| 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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