| 4710c53d |
1 | "Utility functions used by the btm_matcher module"\r |
| 2 | \r |
| 3 | from . import pytree\r |
| 4 | from .pgen2 import grammar, token\r |
| 5 | from .pygram import pattern_symbols, python_symbols\r |
| 6 | \r |
| 7 | syms = pattern_symbols\r |
| 8 | pysyms = python_symbols\r |
| 9 | tokens = grammar.opmap\r |
| 10 | token_labels = token\r |
| 11 | \r |
| 12 | TYPE_ANY = -1\r |
| 13 | TYPE_ALTERNATIVES = -2\r |
| 14 | TYPE_GROUP = -3\r |
| 15 | \r |
| 16 | class MinNode(object):\r |
| 17 | """This class serves as an intermediate representation of the\r |
| 18 | pattern tree during the conversion to sets of leaf-to-root\r |
| 19 | subpatterns"""\r |
| 20 | \r |
| 21 | def __init__(self, type=None, name=None):\r |
| 22 | self.type = type\r |
| 23 | self.name = name\r |
| 24 | self.children = []\r |
| 25 | self.leaf = False\r |
| 26 | self.parent = None\r |
| 27 | self.alternatives = []\r |
| 28 | self.group = []\r |
| 29 | \r |
| 30 | def __repr__(self):\r |
| 31 | return str(self.type) + ' ' + str(self.name)\r |
| 32 | \r |
| 33 | def leaf_to_root(self):\r |
| 34 | """Internal method. Returns a characteristic path of the\r |
| 35 | pattern tree. This method must be run for all leaves until the\r |
| 36 | linear subpatterns are merged into a single"""\r |
| 37 | node = self\r |
| 38 | subp = []\r |
| 39 | while node:\r |
| 40 | if node.type == TYPE_ALTERNATIVES:\r |
| 41 | node.alternatives.append(subp)\r |
| 42 | if len(node.alternatives) == len(node.children):\r |
| 43 | #last alternative\r |
| 44 | subp = [tuple(node.alternatives)]\r |
| 45 | node.alternatives = []\r |
| 46 | node = node.parent\r |
| 47 | continue\r |
| 48 | else:\r |
| 49 | node = node.parent\r |
| 50 | subp = None\r |
| 51 | break\r |
| 52 | \r |
| 53 | if node.type == TYPE_GROUP:\r |
| 54 | node.group.append(subp)\r |
| 55 | #probably should check the number of leaves\r |
| 56 | if len(node.group) == len(node.children):\r |
| 57 | subp = get_characteristic_subpattern(node.group)\r |
| 58 | node.group = []\r |
| 59 | node = node.parent\r |
| 60 | continue\r |
| 61 | else:\r |
| 62 | node = node.parent\r |
| 63 | subp = None\r |
| 64 | break\r |
| 65 | \r |
| 66 | if node.type == token_labels.NAME and node.name:\r |
| 67 | #in case of type=name, use the name instead\r |
| 68 | subp.append(node.name)\r |
| 69 | else:\r |
| 70 | subp.append(node.type)\r |
| 71 | \r |
| 72 | node = node.parent\r |
| 73 | return subp\r |
| 74 | \r |
| 75 | def get_linear_subpattern(self):\r |
| 76 | """Drives the leaf_to_root method. The reason that\r |
| 77 | leaf_to_root must be run multiple times is because we need to\r |
| 78 | reject 'group' matches; for example the alternative form\r |
| 79 | (a | b c) creates a group [b c] that needs to be matched. Since\r |
| 80 | matching multiple linear patterns overcomes the automaton's\r |
| 81 | capabilities, leaf_to_root merges each group into a single\r |
| 82 | choice based on 'characteristic'ity,\r |
| 83 | \r |
| 84 | i.e. (a|b c) -> (a|b) if b more characteristic than c\r |
| 85 | \r |
| 86 | Returns: The most 'characteristic'(as defined by\r |
| 87 | get_characteristic_subpattern) path for the compiled pattern\r |
| 88 | tree.\r |
| 89 | """\r |
| 90 | \r |
| 91 | for l in self.leaves():\r |
| 92 | subp = l.leaf_to_root()\r |
| 93 | if subp:\r |
| 94 | return subp\r |
| 95 | \r |
| 96 | def leaves(self):\r |
| 97 | "Generator that returns the leaves of the tree"\r |
| 98 | for child in self.children:\r |
| 99 | for x in child.leaves():\r |
| 100 | yield x\r |
| 101 | if not self.children:\r |
