Arbitrary `prev_action_emb` when pointer maps have multiple entries

[rshin]

For choosing a table in Spider, we allow the model to point to the embedding for any of its columns or the embedding for the table itself:

seq2struct/seq2struct/models/spider_enc.py

Lines 321 to 328 in e69c8eb

	table_pointer_maps = {
	i: [
	idx
	for col in desc['table_to_columns'][str(i)]
	for idx in column_pointer_maps[col]
	] + list(range(left + c_enc_length, right + c_enc_length))
	for i, (left, right) in enumerate(zip(t_boundaries, t_boundaries[1:]))
	}

However, when computing the prev_action_emb, we only use the first of these embeddings (i.e. the first column of the table):

seq2struct/seq2struct/models/nl2code/decoder.py

Lines 501 to 516 in e69c8eb

	pointer_map = desc_enc.pointer_maps.get(parent_field_type)
	if pointer_map:
	values = pointer_map[node]
	if self.sup_att == '1h':
	if len(pointer_map) == len(enc_input['columns']):
	if self.attn_type != 'sep':
	traversal.step(values[0], values[1:], node + len(enc_input['question']))
	else:
	traversal.step(values[0], values[1:], node)
	else:
	if self.attn_type != 'sep':
	traversal.step(values[0], values[1:], node + len(enc_input['question']) + len(enc_input['columns']))
	else:
	traversal.step(values[0], values[1:], node + len(enc_input['columns']))
	else:
	traversal.step(values[0], values[1:])

seq2struct/seq2struct/models/nl2code/decoder.py

Line 1263 in e69c8eb

self.update_prev_action_emb = TreeTraversal._update_prev_action_emb_pointer

seq2struct/seq2struct/models/nl2code/decoder.py

Lines 1465 to 1468 in e69c8eb

	def _update_prev_action_emb_pointer(cls, self, last_choice, extra_choice_info):
	# TODO batching
	self.prev_action_emb = self.model.pointer_action_emb_proj[self.cur_item.node_type](
	self.desc_enc.pointer_memories[self.cur_item.node_type][:, last_choice])

seq2struct/seq2struct/models/nl2code/decoder.py

Line 1442 in e69c8eb

self.update_prev_action_emb(self, last_choice, extra_choice_info)