bpo-34983: Expose symtable.Symbol.is_nonlocal() in the symtable module (GH-9872)

The symbol table was not exposing functionality to query the nonlocal symbols
in a function or to check if a particular symbol is nonlocal.

1 files changed, 10 insertions, 1 deletions

diff --git a/Lib/symtable.py b/Lib/symtable.py
index c7627a6..5bea7cf 100644
--- a/Lib/symtable.py
+++ b/Lib/symtable.py
@@ -1,7 +1,7 @@
 """Interface to the compiler's internal symbol tables"""
 
 import _symtable
-from _symtable import (USE, DEF_GLOBAL, DEF_LOCAL, DEF_PARAM,
+from _symtable import (USE, DEF_GLOBAL, DEF_NONLOCAL, DEF_LOCAL, DEF_PARAM,
      DEF_IMPORT, DEF_BOUND, DEF_ANNOT, SCOPE_OFF, SCOPE_MASK, FREE,
      LOCAL, GLOBAL_IMPLICIT, GLOBAL_EXPLICIT, CELL)
 
@@ -117,6 +117,7 @@ class Function(SymbolTable):
     __locals = None
     __frees = None
     __globals = None
+    __nonlocals = None
 
     def __idents_matching(self, test_func):
         return tuple(ident for ident in self.get_identifiers()
@@ -141,6 +142,11 @@ class Function(SymbolTable):
             self.__globals = self.__idents_matching(test)
         return self.__globals
 
+    def get_nonlocals(self):
+        if self.__nonlocals is None:
+            self.__nonlocals = self.__idents_matching(lambda x:x & DEF_NONLOCAL)
+        return self.__nonlocals
+
     def get_frees(self):
         if self.__frees is None:
             is_free = lambda x:((x >> SCOPE_OFF) & SCOPE_MASK) == FREE
@@ -184,6 +190,9 @@ class Symbol(object):
     def is_global(self):
         return bool(self.__scope in (GLOBAL_IMPLICIT, GLOBAL_EXPLICIT))
 
+    def is_nonlocal(self):
+        return bool(self.__flags & DEF_NONLOCAL)
+
     def is_declared_global(self):
         return bool(self.__scope == GLOBAL_EXPLICIT)