1  using System;
 2  
 3  namespace ARMeilleure.CodeGen.Linking
 4  {
 5      /// <summary>
 6      /// Represents a symbol.
 7      /// </summary>
 8      readonly struct Symbol
 9      {
10          private readonly ulong _value;
11  
12          /// <summary>
13          /// Gets the <see cref="SymbolType"/> of the <see cref="Symbol"/>.
14          /// </summary>
15          public SymbolType Type { get; }
16  
17          /// <summary>
18          /// Gets the value of the <see cref="Symbol"/>.
19          /// </summary>
20          /// <exception cref="InvalidOperationException"><see cref="Type"/> is <see cref="SymbolType.None"/></exception>
21          public ulong Value
22          {
23              get
24              {
25                  if (Type == SymbolType.None)
26                  {
27                      ThrowSymbolNone();
28                  }
29  
30                  return _value;
31              }
32          }
33  
34          /// <summary>
35          /// Initializes a new instance of the <see cref="Symbol"/> structure with the specified <see cref="SymbolType"/> and value.
36          /// </summary>
37          /// <param name="type">Type of symbol</param>
38          /// <param name="value">Value of symbol</param>
39          public Symbol(SymbolType type, ulong value)
40          {
41              (Type, _value) = (type, value);
42          }
43  
44          /// <summary>
45          /// Determines if the specified <see cref="Symbol"/> instances are equal.
46          /// </summary>
47          /// <param name="a">First instance</param>
48          /// <param name="b">Second instance</param>
49          /// <returns><see langword="true"/> if equal; otherwise <see langword="false"/></returns>
50          public static bool operator ==(Symbol a, Symbol b)
51          {
52              return a.Equals(b);
53          }
54  
55          /// <summary>
56          /// Determines if the specified <see cref="Symbol"/> instances are not equal.
57          /// </summary>
58          /// <param name="a">First instance</param>
59          /// <param name="b">Second instance</param>
60          /// <returns><see langword="true"/> if not equal; otherwise <see langword="false"/></returns>
61          public static bool operator !=(Symbol a, Symbol b)
62          {
63              return !(a == b);
64          }
65  
66          /// <summary>
67          /// Determines if the specified <see cref="Symbol"/> is equal to this <see cref="Symbol"/> instance.
68          /// </summary>
69          /// <param name="other">Other <see cref="Symbol"/> instance</param>
70          /// <returns><see langword="true"/> if equal; otherwise <see langword="false"/></returns>
71          public bool Equals(Symbol other)
72          {
73              return other.Type == Type && other._value == _value;
74          }
75  
76          /// <inheritdoc/>
77          public override bool Equals(object obj)
78          {
79              return obj is Symbol sym && Equals(sym);
80          }
81  
82          /// <inheritdoc/>
83          public override int GetHashCode()
84          {
85              return HashCode.Combine(Type, _value);
86          }
87  
88          /// <inheritdoc/>
89          public override string ToString()
90          {
91              return $"{Type}:{_value}";
92          }
93  
94          private static void ThrowSymbolNone()
95          {
96              throw new InvalidOperationException("Symbol refers to nothing.");
97          }
98      }
99  }