1 | using System;
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2 | using System.Collections.Generic;
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3 | using System.Linq;
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4 |
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5 | namespace HeuristicLab.Problems.ProgramSynthesis.Push.Expressions {
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6 | using System.Diagnostics;
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7 |
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8 | using HeuristicLab.Problems.ProgramSynthesis.Push.Data.Pool;
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9 |
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10 | using Interpreter;
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11 |
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12 | public interface IMutablePushProgram {
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13 | void SetAtIndex(int index, Expression expression);
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14 | }
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15 |
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16 | [Serializable]
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17 | public sealed class PushProgram : Expression, IPooledObject, IMutablePushProgram {
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18 | #if DEBUG
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19 | private const int StringRepresentationCountBeforeAggregate = 50;
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20 | #else
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21 | private const int StringRepresentationCountBeforeAggregate = 10;
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22 | #endif
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23 |
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24 | private static readonly Expression[] EmptyExpressions = new Expression[0];
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25 | public static readonly PushProgram Empty = new PushProgram();
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26 |
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27 | private const string Prefix = "(";
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28 | private const string PrefixReduced = "[";
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29 | private const string Postfix = ")";
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30 | private const string PostfixReduced = "]";
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31 | private const string Delimiter = " ";
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32 |
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33 | private IReadOnlyList<Expression> expressions;
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34 |
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35 | public PushProgram() : this(EmptyExpressions) {
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36 | }
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37 |
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38 | public PushProgram(IReadOnlyList<Expression> expressions) {
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39 | this.expressions = expressions;
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40 | }
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41 |
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42 | public bool IsEmpty { get { return Count == 0; } }
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43 | public int Count { get { return expressions.Count; } }
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44 |
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45 | public IReadOnlyList<Expression> Expressions { get { return this.expressions; } }
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46 |
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47 | public static PushProgram Create(IManagedPool<PushProgram> pool, IReadOnlyList<Expression> expressions) {
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48 | var program = pool.Get();
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49 | program.expressions = expressions;
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50 | return program;
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51 | }
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52 |
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53 | void IPooledObject.Reset() {
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54 | expressions = null;
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55 | stringRepresentation = null;
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56 | depth = null;
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57 | treeIndex = null;
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58 | hashCode = null;
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59 | }
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60 |
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61 | public static PushProgram Merge(IManagedPool<PushProgram> pool, IManagedPool<PooledList<Expression>> expressionListPool,
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62 | PushProgram first, Expression second) {
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63 | var program = pool.Get();
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64 | var list = expressionListPool.Get();
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65 |
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66 | list.AddRange(first.Expressions);
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67 | list.Add(second);
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68 |
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69 | program.expressions = list;
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70 |
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71 | return program;
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72 | }
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73 |
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74 | public static PushProgram Merge(IManagedPool<PushProgram> pool, IManagedPool<PooledList<Expression>> expressionListPool,
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75 | Expression first, PushProgram second) {
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76 | var program = pool.Get();
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77 | var list = expressionListPool.Get();
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78 |
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79 | list.Add(first);
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80 | list.AddRange(second.Expressions);
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81 |
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82 | program.expressions = list;
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83 |
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84 | return program;
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85 | }
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86 |
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87 | public static PushProgram Merge(IManagedPool<PushProgram> pool, IManagedPool<PooledList<Expression>> expressionListPool,
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88 | PushProgram first, PushProgram second) {
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89 | var program = pool.Get();
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90 | var list = expressionListPool.Get();
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91 |
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92 | list.AddRange(first.Expressions);
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93 | list.AddRange(second.Expressions);
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94 |
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95 | program.expressions = list;
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96 |
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97 | return program;
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98 | }
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99 |
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100 | public int IndexOf(Expression expression) {
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101 | var max = expressions.Count - 1;
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102 | for (var i = max; i >= 0; i--) {
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103 | if (expression.Equals(expressions[i])) return max - i;
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104 | }
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105 |
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106 | return -1;
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107 | }
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108 |
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109 | private string stringRepresentation;
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110 | public override string StringRepresentation
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111 | {
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112 | get
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113 | {
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114 | if (stringRepresentation == null) stringRepresentation = BuildString();
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115 | return stringRepresentation;
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116 | }
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117 | }
