gitmirror/lark/tree.py

from copy import deepcopy

from .utils import inline_args

class Tree(object):
    def __init__(self, data, children):
        self.data = data
        self.children = list(children)

    def __repr__(self):
        return 'Tree(%s, %s)' % (self.data, self.children)

    def _pretty(self, level, indent_str):
        if len(self.children) == 1 and not isinstance(self.children[0], Tree):
            return [ indent_str*level, self.data, '\t', '%s' % self.children[0], '\n']

        l = [ indent_str*level, self.data, '\n' ]
        for n in self.children:
            if isinstance(n, Tree):
                l += n._pretty(level+1, indent_str)
            else:
                l += [ indent_str*(level+1), '%s' % n, '\n' ]

        return l

    def pretty(self, indent_str='  '):
        return ''.join(self._pretty(0, indent_str))

    def expand_kids_by_index(self, *indices):
        for i in sorted(indices, reverse=True): # reverse so that changing tail won't affect indices
            kid = self.children[i]
            self.children[i:i+1] = kid.children

    def __eq__(self, other):
        return self.data == other.data and self.children == other.children
    def __hash__(self):
        return hash((self.data, tuple(self.children)))

    def find_pred(self, pred):
        if pred(self):
            yield self

        for c in self.children:
            if isinstance(c, Tree):
                for t in c.find_pred(pred):
                    yield t

    def find_data(self, data):
        return self.find_pred(lambda t: t.data == data)

    def scan_values(self, pred):
        for c in self.children:
            if isinstance(c, Tree):
                for t in c.scan_values(pred):
                    yield t
            else:
                if pred(c):
                    yield c


    def __deepcopy__(self, memo):
        return type(self)(self.data, deepcopy(self.children, memo))



class Transformer(object):
    def _get_func(self, name):
        return getattr(self, name)

    def transform(self, tree):
        items = [self.transform(c) if isinstance(c, Tree) else c for c in tree.children]
        try:
            f = self._get_func(tree.data)
        except AttributeError:
            return self.__default__(tree.data, items)
        else:
            return f(items)

    def __default__(self, data, children):
        return Tree(data, children)


class InlineTransformer(Transformer):
    def _get_func(self, name):
        return inline_args(getattr(self, name)).__get__(self)


class Visitor(object):
    def visit(self, tree):
        for child in tree.children:
            if isinstance(child, Tree):
                self.visit(child)

        f = getattr(self, tree.data, self.__default__)
        f(tree)
        return tree

    def __default__(self, tree):
        pass