gh-133390: Support SQL keyword completion for sqlite3 CLI (#133393)

Doc/whatsnew/3.15.rst

@@ -134,6 +134,13 @@ shelve
   (Contributed by Andrea Oliveri in :gh:`134004`.)
 
 
+sqlite3
+-------
+
+* Support SQL keyword completion in the :mod:`sqlite3` command-line interface.
+  (Contributed by Long Tan in :gh:`133393`.)
+
+
 ssl
 ---
 

Lib/sqlite3/__main__.py

@@ -12,6 +12,8 @@
 from textwrap import dedent
 from _colorize import get_theme, theme_no_color
 
+from ._completer import completer
+
 
 def execute(c, sql, suppress_errors=True, theme=theme_no_color):
     """Helper that wraps execution of SQL code.
@@ -136,12 +138,9 @@ def main(*args):
             execute(con, args.sql, suppress_errors=False, theme=theme)
         else:
             # No SQL provided; start the REPL.
-            console = SqliteInteractiveConsole(con, use_color=True)
-            try:
-                import readline  # noqa: F401
-            except ImportError:
-                pass
-            console.interact(banner, exitmsg="")
+            with completer():
+                console = SqliteInteractiveConsole(con, use_color=True)
+                console.interact(banner, exitmsg="")
     finally:
         con.close()
 

Lib/sqlite3/_completer.py

@@ -0,0 +1,42 @@
+from contextlib import contextmanager
+
+try:
+    from _sqlite3 import SQLITE_KEYWORDS
+except ImportError:
+    SQLITE_KEYWORDS = ()
+
+_completion_matches = []
+
+
+def _complete(text, state):
+    global _completion_matches
+
+    if state == 0:
+        text_upper = text.upper()
+        _completion_matches = [c for c in SQLITE_KEYWORDS if c.startswith(text_upper)]
+    try:
+        return _completion_matches[state] + " "
+    except IndexError:
+        return None
+
+
+@contextmanager
+def completer():
+    try:
+        import readline
+    except ImportError:
+        yield
+        return
+
+    old_completer = readline.get_completer()
+    try:
+        readline.set_completer(_complete)
+        if readline.backend == "editline":
+            # libedit uses "^I" instead of "tab"
+            command_string = "bind ^I rl_complete"
+        else:
+            command_string = "tab: complete"
+        readline.parse_and_bind(command_string)
+        yield
+    finally:
+        readline.set_completer(old_completer)

Lib/test/test_sqlite3/test_cli.py

@@ -1,14 +1,22 @@
 """sqlite3 CLI tests."""
 import sqlite3
+import sys
+import textwrap
 import unittest
+import unittest.mock
+import os
 
 from sqlite3.__main__ import main as cli
+from test.support.import_helper import import_module
 from test.support.os_helper import TESTFN, unlink
+from test.support.pty_helper import run_pty
 from test.support import (
     captured_stdout,
     captured_stderr,
     captured_stdin,
     force_not_colorized_test_class,
+    requires_subprocess,
+    verbose,
 )
 
 
@@ -200,5 +208,108 @@ def test_color(self):
             self.assertIn('\x1b[1;35mOperationalError (SQLITE_ERROR)\x1b[0m: '
                           '\x1b[35mnear "sel": syntax error\x1b[0m', err)
 
