1 | PROBLEM Factorial
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2 | CODE<<
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3 | string[] allTerminals = new string[] {"a", "b", "c", "d", "e", "n"} ;
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4 | SymTab symTab = new SymTab();
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5 |
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6 | class SymTab {
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7 | private Dictionary<string, int> values = new Dictionary<string,int>();
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8 | public void SetValue(string id, int val) {
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9 | values[id] = val;
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10 | }
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11 | public int GetValue(string id) {
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12 | int val = 0;
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13 | values.TryGetValue(id, out val);
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14 | return val;
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15 | }
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16 | }
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17 | >>
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18 |
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19 | NONTERMINALS
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20 | Program<<int n, out int r>>. /* return value is the result of the last statement. */
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21 | StatSeq<<out int r>>.
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22 | AssignStat<<out int r>>. /* result of assignment is the assigned value */
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23 | IncStat<<out int r>>.
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24 | DecStat<<out int r>>.
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25 | WhileStat<<out int r>>. /* result of while loop is the result of the last executed statement */
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26 | ReturnStat<<out int r>>.
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27 | Expr<<out int r>>.
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28 | AdditionExpr<<out int r>>.
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29 | SubtractionExpr<<out int r>>.
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30 | DivisionExpr<<out int r>>.
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31 | MultiplicationExpr<<out int r>>.
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32 | BooleanExpr<<out bool b>>.
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33 | NotExpr<<out bool b>>.
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34 | LessThanExpr<<out bool b>>.
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35 | EqualExpr<<out bool b>>.
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36 | AssignStatAndStatSeq<<out int r>>.
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37 | WhileStatAndStatSeq<<out int r>>.
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38 | ReturnStatAndStatSeq<<out int r>>.
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39 |
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40 | TERMINALS
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41 | ident<<out string id>>
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42 | CONSTRAINTS
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43 | id IN SET << allTerminals; >>
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44 | .
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45 | Const<<out int val>>
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46 | CONSTRAINTS
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47 | val IN SET << Enumerable.Range(0, 100); >>
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48 | .
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49 | Nothing<<out int val>>
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50 | CONSTRAINTS
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51 | val IN SET << Enumerable.Repeat(0, 1); >>
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52 | .
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53 |
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54 | RULES
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55 | Program<<int n, out int r>> = StatSeq<<out r>> SEM << symTab.SetValue("n", n); >>
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56 | .
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57 | StatSeq<<out int r>> = LOCAL << r = 0; >>
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58 | Nothing<<out r>>
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59 | | AssignStatAndStatSeq<<out r>>
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60 | | WhileStatAndStatSeq<<out r>>
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61 | | ReturnStatAndStatSeq<<out r>>
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62 | | IncStat<<out r>>
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63 | | DecStat<<out r>>
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64 | .
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65 |
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66 | AssignStatAndStatSeq<<out int r>> =
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67 | StatSeq<<out r>> AssignStat<<out r>>
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68 | .
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69 | WhileStatAndStatSeq<<out int r>> =
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70 | StatSeq<<out r>> WhileStat<<out r>>
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71 | .
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72 | ReturnStatAndStatSeq<<out int r>> =
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73 | StatSeq<<out r>> ReturnStat<<out r>>
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74 | .
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75 |
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76 | AssignStat<<out int r>> = LOCAL << int e; string id;>>
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77 | ident<<out id>> Expr<<out e>> SEM << symTab.SetValue(id, e); r = e; >>
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78 | .
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79 | IncStat<<out int r>> = LOCAL << int e; string id;>>
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80 | ident<<out id>> SEM << r = symTab.GetValue(id) + 1; symTab.SetValue(id, r); >>
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81 | .
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82 | DecStat<<out int r>> = LOCAL << int e; string id;>>
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83 | ident<<out id>> SEM << r = symTab.GetValue(id) - 1; symTab.SetValue(id, r); >>
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84 | .
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85 |
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86 | WhileStat<<out int r>> = LOCAL << bool b; int c = 0; >>
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87 | SEM << r = 0; >>
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88 | SEM << while(true && c++ < 100) { >>
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89 | BooleanExpr<<out b>> SEM << if(!b) break; >>
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90 | StatSeq<<out r>> SEM << } >>
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91 | .
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92 | ReturnStat<<out int r>> = Expr<<out r>> SEM << return; >>
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93 | .
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94 | Expr<<out int r>> = LOCAL << string id; >>
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95 | AdditionExpr<<out r>>
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96 | | SubtractionExpr<<out r>>
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97 | | MultiplicationExpr<<out r>>
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98 | | DivisionExpr<<out r>>
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99 | | Const<<out r>>
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100 | | ident<<out id>> SEM << r = symTab.GetValue(id); >>
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101 | .
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102 | AdditionExpr<<out int r>> = LOCAL << int e1, e2; >>
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103 | Expr<<out e1>> Expr<<out e2>> SEM << r = e1 + e2; >>
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104 | .
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105 | SubtractionExpr<<out int r>> = LOCAL << int e1, e2; >>
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106 | Expr<<out e1>> Expr<<out e2>> SEM << r = e1 - e2; >>
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107 | .
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108 | MultiplicationExpr<<out int r>> = LOCAL << int e1, e2; >>
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109 | Expr<<out e1>> Expr<<out e2>> SEM << r = e1 * e2; >>
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110 | .
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111 | DivisionExpr<<out int r>> = LOCAL << int e1, e2; >>
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112 | Expr<<out e1>> Expr<<out e2>> SEM << r = e2 == 0 ? 1 : e1 / e2; >>
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113 | .
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114 | BooleanExpr<<out bool b>> =
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115 | LessThanExpr<<out b>>
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116 | | EqualExpr<<out b>>
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117 | | NotExpr<<out b>>
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118 | .
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119 | NotExpr<<out bool b>> = LOCAL << bool notB; >>
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120 | BooleanExpr<<out notB>> SEM << b = !notB; >>
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121 | .
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122 | LessThanExpr<<out bool b>> = LOCAL << int lhs, rhs; >>
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123 | Expr<<out lhs>> Expr<<out rhs>> SEM << b = lhs < rhs; >>
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124 | .
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125 | EqualExpr<<out bool b>> = LOCAL << int lhs, rhs; >>
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126 | Expr<<out lhs>> Expr<<out rhs>> SEM << b = lhs == rhs; >>
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127 | .
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128 |
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129 |
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130 | MINIMIZE /* could also use the keyword MAXIMIZE here */
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131 | <<
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132 | var ns = new int[] {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
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133 | var expected = new int[] { 1,1,2,6,24,120,720,5040,40320,362880,3628800 };
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134 |
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135 | double sumOfLogAbsoluteErrors = 0;
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136 | for(int i=0;i<ns.Length;i++) {
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137 | int actualResult;
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138 | Program(ns[i], out actualResult);
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139 | sumOfLogAbsoluteErrors += Math.Log(Math.Abs(expected[i] - actualResult) + 1);
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140 | }
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141 |
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142 | return sumOfLogAbsoluteErrors;
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143 | >>
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144 |
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145 |
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146 | END Factorial.
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