Handle PostgreSQL enums in remote schemas

Fixed issue where a :class:`.postgresql.ENUM` or a custom domain present
in a remote schema would not be recognized within column reflection if
the name of the enum/domain or the name of the schema required quoting.
A new parsing scheme now fully parses out quoted or non-quoted tokens
including support for SQL-escaped quotes.

Fixed issue where multiple :class:`.postgresql.ENUM` objects referred to
by the same :class:`.MetaData` object would fail to be created if
multiple objects had the same name under different schema names.  The
internal memoization the Postgresql dialect uses to track if it has
created a particular :class:`.postgresql.ENUM` in the database during
a DDL creation sequence now takes schema name into account.

Fixes: #4416
Change-Id: I8cf03069e10b12f409e9b6796e24fc5850979955

2 files changed, 46 insertions, 1 deletions

diff --git a/lib/sqlalchemy/util/__init__.py b/lib/sqlalchemy/util/__init__.py
index 031376d78..9229d0797 100644
--- a/lib/sqlalchemy/util/__init__.py
+++ b/lib/sqlalchemy/util/__init__.py
@@ -34,7 +34,7 @@ from .langhelpers import iterate_attributes, class_hierarchy, \
     classproperty, set_creation_order, warn_exception, warn, NoneType,\
     constructor_copy, methods_equivalent, chop_traceback, asint,\
     generic_repr, counter, PluginLoader, hybridproperty, hybridmethod, \
-    safe_reraise,\
+    safe_reraise, quoted_token_parser,\
     get_callable_argspec, only_once, attrsetter, ellipses_string, \
     warn_limited, map_bits, MemoizedSlots, EnsureKWArgType, wrap_callable
 
diff --git a/lib/sqlalchemy/util/langhelpers.py b/lib/sqlalchemy/util/langhelpers.py
index 8815ed837..6a1db7a98 100644
--- a/lib/sqlalchemy/util/langhelpers.py
+++ b/lib/sqlalchemy/util/langhelpers.py
@@ -1422,3 +1422,48 @@ def wrap_callable(wrapper, fn):
             _f.__doc__ = fn.__doc__
 
         return _f
+
+
+def quoted_token_parser(value):
+    """Parse a dotted identifier with accomodation for quoted names.
+
+    Includes support for SQL-style double quotes as a literal character.
+
+    E.g.::
+
+        >>> quoted_token_parser("name")
+        ["name"]
+        >>> quoted_token_parser("schema.name")
+        ["schema", "name"]
+        >>> quoted_token_parser('"Schema"."Name"')
+        ['Schema', 'Name']
+        >>> quoted_token_parser('"Schema"."Name""Foo"')
+        ['Schema', 'Name""Foo']
+
+    """
+
+    if '"' not in value:
+        return value.split(".")
+
+    # 0 = outside of quotes
+    # 1 = inside of quotes
+    state = 0
+    result = [[]]
+    idx = 0
+    lv = len(value)
+    while idx < lv:
+        char = value[idx]
+        if char == '"':
+            if state == 1 and idx < lv - 1 and value[idx + 1] == '"':
+                result[-1].append('"')
+                idx += 1
+            else:
+                state ^= 1
+        elif char == "." and state == 0:
+            result.append([])
+        else:
+            result[-1].append(char)
+        idx += 1
+
+    return ["".join(token) for token in result]
+