1 |
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2 | using System;
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3 |
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4 | namespace SyntaxAnalyzer { |
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5 | |
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6 |
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7 |
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8 | public class Parser {
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9 | public const int _EOF = 0; |
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10 | public const int _ident = 1; |
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11 | public const int maxT = 30; |
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12 |
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13 | const bool T = true;
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14 | const bool x = false;
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15 | const int minErrDist = 2;
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16 |
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17 | public Scanner scanner;
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18 | public Errors errors;
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19 |
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20 | public Token t; // last recognized token
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21 | public Token la; // lookahead token
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22 | int errDist = minErrDist;
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23 |
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24 |
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25 |
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26 | public Parser(Scanner scanner) {
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27 | this.scanner = scanner;
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28 | errors = new Errors();
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29 | }
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30 |
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31 | void SynErr (int n) {
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32 | if (errDist >= minErrDist) errors.SynErr(la.line, la.col, n);
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33 | errDist = 0;
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34 | }
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35 |
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36 | public void SemErr (string msg) {
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37 | if (errDist >= minErrDist) errors.SemErr(t.line, t.col, msg);
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38 | errDist = 0;
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39 | }
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40 |
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41 | void Get () {
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42 | for (;;) {
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43 | t = la;
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44 | la = scanner.Scan();
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45 | if (la.kind <= maxT) { ++errDist; break; }
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46 |
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47 | la = t;
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48 | }
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49 | }
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50 |
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51 | void Expect (int n) {
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52 | if (la.kind==n) Get(); else { SynErr(n); }
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53 | }
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54 |
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55 | bool StartOf (int s) {
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56 | return set[s, la.kind];
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57 | }
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58 |
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59 | void ExpectWeak (int n, int follow) {
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60 | if (la.kind == n) Get();
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61 | else {
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62 | SynErr(n);
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63 | while (!StartOf(follow)) Get();
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64 | }
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65 | }
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66 |
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67 |
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68 | bool WeakSeparator(int n, int syFol, int repFol) {
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69 | int kind = la.kind;
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70 | if (kind == n) {Get(); return true;}
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71 | else if (StartOf(repFol)) {return false;}
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72 | else {
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73 | SynErr(n);
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74 | while (!(set[syFol, kind] || set[repFol, kind] || set[0, kind])) {
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75 | Get();
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76 | kind = la.kind;
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77 | }
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78 | return StartOf(syFol);
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79 | }
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80 | }
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81 |
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82 |
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83 | void GPDefSyntaxAnalyzer() { |
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84 | Expect(2); |
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85 | Expect(1); |
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86 | if (la.kind == 3) { |
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87 | Get(); |
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88 | Expect(4); |
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89 | while (StartOf(1)) { |
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90 | Get(); |
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91 | } |
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92 | Expect(5); |
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93 | } |
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94 | if (la.kind == 6) { |
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95 | Get(); |
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96 | Expect(4); |
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97 | while (StartOf(1)) { |
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98 | Get(); |
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99 | } |
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100 | Expect(5); |
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101 | } |
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102 | Expect(7); |
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103 | while (la.kind == 1) { |
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104 | NonterminalDecl(); |
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105 | } |
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106 | Expect(8); |
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107 | while (la.kind == 1) { |
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108 | TerminalDecl(); |
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109 | } |
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110 | Expect(9); |
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111 | while (la.kind == 1) { |
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112 | RuleDef(); |
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113 | } |
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114 | if (la.kind == 10) { |
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115 | Get(); |
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116 | } else if (la.kind == 11) { |
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117 | Get(); |
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118 | } else SynErr(31); |
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119 | Expect(4); |
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120 | while (StartOf(1)) { |
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121 | Get(); |
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122 | } |
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123 | Expect(5); |
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124 | Expect(12); |
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125 | Expect(1); |
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126 | Expect(13); |
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127 | } |
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128 | |
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129 | void NonterminalDecl() { |
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130 | Expect(1); |
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131 | if (la.kind == 4) { |
