cli: support autocomplete

Release note (cli change): CLI now auto completes on tab
by using `SHOW COMPLETIONS AT OFFSET`.

pkg/BUILD.bazel

@@ -255,6 +255,7 @@ ALL_TESTS = [
     "//pkg/sql/contention/txnidcache:txnidcache_test",
     "//pkg/sql/contention:contention_test",
     "//pkg/sql/covering:covering_test",
+    "//pkg/sql/delegate:delegate_test",
     "//pkg/sql/distsql:distsql_test",
     "//pkg/sql/doctor:doctor_test",
     "//pkg/sql/enum:enum_test",

pkg/cli/clisqlshell/sql.go

@@ -900,18 +900,35 @@ func (c *cliState) GetCompletions(_ string) []string {
 	sql, _ := c.ins.GetLineInfo()
 
 	if !strings.HasSuffix(sql, "??") {
-		fmt.Fprintf(c.iCtx.stdout,
-			"\ntab completion not supported; append '??' and press tab for contextual help\n\n")
-	} else {
-		helpText, err := c.serverSideParse(sql)
-		if helpText != "" {
-			// We have a completion suggestion. Use that.
-			fmt.Fprintf(c.iCtx.stdout, "\nSuggestion:\n%s\n", helpText)
-		} else if err != nil {
-			// Some other error. Display it.
-			fmt.Fprintln(c.iCtx.stdout)
+		query := fmt.Sprintf(`SHOW COMPLETIONS AT OFFSET %d FOR %s`, len(sql), lexbase.EscapeSQLString(sql))
+		var rows [][]string
+		var err error
+		err = c.runWithInterruptableCtx(func(ctx context.Context) error {
+			_, rows, err = c.sqlExecCtx.RunQuery(ctx, c.conn,
+				clisqlclient.MakeQuery(query), true)
+			return err
+		})
+
+		if err != nil {
 			clierror.OutputError(c.iCtx.stdout, err, true /*showSeverity*/, false /*verbose*/)
 		}
+
+		var completions []string
+		for _, row := range rows {
+			completions = append(completions, row[0])
+		}
+
+		return completions
+	}
+
+	helpText, err := c.serverSideParse(sql)
+	if helpText != "" {
+		// We have a completion suggestion. Use that.
+		fmt.Fprintf(c.iCtx.stdout, "\nSuggestion:\n%s\n", helpText)
+	} else if err != nil {
+		// Some other error. Display it.
+		fmt.Fprintln(c.iCtx.stdout)
+		clierror.OutputError(c.iCtx.stdout, err, true /*showSeverity*/, false /*verbose*/)
 	}
 
 	// After the suggestion or error, re-display the prompt and current entry.

pkg/sql/conn_executor_exec.go

@@ -16,6 +16,7 @@ import (
 	"encoding/base64"
 	"fmt"
 	"runtime/pprof"
+	"strconv"
 	"strings"
 	"sync/atomic"
 	"time"
@@ -28,6 +29,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descs"
 	"github.com/cockroachdb/cockroach/pkg/sql/contentionpb"
+	"github.com/cockroachdb/cockroach/pkg/sql/delegate"
 	"github.com/cockroachdb/cockroach/pkg/sql/execinfrapb"
 	"github.com/cockroachdb/cockroach/pkg/sql/execstats"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/exec/explain"
@@ -1656,6 +1658,8 @@ func (ex *connExecutor) runObserverStatement(
 		return ex.runShowLastQueryStatistics(ctx, res, sqlStmt)
 	case *tree.ShowTransferState:
 		return ex.runShowTransferState(ctx, res, sqlStmt)
+	case *tree.ShowCompletions:
+		return ex.runShowCompletions(ctx, sqlStmt, res)
 	default:
 		res.SetError(errors.AssertionFailedf("unrecognized observer statement type %T", ast))
 		return nil
@@ -1779,6 +1783,33 @@ func (ex *connExecutor) runShowTransferState(
 	return res.AddRow(ctx, row)
 }
 
+// runShowCompletions executes a SHOW COMPLETIONS statement.
+func (ex *connExecutor) runShowCompletions(
+	ctx context.Context, n *tree.ShowCompletions, res RestrictedCommandResult,
+) error {
+	res.SetColumns(ctx, colinfo.ResultColumns{{Name: "COMPLETIONS", Typ: types.String}})
+	offsetVal, ok := n.Offset.AsConstantInt()
+	if !ok {
+		return errors.Newf("invalid offset %v", n.Offset)
+	}
+	offset, err := strconv.Atoi(offsetVal.String())
+	if err != nil {
+		return err
+	}
+	completions, err := delegate.RunShowCompletions(n.Statement.RawString(), offset)
+	if err != nil {
+		return err
+	}
+
+	for _, completion := range completions {
+		err = res.AddRow(ctx, tree.Datums{tree.NewDString(completion)})
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // showQueryStatsFns maps column names as requested by the SQL clients
 // to timing retrieval functions from the execution phase times.
 var showQueryStatsFns = map[tree.Name]func(*sessionphase.Times) time.Duration{

pkg/sql/delegate/BUILD.bazel

@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "delegate",
@@ -7,6 +7,7 @@ go_library(
         "job_control.go",
         "show_all_cluster_settings.go",
         "show_changefeed_jobs.go",
+        "show_completions.go",
         "show_database_indexes.go",
         "show_databases.go",
         "show_default_privileges.go",
@@ -57,3 +58,9 @@ go_library(
         "@com_github_cockroachdb_errors//:errors",
     ],
 )
+
+go_test(
+    name = "delegate_test",
+    srcs = ["show_completions_test.go"],
+    embed = [":delegate"],
+)

pkg/sql/delegate/show_completions.go

@@ -1,3 +1,13 @@
+// Copyright 2022 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
 package delegate
 
 import (
@@ -24,7 +34,7 @@ func (d *delegator) delegateShowCompletions(n *tree.ShowCompletions) (tree.State
 		return nil, err
 	}
 
