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Python Compiled Bytecode | 2009-11-11 | 6KB | 185 lines

# Source Generated with Decompyle++
# File: in.pyc (Python 2.6)

'''Pattern compiler.

The grammer is taken from PatternGrammar.txt.

The compiler compiles a pattern to a pytree.*Pattern instance.
'''
__author__ = 'Guido van Rossum <[e-mail]>'
import os
from pgen2 import driver
from pgen2 import literals
from pgen2 import token
from pgen2 import tokenize
from  import pytree
from  import pygram
_PATTERN_GRAMMAR_FILE = os.path.join(os.path.dirname(__file__), 'PatternGrammar.txt')

def tokenize_wrapper(input):
    '''Tokenizes a string suppressing significant whitespace.'''
    skip = (token.NEWLINE, token.INDENT, token.DEDENT)
    tokens = tokenize.generate_tokens(driver.generate_lines(input).next)
    for quintuple in tokens:
        (type, value, start, end, line_text) = quintuple
        if type not in skip:
            yield quintuple
            continue



class PatternCompiler(object):

    def __init__(self, grammar_file = _PATTERN_GRAMMAR_FILE):
        '''Initializer.

        Takes an optional alternative filename for the pattern grammar.
        '''
        self.grammar = driver.load_grammar(grammar_file)
        self.syms = pygram.Symbols(self.grammar)
        self.pygrammar = pygram.python_grammar
        self.pysyms = pygram.python_symbols
        self.driver = driver.Driver(self.grammar, convert = pattern_convert)


    def compile_pattern(self, input, debug = False):
        '''Compiles a pattern string to a nested pytree.*Pattern object.'''
        tokens = tokenize_wrapper(input)
        root = self.driver.parse_tokens(tokens, debug = debug)
        return self.compile_node(root)


    def compile_node(self, node):
        '''Compiles a node, recursively.

        This is one big switch on the node type.
        '''
        if node.type == self.syms.Matcher:
            node = node.children[0]

        if node.type == self.syms.Alternatives:
            alts = [ self.compile_node(ch) for ch in node.children[::2] ]
            if len(alts) == 1:
                return alts[0]
            p = []([ [
                a] for a in alts ], min = 1, max = 1)
            return p.optimize()
        if node.type == self.syms.Alternative:
            units = [ self.compile_node(ch) for ch in node.children ]
            if len(units) == 1:
                return units[0]
            p = pytree.WildcardPattern([
                units], min = 1, max = 1)
            return p.optimize()
        if node.type == self.syms.NegatedUnit:
            pattern = self.compile_basic(node.children[1:])
            p = pytree.NegatedPattern(pattern)
            return p.optimize()
        if not node.type == self.syms.Unit:
            raise AssertionError
        name = None
        nodes = node.children
        repeat = None
        pattern = self.compile_basic(nodes, repeat)
        if repeat is not None:
            if not repeat.type == self.syms.Repeater:
                raise AssertionError
            children = repeat.children
            child = children[0]
            if child.type == token.STAR:
                min = 0
                max = pytree.HUGE
            elif child.type == token.PLUS:
                min = 1
                max = pytree.HUGE
            elif child.type == token.LBRACE:
                if not children[-1].type == token.RBRACE:
                    raise AssertionError
                if not len(children) in (3, 5):
                    raise AssertionError
                if len(children) == 5:
                    max = self.get_int(children[3])

            elif not False:
                raise AssertionError
            len(children) in (3, 5)
            if min != 1 or max != 1:
                pattern = pattern.optimize()
                pattern = pytree.WildcardPattern([
                    [
                        pattern]], min = min, max = max)


        if name is not None:
            pattern.name = name

        return pattern.optimize()


    def compile_basic(self, nodes, repeat = None):
        if not len(nodes) >= 1:
            raise AssertionError
        node = nodes[0]
        if node.type == token.STRING:
            value = literals.evalString(node.value)
            return pytree.LeafPattern(content = value)
        if node.type == token.NAME:
            value = node.value
            if value.isupper():
                if value not in TOKEN_MAP:
                    raise SyntaxError('Invalid token: %r' % value)
                value not in TOKEN_MAP
                return pytree.LeafPattern(TOKEN_MAP[value])
            if value == 'any':
                type = None
            elif not value.startswith('_'):
                type = getattr(self.pysyms, value, None)
                if type is None:
                    raise SyntaxError('Invalid symbol: %r' % value)
                type is None

            if nodes[1:]:
                content = [
                    self.compile_node(nodes[1].children[1])]
            else:
                content = None
            return pytree.NodePattern(type, content)
        node.type == token.NAME
        if node.value == '(':
            return self.compile_node(nodes[1])
        if node.value == '[':
            if not repeat is None:
                raise AssertionError
            subpattern = self.compile_node(nodes[1])
            return pytree.WildcardPattern([
                [
                    subpattern]], min = 0, max = 1)
        if not False:
            raise AssertionError, node


    def get_int(self, node):
        if not node.type == token.NUMBER:
            raise AssertionError
        return int(node.value)


TOKEN_MAP = {
    'NAME': token.NAME,
    'STRING': token.STRING,
    'NUMBER': token.NUMBER,
    'TOKEN': None }

def pattern_convert(grammar, raw_node_info):
    '''Converts raw node information to a Node or Leaf instance.'''
    (type, value, context, children) = raw_node_info
    if children or type in grammar.number2symbol:
        return pytree.Node(type, children, context = context)
    return pytree.Leaf(type, value, context = context)


def compile_pattern(pattern):
    return PatternCompiler().compile_pattern(pattern)