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184
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1 import unittest, pprint
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194
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2 from pyyacc import Grammar, Item, ParserGenerationException, ParserException, EPS, EOF
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191
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3 from ppci import Token
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184
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4
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191
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5 def genTokens(lst):
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6 for t in lst:
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194
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7 yield Token(t, t)
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184
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8
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9 class testLR(unittest.TestCase):
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194
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10 """ Test basic LR(1) parser generator constructs """
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184
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11 def testSimpleGrammar(self):
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12 # 1. define a simple grammar:
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194
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13 g = Grammar(['identifier', '(', ')', '+', '*'])
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184
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14 g.add_production('input', ['expression'])
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15 g.add_production('expression', ['term'])
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16 g.add_production('expression', ['expression', '+', 'term'])
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17 g.add_production('term', ['factor'])
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18 g.add_production('term', ['term', '*', 'factor'])
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19 g.add_production('factor', ['(', 'expression', ')'])
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20 g.add_production('factor', ['identifier'])
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21 g.start_symbol = 'input'
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22 # 2. define input:
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191
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23 tokens = genTokens(['identifier', '+', 'identifier', '+', 'identifier'])
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184
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24 # 3. build parser:
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25 p = g.genParser()
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26 # 4. feed input:
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27 p.parse(tokens)
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192
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28 def testReduceReduceConflict(self):
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29 """ Check if a reduce-reduce conflict is detected """
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30 # Define a grammar with an obvious reduce-reduce conflict:
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194
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31 g = Grammar(['id'])
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192
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32 g.add_production('goal', ['a'])
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33 g.add_production('a', ['b'])
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34 g.add_production('a', ['c'])
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35 g.add_production('b', ['id'])
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36 g.add_production('c', ['id'])
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37 g.start_symbol = 'goal'
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38 with self.assertRaises(ParserGenerationException):
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39 p = g.genParser()
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40 def testShiftReduceConflict(self):
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194
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41 """ Must be handled automatically by doing shift """
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42 g = Grammar([EOF, 'if', 'then', 'else', 'ass'])
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43 # Ambiguous grammar:
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44 g.add_production('if_stmt', ['if', 'then', 'stmt'])
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45 g.add_production('if_stmt', ['if', 'then', 'stmt', 'else', 'stmt'])
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46 g.add_production('stmt', ['if_stmt'])
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47 g.add_production('stmt', ['ass'])
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192
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48 g.start_symbol = 'stmt'
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49 p = g.genParser()
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50 # Ambiguous program:
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51 tokens = genTokens(['if', 'then','if', 'then', 'ass', 'else', 'ass' ])
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52 p.parse(tokens)
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53
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192
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54 def testUndefinedTerminal(self):
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55 """ Test correct behavior when a terminal is undefined """
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56 g = Grammar(['b'])
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57 g.add_production('goal', ['a'])
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58 g.add_production('a', ['b'])
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59 g.add_production('a', ['c'])
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60 g.start_symbol = 'goal'
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61 with self.assertRaises(ParserGenerationException):
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62 g.genParser()
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63 def testRedefineTerminal(self):
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64 """ Test correct behavior when a terminal is redefined """
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65 g = Grammar([EOF, 'b', 'c'])
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66 g.add_production('goal', ['a'])
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67 with self.assertRaises(ParserGenerationException):
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68 g.add_production('b', ['c']) # Not allowed
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69 g.add_production('a', ['c'])
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70 g.start_symbol = 'goal'
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71 g.genParser()
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194
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72 def testEmpty(self):
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73 """ Test empty token stream """
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74 g = Grammar([','])
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75 g.add_production('input', [','])
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76 g.start_symbol = 'input'
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77 p = g.genParser()
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78 tokens = genTokens([])
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79 with self.assertRaises(ParserException):
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80 p.parse(tokens)
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81
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82 def testEps(self):
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83 """ Test epsilon terminal """
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84 g = Grammar(['a', 'b'])
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85 g.add_production('input', ['optional_a', 'b'])
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86 g.add_production('optional_a', ['a'])
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87 g.add_production('optional_a', [])
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88 g.start_symbol = 'input'
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89 p = g.genParser()
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90 tokens = genTokens(['b'])
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91 p.parse(tokens)
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92
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93 def testEps2(self):
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94 g = Grammar(['id', ':'])
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95 g.add_production('input', ['opt_lab', 'ins', 'op1'])
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96 g.add_production('input', ['ins', 'op1'])
