1 | /// <summary>
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2 | /// For explicit code manipulation and execution. May also be used as a general list data type.
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3 | /// This type must always be present, as the top level interpreter will push any code to be executed on the
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4 | /// CODE stack prior to execution. However, one may turn off all CODE instructions if code manipulation is not needed.
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5 | /// </summary>
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6 |
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7 | namespace HeuristicLab.Problems.ProgramSynthesis.Push.Expressions {
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8 | using System;
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9 | using System.Collections.Generic;
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10 | using System.Linq;
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11 |
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12 | using HeuristicLab.Problems.ProgramSynthesis.Push.Attributes;
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13 | using HeuristicLab.Problems.ProgramSynthesis.Push.Stack;
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14 |
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15 | using Interpreter;
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16 |
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17 | /// <summary>
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18 | /// Recursively invokes the interpreter on the program on top of the CODE stack. After evaluation the
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19 | /// CODE stack is popped; normally this pops the program that was just executed, but if the expression itself
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20 | /// manipulates the stack then this final pop may end up popping something else.
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21 | /// </summary>
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22 | [PushExpression(StackType.Code, "CODE.DO")]
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23 | public class CodeDoExpression : StatelessExpression {
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24 | public override bool Eval(IPushInterpreter interpreter) {
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25 | // not enough arguments on stack
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26 | if (interpreter.CodeStack.Count == 0) return false;
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27 |
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28 | var codePopExpression = ExpressionTable.GetStatelessExpression<CodePopExpression>();
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29 | interpreter.ExecStack.Push(codePopExpression, interpreter.CodeStack.Top);
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30 |
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31 | return true;
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32 | }
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33 | }
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34 |
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35 | /// <summary>
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36 | /// Like CODE.DO but pops the stack before, rather than after, the recursive execution
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37 | /// </summary>
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38 | [PushExpression(StackType.Code, "CODE.DO*")]
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39 | public class CodeDoXExpression : StatelessExpression {
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40 | public override bool Eval(IPushInterpreter interpreter) {
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41 | // not enough arguments on stack
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42 | if (interpreter.CodeStack.Count == 0) return false;
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43 |
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44 | var expression = interpreter.CodeStack.Pop();
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45 | interpreter.ExecStack.Push(expression);
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46 |
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47 | return true;
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48 | }
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49 | }
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50 |
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51 | /// <summary>
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52 | /// Does nothing.
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53 | /// </summary>
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54 | [PushExpression(StackType.Code, "CODE.NOOP")]
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55 | public class CodeNoopExpression : StatelessExpression {
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56 | public override bool Eval(IPushInterpreter interpreter) {
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57 | return false;
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58 | }
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59 | }
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60 |
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61 | /// <summary>
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62 | /// Specifies that the next expression submitted for execution will instead be pushed literally onto the CODE stack.
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63 | /// This can be implemented by moving the top item on the EXEC stack onto the CODE stack.
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64 | /// </summary>
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65 | [PushExpression(StackType.Code, "CODE.QUOTE")]
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66 | public class CodeQuoteExpression : StatelessExpression {
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67 | public override bool Eval(IPushInterpreter interpreter) {
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68 | // not enough arguments on stack
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69 | if (interpreter.ExecStack.Count == 0) return false;
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70 |
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71 | var expression = interpreter.ExecStack.Pop();
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72 | interpreter.CodeStack.Push(expression);
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73 |
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74 | return true;
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75 | }
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76 | }
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77 |
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78 | /// <summary>
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79 | /// If the top item of the BOOLEAN stack is TRUE this recursively executes the second item of the CODE stack;
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80 | /// otherwise it recursively executes the first item of the CODE stack. Either way both elements of the CODE stack
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81 | /// (and the BOOLEAN value upon which the decision was made) are popped.
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82 | /// </summary>
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83 | [PushExpression(StackType.Code, "CODE.IF")]
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84 | public class CodeIfExpression : StatelessExpression {
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85 | public override bool Eval(IPushInterpreter interpreter) {
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86 | // not enough arguments on stack
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87 | if ((interpreter.BooleanStack.Count == 0) || (interpreter.CodeStack.Count < 2)) return false;
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88 |
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89 | var condition = interpreter.BooleanStack.Pop();
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90 | var items = interpreter.CodeStack.Pop(2);
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91 |
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92 | interpreter.ExecStack.Push(condition ? items[0] : items[1]);
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93 |
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94 | return true;
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95 | }
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96 | }
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97 |
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98 | /// <summary>
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99 | /// Pushes the result of appending the top two pieces of code. If one of the pieces of code is a single instruction or
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100 | /// literal (that is, something not surrounded by parentheses) then it is surrounded by parentheses first.
