1 | "Utility functions used by the btm_matcher module" |
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2 | |
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3 | from . import pytree |
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4 | from .pgen2 import grammar, token |
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5 | from .pygram import pattern_symbols, python_symbols |
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6 | |
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7 | syms = pattern_symbols |
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8 | pysyms = python_symbols |
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9 | tokens = grammar.opmap |
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10 | token_labels = token |
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11 | |
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12 | TYPE_ANY = -1 |
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13 | TYPE_ALTERNATIVES = -2 |
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14 | TYPE_GROUP = -3 |
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15 | |
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16 | class MinNode(object): |
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17 | """This class serves as an intermediate representation of the |
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18 | pattern tree during the conversion to sets of leaf-to-root |
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19 | subpatterns""" |
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20 | |
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21 | def __init__(self, type=None, name=None): |
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22 | self.type = type |
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23 | self.name = name |
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24 | self.children = [] |
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25 | self.leaf = False |
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26 | self.parent = None |
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27 | self.alternatives = [] |
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28 | self.group = [] |
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29 | |
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30 | def __repr__(self): |
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31 | return str(self.type) + ' ' + str(self.name) |
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32 | |
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33 | def leaf_to_root(self): |
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34 | """Internal method. Returns a characteristic path of the |
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35 | pattern tree. This method must be run for all leaves until the |
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36 | linear subpatterns are merged into a single""" |
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37 | node = self |
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38 | subp = [] |
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39 | while node: |
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40 | if node.type == TYPE_ALTERNATIVES: |
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41 | node.alternatives.append(subp) |
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42 | if len(node.alternatives) == len(node.children): |
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43 | #last alternative |
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44 | subp = [tuple(node.alternatives)] |
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45 | node.alternatives = [] |
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46 | node = node.parent |
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47 | continue |
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48 | else: |
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49 | node = node.parent |
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50 | subp = None |
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51 | break |
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52 | |
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53 | if node.type == TYPE_GROUP: |
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54 | node.group.append(subp) |
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55 | #probably should check the number of leaves |
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56 | if len(node.group) == len(node.children): |
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57 | subp = get_characteristic_subpattern(node.group) |
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58 | node.group = [] |
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59 | node = node.parent |
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60 | continue |
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61 | else: |
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62 | node = node.parent |
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63 | subp = None |
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64 | break |
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65 | |
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66 | if node.type == token_labels.NAME and node.name: |
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67 | #in case of type=name, use the name instead |
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68 | subp.append(node.name) |
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69 | else: |
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70 | subp.append(node.type) |
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71 | |
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72 | node = node.parent |
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73 | return subp |
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74 | |
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75 | def get_linear_subpattern(self): |
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76 | """Drives the leaf_to_root method. The reason that |
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77 | leaf_to_root must be run multiple times is because we need to |
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78 | reject 'group' matches; for example the alternative form |
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79 | (a | b c) creates a group [b c] that needs to be matched. Since |
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80 | matching multiple linear patterns overcomes the automaton's |
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81 | capabilities, leaf_to_root merges each group into a single |
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82 | choice based on 'characteristic'ity, |
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83 | |
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84 | i.e. (a|b c) -> (a|b) if b more characteristic than c |
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85 | |
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86 | Returns: The most 'characteristic'(as defined by |
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87 | get_characteristic_subpattern) path for the compiled pattern |
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88 | tree. |
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89 | """ |
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90 | |
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91 | for l in self.leaves(): |
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92 | subp = l.leaf_to_root() |
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93 | if subp: |
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94 | return subp |
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95 | |
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96 | def leaves(self): |
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97 | "Generator that returns the leaves of the tree" |
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98 | for child in self.children: |
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99 | for x in child.leaves(): |
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100 | yield x |
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101 | if not self.children: |
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102 | yield self |
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103 | |
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104 | def reduce_tree(node, parent=None): |
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105 | """ |
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106 | Internal function. Reduces a compiled pattern tree to an |
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107 | intermediate representation suitable for feeding the |
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108 | automaton. This also trims off any optional pattern elements(like |
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109 | [a], a*). |
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110 | """ |
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111 | |
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112 | new_node = None |
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113 | #switch on the node type |
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114 | if node.type == syms.Matcher: |
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115 | #skip |
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116 | node = node.children[0] |
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117 | |
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118 | if node.type == syms.Alternatives : |
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119 | #2 cases |
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120 | if len(node.children) <= 2: |
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121 | #just a single 'Alternative', skip this node |
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122 | new_node = reduce_tree(node.children[0], parent) |
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123 | else: |
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124 | #real alternatives |
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125 | new_node = MinNode(type=TYPE_ALTERNATIVES) |
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126 | #skip odd children('|' tokens) |
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127 | for child in node.children: |
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128 | if node.children.index(child)%2: |
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129 | continue |
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130 | reduced = reduce_tree(child, new_node) |
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131 | if reduced is not None: |
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132 | new_node.children.append(reduced) |
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133 | elif node.type == syms.Alternative: |
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134 | if len(node.children) > 1: |
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135 | |
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136 | new_node = MinNode(type=TYPE_GROUP) |
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137 | for child in node.children: |
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138 | reduced = reduce_tree(child, new_node) |
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139 | if reduced: |
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140 | new_node.children.append(reduced) |
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141 | if not new_node.children: |
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142 | # delete the group if all of the children were reduced to None |
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143 | new_node = None |
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144 | |
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145 | else: |