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118 |
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119 |
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120 | private int? depth;
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121 | public int Depth
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122 | {
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123 | get
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124 | {
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125 | if (depth == null) depth = CalcDepth();
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126 | return depth.Value;
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127 | }
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128 | }
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129 |
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130 | private int[] treeIndex;
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131 | private int[] TreeIndex
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132 | {
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133 | get
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134 | {
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135 | if (treeIndex == null) treeIndex = BuildTreeIndex();
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136 | return treeIndex;
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137 | }
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138 | }
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139 |
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140 | private int? hashCode;
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141 | public override int GetHashCode() {
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142 | if (hashCode == null) hashCode = HashExpressions();
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143 | return hashCode.Value;
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144 | }
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145 |
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146 | void IMutablePushProgram.SetAtIndex(int index, Expression expression) {
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147 |
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148 | }
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149 |
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150 | public override bool Equals(object obj) {
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151 | if (ReferenceEquals(this, obj))
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152 | return true;
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153 |
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154 | if (this.GetType() != obj.GetType())
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155 | return false;
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156 |
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157 | var other = (PushProgram)obj;
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158 |
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159 | return ReferenceEquals(expressions, other.expressions) ||
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160 | GetHashCode() == other.GetHashCode();
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161 | }
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162 |
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163 | public bool Equals(PushProgram other) {
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164 | return ReferenceEquals(this, other) ||
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165 | ReferenceEquals(expressions, other.expressions) ||
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166 | GetHashCode() == other.GetHashCode();
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167 | }
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168 |
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169 | public override bool Eval(IInternalPushInterpreter interpreter) {
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170 | interpreter.ExecStack.Push(this.expressions);
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171 | return true;
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172 | }
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173 |
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174 | public override string ToString() {
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175 | return StringRepresentation;
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176 | }
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177 |
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178 | /// <summary>
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179 | /// Returns the amount of elements in the whole tree
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180 | /// </summary>
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181 | /// <returns></returns>
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182 | public int TotalCount
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183 | {
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184 | get
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185 | {
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186 | return this.IsEmpty
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187 | ? 1
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188 | // + 1 because "this" is also counted
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189 | : TreeIndex[0] + 1;
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190 | }
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191 | }
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192 |
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193 | public IEnumerable<Expression> DepthLast() {
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194 | foreach (var expr in this.expressions) {
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195 | if (expr.IsProgram)
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196 | foreach (var sub in ((PushProgram)expr).DepthLast())
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197 | yield return sub;
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198 | else yield return expr;
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199 | }
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200 | }
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201 |
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202 | public PushProgram Copy() {
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203 | if (IsEmpty) return this;
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204 |
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205 | return new PushProgram(expressions) {
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206 | stringRepresentation = stringRepresentation,
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207 | hashCode = hashCode,
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208 | depth = depth,
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209 | treeIndex = treeIndex
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210 | };
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211 | }
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212 |
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213 | public PushProgram Copy(IManagedPool<PushProgram> pool) {
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214 | if (IsEmpty) return this;
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215 |
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216 | var program = pool.Get(reset: false);
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217 |
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218 | program.expressions = expressions;
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219 | program.stringRepresentation = stringRepresentation;
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220 | program.hashCode = hashCode;
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221 | program.depth = depth;
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222 | program.treeIndex = treeIndex;
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223 |
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224 | return program;
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225 | }
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226 |
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227 | public IList<Expression> CopyExpressions() {
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228 | return new List<Expression>(this.expressions);
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229 | }
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230 |
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231 | public IList<Expression> CopyExpressions(IManagedPool<PooledList<Expression>> expressionListPool) {
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232 | if (IsEmpty) return EmptyExpressions;
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233 |
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234 | var copy = expressionListPool.Get();
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235 | copy.AddRange(this.expressions);
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236 |
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237 | return copy;
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238 | }
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239 |
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240 | private int CalcDepth() {