| 102 | yield self\r |
| 103 | \r |
| 104 | def reduce_tree(node, parent=None):\r |
| 105 | """\r |
| 106 | Internal function. Reduces a compiled pattern tree to an\r |
| 107 | intermediate representation suitable for feeding the\r |
| 108 | automaton. This also trims off any optional pattern elements(like\r |
| 109 | [a], a*).\r |
| 110 | """\r |
| 111 | \r |
| 112 | new_node = None\r |
| 113 | #switch on the node type\r |
| 114 | if node.type == syms.Matcher:\r |
| 115 | #skip\r |
| 116 | node = node.children[0]\r |
| 117 | \r |
| 118 | if node.type == syms.Alternatives :\r |
| 119 | #2 cases\r |
| 120 | if len(node.children) <= 2:\r |
| 121 | #just a single 'Alternative', skip this node\r |
| 122 | new_node = reduce_tree(node.children[0], parent)\r |
| 123 | else:\r |
| 124 | #real alternatives\r |
| 125 | new_node = MinNode(type=TYPE_ALTERNATIVES)\r |
| 126 | #skip odd children('|' tokens)\r |
| 127 | for child in node.children:\r |
| 128 | if node.children.index(child)%2:\r |
| 129 | continue\r |
| 130 | reduced = reduce_tree(child, new_node)\r |
| 131 | if reduced is not None:\r |
| 132 | new_node.children.append(reduced)\r |
| 133 | elif node.type == syms.Alternative:\r |
| 134 | if len(node.children) > 1:\r |
| 135 | \r |
| 136 | new_node = MinNode(type=TYPE_GROUP)\r |
| 137 | for child in node.children:\r |
| 138 | reduced = reduce_tree(child, new_node)\r |
| 139 | if reduced:\r |
| 140 | new_node.children.append(reduced)\r |
| 141 | if not new_node.children:\r |
| 142 | # delete the group if all of the children were reduced to None\r |
| 143 | new_node = None\r |
| 144 | \r |
| 145 | else:\r |
| 146 | new_node = reduce_tree(node.children[0], parent)\r |
| 147 | \r |
| 148 | elif node.type == syms.Unit:\r |
| 149 | if (isinstance(node.children[0], pytree.Leaf) and\r |
| 150 | node.children[0].value == '('):\r |
| 151 | #skip parentheses\r |
| 152 | return reduce_tree(node.children[1], parent)\r |
| 153 | if ((isinstance(node.children[0], pytree.Leaf) and\r |
| 154 | node.children[0].value == '[')\r |
| 155 | or\r |
| 156 | (len(node.children)>1 and\r |
| 157 | hasattr(node.children[1], "value") and\r |
| 158 | node.children[1].value == '[')):\r |
| 159 | #skip whole unit if its optional\r |
| 160 | return None\r |
| 161 | \r |
| 162 | leaf = True\r |
| 163 | details_node = None\r |
| 164 | alternatives_node = None\r |
| 165 | has_repeater = False\r |
| 166 | repeater_node = None\r |
| 167 | has_variable_name = False\r |
| 168 | \r |
| 169 | for child in node.children:\r |
| 170 | if child.type == syms.Details:\r |
| 171 | leaf = False\r |
| 172 | details_node = child\r |
| 173 | elif child.type == syms.Repeater:\r |
| 174 | has_repeater = True\r |
| 175 | repeater_node = child\r |
| 176 | elif child.type == syms.Alternatives:\r |
| 177 | alternatives_node = child\r |
| 178 | if hasattr(child, 'value') and child.value == '=': # variable name\r |
| 179 | has_variable_name = True\r |
| 180 | \r |
| 181 | #skip variable name\r |
| 182 | if has_variable_name:\r |
| 183 | #skip variable name, '='\r |
| 184 | name_leaf = node.children[2]\r |
| 185 | if hasattr(name_leaf, 'value') and name_leaf.value == '(':\r |
| 186 | # skip parenthesis\r |
| 187 | name_leaf = node.children[3]\r |
| 188 | else:\r |
| 189 | name_leaf = node.children[0]\r |
| 190 | \r |
| 191 | #set node type\r |
| 192 | if name_leaf.type == token_labels.NAME:\r |
| 193 | #(python) non-name or wildcard\r |
| 194 | if name_leaf.value == 'any':\r |
| 195 | new_node = MinNode(type=TYPE_ANY)\r |
| 196 | else:\r |
| 197 | if hasattr(token_labels, name_leaf.value):\r |