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101 | /// </summary>
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102 | [PushExpression(StackType.Code, "CODE.APPEND")]
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103 | public class CodeAppendExpression : StatelessExpression {
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104 | public override bool Eval(IPushInterpreter interpreter) {
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105 | if (interpreter.CodeStack.Count < 2) return false;
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106 |
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107 | var first = interpreter.CodeStack.Pop();
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108 | var second = interpreter.CodeStack.Top;
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109 |
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110 | var isFirstList = first.CanExpand;
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111 | var isSecondList = second.CanExpand;
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112 |
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113 | Expression[] result = null;
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114 |
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115 | if (isFirstList) {
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116 | var expand1 = first as ExecExpandExpression;
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117 |
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118 | if (isSecondList) {
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119 | var expand2 = second as ExecExpandExpression;
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120 | var size = expand2.State.Expressions.Count + expand1.State.Expressions.Count;
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121 |
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122 | // if size > maxPointsInProgram this expressions results in a NOOP
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123 | if (size > interpreter.Configuration.MaxPointsInProgram) return false;
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124 |
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125 | result = new Expression[size];
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126 |
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127 | Array.Copy(expand2.State.Expressions as Expression[], result, expand2.State.Expressions.Count);
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128 | Array.Copy(
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129 | expand1.State.Expressions as Expression[],
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130 | 0,
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131 | result,
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132 | expand2.State.Expressions.Count,
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133 | expand1.State.Expressions.Count);
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134 | } else {
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135 | var size = expand1.State.Expressions.Count + 1;
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136 |
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137 | // if size > maxPointsInProgram this expressions results in a NOOP
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138 | if (size > interpreter.Configuration.MaxPointsInProgram) return false;
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139 |
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140 | result = new Expression[size];
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141 | result[0] = second;
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142 |
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143 | Array.Copy(expand1.State.Expressions as Expression[], 0, result, 1, expand1.State.Expressions.Count);
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144 | }
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145 | } else if (isSecondList) {
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146 | var expand2 = second as ExecExpandExpression;
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147 |
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148 | var size = expand2.State.Expressions.Count + 1;
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149 |
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150 | // if size > maxPointsInProgram this expressions results in a NOOP
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151 | if (size > interpreter.Configuration.MaxPointsInProgram) return false;
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152 |
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153 | result = new Expression[size];
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154 | result[0] = first;
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155 |
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156 | Array.Copy(expand2.State.Expressions as Expression[], 0, result, 1, expand2.State.Expressions.Count);
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157 | } else {
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158 | result = new[] { second, first };
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159 | }
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160 |
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161 | var expression = new ExecExpandExpression(result);
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162 |
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163 | interpreter.CodeStack.SetTop(expression);
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164 |
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165 | return true;
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166 | }
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167 | }
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168 |
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169 | /// <summary>
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170 | /// Pushes TRUE onto the BOOLEAN stack if the top piece of code is a single instruction or a literal,
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171 | /// and FALSE otherwise (that is, if it is something surrounded by parentheses).
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172 | /// </summary>
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173 | [PushExpression(StackType.Code, "CODE.ATOM")]
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174 | public class CodeAtomExpression : StatelessExpression {
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175 | public override bool Eval(IPushInterpreter interpreter) {
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176 | if (interpreter.CodeStack.Count == 0) return false;
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177 |
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178 | var expression = interpreter.CodeStack.Pop();
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179 | var isExpandExpression = expression.CanExpand;
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180 |
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181 | interpreter.BooleanStack.Push(!isExpandExpression);
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182 | return true;
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183 | }
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184 | }
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185 |
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186 | /// <summary>
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187 | /// Pushes the first item of the list on top of the CODE stack. For example, if the top piece of code is "( A B )"
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188 | /// then this pushes "A" (after popping the argument). If the code on top of the stack is not a list then this has no
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189 | /// effect.
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190 | /// The name derives from the similar Lisp function; a more generic name would be "FIRST".
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191 | /// </summary>
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192 | [PushExpression(StackType.Code, "CODE.CAR")]
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193 | public class CodeCarExpression : StatelessExpression {
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194 | public override bool Eval(IPushInterpreter interpreter) {
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195 | if ((interpreter.CodeStack.Count == 0) ||
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196 | (interpreter.CodeStack.Top.GetType() != typeof(ExecExpandExpression))) return false;
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197 |
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198 | var expand = interpreter.CodeStack.Top as ExecExpandExpression;
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199 |
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200 | if (expand.State.IsEmpty) return false;
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201 | var first = expand.State.Expressions[expand.State.Expressions.Count - 1];
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202 |
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203 | interpreter.CodeStack.SetTop(first);
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204 | return true;
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205 | }
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206 | }
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207 |
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208 | /// <summary>
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209 | /// Pushes a version of the list from the top of the CODE stack without its first element.
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210 | /// For example, if the top piece of code is "( A B )" then this pushes "( B )" (after popping the argument).
