def get_oracle(self,
configuration: Configuration,
tree: DependencyTree) -> str:
"""
Provide a static-oracle recommendation for the next parsing step to take
"""
word1 = configuration.get_stack(1)
word2 = configuration.get_stack(0)
if word1 > 0 and tree.get_head(word1) == word2:
return "L(" + tree.get_label(word1) + ")"
elif word1 >= 0 and tree.get_head(word2) == word1 and not configuration.has_other_child(word2, tree):
return "R(" + tree.get_label(word2) + ")"
return "S"
class Configuration:
def __init__(self, sentence):
self.stack = []
self.buffer = []
self.tree = DependencyTree()
self.sentence = sentence
def shift(self):
k = self.get_buffer(0)
if k == constants.NONEXIST:
return False
self.buffer.pop(0)
self.stack.append(k)
return True
def remove_second_top_stack(self):
n_stack = self.get_stack_size()
if n_stack < 2:
return False
self.stack.pop(-2)
return True
def remove_top_stack(self):
n_stack = self.get_stack_size()
if n_stack <= 1:
return False
self.stack.pop()
return True
def get_stack_size(self):
return len(self.stack)
def get_buffer_size(self):
return len(self.buffer)
def getSentenceSize(self):
return len(self.sentence)
def get_head(self, k):
return self.tree.get_head(k)
def get_label(self, k):
return self.tree.get_label(k)
def get_stack(self, k):
"""
Get the token index of the kth word on the stack.
If stack doesn't have an element at this index, return constants.NONEXIST
"""
n_stack = self.get_stack_size()
if k >= 0 and k < n_stack:
return self.stack[n_stack - 1 - k]
return constants.NONEXIST
def get_buffer(self, k):
"""
Get the token index of the kth word on the buffer.
If buffer doesn't have an element at this index, return constants.NONEXIST
"""
if k >= 0 and k < self.get_buffer_size():
return self.buffer[k]
return constants.NONEXIST
def get_word(self, k):
"""
Get the word at index k
"""
if k == 0:
return constants.ROOT
else:
k -= 1
if k < 0 or k >= len(self.sentence):
return constants.NULL
return self.sentence[k].word
def get_pos(self, k):
"""
Get the pos at index k
"""
if k == 0:
return constants.ROOT
else:
k -= 1
if k < 0 or k >= len(self.sentence):
return constants.NULL
return self.sentence[k].pos
def add_arc(self, h, t, l):
"""
Add an arc with the label l from the head node h to the dependent node t.
"""
self.tree.set(t, h, l)
def get_left_child(self, k, cnt):
"""
Get cnt-th leftmost child of k.
(i.e., if cnt = 1, the leftmost child of k will be returned,
if cnt = 2, the 2nd leftmost child of k will be returned.)
"""
if k < 0 or k > self.tree.n:
return constants.NONEXIST
c = 0
for i in range(1, k):
if self.tree.get_head(i) == k:
c += 1
if c == cnt:
return i
return constants.NONEXIST
def get_right_child(self, k, cnt):
"""
Get cnt-th rightmost child of k.
(i.e., if cnt = 1, the rightmost child of k will be returned,
if cnt = 2, the 2nd rightmost child of k will be returned.)
"""
if k < 0 or k > self.tree.n:
return constants.NONEXIST
c = 0
for i in range(self.tree.n, k, -1):
if self.tree.get_head(i) == k:
c += 1
if c == cnt:
return i
return constants.NONEXIST
def has_other_child(self, k, goldTree):
for i in range(1, self.tree.n + 1):
if goldTree.get_head(i) == k and self.tree.get_head(i) != k:
return True
return False
def get_str(self):
"""
Returns a string that concatenates all elements on the stack and buffer, and head / label
"""
s = "[S]"
for i in range(self.get_stack_size()):
if i > 0:
s += ","
s += self.stack[i]
s += "[B]"
for i in range(self.get_buffer_size()):
if i > 0:
s += ","
s += self.buffer[i]
s += "[H]"
for i in range(1, self.tree.n + 1):
if i > 1:
s += ","
s += self.get_head(i) + "(" + self.get_label(i) + ")"
return s