From 45a378231bd82e15d152edb3c882bb6aafce60d6 Mon Sep 17 00:00:00 2001
From: "zik.saleeba" <zik.saleeba@21eae674-98b7-11dd-bd71-f92a316d2d60>
Date: Sun, 29 Mar 2009 11:08:03 +0000
Subject: [PATCH] More work on expressions

git-svn-id: http://picoc.googlecode.com/svn/trunk@213 21eae674-98b7-11dd-bd71-f92a316d2d60
---
 expression.c | 19 +++++++++++++++----
 picoc.h      |  3 ++-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/expression.c b/expression.c
index 1da7a60..f9f1ca5 100644
--- a/expression.c
+++ b/expression.c
@@ -422,6 +422,7 @@ int ExpressionParse(struct ParseState *Parser, struct Value **Result)
 
 enum OperatorOrder
 {
+    OrderNone,
     OrderPrefix,
     OrderInfix,
     OrderPostfix
@@ -447,6 +448,7 @@ struct OpPrecedence
 
 static struct OpPrecedence OperatorPrecedence[] =
 {
+    /* TokenNone, */ { 0, 0, 0 },
     /* TokenComma, */ { 0, 0, 1 },
     /* TokenAssign, */ { 0, 0, 2 }, /* TokenAddAssign, */ { 0, 0, 2 }, /* TokenSubtractAssign, */ { 0, 0, 2 }, 
     /* TokenMultiplyAssign, */ { 0, 0, 2 }, /* TokenDivideAssign, */ { 0, 0, 2 }, /* TokenModulusAssign, */ { 0, 0, 2 },
@@ -734,7 +736,7 @@ void ExpressionStackCollapse(struct ParseState *Parser, struct ExpressionStack *
     struct ExpressionStack *TopStackNode = *StackTop;
     struct ExpressionStack *TopOperatorNode;
     
-    while (TopStackNode != NULL && FoundPrecedence >= Precedence)
+    while (TopStackNode != NULL && TopStackNode->Next != NULL && FoundPrecedence >= Precedence)
     {
         /* find the top operator on the stack */
         if (TopStackNode->Val != NULL)
@@ -743,7 +745,7 @@ void ExpressionStackCollapse(struct ParseState *Parser, struct ExpressionStack *
             TopOperatorNode = TopStackNode;
         
         /* does it have a high enough precedence? */
-        if (FoundPrecedence >= Precedence)
+        if (FoundPrecedence >= Precedence && TopOperatorNode != NULL)
         {
             /* execute this operator */
             switch (TopOperatorNode->Order)
@@ -783,6 +785,9 @@ void ExpressionStackCollapse(struct ParseState *Parser, struct ExpressionStack *
                     /* do the infix operation */
                     ExpressionInfixOperator(Parser, StackTop, TopOperatorNode->Op, BottomValue, TopValue);
                     break;
+
+                case OrderNone:
+                    break;
             }
         }
     }
@@ -803,7 +808,7 @@ void ExpressionStackPushOperator(struct ParseState *Parser, struct ExpressionSta
 int ExpressionParse(struct ParseState *Parser, struct Value **Result)
 {
     struct Value *LexValue;
-    int PrefixState = FALSE;
+    int PrefixState = TRUE;
     int Done = FALSE;
     int BracketPrecedence = 0;
     int LocalPrecedence;
@@ -906,7 +911,13 @@ int ExpressionParse(struct ParseState *Parser, struct Value **Result)
     
     /* scan and collapse the stack to precedence 0 */
     ExpressionStackCollapse(Parser, &StackTop, 0);
-    //XXX - fix up the stack and return the result if we're in run mode
+    
+    /* fix up the stack and return the result if we're in run mode */
+    if (StackTop != NULL)
+    {
+        /* all that should be left is a single value on the stack */
+        HeapPopStack((void *)StackTop - sizeof(struct ExpressionStack), sizeof(struct ExpressionStack));
+    }
     
     return TRUE;
 }
diff --git a/picoc.h b/picoc.h
index faaad7b..5599357 100644
--- a/picoc.h
+++ b/picoc.h
@@ -31,6 +31,7 @@ struct Table;
 /* lexical tokens */
 enum LexToken
 {
+    TokenNone, 
     TokenComma,
     TokenAssign, TokenAddAssign, TokenSubtractAssign, TokenMultiplyAssign, TokenDivideAssign, TokenModulusAssign,
     TokenShiftLeftAssign, TokenShiftRightAssign, TokenArithmeticAndAssign, TokenArithmeticOrAssign, TokenArithmeticExorAssign,
@@ -55,7 +56,7 @@ enum LexToken
     TokenLongType, TokenSignedType, TokenShortType, TokenStructType, TokenUnionType, TokenUnsignedType, TokenTypedef,
     TokenContinue, TokenDo, TokenElse, TokenFor, TokenIf, TokenWhile, TokenBreak, TokenSwitch, TokenCase, TokenDefault, TokenReturn,
     TokenHashDefine, TokenHashInclude, TokenNew, TokenDelete,
-    TokenNone, TokenEOF, TokenEndOfLine, TokenEndOfFunction
+    TokenEOF, TokenEndOfLine, TokenEndOfFunction
 };
 
 /* used in dynamic memory allocation */