tables and views commands accept optional table/view names

The tables and views commands now take one or more optional table (or view)
names as positional arguments after the database path, restricting the output
to just those tables. This is handy with --counts against a database that has
a large table you would rather skip.

Names are listed in the order they are passed. If any named table or view does
not exist the command raises an error and exits with a non-zero status, so the
exit code can be used to confirm a set of expected tables is present.

Closes #478

sqlite_utils/cli.py

@@ -187,6 +187,7 @@ def cli():
     type=click.Path(exists=True, file_okay=True, dir_okay=False, allow_dash=False),
     required=True,
 )
+@click.argument("names", nargs=-1)
 @click.option(
     "--fts4", help="Just show FTS4 enabled tables", default=False, is_flag=True
 )
@@ -212,6 +213,7 @@ def cli():
 @load_extension_option
 def tables(
     path,
+    names,
     fts4,
     fts5,
     counts,
@@ -235,6 +237,11 @@ def tables(
 
     \b
         sqlite-utils tables trees.db
+
+    Pass one or more table names to restrict the output to just those tables:
+
+    \b
+        sqlite-utils tables trees.db plants seeds
     """
     db = sqlite_utils.Database(path)
     _register_db_for_cleanup(db)
@@ -249,8 +256,25 @@ def tables(
 
     method = db.view if views else db.table
 
+    if names:
+        existing = set(db.view_names() if views else db.table_names())
+        missing = [name for name in names if name not in existing]
+        if missing:
+            label = "view" if views else "table"
+            if len(missing) == 1:
+                message = "The following {} does not exist: {}".format(
+                    label, missing[0]
+                )
+            else:
+                message = "The following {}s do not exist: {}".format(
+                    label, ", ".join(missing)
+                )
+            raise click.ClickException(message)
+
     def _iter():
-        if views:
+        if names:
+            items = list(names)
+        elif views:
             items = db.view_names()
         else:
             items = db.table_names(fts4=fts4, fts5=fts5)
@@ -293,6 +317,7 @@ def tables(
     type=click.Path(exists=True, file_okay=True, dir_okay=False, allow_dash=False),
     required=True,
 )
+@click.argument("names", nargs=-1)
 @click.option(
     "--counts", help="Include row counts per view", default=False, is_flag=True
 )
@@ -312,6 +337,7 @@ def tables(
 @load_extension_option
 def views(
     path,
+    names,
     counts,
     nl,
     arrays,
@@ -332,10 +358,16 @@ def views(
 
     \b
         sqlite-utils views trees.db
+
+    Pass one or more view names to restrict the output to just those views:
+
+    \b
+        sqlite-utils views trees.db recent_plants
     """
     assert tables.callback is not None
     tables.callback(
         path=path,
+        names=names,
         fts4=False,
         fts5=False,
         counts=counts,