1 files changed, 61 insertions, 0 deletions
diff --git a/expr.h b/expr.h
new file mode 100644
index 0000000..0d7422d
--- /dev/null
+++ b/expr.h
@@ -0,0 +1,61 @@
+typedef struct sheet sheet;
+
+typedef struct expr expr; 
+typedef struct value value;  /* for recursive case */
+typedef struct postfix postfix;
+
+typedef enum exprType {
+	VALUE,
+	POSTFIX,	
+	NESTED,
+} exprType;
+
+typedef enum valueType {
+	NUM,
+	LOC,
+} valueType;
+
+typedef struct loc {
+        int x, y;
+} loc;
+
+typedef struct expr {
+	char *expr;
+	exprType t;
+	union {
+		expr *nested;
+		struct {
+			value *value;
+			postfix *postfix;
+		};
+	};
+} expr;
+
+typedef struct postfix {
+	char op;
+	expr *expr;
+} postfix;
+
+typedef struct value {
+	valueType t;
+	union {
+		int num;
+		loc *loc;
+	};
+} value;
+
+extern char *in;
+extern char *Pin;
+
+char isop(char c);
+void consumeleading(char c);
+expr *parseExpr(); 
+loc *parseLoc();
+postfix *parsePostfix(); 
+value *parseValue(); 
+expr *parseExpr(); 
+double evalValue(value *v, sheet *s);
+double evalPostfix(value *v, postfix *p, sheet *s);
+double evalExpr(expr *e, sheet *s); 
+expr *makeNumber(int n);
+void freeExpr(expr *e);