| 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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