Restore bit and varbit support with tests

README.md

@@ -48,6 +48,7 @@ Features
 - `mod()` is pushdowned. In PostgreSQL gives [argument-dependend data type](https://www.postgresql.org/docs/current/functions-math.html), but result from SQLite always [have `real` affinity](https://www.sqlite.org/lang_mathfunc.html#mod).
 - `upper`, `lower` and other character case functions are **not** pushed down because they does not work with UNICODE character in SQLite.
 - `WITH TIES` option is **not** pushed down.
+- Bit string `#` (XOR) operator is **not** pushed down becasuse there is no equal SQLite operator.
 
 ### Notes about pushdowning
 
@@ -117,7 +118,7 @@ Usage
 ### Datatypes
 **WARNING! The table above represents roadmap**, work still in progress. Untill it will be ended please refer real behaviour in non-obvious cases, where there is no ✔ or ∅ mark.
 
-This table represents `sqlite_fdw` behaviour if in PostgreSQL foreign table column some [affinity](https://www.sqlite.org/datatype3.html) of SQLite data is detected.
+This table represents `sqlite_fdw` behaviour if in PostgreSQL foreign table column some [affinity](https://www.sqlite.org/datatype3.html) of SQLite data is detected. Some details about data values support see in [limitations](#limitations).
 
 * **∅** - no support (runtime error)
 * **V** - transparent transformation
@@ -133,7 +134,7 @@ SQLite `NULL` affinity always can be transparent converted for a nullable column
 | PostgreSQL   | SQLite <br> INT  | SQLite <br> REAL | SQLite <br> BLOB | SQLite <br> TEXT | SQLite <br> TEXT but <br>empty|SQLite<br>nearest<br>affinity|
 |-------------:|:------------:|:------------:|:------------:|:------------:|:------------:|-------------:|
 |         bool |      V       |       ?      |      T       |      -       |      ∅       | INT          |
-|       bit(n) |      V       |       ∅      |      V       |      ?       |      ∅       | INT          |
+|       bit(n) |    V n<=64   |       ∅      |      V       |      ?       |      ∅       | INT          |
 |        bytea |      b       |       b      |      ✔       |      -       |      ?       | BLOB         |
 |         date |      V       |       V      |      T       |      V+      |    `NULL`    | ?            |
 |       float4 |      V+      |       ✔      |      T       |      -       |    `NULL`    | REAL         |
@@ -150,8 +151,7 @@ SQLite `NULL` affinity always can be transparent converted for a nullable column
 |timestamp + tz|      V       |       V      |      T       |      V+      |    `NULL`    | ?            |
 |         uuid |      ∅       |       ∅      |V+<br>(only<br>16 bytes)| V+ |      ∅       | TEXT, BLOB   |
 |      varchar |      ?       |       ?      |      T       |      ✔       |      V       | TEXT         |
-
-
+|    varbit(n) |    V n<=64   |       ∅      |      V       |      ?       |      ∅       | INT          |
 
 ### CREATE SERVER options
 
@@ -523,6 +523,10 @@ Limitations
 - Expected affinity of UUID value in SQLite table determined by `column_type` option of the column
 for `INSERT` and `UPDATE` commands.
 
+### bit and varbit support
+- `sqlite_fdw` PostgreSQL `bit`/`varbit` values support based on `int` SQLite data affinity, because there is no per bit operations for SQLite `blob` affinity data. Maximum SQLite `int` affinity value is 8 bytes length, hence maximum `bit`/`varbit` values length is 64 bits.
+- `sqlite_fdw` doesn't pushdown `#` (XOR) operator becasuse there is no equal SQLite operator.
+
 Tests
 -----
 Test directory have structure as following:
@@ -566,10 +570,24 @@ Contributing
 
 Opening issues and pull requests on GitHub are welcome.
 For pull request, please make sure these items below for testing:
-- Create test cases (if needed) for the latest version of PostgreSQL supported by sqlite_fdw.
+- Create test cases (if needed) for the latest version of PostgreSQL supported by `sqlite_fdw`. All error testcases should have a comment about test purpose.
 - Execute test cases and update expectations for the latest version of PostgreSQL
 - Test creation and execution for other PostgreSQL versions are welcome but not required.
 
