1 files changed, 77 insertions, 0 deletions

diff --git a/src/old/formula.h b/src/old/formula.h
new file mode 100644
index 0000000..939eb09
--- /dev/null
+++ b/src/old/formula.h
@@ -0,0 +1,77 @@
+#ifndef FORMULA_H
+#define FORMULA_H
+
+#include <stdint.h>
+
+#include <math.h>
+#include <stack>
+#include "sbuffer.h"
+
+#include "exceptionbase.h"
+#include "hash.h"
+
+subExceptionDecl( ParseException );
+
+/**
+ * Implements a very simple formula parser that allows use of variables and
+ * custom functions.  This is based on a simple calculator-type parser that
+ * executes as it processes, accounting for operator precedence and grouping.
+ */
+class Formula
+{
+public:
+        Formula();
+        virtual ~Formula();
+
+        double run( char *sFormula );
+
+        typedef Hash<std::string, double> varHash;
+        varHash hVars;
+
+        typedef struct Func
+        {
+                double operator()( double x )
+                {
+                        return 0.0;
+                }
+        } Func;
+
+        typedef Hash<std::string, Func> funcHash;
+        funcHash hFunc;
+
+        typedef struct FuncSin : Func
+        {
+                double operator()( double x )
+                {
+                        return sin( x );
+                }
+        } FuncSin;
+
+private:
+        enum
+        {
+                symEOS,
+                symAdd,
+                symSubtract,
+                symMultiply,
+                symDivide,
+                symOpenParen,
+                symCloseParen,
+                symNumber,
+                symVariable,
+                symExponent,
+                symModulus
+        };
+
+        typedef uint8_t symType;
+
+        std::stack<symType> sOper;
+        std::stack<double> sValue;
+
+private:
+        symType getPrec( symType nOper );
+        symType nextToken( char **sBuf );
+        void reduce( bool bCloseParen = false );
+};
+
+#endif