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132 | Get(); |
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133 | while (StartOf(1)) { |
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134 | Get(); |
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135 | } |
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136 | Expect(5); |
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137 | } |
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138 | Expect(13); |
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139 | } |
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140 | |
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141 | void TerminalDecl() { |
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142 | Expect(1); |
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143 | if (la.kind == 4) { |
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144 | Get(); |
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145 | while (StartOf(1)) { |
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146 | Get(); |
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147 | } |
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148 | Expect(5); |
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149 | } |
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150 | if (la.kind == 16) { |
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151 | Get(); |
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152 | ConstraintDef(); |
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153 | } |
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154 | Expect(13); |
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155 | } |
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156 | |
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157 | void RuleDef() { |
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158 | Expect(1); |
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159 | if (la.kind == 4) { |
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160 | Get(); |
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161 | while (StartOf(1)) { |
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162 | Get(); |
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163 | } |
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164 | Expect(5); |
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165 | } |
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166 | Expect(21); |
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167 | if (la.kind == 14) { |
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168 | SemDecl(); |
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169 | } |
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170 | SynExpr(); |
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171 | Expect(13); |
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172 | } |
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173 | |
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174 | void SemDecl() { |
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175 | Expect(14); |
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176 | Expect(4); |
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177 | while (StartOf(1)) { |
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178 | Get(); |
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179 | } |
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180 | Expect(5); |
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181 | } |
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182 | |
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183 | void SemAction() { |
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184 | Expect(15); |
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185 | Expect(4); |
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186 | while (StartOf(1)) { |
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187 | Get(); |
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188 | } |
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189 | Expect(5); |
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190 | } |
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191 | |
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192 | void ConstraintDef() { |
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193 | while (la.kind == 1) { |
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194 | ConstraintRule(); |
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195 | } |
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196 | } |
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197 | |
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198 | void ConstraintRule() { |
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199 | Expect(1); |
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200 | Expect(17); |
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201 | SetDefinition(); |
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202 | } |
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203 | |
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204 | void SetDefinition() { |
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205 | if (la.kind == 18) { |
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206 | Get(); |
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207 | Expect(4); |
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208 | while (StartOf(1)) { |
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209 | Get(); |
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210 | } |
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211 | Expect(5); |
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212 | } else if (la.kind == 19) { |
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213 | Get(); |
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214 | Expect(4); |
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215 | while (StartOf(1)) { |
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216 | Get(); |
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217 | } |
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218 | Expect(5); |
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219 | Expect(20); |
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220 | Expect(4); |
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221 | while (StartOf(1)) { |
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222 | Get(); |
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223 | } |
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224 | Expect(5); |
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225 | } else SynErr(32); |
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226 | } |
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227 | |
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228 | void SynExpr() { |
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229 | SynTerm(); |
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230 | while (la.kind == 22) { |
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231 | Get(); |
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232 | SynTerm(); |
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233 | } |
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234 | } |
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235 | |
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236 | void SynTerm() { |
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237 | SynFact(); |
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238 | while (StartOf(2)) { |
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239 | SynFact(); |
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240 | } |
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241 | } |
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242 | |
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243 | void SynFact() { |
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244 | switch (la.kind) { |
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245 | case 1: { |
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246 | Get(); |
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247 | if (la.kind == 4) { |
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248 | Get(); |
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249 | while (StartOf(1)) { |
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250 | Get(); |
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251 | } |
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252 | Expect(5); |
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253 | } |
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254 | break; |
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255 | } |
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256 | case 23: { |
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257 | Get(); |
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258 | break; |
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259 | } |
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260 | case 24: { |
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261 | Get(); |
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262 | SynExpr(); |
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263 | Expect(25); |
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264 | break; |
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265 | } |
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266 | case 26: { |