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211 | /// If the code on top of the stack is not a list then this pushes the empty list ("( )"). The name derives from
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212 | /// the similar Lisp function; a more generic name would be "REST".
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213 | /// </summary>
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214 | [PushExpression(StackType.Code, "CODE.CDR")]
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215 | public class CodeCdrExpression : StatelessExpression {
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216 | public override bool Eval(IPushInterpreter interpreter) {
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217 | if (interpreter.CodeStack.Count == 0) return false;
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218 |
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219 | ExecExpandExpression expandExpression;
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220 | var top = interpreter.CodeStack.Top;
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221 |
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222 | if (top.CanExpand) {
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223 | var expand = (ExecExpandExpression)top;
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224 |
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225 | if (expand.State.IsEmpty) return false;
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226 | var length = expand.State.Expressions.Count - 1;
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227 | var newExpressions = new Expression[length];
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228 |
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229 | Array.Copy((Expression[])expand.State.Expressions, 0, newExpressions, 0, length);
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230 |
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231 | expandExpression = new ExecExpandExpression(newExpressions);
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232 | } else {
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233 | expandExpression = ExecExpandExpression.Empty;
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234 | }
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235 |
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236 | interpreter.CodeStack.SetTop(expandExpression);
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237 | return true;
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238 | }
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239 | }
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240 |
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241 | /// <summary>
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242 | /// Pushes the result of "consing" (in the Lisp sense) the second stack item onto the first stack item
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243 | /// (which is coerced to a list if necessary). For example, if the top piece of code is "( A B )" and the
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244 | /// second piece of code is "X" then this pushes "( X A B )" (after popping the argument).
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245 | /// </summary>
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246 | [PushExpression(StackType.Code, "CODE.CONS")]
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247 | public class CodeConsExpression : StatelessExpression {
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248 | public override bool Eval(IPushInterpreter interpreter) {
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249 | if (interpreter.CodeStack.Count < 2)
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250 | return false;
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251 |
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252 | ExecExpandExpression result;
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253 |
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254 | if (interpreter.CodeStack.Top.CanExpand) {
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255 | var first = (ExecExpandExpression)interpreter.CodeStack.Pop();
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256 | var size = first.State.Expressions.Count + 1;
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257 |
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258 | if (size > interpreter.Configuration.MaxPointsInProgram) return false;
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259 |
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260 | var expressions = new Expression[size];
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261 |
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262 | expressions[first.State.Expressions.Count] = interpreter.CodeStack.Top;
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263 | Array.Copy(first.State.Expressions as Expression[], expressions, first.State.Expressions.Count);
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264 |
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265 | result = new ExecExpandExpression(expressions);
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266 | } else {
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267 | result = new ExecExpandExpression(interpreter.CodeStack.Pop(), interpreter.CodeStack.Top);
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268 | }
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269 |
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270 | interpreter.CodeStack.SetTop(result);
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271 | return true;
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272 | }
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273 | }
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274 |
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275 | /// <summary>
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276 | /// Pushes the "container" of the second CODE stack item within the first CODE stack item onto the CODE stack.
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277 | /// If second item contains the first anywhere (i.e. in any nested list) then the container is the smallest sub-list
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278 | /// that contains but is not equal to the first instance. For example, if the top piece of code is "( B ( C ( A ) ) ( D
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279 | /// ( A ) ) )"
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280 | /// and the second piece of code is "( A )" then this pushes ( C ( A ) ). Pushes an empty list if there is no such
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281 | /// container.
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282 | /// </summary>
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283 | [PushExpression(StackType.Code, "CODE.CONTAINER")]
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284 | public class CodeContainerExpression : StatelessExpression {
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285 | public override bool Eval(IPushInterpreter interpreter) {
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286 | if ((interpreter.CodeStack.Count < 2) ||
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287 | (interpreter.CodeStack[interpreter.CodeStack.Count - 2].GetType() !=
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288 | typeof(ExecExpandExpression))) return false;
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289 |
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290 | var target = interpreter.CodeStack.Pop();
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291 | var source = interpreter.CodeStack.Top;
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292 |
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293 | var container = GetContainer(source as ExecExpandExpression, target);
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294 | var result = container ?? ExecExpandExpression.Empty;
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295 |
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296 | interpreter.CodeStack.SetTop(result);
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297 | return true;
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298 | }
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299 |
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300 | private static ExecExpandExpression GetContainer(ExecExpandExpression current, Expression target) {
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301 | if (current == target)
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302 | return null;
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303 |
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304 | var subContainer =
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305 | current.State.Expressions.Where(e => e.CanExpand)
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306 | .Select(e => GetContainer(e as ExecExpandExpression, target))
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307 | .Where(e => e != null);
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308 |
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309 | var execExpandExpressions = subContainer as IList<ExecExpandExpression> ?? subContainer.ToList();
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310 | return execExpandExpressions.Any()
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311 | ? execExpandExpressions.OrderBy(c => c.State.Expressions.Count).LastOrDefault()
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312 | : current.State.Expressions.Contains(target)
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313 | ? current
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314 | : null;
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315 | }
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316 | }
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317 |
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318 | /// <summary>
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319 | /// Pushes TRUE on the BOOLEAN stack if the second CODE stack item contains the first CODE stack
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320 | /// item anywhere (e.g. in a sub-list).
