Begin implementation of expressions and stack

Makefile

@@ -3,6 +3,9 @@ NAME=abCalc
 
 all: $(NAME)
 
+abCalcExpr.o: abCalcExpr.h
+abCalcStack.o: abCalcExpr.h abCalcStack.h
+
 $(NAME): $(OBJS)
 	cc -o $(NAME) $(OBJS)
 

abCalcExpr.c

@@ -1 +1,61 @@
+/* 
+    abCalcExpr.c
+        By: Jeremy Rand
+ */
+
+
+#include <stdlib.h>
+
 #include "abCalcExpr.h"
+
+
+static abCalcExprCallbacks *gCallbacks[abCalcExprTypeMax];
+
+
+#define AB_CALC_EXPR_TYPE_INVALID(type) (((type) < abCalcExprTypeMin) || ((type) >= abCalcExprTypeMax))
+
+void abCalcExprInit(void)
+{
+    abCalcExprType type;
+
+    for (type = abCalcExprTypeMin; type < abCalcExprTypeMax; type++) {
+        gCallbacks[type] = NULL;
+    }
+}
+
+
+void abCalcRegisterExprType(abCalcExprType type, abCalcExprCallbacks *callbacks)
+{
+    if (AB_CALC_EXPR_TYPE_INVALID(type))
+        return;
+
+    gCallbacks[type] = callbacks;
+}
+
+
+abCalcExpr *abCalcParseExpr(abCalcExpr *expr, char *buffer)
+{
+    abCalcExpr *result = NULL;
+    abCalcExprType type;
+
+    for (type = abCalcExprTypeMin; type < abCalcExprTypeMax; type++) {
+        if (gCallbacks[type] != NULL) {
+            result = (gCallbacks[type]->parseExpr)(expr, buffer);
+            if (result != NULL)
+                return result;
+        }
+    }
+    return result;
+}
+
+
+char *abCalcFormatExpr(abCalcExpr *expr, char *buffer)
+{
+    if (AB_CALC_EXPR_TYPE_INVALID(expr->type))
+        return NULL;
+
+    if (gCallbacks[expr->type] == NULL)
+        return NULL;
+
+    return (gCallbacks[expr->type]->formatExpr(expr, buffer));
+}

abCalcExpr.h

@@ -5,8 +5,11 @@
 
 
 typedef enum abCalcExprType {
-    abCalcExprTypeReal,
+    abCalcExprTypeMin = 0,
-    abCalcExprTypeInt
+    abCalcExprTypeReal = 0,
+    abCalcExprTypeInt,
+
+    abCalcExprTypeMax
 } abCalcExprType;
 
 
@@ -24,5 +27,13 @@ typedef struct abCalcExpr {
 
 
 typedef struct abCalcExprCallbacks {
-    abCalcExpr * (*parseExpression)(abCalcExpr *expr, char *buffer);
+    abCalcExpr * (*parseExpr)(abCalcExpr *expr, char *buffer);
+    char * (*formatExpr)(abCalcExpr *expr, char *buffer);
 } abCalcExprCallbacks;
+
+
+void abCalcExprInit(void);
+void abCalcRegisterExprType(abCalcExprType type, abCalcExprCallbacks *callbacks);
+
+abCalcExpr *abCalcParseExpr(abCalcExpr *expr, char *buffer);
+char *abCalcFormatExpr(abCalcExpr *expr, char *buffer);

abCalcStack.c

@@ -0,0 +1,66 @@
+/* 
+    abCalcStack.c
+        By: Jeremy Rand
+ */
+
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "abCalcStack.h"
+
+
+#define AB_CALC_STACK_DEPTH 128
+
+
+static abCalcExpr gStack[AB_CALC_STACK_DEPTH];
+static int gStackNumItems = 0;
+
+
+void abCalcStackInit(void)
+{
+}
+
+
+abCalcExpr *abCalcStackExprPush(abCalcExpr *expr)
+{
+    abCalcExpr *result = NULL;
+    if ((gStackNumItems < AB_CALC_STACK_DEPTH) &&
+        (expr != NULL)) {
+        result = &(gStack[gStackNumItems]);
+        memcpy(result, expr, sizeof(*expr));
+        gStackNumItems++;
+    }
+    return result;
+}
+
+
+abCalcExpr *abCalcStackExprPop(abCalcExpr *expr)
+{
+    abCalcExpr *result = NULL;
+    if ((gStackNumItems > 0) &&
+        (expr != NULL)) {
+        gStackNumItems--;
+        result = expr;
+        memcpy(expr, &(gStack[gStackNumItems]), sizeof(*expr));
+    }
+    return result;
+}
+
+
+int abCalcStackNumItems(void)
+{
+    return gStackNumItems;
+}
+
+
+abCalcExpr *abCalcStackExprAt(abCalcExpr *expr, int depth)
+{
+    abCalcExpr *result = NULL;
+    if ((depth < gStackNumItems) &&
+        (expr != NULL)) {
+        result = &(gStack[gStackNumItems - 1 - depth]);
+    }
+
+    return result;
+}

abCalcStack.h

@@ -0,0 +1,15 @@
+/* 
+    abCalcStack.h
+        By: Jeremy Rand
+ */
+
+
+#include "abCalcExpr.h"
+
+void abCalcStackInit(void);
+
+abCalcExpr *abCalcStackExprPush(abCalcExpr *expr);
+
+abCalcExpr *abCalcStackExprPop(abCalcExpr *expr);
+
+abCalcExpr *abCalcStackExprAt(abCalcExpr *expr, int depth);