1 files changed, 86 insertions, 0 deletions
diff --git a/ext/dsent/libutil/Calculator.h b/ext/dsent/libutil/Calculator.h
new file mode 100644
index 000000000..4fcdf471f
--- /dev/null
+++ b/ext/dsent/libutil/Calculator.h
@@ -0,0 +1,86 @@
+#ifndef __LIBUTIL_CALCULATOR_H__
+#define __LIBUTIL_CALCULATOR_H__
+
+#include <sstream>
+
+#include "String.h"
+#include "Map.h"
+#include "Assert.h"
+
+namespace LibUtil
+{
+    using std::istringstream;
+
+    /*
+     *  program:
+     *      END                         // END is end-of-input
+     *      expr_list END
+     *
+     *  expr_list:
+     *      expression SEP expr_list    // SEP is semicolon
+     *      expression                  
+     *      print expression
+     *      print STRING
+     *      print STRING expression
+     *      print STRING expression SEP expr_list
+     *
+     *
+     *  expression:
+     *      expression + term
+     *      expression - term
+     *      term
+     *
+     *  term:
+     *      term / primary
+     *      term * primary
+     *      primary
+     *
+     *  primary:
+     *      NUMBER
+     *      NAME
+     *      NAME = expression
+     *      NAME string expression      // NAME is print
+     *      - primary
+     *      ( expression )
+     *
+     *  string:
+     *      
+     **/
+
+    class Calculator
+    {
+        protected:
+            enum Token
+            {
+                NAME, NAME2, NUMBER, STRING, END,
+                PLUS = '+', MINUS = '-', MUL = '*', DIV = '/',
+                SEP = ';', ASSIGN = '=', LP = '(', RP = ')'
+            };
+
+        public:
+            Calculator();
+            virtual ~Calculator();
+
+        public:
+            void reset();
+            void evaluateString(const String& str_);
+
+        protected:
+            Token getToken(istringstream& ist_);
+            double prim(istringstream& ist_, bool is_get_);
+            double term(istringstream& ist_, bool is_get_);
+            double expr(istringstream& ist_, bool is_get_);
+            virtual double getEnvVar(const String& var_name_) const;
+
+        protected:
+            String m_reserved_chars_;
+            Map<double> m_var_;
+
+            Token m_curr_token_;
+            double m_value_number_;
+            String m_value_string_;
+    }; // class Calculator
+} // namespace LibUtil
+
+#endif // __LIBUTIL_CALCULATOR_H__
+