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321 | /// </summary>
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322 | [PushExpression(StackType.Code, "CODE.CONTAINS")]
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323 | public class CodeContainsExpression : StatelessExpression {
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324 | public override bool Eval(IPushInterpreter interpreter) {
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325 | if (interpreter.CodeStack.Count < 2 ||
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326 | !interpreter.CodeStack[interpreter.CodeStack.Count - 2].CanExpand)
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327 | return false;
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328 |
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329 | var values = interpreter.CodeStack.Pop(2);
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330 | var second = (ExecExpandExpression)values[0];
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331 | var contains = second.State.Expressions.Contains(values[1]);
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332 |
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333 | interpreter.BooleanStack.Push(contains);
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334 |
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335 | return true;
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336 | }
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337 | }
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338 |
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339 | /// <summary>
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340 | /// Pushes the definition associated with the top NAME on the NAME stack (if any) onto the CODE stack.
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341 | /// This extracts the definition for inspection/manipulation, rather than for immediate execution (although it
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342 | /// may then be executed with a call to CODE.DO or a similar instruction).
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343 | /// </summary>
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344 | [PushExpression(StackType.Code, "CODE.DEFINITION")]
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345 | public class CodeDefinitionExpression : StatelessExpression {
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346 | public override bool Eval(IPushInterpreter interpreter) {
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347 | if ((interpreter.NameStack.Count == 0) ||
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348 | !interpreter.CustomExpressions.ContainsKey(interpreter.NameStack.Top)) return false;
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349 |
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350 | var name = interpreter.NameStack.Pop();
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351 | var definition = interpreter.CustomExpressions[name];
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352 |
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353 | interpreter.CodeStack.Push(definition);
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354 |
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355 | return true;
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356 | }
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357 | }
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358 |
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359 | /// <summary>
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360 | /// Pushes a measure of the discrepancy between the top two CODE stack items onto the INTEGER stack. This will be zero
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361 | /// if the top two items are equivalent, and will be higher the 'more different' the items are from one another. The calculation
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362 | /// is as follows:
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363 | /// <list type="bullet">
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364 | /// <item>
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365 | /// <description>
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366 | /// Construct a list of all of the unique items in both of the lists(where uniqueness is determined by equalp).
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367 | /// Sub-lists and atoms all count as items.
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368 | /// </item>
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369 | /// <item>
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370 | /// <description>Initialize the result to zero.
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371 | /// </item>
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372 | /// <item>
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373 | /// <description>
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374 | /// For each unique item increment the result by the difference between the number of occurrences of the
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375 | /// item in the two pieces of code.
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376 | /// </item>
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377 | /// <item>
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378 | /// <description>Push the result.
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379 | /// </item>
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380 | /// </list>
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381 | /// </summary>
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382 | [PushExpression(StackType.Code, "CODE.DISCREPANCY")]
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383 | public class CodeDiscrepancyExpression : StatelessExpression {
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384 | public override bool Eval(IPushInterpreter interpreter) {
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385 | if (interpreter.CodeStack.Count < 2) return false;
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386 |
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387 | var expressions = interpreter.CodeStack.Pop(2);
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388 | var firstItems = new Dictionary<int, int>();
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389 | var secondItems = new Dictionary<int, int>();
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390 |
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391 | DetermineUniqueItems(expressions[0], secondItems);
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392 | DetermineUniqueItems(expressions[1], firstItems);
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393 |
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394 | var discrepancy = GetDiscrepancy(firstItems, secondItems);
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395 |
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396 | interpreter.IntegerStack.Push(discrepancy);
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397 |
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398 | return true;
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399 | }
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400 |
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401 | private int GetDiscrepancy(IDictionary<int, int> first, IDictionary<int, int> second) {
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402 | var discrepancy = 0;
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403 | var keys = first.Keys.Concat(second.Keys).Distinct();
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404 |
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405 | foreach (var key in keys)
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406 | if (first.ContainsKey(key) && second.ContainsKey(key))
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407 | discrepancy += Math.Abs(first[key] - second[key]);
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408 | else if (first.ContainsKey(key)) discrepancy += first[key];
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409 | else discrepancy += second[key];
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410 |
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411 | return discrepancy;
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412 | }
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413 |
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414 | private void DetermineUniqueItems(Expression source, IDictionary<int, int> items) {
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415 | if (source.CanExpand) {
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416 | var expand = source as ExecExpandExpression;
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417 |
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418 | foreach (var e in expand.State.Expressions) {
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419 | var id = e.GetHashCode();
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420 | if (!items.ContainsKey(id)) items.Add(id, 1);
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421 | else items[id]++;
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422 | }
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423 | } else {
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424 | items.Add(source.GetHashCode(), 1);
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425 | }
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426 | }
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427 | }
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428 |
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429 | /// <summary>
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430 | /// Pushes the sub-expression of the top item of the CODE stack that is indexed by the top item of the INTEGER stack.
