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  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq.Expressions;
  4. using System.Linq;
  5.  
  6.  
  7. namespace Assembler
  8. {
  9.     internal class State
  10.     {
  11.         public readonly IDictionary<string, ulong> SymbolTable = new Dictionary<string, ulong>();
  12.  
  13.         public void Clear() 
  14.         {
  15.             SymbolTable.Clear();
  16.         }
  17.     }
  18.  
  19.     internal interface IReference
  20.     {
  21.         ulong EvalAddress(State s); // evaluate reference to address
  22.     }
  23.  
  24.     internal abstract class ReferenceBase : IReference
  25.     {
  26.         public static IndexedReference operator+(long directOffset, ReferenceBase baseRef) { return new IndexedReference(baseRef, directOffset); }
  27.         public static IndexedReference operator+(ReferenceBase baseRef, long directOffset) { return new IndexedReference(baseRef, directOffset); }
  28.  
  29.         public abstract ulong EvalAddress(State s);
  30.     }
  31.  
  32.     internal class SymbolicReference : ReferenceBase
  33.     {
  34.         public static explicit operator SymbolicReference(string symbol)    { return new SymbolicReference(symbol); }
  35.         public SymbolicReference(string symbol) { _symbol = symbol; }
  36.  
  37.         private readonly string _symbol;
  38.  
  39.         public override ulong EvalAddress(State s) 
  40.         {
  41.             return s.SymbolTable[_symbol];
  42.         }
  43.  
  44.         public override string ToString() { return string.Format("Sym({0})", _symbol); }
  45.     }
  46.  
  47.     internal class IndexedReference : ReferenceBase
  48.     {
  49.         public IndexedReference(IReference baseRef, long directOffset) 
  50.         {
  51.             _baseRef = baseRef;
  52.             _directOffset = directOffset;
  53.         }
  54.  
  55.         private readonly IReference _baseRef;
  56.         private readonly long _directOffset;
  57.  
  58.         public override ulong EvalAddress(State s) 
  59.         {
  60.             return (_directOffset<0)
  61.                 ? _baseRef.EvalAddress(s) - (ulong) Math.Abs(_directOffset)
  62.                 : _baseRef.EvalAddress(s) + (ulong) Math.Abs(_directOffset);
  63.         }
  64.  
  65.         public override string ToString() { return string.Format("{0} + {1}", _directOffset, _baseRef); }
  66.     }
  67. }
  68.  
  69. namespace Program
  70. {
  71.     using Assembler;
  72.  
  73.     public static class Program
  74.     {
  75.         public static void Main(string[] args)
  76.         {
  77.             var myBaseRef1 = new SymbolicReference("mystring1");
  78.  
  79.             Expression<Func<IReference>> anyRefExpr = () => 64 + myBaseRef1;
  80.             Console.WriteLine(anyRefExpr);
  81.  
  82.             var myBaseRef2 = (SymbolicReference) "mystring2"; // uses explicit conversion operator
  83.  
  84.             Expression<Func<IndexedReference>> indexedRefExpr = () => 64 + myBaseRef2;
  85.             Console.WriteLine(indexedRefExpr);
  86.  
  87.             Console.WriteLine(Console.Out.NewLine + "=== show compiletime types of returned values:");
  88.             Console.WriteLine("myBaseRef1     -> {0}", myBaseRef1);
  89.             Console.WriteLine("myBaseRef2     -> {0}", myBaseRef2);
  90.             Console.WriteLine("anyRefExpr     -> {0}", anyRefExpr.Compile().Method.ReturnType);
  91.             Console.WriteLine("indexedRefExpr -> {0}", indexedRefExpr.Compile().Method.ReturnType);
  92.  
  93.             Console.WriteLine(Console.Out.NewLine + "=== show runtime types of returned values:");
  94.             Console.WriteLine("myBaseRef1     -> {0}", myBaseRef1);
  95.             Console.WriteLine("myBaseRef2     -> {0}", myBaseRef2);
  96.             Console.WriteLine("anyRefExpr     -> {0}", anyRefExpr.Compile()());     // compile() returns Func<...>
  97.             Console.WriteLine("indexedRefExpr -> {0}", indexedRefExpr.Compile()());
  98.  
  99.             Console.WriteLine(Console.Out.NewLine + "=== observe how you could add an evaluation model using some kind of symbol table:");
  100.             var compilerState = new State();
  101.             compilerState.SymbolTable.Add("mystring1", 0xdeadbeef); // raw addresses
  102.             compilerState.SymbolTable.Add("mystring2", 0xfeedface);
  103.  
  104.             Console.WriteLine("myBaseRef1 evaluates to     0x{0:x8}", myBaseRef1.EvalAddress(compilerState));
  105.             Console.WriteLine("myBaseRef2 evaluates to     0x{0:x8}", myBaseRef2.EvalAddress(compilerState));
  106.             Console.WriteLine("anyRefExpr displays as      {0:x8}",   anyRefExpr.Compile()());
  107.             Console.WriteLine("indexedRefExpr displays as  {0:x8}",   indexedRefExpr.Compile()());
  108.             Console.WriteLine("anyRefExpr evaluates to     0x{0:x8}", anyRefExpr.Compile()().EvalAddress(compilerState));
  109.             Console.WriteLine("indexedRefExpr evaluates to 0x{0:x8}", indexedRefExpr.Compile()().EvalAddress(compilerState));
  110.         }
  111.     }
  112. }
  113.  
Success #stdin #stdout 0.05s 38688KB
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stdin
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Standard input is empty
stdout
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() => (64 + value(Program.Program+<Main>c__AnonStorey0).myBaseRef1)
() => (64 + value(Program.Program+<Main>c__AnonStorey0).myBaseRef2)

=== show compiletime types of returned values:
myBaseRef1     -> Sym(mystring1)
myBaseRef2     -> Sym(mystring2)
anyRefExpr     -> Assembler.IReference
indexedRefExpr -> Assembler.IndexedReference

=== show runtime types of returned values:
myBaseRef1     -> Sym(mystring1)
myBaseRef2     -> Sym(mystring2)
anyRefExpr     -> 64 + Sym(mystring1)
indexedRefExpr -> 64 + Sym(mystring2)

=== observe how you could add an evaluation model using some kind of symbol table:
myBaseRef1 evaluates to     0xdeadbeef
myBaseRef2 evaluates to     0xfeedface
anyRefExpr displays as      64 + Sym(mystring1)
indexedRefExpr displays as  64 + Sym(mystring2)
anyRefExpr evaluates to     0xdeadbf2f
indexedRefExpr evaluates to 0xfeedfb0e
https://ideone.com/iLDJo
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
public

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