+
+@requires_subprocess()
+@force_not_colorized_test_class
+class Completion(unittest.TestCase):
+    PS1 = "sqlite> "
+
+    @classmethod
+    def setUpClass(cls):
+        _sqlite3 = import_module("_sqlite3")
+        if not hasattr(_sqlite3, "SQLITE_KEYWORDS"):
+            raise unittest.SkipTest("unable to determine SQLite keywords")
+
+        readline = import_module("readline")
+        if readline.backend == "editline":
+            raise unittest.SkipTest("libedit readline is not supported")
+
+    def write_input(self, input_, env=None):
+        script = textwrap.dedent("""
+            import readline
+            from sqlite3.__main__ import main
+
+            readline.parse_and_bind("set colored-completion-prefix off")
+            main()
+        """)
+        return run_pty(script, input_, env)
+
+    def test_complete_sql_keywords(self):
+        # List candidates starting with 'S', there should be multiple matches.
+        input_ = b"S\t\tEL\t 1;\n.quit\n"
+        output = self.write_input(input_)
+        self.assertIn(b"SELECT", output)
+        self.assertIn(b"SET", output)
+        self.assertIn(b"SAVEPOINT", output)
+        self.assertIn(b"(1,)", output)
+
+        # Keywords are completed in upper case for even lower case user input.
+        input_ = b"sel\t\t 1;\n.quit\n"
+        output = self.write_input(input_)
+        self.assertIn(b"SELECT", output)
+        self.assertIn(b"(1,)", output)
+
+    @unittest.skipIf(sys.platform.startswith("freebsd"),
+                    "Two actual tabs are inserted when there are no matching"
+                    " completions in the pseudo-terminal opened by run_pty()"
+                    " on FreeBSD")
+    def test_complete_no_match(self):
+        input_ = b"xyzzy\t\t\b\b\b\b\b\b\b.quit\n"
+        # Set NO_COLOR to disable coloring for self.PS1.
+        output = self.write_input(input_, env={**os.environ, "NO_COLOR": "1"})
+        lines = output.decode().splitlines()
+        indices = (
+            i for i, line in enumerate(lines, 1)
+            if line.startswith(f"{self.PS1}xyzzy")
+        )
+        line_num = next(indices, -1)
+        self.assertNotEqual(line_num, -1)
+        # Completions occupy lines, assert no extra lines when there is nothing
+        # to complete.
+        self.assertEqual(line_num, len(lines))
+
+    def test_complete_no_input(self):
+        from _sqlite3 import SQLITE_KEYWORDS
+
+        script = textwrap.dedent("""
+            import readline
+            from sqlite3.__main__ import main
+
+            # Configure readline to ...:
+            # - hide control sequences surrounding each candidate
+            # - hide "Display all xxx possibilities? (y or n)"
+            # - hide "--More--"
+            # - show candidates one per line
+            readline.parse_and_bind("set colored-completion-prefix off")
+            readline.parse_and_bind("set colored-stats off")
+            readline.parse_and_bind("set completion-query-items 0")
+            readline.parse_and_bind("set page-completions off")
+            readline.parse_and_bind("set completion-display-width 0")
+            readline.parse_and_bind("set show-all-if-ambiguous off")
+            readline.parse_and_bind("set show-all-if-unmodified off")
+
+            main()
+        """)
+        input_ = b"\t\t.quit\n"
+        output = run_pty(script, input_, env={**os.environ, "NO_COLOR": "1"})
+        try:
+            lines = output.decode().splitlines()
+            indices = [
+                i for i, line in enumerate(lines)
+                if line.startswith(self.PS1)
+            ]
+            self.assertEqual(len(indices), 2)
+            start, end = indices
+            candidates = [l.strip() for l in lines[start+1:end]]
+            self.assertEqual(candidates, sorted(SQLITE_KEYWORDS))
+        except:
+            if verbose:
+                print(' PTY output: '.center(30, '-'))
+                print(output.decode(errors='replace'))
+                print(' end PTY output '.center(30, '-'))
+            raise
+
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/ACKS

@@ -1868,6 +1868,7 @@ Neil Tallim
 Geoff Talvola
 Anish Tambe
 Musashi Tamura
+Long Tan
 William Tanksley
 Christian Tanzer
 Steven Taschuk

Misc/NEWS.d/next/Library/2025-05-05-03-14-08.gh-issue-133390.AuTggn.rst

@@ -0,0 +1 @@
+Support keyword completion in the :mod:`sqlite3` command-line interface.

Modules/_sqlite/module.c

@@ -32,6 +32,7 @@
 #include "microprotocols.h"
 #include "row.h"
 #include "blob.h"
+#include "util.h"
 
 #if SQLITE_VERSION_NUMBER < 3015002
 #error "SQLite 3.15.2 or higher required"
@@ -404,6 +405,40 @@ pysqlite_error_name(int rc)
     return NULL;
 }
 
+static int
+add_keyword_tuple(PyObject *module)
+{
+#if SQLITE_VERSION_NUMBER >= 3024000
+    int count = sqlite3_keyword_count();
+    PyObject *keywords = PyTuple_New(count);
+    if (keywords == NULL) {
+        return -1;
+    }
+    for (int i = 0; i < count; i++) {
+        const char *keyword;
+        int size;
+        int result = sqlite3_keyword_name(i, &keyword, &size);
+        if (result != SQLITE_OK) {
+            pysqlite_state *state = pysqlite_get_state(module);
+            set_error_from_code(state, result);
+            goto error;
+        }
+        PyObject *kwd = PyUnicode_FromStringAndSize(keyword, size);
+        if (!kwd) {
+            goto error;
+        }
+        PyTuple_SET_ITEM(keywords, i, kwd);
+    }
+    return PyModule_Add(module, "SQLITE_KEYWORDS", keywords);
+
+error:
+    Py_DECREF(keywords);
+    return -1;
+#else
+    return 0;
+#endif
+}
+
 static int
 add_integer_constants(PyObject *module) {
 #define ADD_INT(ival)                                           \
@@ -702,6 +737,10 @@ module_exec(PyObject *module)
         goto error;
     }
 
+    if (add_keyword_tuple(module) < 0) {
+        goto error;
+    }
+
     if (PyModule_AddStringConstant(module, "sqlite_version", sqlite3_libversion())) {
         goto error;
     }