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431 | /// The indexing here counts "points," where each parenthesized expression and each literal/instruction is considered a
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432 | /// point,
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433 | /// and it proceeds in depth first order. The entire piece of code is at index 0; if it is a list then the first item
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434 | /// in the list
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435 | /// is at index 1, etc. The integer used as the index is taken modulo the number of points in the overall expression
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436 | /// (and its
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437 | /// absolute value is taken in case it is negative) to ensure that it is within the meaningful range.
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438 | /// </summary>
|
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439 | [PushExpression(StackType.Code, "CODE.EXTRACT")]
|
---|
440 | public class CodeExtractExpression : StatelessExpression {
|
---|
441 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
442 | if (interpreter.IntegerStack.Count == 0 ||
|
---|
443 | interpreter.CodeStack.Count == 0 ||
|
---|
444 | !interpreter.CodeStack.Top.CanExpand)
|
---|
445 | return false;
|
---|
446 |
|
---|
447 | var expression = (ExecExpandExpression)interpreter.CodeStack.Top;
|
---|
448 | var index = (int)Math.Abs(interpreter.IntegerStack.Pop() % expression.State.TotalCount);
|
---|
449 | var result = expression.GetFromTree(index);
|
---|
450 |
|
---|
451 | interpreter.CodeStack.SetTop(result);
|
---|
452 |
|
---|
453 | return true;
|
---|
454 | }
|
---|
455 | }
|
---|
456 |
|
---|
457 | /// <summary>
|
---|
458 | /// Pops the BOOLEAN stack and pushes the popped item (TRUE or FALSE) onto the CODE stack.
|
---|
459 | /// </summary>
|
---|
460 | [PushExpression(StackType.Code, "CODE.FROMBOOLEAN")]
|
---|
461 | public class CodeFromBooleanExpression : StatelessExpression {
|
---|
462 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
463 | if (interpreter.BooleanStack.Count == 0) return false;
|
---|
464 |
|
---|
465 | var value = interpreter.BooleanStack.Pop();
|
---|
466 | var expression = new BooleanPushExpression(value);
|
---|
467 |
|
---|
468 | interpreter.CodeStack.Push(expression);
|
---|
469 |
|
---|
470 | return true;
|
---|
471 | }
|
---|
472 | }
|
---|
473 |
|
---|
474 | /// <summary>
|
---|
475 | /// Pops the FLOAT stack and pushes the popped item onto the CODE stack.
|
---|
476 | /// </summary>
|
---|
477 | [PushExpression(StackType.Code, "CODE.FROMFLOAT")]
|
---|
478 | public class CodeFromFloatExpression : StatelessExpression {
|
---|
479 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
480 | if (interpreter.FloatStack.Count == 0) return false;
|
---|
481 |
|
---|
482 | var value = interpreter.FloatStack.Pop();
|
---|
483 | var expression = new FloatPushExpression(value);
|
---|
484 |
|
---|
485 | interpreter.CodeStack.Push(expression);
|
---|
486 |
|
---|
487 | return true;
|
---|
488 | }
|
---|
489 | }
|
---|
490 |
|
---|
491 | /// <summary>
|
---|
492 | /// Pops the INTEGER stack and pushes the popped integer onto the CODE stack.
|
---|
493 | /// </summary>
|
---|
494 | [PushExpression(StackType.Code, "CODE.FROMINTEGER")]
|
---|
495 | public class CodeFromIntegerExpression : StatelessExpression {
|
---|
496 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
497 | if (interpreter.IntegerStack.Count == 0) return false;
|
---|
498 |
|
---|
499 | var value = interpreter.IntegerStack.Pop();
|
---|
500 | var expression = new IntegerPushExpression(value);
|
---|
501 |
|
---|
502 | interpreter.CodeStack.Push(expression);
|
---|
503 |
|
---|
504 | return true;
|
---|
505 | }
|
---|
506 | }
|
---|
507 |
|
---|
508 | /// <summary>
|
---|
509 | /// Pops the NAME stack and pushes the popped item onto the CODE stack.