+Preferred code style see in PostgreSQL source codes. For example
+
+```C
+type
+funct_name (type arg ...)
+{
+	for (;;)
+	{
+	}
+	if ()
+	{
+	}
+}
+```
 Useful links
 ------------
 

deparse.c

@@ -675,17 +675,17 @@ sqlite_foreign_expr_walker(Node *node,
 				ReleaseSysCache(tuple);
 
 				/*
-				 * Factorial (!) and Bitwise XOR (^) cannot be pushed down to
-				 * SQLite
+				 * Factorial (!) and Bitwise XOR (^), (#) 
+				 * cannot be pushed down to SQLite
+				 * Full list see in https://www.postgresql.org/docs/current/functions-bitstring.html
+				 * ILIKE cannot be pushed down to SQLite
+				 * Full list see in https://www.postgresql.org/docs/current/functions-matching.html
 				 */
 				if (strcmp(cur_opname, "!") == 0
-					|| strcmp(cur_opname, "^") == 0)
-				{
-					return false;
-				}
-
-				/* ILIKE cannot be pushed down to SQLite */
-				if (strcmp(cur_opname, "~~*") == 0 || strcmp(cur_opname, "!~~*") == 0)
+					|| strcmp(cur_opname, "^") == 0
+					|| strcmp(cur_opname, "#") == 0
+					|| strcmp(cur_opname, "~~*") == 0
+					|| strcmp(cur_opname, "!~~*") == 0)
 				{
 					return false;
 				}
@@ -2621,8 +2621,16 @@ sqlite_deparse_const(Const *node, deparse_expr_cxt *context, int showtype)
 			break;
 		case BITOID:
 		case VARBITOID:
-			extval = OidOutputFunctionCall(typoutput, node->constvalue);
-			appendStringInfo(buf, "B\'%s\'", extval);
+			{
+				extval = OidOutputFunctionCall(typoutput, node->constvalue);
+				if (strlen(extval) > SQLITE_FDW_BIT_DATATYPE_BUF_SIZE - 1 )
+				{
+					ereport(ERROR, (errcode(ERRCODE_FDW_INVALID_DATA_TYPE),
+							errmsg("SQLite FDW dosens't support very long bit/varbit data"),
+							errhint("bit length %ld, maxmum %ld", strlen(extval), SQLITE_FDW_BIT_DATATYPE_BUF_SIZE - 1)));
+				}
+				appendStringInfo(buf, "%lld", binstr2int64(extval));
+			}
 			break;
 		case BOOLOID:
 			{
@@ -2880,14 +2888,16 @@ sqlite_deparse_operator_name(StringInfo buf, Form_pg_operator opform)
 		}
 		else if (strcmp(cur_opname, "~~*") == 0 ||
 				 strcmp(cur_opname, "!~~*") == 0 ||
-				 strcmp(cur_opname, "~") == 0 ||
+				 /* ~ operator is both one of text RegEx operators and bit string NOT */
+				 (strcmp(cur_opname, "~") == 0 && opform->oprresult != VARBITOID && opform->oprresult != BITOID) ||
 				 strcmp(cur_opname, "!~") == 0 ||
 				 strcmp(cur_opname, "~*") == 0 ||
 				 strcmp(cur_opname, "!~*") == 0)
 		{
-			elog(ERROR, "OPERATOR is not supported");
+			ereport(ERROR, (errcode(ERRCODE_FDW_ERROR),
+							errmsg("SQL operator is not supported"),
+							errhint("operator name: %s", cur_opname)));
 		}
-
 		else
 		{
 			appendStringInfoString(buf, cur_opname);