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-rw-r--r--prolog/util.py15
1 files changed, 12 insertions, 3 deletions
diff --git a/prolog/util.py b/prolog/util.py
index e682edb..83f891f 100644
--- a/prolog/util.py
+++ b/prolog/util.py
@@ -16,6 +16,8 @@
from collections import namedtuple
from collections.abc import Iterable
+import string
+
from nltk import Tree
# Stores a token's type and value, and optionally the position of the first
@@ -78,6 +80,13 @@ def stringify(obj):
return ''.join([stringify(child) for child in obj]) + '\n'
return ''.join([stringify(child) for child in obj])
+# Return a canonical name for the [n]th variable in scope.
+def canonical_varname(n):
+ names = string.ascii_uppercase
+ if n < len(names):
+ return names[n]
+ return 'X{}'.format(n)
+
# Rename variables in [tokens] to A0, A1, A2,… in order of appearance.
def rename_vars_list(tokens, names=None):
if names is None:
@@ -90,7 +99,7 @@ def rename_vars_list(tokens, names=None):
if t.type == 'VARIABLE' and t.val != '_':
cur_name = t.val
if cur_name not in names:
- names[cur_name] = 'A{}'.format(next_id)
+ names[cur_name] = canonical_varname(next_id)
next_id += 1
tokens[i] = t.clone(val=names[cur_name])
return tokens
@@ -115,7 +124,7 @@ def rename_vars_ast(root, fixed_names=None):
if node.type == 'VARIABLE':
token = node
if token.val.startswith('_'):
- new_node = token.clone(val='A{}'.format(next_id))
+ new_node = token.clone(val=canonical_varname(next_id))
next_id += 1
else:
cur_name = token.val
@@ -123,7 +132,7 @@ def rename_vars_ast(root, fixed_names=None):
new_name = fixed_names[cur_name]
else:
if cur_name not in names:
- names[cur_name] = 'A{}'.format(next_id)
+ names[cur_name] = canonical_varname(next_id)
next_id += 1
new_name = names[cur_name]
new_node = token.clone(val=new_name)