        p.getNonTerminalId("expr")
                                         )
                                 ).append(
                                 Parser::State(
@@ -185,9 +214,11 @@ int main( int argc, char *argv[] )
                                 )
                         );
                 nt.addProduction(
-                        Parser::Production()
+                        Parser::Production(
+                                )
                         );
-                p.addNonTerminal( "expr", nt );
+                nt.setCanSkip();
+                p.setNonTerminal("expr''", nt );
         }
         {
                 Parser::NonTerminal nt;
@@ -197,14 +228,26 @@ int main( int argc, char *argv[] )
                                         Parser::State::typeTerminalPush,
                                         tokNumber
                                         )
+                                )
+                        );
+                p.setNonTerminal("expr'", nt );
+        }
+        {
+                Parser::NonTerminal nt;
+                nt.addProduction(
+                        Parser::Production(
+                                Parser::State(
+                                        Parser::State::typeNonTerminal,
+                                        p.getNonTerminalId("expr'")
+                                        )
                                 ).append(
                                 Parser::State(
                                         Parser::State::typeNonTerminal,
-                                        p.getNonTerminalId("expr")
+                                        p.getNonTerminalId("expr''")
                                         )
                                 )
                         );
-                p.addNonTerminal( "expr'", nt );
+                p.setNonTerminal("expr", nt );
         }
         {
                 Parser::NonTerminal nt;
@@ -212,7 +255,7 @@ int main( int argc, char *argv[] )
                         Parser::Production(
                                 Parser::State(
                                         Parser::State::typeNonTerminal,
-                                        p.getNonTerminalId("expr'")
+                                        p.getNonTerminalId("expr")
                                         )
                                 ).append(
                                 Parser::State(