1 using System;
 2 using System.Collections;
 3 
 4 namespace Calculator
 5 {
 6     public class SymbolTable
 7     {
 8         static SymbolTable() : instance(new SymbolTable())
 9         {
10         }
11         public static SymbolTable& Instance()
12         {
13             return *instance;
14         }
15         private SymbolTable() : variableMap()
16         {
17         }
18         public void SetVariable(const ustring& variableName, double variableValue)
19         {
20             variableMap[variableName] = variableValue;
21         }
22         public double GetVariableValue(const ustring& variableName)
23         {
24             Map<ustring, double>.ConstIterator it = variableMap.CFind(variableName);
25             if (it != variableMap.CEnd())
26             {
27                 double value = it->second;
28                 return value;
29             }
30             else
31             {
32                 throw VariableNotFoundException("variable '" + ToUtf8(variableName) + "' not found");
33             }
34         }
35         public void Print()
36         {
37             Console.WriteLine("variables:");
38             for (const Pair<ustring, double>& pair : variableMap)
39             {
40                 Console.Out() << pair.first << " = " << pair.second << endl();
41             }
42         }
43         private static UniquePtr<SymbolTable> instance;
44         private Map<ustring, double> variableMap;
45     }
46 }