Rewrite positional handling, test for "numeric"

Changed how the positional compilation is performed. It's rendered by the compiler
the same as the pyformat compilation. The string is then processed to replace
the placeholders with the correct ones, and to obtain the correct order of the
parameters.
This vastly simplifies the computation of the order of the parameters, that in
case of nested CTE is very hard to compute correctly.

Reworked how numeric paramstyle behavers:
- added support for repeated parameter, without duplicating them like in normal
positional dialects
- implement insertmany support. This requires that the dialect supports out of
order placehoders, since all parameters that are not part of the VALUES clauses
are placed at the beginning of the parameter tuple
- support for different identifiers for a numeric parameter. It's for example
possible to use postgresql style placeholder $1, $2, etc

Added two new dialect based on sqlite to test "numeric" fully using
both :1 style and $1 style. Includes a workaround for SQLite's
not-really-correct numeric implementation.

Changed parmstyle of asyncpg dialect to use numeric, rendering with its native
$ identifiers

Fixes: #8926
Fixes: #8849
Change-Id: I7c640467d49adfe6d795cc84296fc7403dcad4d6

1 files changed, 107 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/sqlite/pysqlite.py b/lib/sqlalchemy/dialects/sqlite/pysqlite.py
index 4475ccae7..c04a3601d 100644
--- a/lib/sqlalchemy/dialects/sqlite/pysqlite.py
+++ b/lib/sqlalchemy/dialects/sqlite/pysqlite.py
@@ -637,3 +637,110 @@ class SQLiteDialect_pysqlite(SQLiteDialect):
 
 
 dialect = SQLiteDialect_pysqlite
+
+
+class _SQLiteDialect_pysqlite_numeric(SQLiteDialect_pysqlite):
+    """numeric dialect for testing only
+
+    internal use only.  This dialect is **NOT** supported by SQLAlchemy
+    and may change at any time.
+
+    """
+
+    supports_statement_cache = True
+    default_paramstyle = "numeric"
+    driver = "pysqlite_numeric"
+
+    _first_bind = ":1"
+    _not_in_statement_regexp = None
+
+    def __init__(self, *arg, **kw):
+        kw.setdefault("paramstyle", "numeric")
+        super().__init__(*arg, **kw)
+
+    def create_connect_args(self, url):
+        arg, opts = super().create_connect_args(url)
+        opts["factory"] = self._fix_sqlite_issue_99953()
+        return arg, opts
+
+    def _fix_sqlite_issue_99953(self):
+        import sqlite3
+
+        first_bind = self._first_bind
+        if self._not_in_statement_regexp:
+            nis = self._not_in_statement_regexp
+
+            def _test_sql(sql):
+                m = nis.search(sql)
+                assert not m, f"Found {nis.pattern!r} in {sql!r}"
+
+        else:
+
+            def _test_sql(sql):
+                pass
+
+        def _numeric_param_as_dict(parameters):
+            if parameters:
+                assert isinstance(parameters, tuple)
+                return {
+                    str(idx): value for idx, value in enumerate(parameters, 1)
+                }
+            else:
+                return ()
+
+        class SQLiteFix99953Cursor(sqlite3.Cursor):
+            def execute(self, sql, parameters=()):
+                _test_sql(sql)
+                if first_bind in sql:
+                    parameters = _numeric_param_as_dict(parameters)
+                return super().execute(sql, parameters)
+
+            def executemany(self, sql, parameters):
+                _test_sql(sql)
+                if first_bind in sql:
+                    parameters = [
+                        _numeric_param_as_dict(p) for p in parameters
+                    ]
+                return super().executemany(sql, parameters)
+
+        class SQLiteFix99953Connection(sqlite3.Connection):
+            def cursor(self, factory=None):
+                if factory is None:
+                    factory = SQLiteFix99953Cursor
+                return super().cursor(factory=factory)
+
+            def execute(self, sql, parameters=()):
+                _test_sql(sql)
+                if first_bind in sql:
+                    parameters = _numeric_param_as_dict(parameters)
+                return super().execute(sql, parameters)
+
+            def executemany(self, sql, parameters):
+                _test_sql(sql)
+                if first_bind in sql:
+                    parameters = [
+                        _numeric_param_as_dict(p) for p in parameters
+                    ]
+                return super().executemany(sql, parameters)
+
+        return SQLiteFix99953Connection
+
+
+class _SQLiteDialect_pysqlite_dollar(_SQLiteDialect_pysqlite_numeric):
+    """numeric dialect that uses $ for testing only
+
+    internal use only.  This dialect is **NOT** supported by SQLAlchemy
+    and may change at any time.
+
+    """
+
+    supports_statement_cache = True
+    default_paramstyle = "numeric_dollar"
+    driver = "pysqlite_dollar"
+
+    _first_bind = "$1"
+    _not_in_statement_regexp = re.compile(r"[^\d]:\d+")
+
+    def __init__(self, *arg, **kw):
+        kw.setdefault("paramstyle", "numeric_dollar")
+        super().__init__(*arg, **kw)