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146 | new_node = reduce_tree(node.children[0], parent) |
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147 | |
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148 | elif node.type == syms.Unit: |
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149 | if (isinstance(node.children[0], pytree.Leaf) and |
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150 | node.children[0].value == '('): |
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151 | #skip parentheses |
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152 | return reduce_tree(node.children[1], parent) |
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153 | if ((isinstance(node.children[0], pytree.Leaf) and |
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154 | node.children[0].value == '[') |
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155 | or |
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156 | (len(node.children)>1 and |
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157 | hasattr(node.children[1], "value") and |
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158 | node.children[1].value == '[')): |
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159 | #skip whole unit if its optional |
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160 | return None |
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161 | |
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162 | leaf = True |
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163 | details_node = None |
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164 | alternatives_node = None |
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165 | has_repeater = False |
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166 | repeater_node = None |
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167 | has_variable_name = False |
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168 | |
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169 | for child in node.children: |
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170 | if child.type == syms.Details: |
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171 | leaf = False |
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172 | details_node = child |
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173 | elif child.type == syms.Repeater: |
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174 | has_repeater = True |
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175 | repeater_node = child |
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176 | elif child.type == syms.Alternatives: |
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177 | alternatives_node = child |
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178 | if hasattr(child, 'value') and child.value == '=': # variable name |
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179 | has_variable_name = True |
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180 | |
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181 | #skip variable name |
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182 | if has_variable_name: |
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183 | #skip variable name, '=' |
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184 | name_leaf = node.children[2] |
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185 | if hasattr(name_leaf, 'value') and name_leaf.value == '(': |
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186 | # skip parenthesis |
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187 | name_leaf = node.children[3] |
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188 | else: |
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189 | name_leaf = node.children[0] |
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190 | |
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191 | #set node type |
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192 | if name_leaf.type == token_labels.NAME: |
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193 | #(python) non-name or wildcard |
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194 | if name_leaf.value == 'any': |
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195 | new_node = MinNode(type=TYPE_ANY) |
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196 | else: |
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197 | if hasattr(token_labels, name_leaf.value): |
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198 | new_node = MinNode(type=getattr(token_labels, name_leaf.value)) |
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199 | else: |
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200 | new_node = MinNode(type=getattr(pysyms, name_leaf.value)) |
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201 | |
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202 | elif name_leaf.type == token_labels.STRING: |
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203 | #(python) name or character; remove the apostrophes from |
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204 | #the string value |
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205 | name = name_leaf.value.strip("'") |
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206 | if name in tokens: |
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207 | new_node = MinNode(type=tokens[name]) |
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208 | else: |
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209 | new_node = MinNode(type=token_labels.NAME, name=name) |
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210 | elif name_leaf.type == syms.Alternatives: |
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211 | new_node = reduce_tree(alternatives_node, parent) |
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212 | |
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213 | #handle repeaters |
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214 | if has_repeater: |
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215 | if repeater_node.children[0].value == '*': |
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216 | #reduce to None |
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217 | new_node = None |
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218 | elif repeater_node.children[0].value == '+': |
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219 | #reduce to a single occurence i.e. do nothing |
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220 | pass |
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221 | else: |
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222 | #TODO: handle {min, max} repeaters |
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223 | raise NotImplementedError |
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224 | pass |
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225 | |
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226 | #add children |
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227 | if details_node and new_node is not None: |
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228 | for child in details_node.children[1:-1]: |
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229 | #skip '<', '>' markers |
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230 | reduced = reduce_tree(child, new_node) |
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231 | if reduced is not None: |
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232 | new_node.children.append(reduced) |
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233 | if new_node: |
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234 | new_node.parent = parent |
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235 | return new_node |
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236 | |
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237 | |
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238 | def get_characteristic_subpattern(subpatterns): |
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239 | """Picks the most characteristic from a list of linear patterns |
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240 | Current order used is: |
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241 | names > common_names > common_chars |
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242 | """ |
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243 | if not isinstance(subpatterns, list): |
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244 | return subpatterns |
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245 | if len(subpatterns)==1: |
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246 | return subpatterns[0] |
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247 | |
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248 | # first pick out the ones containing variable names |
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249 | subpatterns_with_names = [] |
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250 | subpatterns_with_common_names = [] |
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251 | common_names = ['in', 'for', 'if' , 'not', 'None'] |
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252 | subpatterns_with_common_chars = [] |
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253 | common_chars = "[]().,:" |
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254 | for subpattern in subpatterns: |
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255 | if any(rec_test(subpattern, lambda x: type(x) is str)): |
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256 | if any(rec_test(subpattern, |
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257 | lambda x: isinstance(x, str) and x in common_chars)): |
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258 | subpatterns_with_common_chars.append(subpattern) |
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259 | elif any(rec_test(subpattern, |
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260 | lambda x: isinstance(x, str) and x in common_names)): |
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261 | subpatterns_with_common_names.append(subpattern) |
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262 | |
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263 | else: |
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264 | subpatterns_with_names.append(subpattern) |
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265 | |
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266 | if subpatterns_with_names: |
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267 | subpatterns = subpatterns_with_names |
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268 | elif subpatterns_with_common_names: |
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269 | subpatterns = subpatterns_with_common_names |
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270 | elif subpatterns_with_common_chars: |
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271 | subpatterns = subpatterns_with_common_chars |
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272 | # of the remaining subpatterns pick out the longest one |
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273 | return max(subpatterns, key=len) |
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274 | |
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275 | def rec_test(sequence, test_func): |
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276 | """Tests test_func on all items of sequence and items of included |
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277 | sub-iterables""" |
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278 | for x in sequence: |
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279 | if isinstance(x, (list, tuple)): |
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280 | for y in rec_test(x, test_func): |
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281 | yield y |
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282 | else: |
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283 | yield test_func(x) |
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