table.virtual_table_using property, closes #196

docs/python-api.rst

@@ -1430,6 +1430,12 @@ The ``detect_fts()`` method returns the associated SQLite FTS table name, if one
     >> db["authors"].detect_fts()
     "authors_fts"
 
+The ``.virtual_table_using`` property reveals if a table is a virtual table. It returns ``None`` for regular tables and the upper case version of the type of virtual table otherwise. For example::
+
+    >> db["authors"].enable_fts(["name"])
+    >> db["authors_fts"].virtual_table_using
+    "FTS5"
+
 .. _python_api_fts:
 
 Enabling full-text search

sqlite_utils/db.py

@@ -10,12 +10,32 @@ import itertools
 import json
 import os
 import pathlib
+import re
 import sys
 import textwrap
 import uuid
 
 SQLITE_MAX_VARS = 999
 
+_virtual_table_using_re = re.compile(
+    r"""
+^ # Start of string
+\s*CREATE\s+VIRTUAL\s+TABLE\s+ # CREATE VIRTUAL TABLE
+(
+    '(?P<squoted_table>[^']*(?:''[^']*)*)' | # single quoted name
+    "(?P<dquoted_table>[^"]*(?:""[^"]*)*)" | # double quoted name
+    `(?P<backtick_table>[^`]+)`            | # `backtick` quoted name
+    \[(?P<squarequoted_table>[^\]]+)\]     | # [...] quoted name
+    (?P<identifier>                          # SQLite non-quoted identifier
+        [A-Za-z_\u0080-\uffff]  # \u0080-\uffff = "any character larger than u007f"
+        [A-Za-z_\u0080-\uffff0-9\$]* # zero-or-more alphanemuric or $
+    )
+)
+\s+(IF\s+NOT\s+EXISTS\s+)?      # IF NOT EXISTS (optional)
+USING\s+(?P<using>\w+)          # e.g. USING FTS5
+""",
+    re.VERBOSE | re.IGNORECASE,
+)
 
 try:
     import pandas as pd
@@ -676,6 +696,14 @@ class Table(Queryable):
                 )
         return fks
 
+    @property
+    def virtual_table_using(self):
+        "Returns type of virtual table or None if this is not a virtual table"
+        match = _virtual_table_using_re.match(self.schema)
+        if match is None:
+            return None
+        return match.groupdict()["using"].upper()
+
     @property
     def indexes(self):
         sql = 'PRAGMA index_list("{}")'.format(self.name)

tests/test_introspect.py

@@ -1,4 +1,4 @@
-from sqlite_utils.db import Index, View
+from sqlite_utils.db import Index, View, Database
 import pytest
 
 
@@ -142,3 +142,49 @@ def test_triggers(fresh_db):
         (t.name, t.table) for t in fresh_db["authors"].triggers
     }
     assert [] == fresh_db["other"].triggers
+
+
+@pytest.mark.parametrize(
+    "sql,expected_name,expected_using",
+    [
+        (
+            """
+            CREATE VIRTUAL TABLE foo USING FTS5(name)
+            """,
+            "foo",
+            "FTS5",
+        ),
+        (
+            """
+            CREATE VIRTUAL TABLE "foo" USING FTS4(name)
+            """,
+            "foo",
+            "FTS4",
+        ),
+        (
+            """
+            CREATE VIRTUAL TABLE IF NOT EXISTS `foo` USING FTS4(name)
+            """,
+            "foo",
+            "FTS4",
+        ),
+        (
+            """
+            CREATE VIRTUAL TABLE IF NOT EXISTS `foo` USING fts5(name)
+            """,
+            "foo",
+            "FTS5",
+        ),
+        (
+            """
+            CREATE TABLE IF NOT EXISTS `foo` (id integer primary key)
+            """,
+            "foo",
+            None,
+        ),
+    ],
+)
+def test_virtual_table_using(sql, expected_name, expected_using):
+    db = Database(memory=True)
+    db.execute(sql)
+    assert db[expected_name].virtual_table_using == expected_using