| 198 | new_node = MinNode(type=getattr(token_labels, name_leaf.value))\r |
| 199 | else:\r |
| 200 | new_node = MinNode(type=getattr(pysyms, name_leaf.value))\r |
| 201 | \r |
| 202 | elif name_leaf.type == token_labels.STRING:\r |
| 203 | #(python) name or character; remove the apostrophes from\r |
| 204 | #the string value\r |
| 205 | name = name_leaf.value.strip("'")\r |
| 206 | if name in tokens:\r |
| 207 | new_node = MinNode(type=tokens[name])\r |
| 208 | else:\r |
| 209 | new_node = MinNode(type=token_labels.NAME, name=name)\r |
| 210 | elif name_leaf.type == syms.Alternatives:\r |
| 211 | new_node = reduce_tree(alternatives_node, parent)\r |
| 212 | \r |
| 213 | #handle repeaters\r |
| 214 | if has_repeater:\r |
| 215 | if repeater_node.children[0].value == '*':\r |
| 216 | #reduce to None\r |
| 217 | new_node = None\r |
| 218 | elif repeater_node.children[0].value == '+':\r |
| 219 | #reduce to a single occurence i.e. do nothing\r |
| 220 | pass\r |
| 221 | else:\r |
| 222 | #TODO: handle {min, max} repeaters\r |
| 223 | raise NotImplementedError\r |
| 224 | pass\r |
| 225 | \r |
| 226 | #add children\r |
| 227 | if details_node and new_node is not None:\r |
| 228 | for child in details_node.children[1:-1]:\r |
| 229 | #skip '<', '>' markers\r |
| 230 | reduced = reduce_tree(child, new_node)\r |
| 231 | if reduced is not None:\r |
| 232 | new_node.children.append(reduced)\r |
| 233 | if new_node:\r |
| 234 | new_node.parent = parent\r |
| 235 | return new_node\r |
| 236 | \r |
| 237 | \r |
| 238 | def get_characteristic_subpattern(subpatterns):\r |
| 239 | """Picks the most characteristic from a list of linear patterns\r |
| 240 | Current order used is:\r |
| 241 | names > common_names > common_chars\r |
| 242 | """\r |
| 243 | if not isinstance(subpatterns, list):\r |
| 244 | return subpatterns\r |
| 245 | if len(subpatterns)==1:\r |
| 246 | return subpatterns[0]\r |
| 247 | \r |
| 248 | # first pick out the ones containing variable names\r |
| 249 | subpatterns_with_names = []\r |
| 250 | subpatterns_with_common_names = []\r |
| 251 | common_names = ['in', 'for', 'if' , 'not', 'None']\r |
| 252 | subpatterns_with_common_chars = []\r |
| 253 | common_chars = "[]().,:"\r |
| 254 | for subpattern in subpatterns:\r |
| 255 | if any(rec_test(subpattern, lambda x: type(x) is str)):\r |
| 256 | if any(rec_test(subpattern,\r |
| 257 | lambda x: isinstance(x, str) and x in common_chars)):\r |
| 258 | subpatterns_with_common_chars.append(subpattern)\r |
| 259 | elif any(rec_test(subpattern,\r |
| 260 | lambda x: isinstance(x, str) and x in common_names)):\r |
| 261 | subpatterns_with_common_names.append(subpattern)\r |
| 262 | \r |
| 263 | else:\r |
| 264 | subpatterns_with_names.append(subpattern)\r |
| 265 | \r |
| 266 | if subpatterns_with_names:\r |
| 267 | subpatterns = subpatterns_with_names\r |
| 268 | elif subpatterns_with_common_names:\r |
| 269 | subpatterns = subpatterns_with_common_names\r |
| 270 | elif subpatterns_with_common_chars:\r |
| 271 | subpatterns = subpatterns_with_common_chars\r |
| 272 | # of the remaining subpatterns pick out the longest one\r |
| 273 | return max(subpatterns, key=len)\r |
| 274 | \r |
| 275 | def rec_test(sequence, test_func):\r |
| 276 | """Tests test_func on all items of sequence and items of included\r |
| 277 | sub-iterables"""\r |
| 278 | for x in sequence:\r |
| 279 | if isinstance(x, (list, tuple)):\r |
| 280 | for y in rec_test(x, test_func):\r |
| 281 | yield y\r |
| 282 | else:\r |
| 283 | yield test_func(x)\r |
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