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267 | Get(); |
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268 | SynExpr(); |
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269 | Expect(27); |
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270 | break; |
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271 | } |
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272 | case 28: { |
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273 | Get(); |
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274 | SynExpr(); |
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275 | Expect(29); |
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276 | break; |
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277 | } |
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278 | case 15: { |
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279 | SemAction(); |
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280 | break; |
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281 | } |
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282 | default: SynErr(33); break; |
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283 | } |
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284 | } |
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285 | |
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286 |
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287 |
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288 | public void Parse() {
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289 | la = new Token();
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290 | la.val = "";
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291 | Get();
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292 | GPDefSyntaxAnalyzer(); |
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293 | Expect(0); |
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294 |
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295 | }
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296 |
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297 | static readonly bool[,] set = {
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298 | {T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x}, |
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299 | {x,T,T,T, T,x,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,x}, |
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300 | {x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, x,x,x,x, x,x,x,T, T,x,T,x, T,x,x,x} |
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301 |
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302 | };
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303 | } // end Parser
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304 |
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305 |
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306 | public class Errors {
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307 | public int count = 0; // number of errors detected
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308 | public System.IO.TextWriter errorStream = Console.Out; // error messages go to this stream
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309 | public string errMsgFormat = "-- line {0} col {1}: {2}"; // 0=line, 1=column, 2=text
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310 |
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311 | public virtual void SynErr (int line, int col, int n) {
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312 | string s;
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313 | switch (n) {
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314 | case 0: s = "EOF expected"; break; |
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315 | case 1: s = "ident expected"; break; |
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316 | case 2: s = "\"PROBLEM\" expected"; break; |
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317 | case 3: s = "\"CODE\" expected"; break; |
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318 | case 4: s = "\"<<\" expected"; break; |
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319 | case 5: s = "\">>\" expected"; break; |
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320 | case 6: s = "\"INIT\" expected"; break; |
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321 | case 7: s = "\"NONTERMINALS\" expected"; break; |
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322 | case 8: s = "\"TERMINALS\" expected"; break; |
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323 | case 9: s = "\"RULES\" expected"; break; |
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324 | case 10: s = "\"MAXIMIZE\" expected"; break; |
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325 | case 11: s = "\"MINIMIZE\" expected"; break; |
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326 | case 12: s = "\"END\" expected"; break; |
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327 | case 13: s = "\".\" expected"; break; |
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328 | case 14: s = "\"LOCAL\" expected"; break; |
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329 | case 15: s = "\"SEM\" expected"; break; |
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330 | case 16: s = "\"CONSTRAINTS\" expected"; break; |
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331 | case 17: s = "\"IN\" expected"; break; |
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332 | case 18: s = "\"SET\" expected"; break; |
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333 | case 19: s = "\"RANGE\" expected"; break; |
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334 | case 20: s = "\"..\" expected"; break; |
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335 | case 21: s = "\"=\" expected"; break; |
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336 | case 22: s = "\"|\" expected"; break; |
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337 | case 23: s = "\"EPS\" expected"; break; |
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338 | case 24: s = "\"(\" expected"; break; |
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339 | case 25: s = "\")\" expected"; break; |
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340 | case 26: s = "\"[\" expected"; break; |
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341 | case 27: s = "\"]\" expected"; break; |
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342 | case 28: s = "\"{\" expected"; break; |
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343 | case 29: s = "\"}\" expected"; break; |
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344 | case 30: s = "??? expected"; break; |
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345 | case 31: s = "invalid GPDefSyntaxAnalyzer"; break; |
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346 | case 32: s = "invalid SetDefinition"; break; |
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347 | case 33: s = "invalid SynFact"; break; |
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348 |
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349 | default: s = "error " + n; break;
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350 | }
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351 | errorStream.WriteLine(errMsgFormat, line, col, s);
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352 | count++;
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353 | }
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354 |
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355 | public virtual void SemErr (int line, int col, string s) {
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356 | errorStream.WriteLine(errMsgFormat, line, col, s);
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357 | count++;
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358 | }
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359 |
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360 | public virtual void SemErr (string s) {
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361 | errorStream.WriteLine(s);
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362 | count++;
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363 | }
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364 |
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365 | public virtual void Warning (int line, int col, string s) {
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366 | errorStream.WriteLine(errMsgFormat, line, col, s);
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367 | }
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368 |
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369 | public virtual void Warning(string s) {
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370 | errorStream.WriteLine(s);
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371 | }
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372 | } // Errors
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373 |
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374 |
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375 | public class FatalError: Exception {
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376 | public FatalError(string m): base(m) {}
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377 | }
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378 | } |
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