def __init__(self, span, lhs, rhs, dot=0, bindings=None):
"""
Construct a new edge. If the edge is incomplete (i.e., if
``dot<len(rhs)``), then store the bindings as-is. If the edge
is complete (i.e., if ``dot==len(rhs)``), then apply the
bindings to all nonterminals in ``lhs`` and ``rhs``, and then
clear the bindings. See ``TreeEdge`` for a description of
the other arguments.
"""
if bindings is None: bindings = {}
# If the edge is complete, then substitute in the bindings,
# and then throw them away. (If we didn't throw them away, we
# might think that 2 complete edges are different just because
# they have different bindings, even though all bindings have
# already been applied.)
if dot == len(rhs) and bindings:
lhs = self._bind(lhs, bindings)
rhs = [self._bind(elt, bindings) for elt in rhs]
bindings = {}
# Initialize the edge.
TreeEdge.__init__(self, span, lhs, rhs, dot)
self._bindings = bindings
self._comparison_key = (self._comparison_key, tuple(sorted(bindings.items())))
def __init__(self, span, lhs, rhs, dot=0, bindings=None):
"""
Construct a new edge. If the edge is incomplete (i.e., if
``dot<len(rhs)``), then store the bindings as-is. If the edge
is complete (i.e., if ``dot==len(rhs)``), then apply the
bindings to all nonterminals in ``lhs`` and ``rhs``, and then
clear the bindings. See ``TreeEdge`` for a description of
the other arguments.
"""
if bindings is None: bindings = {}
# If the edge is complete, then substitute in the bindings,
# and then throw them away. (If we didn't throw them away, we
# might think that 2 complete edges are different just because
# they have different bindings, even though all bindings have
# already been applied.)
if dot == len(rhs) and bindings:
lhs = self._bind(lhs, bindings)
rhs = [self._bind(elt, bindings) for elt in rhs]
bindings = {}
# Initialize the edge.
TreeEdge.__init__(self, span, lhs, rhs, dot)
self._bindings = bindings
self._comparison_key = (self._comparison_key,
tuple(sorted(bindings.items())))
def __str__(self):
if self.is_complete():
return TreeEdge.__unicode__(self)
else:
bindings = '{%s}' % ', '.join('%s: %r' % item for item in
sorted(self._bindings.items()))
return '%s %s' % (TreeEdge.__unicode__(self), bindings)
def __str__(self):
if self.is_complete():
return TreeEdge.__unicode__(self)
else:
bindings = '{%s}' % ', '.join(
'%s: %r' % item for item in sorted(self._bindings.items()))
return '%s %s' % (TreeEdge.__unicode__(self), bindings)
def apply_iter(self, chart, grammar, right_edge):
if (right_edge.is_incomplete() or # use only completed edges
isinstance(right_edge, LeafEdge) or # skip terminal leaves
is_lexical(right_edge) or # skip lexical productions
right_edge.lhs().symbol() == 'G'): # skip BRM rules
return
# We only merge if both the right end left edge are completed. The
# left edge must be adjacent to the right edge in the chart.
for left_edge in chart.select(end=right_edge.start(), is_complete=True):
if isinstance(left_edge, LeafEdge) or is_lexical(left_edge):
continue
new_edge = TreeEdge(span=(left_edge.start(), right_edge.end()),
lhs=right_edge.lhs(),
rhs=[left_edge.lhs(), right_edge.lhs()],
dot=2) # edge is completed at initialization
if chart.insert(new_edge, (left_edge, right_edge)):
yield new_edge
def __init__(self, prob, *args, **kwargs):
TreeEdge.__init__(self, *args, **kwargs)
self._prob = prob
# two edges with different probabilities are not equal.
self._comparison_key = (self._comparison_key, prob)
def __init__(self, prob, *args, **kwargs):
TreeEdge.__init__(self, *args, **kwargs)
self._prob = prob
# two edges with different probabilities are not equal.
self._comparison_key = (self._comparison_key, prob)
def __cmp__(self, other):
if self._prob != other.prob(): return -1
return TreeEdge.__cmp__(self, other)
def __init__(self, prob, *args, **kwargs):
self._prob = prob
TreeEdge.__init__(self, *args, **kwargs)
def __str__(self):
if self.is_complete():
return TreeEdge.__unicode__(self)
else:
bindings = "{%s}" % ", ".join("%s: %r" % item for item in sorted(self._bindings.items()))
return "%s %s" % (TreeEdge.__unicode__(self), bindings)
def __cmp__(self, other):
if self._prob != other.prob(): return -1
return TreeEdge.__cmp__(self, other)
def __init__(self, prob, *args, **kwargs):
self._prob = prob
TreeEdge.__init__(self, *args, **kwargs)
