From 32b48aeb75db4ad40fe0173614e585f9bee72257 Mon Sep 17 00:00:00 2001
From: Mike Buland <eichlan@xagasoft.com>
Date: Thu, 1 Dec 2016 11:16:25 -0700
Subject: Found a big problem with order of operations.

I believe this is because I'm using right tail recursion, but I'm not really
sure how I could change it for this program.

order of operations is being observed perfectly, but then operations are being
performed from right to left, not left to right.  I think I may be reducing
too frequently, honestly.
---
 src/parser.cpp       | 38 +++++++++++++++++++++++++-------------
 src/parser.h         |  1 +
 src/scriptengine.cpp | 24 ++++++++++++++++++++----
 src/token.h          |  1 -
 4 files changed, 46 insertions(+), 18 deletions(-)

(limited to 'src')

diff --git a/src/parser.cpp b/src/parser.cpp
index c7cf994..701c4bd 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -20,8 +20,7 @@ Parser::~Parser()
 Expression *Parser::parse()
 {
     pCurExp = new Expression();
-    exprR();
-    reduce();
+    statement();
 
     printState("Final");
 
@@ -40,7 +39,7 @@ void Parser::exprR()
 
 void Parser::expr()
 {
-    //Bu::sio << "::expr " << lex[0] << Bu::sio.nl;
+    Bu::sio << "::expr " << lex[0] << Bu::sio.nl;
     if( lex[0].eType == Token::tEndOfInput )
         return;
 
@@ -57,7 +56,7 @@ void Parser::expr()
         case Token::tModulus:
             Token t = lex[0];
             lex.nextToken();
-            //Bu::sio << "->expr " << t << " " << lex[0] << Bu::sio.nl;
+            Bu::sio << "->expr " << t << " " << lex[0] << Bu::sio.nl;
             if( lex[0].eType == Token::tOpenParen )
             {
                 exprP();
@@ -70,10 +69,10 @@ void Parser::expr()
                 if( lex[0].eType == Token::tNumber ||
                     lex[0].eType == Token::tVariable )
                 {
-                    //Bu::sio << "->expr " << t <<
-                    //    " " << lex[0] <<
-                    //    " " << lex[1] <<
-                    //    Bu::sio.nl;
+                    Bu::sio << "->expr " << t <<
+                        " " << lex[0] <<
+                        " " << lex[1] <<
+                        Bu::sio.nl;
                     shift( lex[0] );
                     if( lex[1].eType&Token::mMetaOperator )
                     {
@@ -111,14 +110,14 @@ void Parser::expr()
                 else if( lex[0].eType == Token::tMinus )
                 {
                     // This is negation
-                    //Bu::sio << "next token: " << lex[0] << Bu::sio.nl;
+                    Bu::sio << "next token: " << lex[0] << Bu::sio.nl;
                     printState("inline-negate");
                     exprP();
                     printState("inline-negate-post");
                     shift( t );
                     printState("inline-negate-post2");
 
-                    //Bu::sio << "??? " << lex[0] << Bu::sio.nl;
+                    Bu::sio << "??? " << lex[0] << Bu::sio.nl;
                 }
             }
             break;
@@ -157,7 +156,7 @@ void Parser::exprP()
             exprR();
             if( lex[0].eType != Token::tCloseParen )
             {
-                //Bu::sio << "::exprP " << lex[0] << Bu::sio.nl;
+                Bu::sio << "::exprP " << lex[0] << Bu::sio.nl;
                 throw Bu::ExceptionBase("Expected close paren");
             }
             shift( lex[0] );
@@ -175,6 +174,21 @@ void Parser::exprP()
             break;
     }
 }
+
+void Parser::statement()
+{
+    if( lex[0].eType == Token::tCommand )
+    {
+        lex.setMode( Lexer::modeCommand );
+        lex.setMode( Lexer::modeNormal );
+    }
+    else
+    {
+        exprR();
+        reduce();
+    }
+}
+
 /*
 case Token::tCommand:
     lex.setMode( Lexer::modeCommand );
@@ -403,7 +417,6 @@ int Parser::getPriority( Token::Type eType )
 
 void Parser::printState( const Bu::String &sTag )
 {
-    /*
     Bu::sio << "----------------" << Bu::sio.nl;
     Bu::sio << sTag << " stack:";
     for( TokenStack::iterator i = tsParse.begin(); i; i++ )
@@ -418,6 +431,5 @@ void Parser::printState( const Bu::String &sTag )
     }
     Bu::sio << Bu::sio.nl;
     Bu::sio << "----------------" << Bu::sio.nl;
-    */
 }
 
diff --git a/src/parser.h b/src/parser.h
index 1e0d1c4..60dd8e1 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -55,6 +55,7 @@ private:
     void expr();
     void exprP();
     void exprR();
+    void statement();
 
 private:
     void shift( const Token &t );
diff --git a/src/scriptengine.cpp b/src/scriptengine.cpp
index 7b5df03..b828409 100644
--- a/src/scriptengine.cpp
+++ b/src/scriptengine.cpp
@@ -56,19 +56,35 @@ Number ScriptEngine::exec( Expression *pExpr )
                 break;
 
             case Token::tPlus:
-                sNums.push( sNums.peekPop() + sNums.peekPop() );
+                {
+                    Number a = sNums.peekPop();
+                    Number b = sNums.peekPop();
+                    sNums.push( a + b );
+                }
                 break;
 
             case Token::tMinus:
-                sNums.push( sNums.peekPop() - sNums.peekPop() );
+                {
+                    Number a = sNums.peekPop();
+                    Number b = sNums.peekPop();
+                    sNums.push( a - b );
+                }
                 break;
 
             case Token::tDivide:
-                sNums.push( sNums.peekPop() / sNums.peekPop() );
+                {
+                    Number a = sNums.peekPop();
+                    Number b = sNums.peekPop();
+                    sNums.push( a / b );
+                }
                 break;
 
             case Token::tMultiply:
-                sNums.push( sNums.peekPop() * sNums.peekPop() );
+                {
+                    Number a = sNums.peekPop();
+                    Number b = sNums.peekPop();
+                    sNums.push( a * b );
+                }
                 break;
 
             case Token::tNegate:
diff --git a/src/token.h b/src/token.h
index 4ad1136..5bede41 100644
--- a/src/token.h
+++ b/src/token.h
@@ -40,7 +40,6 @@ public:
         mMetaOperator   = 0x4000,
         mMetaAltOp      = 0x8000,
         mMetaMeta       = 0x0100,
-
     };
 
     Token();
-- 
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