|
---|
510 | /// </summary>
|
---|
511 | [PushExpression(StackType.Code, "CODE.FROMNAME")]
|
---|
512 | public class CodeFromNameExpression : StatelessExpression {
|
---|
513 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
514 | if (interpreter.NameStack.Count == 0) return false;
|
---|
515 |
|
---|
516 | var value = interpreter.NameStack.Pop();
|
---|
517 | var expression = new NameDefineXExecExpression(value);
|
---|
518 |
|
---|
519 | interpreter.CodeStack.Push(expression);
|
---|
520 |
|
---|
521 | return true;
|
---|
522 | }
|
---|
523 | }
|
---|
524 |
|
---|
525 | /// <summary>
|
---|
526 | /// Pushes the result of inserting the second item of the CODE stack into the first item, at the position indexed
|
---|
527 | /// by the top item of the INTEGER stack (and replacing whatever was there formerly).
|
---|
528 | /// </summary>
|
---|
529 | [PushExpression(StackType.Code, "CODE.CODEINSERT")]
|
---|
530 | public class CodeInsertExpression : StatelessExpression {
|
---|
531 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
532 | if (interpreter.IntegerStack.Count == 0 ||
|
---|
533 | interpreter.CodeStack.Count < 2 ||
|
---|
534 | !interpreter.CodeStack.Top.CanExpand)
|
---|
535 | return false;
|
---|
536 |
|
---|
537 | var source = interpreter.CodeStack[interpreter.CodeStack.Count - 2];
|
---|
538 | var target = (ExecExpandExpression)interpreter.CodeStack.Pop();
|
---|
539 | var index = (int)interpreter.IntegerStack.Pop();
|
---|
540 |
|
---|
541 | Expression[] newExpressions;
|
---|
542 | if (target.State.Expressions.Count > 0) {
|
---|
543 | index = target.State.Expressions.Count - 1 - Math.Abs(index % target.State.Expressions.Count);
|
---|
544 |
|
---|
545 | newExpressions = target.State.CopyExpressions();
|
---|
546 | newExpressions[index] = source.CanExpand
|
---|
547 | ? ((ExecExpandExpression)source).Copy()
|
---|
548 | : source;
|
---|
549 | } else {
|
---|
550 | newExpressions = new[] { source };
|
---|
551 | }
|
---|
552 |
|
---|
553 | var result = new ExecExpandExpression(newExpressions);
|
---|
554 | interpreter.CodeStack.SetTop(result);
|
---|
555 |
|
---|
556 | return true;
|
---|
557 | }
|
---|
558 | }
|
---|
559 |
|
---|
560 | /// <summary>
|
---|
561 | /// Pushes the length of the top item on the CODE stack onto the INTEGER stack.
|
---|
562 | /// If the top item is not a list then this pushes a 1. If the top item is a list then this pushes the
|
---|
563 | /// number of items in the top level of the list; that is, nested lists contribute only 1 to this count, no
|
---|
564 | /// matter what they contain.
|
---|
565 | /// </summary>
|
---|
566 | [PushExpression(StackType.Code, "CODE.LENGTH")]
|
---|
567 | public class CodeLengthExpression : StatelessExpression {
|
---|
568 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
569 | if (interpreter.CodeStack.Count == 0) return false;
|
---|
570 |
|
---|
571 | var expression = interpreter.CodeStack.Pop();
|
---|
572 | var count = 1;
|
---|
573 |
|
---|
574 | if (expression.CanExpand)
|
---|
575 | count = ((ExecExpandExpression)expression).State.Expressions.Count;
|
---|
576 |
|
---|
577 | interpreter.IntegerStack.Push(count);
|
---|
578 |
|
---|
579 | return true;
|
---|
580 | }
|
---|
581 | }
|
---|
582 |
|
---|
583 | /// <summary>
|
---|
584 | /// Pushes a list of the top two items of the CODE stack onto the CODE stack.
|
---|
585 | /// </summary>
|
---|
586 | [PushExpression(StackType.Code, "CODE.LIST")]
|
---|
587 | public class CodeListExpression : StatelessExpression {
|
---|
588 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
589 | if (interpreter.CodeStack.Count < 2) return false;
|
---|
590 |
|
---|
591 | var first = interpreter.CodeStack.Pop();
|
---|
592 | var second = interpreter.CodeStack.Top;
|
---|
593 | var expandExpression = new ExecExpandExpression(second, first);
|
---|
594 |
|
---|
595 | interpreter.CodeStack.SetTop(expandExpression);
|
---|
596 |
|
---|
597 | return true;
|
---|
598 | }
|
---|
599 | }
|
---|
600 |
|
---|
601 | /// <summary>
|
---|
602 | /// Pushes TRUE onto the BOOLEAN stack if the second item of the CODE stack is a member of the first item
|
---|
603 | /// (which is coerced to a list if necessary). Pushes FALSE onto the BOOLEAN stack otherwise.