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97 g.add_production('opt_lab', ['id', ':'])
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98 g.add_production('ins', ['id'])
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99 g.add_production('op1', ['id'])
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100 g.start_symbol = 'input'
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101 p = g.genParser()
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102 tokens = genTokens(['id', ':', 'id', 'id']) # i.e. "lab_0: inc rax"
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103 p.parse(tokens)
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104 tokens = genTokens(['id', 'id']) # i.e. "inc rax"
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105 p.parse(tokens)
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106
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184
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107
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185
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108 class testExpressionGrammar(unittest.TestCase):
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109 def setUp(self):
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110 g = Grammar(['EOF', 'identifier', '(', ')', '+', '*', 'num'])
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111 g.add_production('input', ['expression'])
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112 g.add_production('expression', ['term'])
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113 g.add_production('expression', ['expression', '+', 'term'])
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114 g.add_production('term', ['factor'])
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115 g.add_production('term', ['term', '*', 'factor'])
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116 g.add_production('factor', ['(', 'expression', ')'])
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117 g.add_production('factor', ['identifier'])
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118 g.add_production('factor', ['num'])
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119 g.start_symbol = 'input'
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120 self.g = g
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121
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122 def testFirstSimpleGrammar(self):
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123 # 1. define a simple grammar:
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124 first = self.g.calcFirstSets()
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125 self.assertEqual(first['input'], {'identifier', '(', 'num'})
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126 self.assertEqual(first['term'], {'identifier', '(', 'num'})
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127
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128 def testCanonical(self):
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129 s0 = self.g.initialItemSet()
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130 s, gt = self.g.genCanonicalSet(s0)
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131 # Must result in 12 sets:
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132 self.assertEqual(len(s), 24)
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133
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184
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134 class testPG(unittest.TestCase):
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135 """ Tests several parts of the parser generator """
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136 def setUp(self):
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137 g = Grammar(['(', ')'])
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138 g.add_production('goal', ['list'])
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139 g.add_production('list', ['list', 'pair'])
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140 g.add_production('list', ['pair'])
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141 g.add_production('pair', ['(', 'pair', ')'])
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142 g.add_production('pair', ['(', ')'])
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143 g.start_symbol = 'goal'
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144 self.g = g
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145
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146 def testFirstSet(self):
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147 for a in ['(', ')', EOF, 'EPS']:
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148 self.assertEqual(self.g.first[a], {a})
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149 for nt in ['list', 'pair', 'goal']:
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150 self.assertEqual(self.g.first[nt], {'('})
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151
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152 def testInitItemSet(self):
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153 p0, p1, p2, p3, p4 = self.g.productions
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154 s0 = self.g.initialItemSet()
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155 self.assertEqual(len(s0), 9) # 9 with the goal rule included!
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156 self.assertIn(Item(p0, 0, EOF), s0)
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157 self.assertIn(Item(p1, 0, EOF), s0)
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158 self.assertIn(Item(p1, 0, '('), s0)
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159 self.assertIn(Item(p2, 0, EOF), s0)
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160 self.assertIn(Item(p2, 0, '('), s0)
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161 self.assertIn(Item(p3, 0, EOF), s0)
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162 self.assertIn(Item(p3, 0, '('), s0)
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163 self.assertIn(Item(p4, 0, EOF), s0)
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164 self.assertIn(Item(p4, 0, '('), s0)
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165
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166 def testCanonical(self):
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167 s0 = self.g.initialItemSet()
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168 s, gt = self.g.genCanonicalSet(s0)
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169 # Must result in 12 sets:
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170 self.assertEqual(len(s), 12)
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171
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172 def testClosure(self):
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173 p0, p1, p2, p3, p4 = self.g.productions
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174 s0 = set()
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175 s0.add(Item(p0, 0, EOF))
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176 self.assertEqual(len(s0), 1) # 1 rule
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177 self.assertIn(Item(p0, 0, EOF), s0)
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178
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179 # Invoke closure on set:
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180 s0 = self.g.closure(s0)
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181 self.assertIn(Item(p0, 0, EOF), s0)
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182 self.assertIn(Item(p1, 0, EOF), s0)
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183 self.assertIn(Item(p1, 0, '('), s0)
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184 self.assertIn(Item(p2, 0, EOF), s0)
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185 self.assertIn(Item(p2, 0, '('), s0)
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186 self.assertIn(Item(p3, 0, EOF), s0)
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187 self.assertIn(Item(p3, 0, '('), s0)
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188 self.assertIn(Item(p4, 0, EOF), s0)
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189 self.assertIn(Item(p4, 0, '('), s0)
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190
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191 def testParser(self):
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192 tokens = ['(', '(', ')', ')', '(', ')']
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184
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193 # 3. build parser:
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194 p = self.g.genParser()
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195 self.assertEqual(len(p.goto_table), 5)
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196 self.assertEqual(len(p.action_table), 19)
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197
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198 # 4. feed input:
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199 p.parse(genTokens(tokens))
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200
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201 if __name__ == '__main__':
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202 unittest.main()
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203
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204
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