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241 | var maxDepth = 1;
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242 | for (var i = 0; i < Count; i++) {
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243 | var expression = this.expressions[i];
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244 | if (!expression.IsProgram) continue;
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245 | var expandExpression = (PushProgram)expression;
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246 |
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247 | if (expandExpression.Depth > maxDepth)
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248 | maxDepth = expandExpression.Depth;
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249 | }
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250 |
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251 | return maxDepth + 1;
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252 | }
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253 |
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254 | private string BuildString() {
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255 | // prevent too big string
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256 | return TotalCount > StringRepresentationCountBeforeAggregate
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257 | ? PrefixReduced + Count + PostfixReduced
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258 | : Prefix + string.Join(Delimiter, expressions) + Postfix;
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259 | }
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260 |
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261 | private int[] BuildTreeIndex() {
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262 | var local_treeIndex = new int[Count];
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263 |
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264 | var next = 1;
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265 |
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266 | for (var i = Count - 1; i >= 0; i--) {
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267 | var subExpression = this.expressions[i];
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268 |
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269 | local_treeIndex[i] = next;
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270 |
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271 | if (subExpression.IsProgram) {
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272 | next += ((PushProgram)subExpression).TotalCount;
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273 | } else {
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274 | next++;
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275 | }
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276 | }
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277 |
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278 | return local_treeIndex;
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279 | }
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280 |
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281 | private int HashExpressions() {
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282 | var hash = 19 * 31 + typeof(PushProgram).GetHashCode();
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283 |
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284 | for (var i = 0; i < Count; i++) {
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285 | hash = hash * 31 + this.expressions[i].GetHashCode();
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286 | }
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287 |
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288 | return hash;
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289 | }
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290 |
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291 | private static void CheckIfNested(int level, PushProgram target, PushProgram current,
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292 | IList<PushProgram> visited) {
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293 | if (visited.Any(x => ReferenceEquals(x, current)))
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294 | Debugger.Break();
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295 |
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296 | visited.Add(current);
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297 | if (level <= 0) {
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298 | // hierarchy depth > level
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299 | Debugger.Break();
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300 | return;
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301 | }
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302 |
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303 | for (var i = 0; i < current.Count; i++) {
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304 | if (current.expressions[i].IsProgram)
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305 | continue;
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306 |
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307 | var subExpression = current.expressions[i] as PushProgram;
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308 |
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309 | if (ReferenceEquals(target, subExpression)) {
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310 | // Endless recursion dedected
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311 | Debugger.Break();
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312 | }
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313 |
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314 | CheckIfNested(level - 1, target, subExpression, visited);
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315 | }
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316 |
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317 | visited.RemoveAt(visited.Count - 1);
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318 | }
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319 |
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320 | /// <summary>
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321 | /// Returns the element with the given index whereby the tree is indexed in depth first manner
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322 | /// </summary>
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323 | /// <param name="index">The index of the required element</param>
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324 | /// <returns>The required element</returns>
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325 | public Expression GetFromTree(int index) {
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326 | return GetFromTree(index, (root, parent, child, childIndex, parentIndex) => child);
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327 | }
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328 |
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329 | /// <returns>The required element</returns>
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330 | public T GetFromTree<T>(int index,
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331 | Func<PushProgram, PushProgram, Expression, int, int, T> resolver) {
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332 | return GetFromTree(index, 0, null, resolver);
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333 | }
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334 |
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335 | private T GetFromTree<T>(int index, int parentIndex, PushProgram parent,
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336 | Func<PushProgram, PushProgram, Expression, int, int, T> resolver) {
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337 | if (index == 0) return resolver(parent, parent, this, 0, parentIndex);
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338 |
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339 | var min = Count - 1;
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340 | var max = 0;
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341 | var mid = (min + max) / 2;
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342 |
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343 | while ((max <= min) && (TreeIndex[mid] != index)) {
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344 | if (TreeIndex[mid] > index) max = mid + 1;
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345 | else min = mid - 1;
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346 |
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347 | mid = (min + max) / 2;
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348 | }
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349 |
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350 | return TreeIndex[mid] == index
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351 | ? resolver(parent, this, this.expressions[mid], mid, parentIndex)
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352 | : (this.expressions[mid + 1] as PushProgram).GetFromTree(index - TreeIndex[mid + 1], mid + 1,
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353 | this, resolver);
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354 | }
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355 | }
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356 | }
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