|
---|
604 | /// </summary>
|
---|
605 | [PushExpression(StackType.Code, "CODE.MEMBER")]
|
---|
606 | public class CodeMemberExpression : StatelessExpression {
|
---|
607 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
608 | if (interpreter.CodeStack.Count < 2) return false;
|
---|
609 |
|
---|
610 | var expressions = interpreter.CodeStack.Pop(2);
|
---|
611 |
|
---|
612 | var contains = expressions[1].CanExpand
|
---|
613 | ? ((ExecExpandExpression)expressions[1]).State.Expressions.Contains(expressions[0])
|
---|
614 | : expressions[1].Equals(expressions[0]);
|
---|
615 |
|
---|
616 | interpreter.BooleanStack.Push(contains);
|
---|
617 |
|
---|
618 | return true;
|
---|
619 | }
|
---|
620 | }
|
---|
621 |
|
---|
622 | /// <summary>
|
---|
623 | /// Pushes the nth element of the expression on top of the CODE stack (which is coerced to a list first if necessary).
|
---|
624 | /// If the expression is an empty list then the result is an empty list. N is taken from the INTEGER stack and is taken
|
---|
625 | /// modulo the length of the expression into which it is indexing.
|
---|
626 | /// </summary>
|
---|
627 | [PushExpression(StackType.Code, "CODE.NTH")]
|
---|
628 | public class CodeNthExpression : StatelessExpression {
|
---|
629 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
630 | if ((interpreter.CodeStack.Count == 0) || (interpreter.IntegerStack.Count == 0)) return false;
|
---|
631 |
|
---|
632 | var n = interpreter.IntegerStack.Pop();
|
---|
633 | var expression = interpreter.CodeStack.Top;
|
---|
634 |
|
---|
635 | Expression nthExpression;
|
---|
636 |
|
---|
637 | if (expression.CanExpand) {
|
---|
638 | var subExpression = (ExecExpandExpression)expression;
|
---|
639 |
|
---|
640 | if (subExpression.State.IsEmpty) {
|
---|
641 | nthExpression = ExecExpandExpression.Empty;
|
---|
642 | } else {
|
---|
643 | var index = (int)(subExpression.State.Expressions.Count - 1 -
|
---|
644 | Math.Abs(n % subExpression.State.Expressions.Count));
|
---|
645 |
|
---|
646 | nthExpression = subExpression.State.Expressions[index];
|
---|
647 | }
|
---|
648 | } else {
|
---|
649 | nthExpression = expression;
|
---|
650 | }
|
---|
651 |
|
---|
652 | interpreter.CodeStack.SetTop(nthExpression);
|
---|
653 |
|
---|
654 | return true;
|
---|
655 | }
|
---|
656 | }
|
---|
657 |
|
---|
658 | /// <summary>
|
---|
659 | /// Pushes the nth "CDR" (in the Lisp sense) of the expression on top of the CODE stack (which is coerced to a list
|
---|
660 | /// first if necessary). If the expression is an empty list then the result is an empty list. N is taken from the
|
---|
661 | /// INTEGER
|
---|
662 | /// stack and is taken modulo the length of the expression into which it is indexing. A "CDR" of a list is the list
|
---|
663 | /// without
|
---|
664 | /// its first element.
|
---|
665 | /// </summary>
|
---|
666 | [PushExpression(StackType.Code, "CODE.NTHCDR")]
|
---|
667 | public class CodeNthCdrExpression : StatelessExpression {
|
---|
668 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
669 | if ((interpreter.CodeStack.Count == 0) || (interpreter.IntegerStack.Count == 0)) return false;
|
---|
670 |
|
---|
671 | var n = interpreter.IntegerStack.Pop();
|
---|
672 | var expression = interpreter.CodeStack.Top;
|
---|
673 |
|
---|
674 | Expression nthExpression = null;
|
---|
675 |
|
---|
676 | if (expression.CanExpand) {
|
---|
677 | var subExpressions = ((ExecExpandExpression)expression).State.Expressions;
|
---|
678 |
|
---|
679 | if (subExpressions.Count < 2) {
|
---|
680 | nthExpression = ExecExpandExpression.Empty;
|
---|
681 | } else {
|
---|
682 | var index = (int)(subExpressions.Count - 2 - Math.Abs(n % (subExpressions.Count - 1)));
|
---|
683 |
|
---|
684 | nthExpression = subExpressions[index];
|
---|
685 | }
|
---|
686 | } else {
|
---|
687 | nthExpression = expression;
|
---|
688 | }
|
---|
689 |
|
---|
690 | interpreter.CodeStack.SetTop(nthExpression);
|
---|
691 |
|
---|
692 | return true;
|
---|
693 | }
|
---|
694 | }
|
---|
695 |
|
---|
696 | /// <summary>
|
---|
697 | /// Pushes TRUE onto the BOOLEAN stack if the top item of the CODE stack is an empty list, or FALSE otherwise.
|
---|
698 | /// </summary>
|
---|
699 | [PushExpression(StackType.Code, "CODE.NULL")]
|
---|
700 | public class CodeNullExpression : StatelessExpression {
|
---|
701 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
702 | if (interpreter.CodeStack.Count == 0) return false;
|
---|
703 |
|
---|
704 | var result = interpreter.CodeStack.Pop().Equals(ExecExpandExpression.Empty);
|
---|
705 | interpreter.BooleanStack.Push(result);
|
---|
706 |
|
---|
707 | return true;
|
---|
708 | }
|
---|
709 | }
|
---|
710 |
|
---|
711 | /// <summary>
|
---|
712 | /// Pushes onto the INTEGER stack the position of the second item on the CODE stack within the first item
|
---|
713 | /// (which is coerced to a list if necessary). Pushes -1 if no match is found.
|
---|
714 | /// </summary>
|
---|
715 | [PushExpression(StackType.Code, "CODE.POSITION")]
|
---|
716 | public class CodePositionExpression : StatelessExpression {
|
---|
717 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
718 | if (interpreter.CodeStack.Count < 2) return false;
|
---|
719 |
|
---|
720 | var expressions = interpreter.CodeStack.Pop(2);
|
---|
721 | var first = expressions[1];
|
---|
722 | var second = expressions[0];
|
---|
723 |
|
---|
724 | var position = -1;
|
---|
725 | if (first.CanExpand) {
|
---|
726 | var expand = (ExecExpandExpression)first;
|
---|
727 | position = expand.State.Expressions.Count - 1
|
---|
728 | - Array.FindIndex((Expression[])expand.State.Expressions, e => e.Equals(second));
|
---|
729 | } else if (first.Equals(second)) {
|
---|
730 | position = 0;
|
---|
731 | }
|
---|
732 |
|
---|
733 | interpreter.IntegerStack.Push(position);
|
---|
734 |
|
---|
735 | return true;
|
---|
736 | }
|
---|
737 | }
|
---|
738 |
|
---|
739 | /// <summary>
|
---|
740 | /// Pushes the number of "points" in the top piece of CODE onto the INTEGER stack. Each instruction, literal,
|
---|
741 | /// and pair of parentheses counts as a point.
|
---|
742 | /// </summary>
|
---|
743 | [PushExpression(StackType.Code, "CODE.SIZE")]
|
---|
744 | public class CodeSizeExpression : StatelessExpression {
|
---|
745 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
746 | if (interpreter.CodeStack.Count == 0) return false;
|
---|
747 |
|
---|
748 | var expression = interpreter.CodeStack.Pop();
|
---|
749 | var points = expression.CanExpand
|
---|
750 | ? ((ExecExpandExpression)expression).State.Expressions.Count
|
---|
751 | : 1;
|
---|
752 |
|
---|
753 | interpreter.IntegerStack.Push(points);
|
---|
754 |
|
---|
755 | return true;
|
---|
756 | }
|
---|
757 | }
|
---|
758 |
|
---|
759 | /// <summary>
|
---|
760 | /// Pushes the result of substituting the third item on the code stack for the second item in the first item.
|
---|
761 | /// As of this writing this is implemented only in the Lisp implementation, within which it relies on the Lisp "subst"
|
---|
762 | /// function. As such, there are several problematic possibilities; for example "dotted-lists" can result in certain
|
---|
763 | /// cases with empty-list arguments. If any of these problematic possibilities occurs the stack is left unchanged.
|
---|
764 | /// </summary>
|
---|
765 | [PushExpression(StackType.Code, "CODE.SUBST")]
|
---|
766 | public class CodeSubstitutionExpression : StatelessExpression {
|
---|
767 | public override bool Eval(IPushInterpreter interpreter) {
|
---|
768 | if ((interpreter.CodeStack.Count < 3) || (interpreter.CodeStack.Top.GetType() !=
|
---|
769 | typeof(ExecExpandExpression))) return false;
|
---|
770 |
|
---|
771 | var expressions = interpreter.CodeStack.Pop(2);
|
---|
772 | var third = interpreter.CodeStack.Top;
|
---|
773 | var second = expressions[0];
|
---|
774 | var first = expressions[1] as ExecExpandExpression;
|
---|
775 | var newExpressions = new Expression[first.State.Expressions.Count];
|
---|
776 |
|
---|
777 | for (var i = 0; i < first.State.Expressions.Count; i++)
|
---|
778 | newExpressions[i] = first.State.Expressions[i].Equals(third)
|
---|
779 | ? second
|
---|
780 | /* no cloning needed here because first is removed and therefore newExpression is the only container of sub expressions */
|
---|
781 | : first.State.Expressions[i];
|
---|
782 |
|
---|
783 | var result = new ExecExpandExpression(newExpressions);
|
---|
784 |
|
---|
785 | interpreter.CodeStack.SetTop(result);
|
---|
786 |
|
---|
787 | return true;
|
---|
788 | }
|
---|
789 | }
|
---|
790 | } |
---|