-	completions, err := runShowCompletions(n.Statement, offset)
+	completions, err := RunShowCompletions(n.Statement.RawString(), offset)
 	if err != nil {
 		return nil, err
 	}
@@ -49,14 +59,15 @@ func (d *delegator) delegateShowCompletions(n *tree.ShowCompletions) (tree.State
 	return parse(query.String())
 }
 
-func runShowCompletions(stmt string, offset int) ([]string, error) {
+// RunShowCompletions returns a list of completion keywords for the given
+// statement and offset.
+func RunShowCompletions(stmt string, offset int) ([]string, error) {
 	if offset <= 0 || offset > len(stmt) {
 		return nil, nil
 	}
 
 	// For simplicity, if we're on a whitespace, return no completions.
-	// Currently, parser.
-	// parser.TokensIgnoreErrors does not consider whitespaces
+	// Currently, parser.TokensIgnoreErrors does not consider whitespaces
 	// after the last token.
 	// Ie "SELECT ", will only return one token being "SELECT".
 	// If we're at the whitespace, we do not want to return completion
@@ -81,8 +92,8 @@ func runShowCompletions(stmt string, offset int) ([]string, error) {
 	// For example if the stmt is SELECT with offset 2, even though SEARCH would
 	// come first for "SE", we want to return "SELECT".
 	// Similarly, if we have SEL with offset 2, we want to return "SEL".
-	allSqlTokens := parser.TokensIgnoreErrors(stmt)
-	lastWordFull := allSqlTokens[len(sqlTokenStrings)-1]
+	allSQLTokens := parser.TokensIgnoreErrors(stmt)
+	lastWordFull := allSQLTokens[len(sqlTokenStrings)-1]
 	if lastWordFull.Str != lastWordTruncated {
 		return []string{strings.ToUpper(lastWordFull.Str)}, nil
 	}

pkg/sql/delegate/show_completions_test.go

@@ -1,3 +1,13 @@
+// Copyright 2022 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
 package delegate
 
 import (
@@ -83,7 +93,7 @@ func TestCompletions(t *testing.T) {
 		if tc.offset == 0 {
 			offset = len(tc.stmt)
 		}
-		completions, err := runShowCompletions(tc.stmt, offset)
+		completions, err := RunShowCompletions(tc.stmt, offset)
 		if err != nil {
 			t.Error(err)
 		}

pkg/sql/logictest/testdata/logic_test/show_completions

@@ -1,40 +1,38 @@
 query T
-show completions at offset 1 for 'select 1'
+SHOW COMPLETIONS AT OFFSET 1 FOR 'select 1'
 ----
 SELECT
 
 query T
-show completions at offset 7 for 'select 1'
+SHOW COMPLETIONS AT OFFSET 7 FOR 'select 1'
 ----
-·
 
 query T
-show completions at offset 7 for 'select 2'
+SHOW COMPLETIONS AT OFFSET 7 FOR 'select 2'
 ----
-·
 
 query T
-show completions at offset 10 for 'select * fro'
+SHOW COMPLETIONS AT OFFSET 10 FOR 'select * fro'
 ----
 FRO
 
 query T
-show completions at offset 11 for 'select * fro'
+SHOW COMPLETIONS AT OFFSET 11 FOR 'select * fro'
 ----
 FRO
 
 query T
-show completions at offset 12 for 'select * fro'
+SHOW COMPLETIONS AT OFFSET 12 FOR 'select * fro'
 ----
 FROM
 
 query T
-show completions at offset 10 for 'select * from'
+SHOW COMPLETIONS AT OFFSET 10 FOR 'select * from'
 ----
 FROM
 
 query T
-show completions at offset 11 for 'select * from'
+SHOW COMPLETIONS AT OFFSET 11 FOR 'select * from'
 ----
 FROM
 
@@ -43,7 +41,7 @@ FROM
 # whether our SQL token is a string const.
 # However we do want to test this so we can ensure we handle escaped strings.
 query T
-show completions at offset 4 for e'\'se\'';
+SHOW COMPLETIONS AT OFFSET 4 FOR e'\'se\'';
 ----
 SEARCH
 SECOND

pkg/sql/parser/sql.y

@@ -6114,7 +6114,7 @@ show_completions_stmt:
   {
     /* SKIP DOC */
     $$.val = &tree.ShowCompletions{
-        Statement: $7,
+        Statement: tree.NewStrVal($7),
         Offset: $5.numVal(),
     }
   }

pkg/sql/parser/testdata/show_completions

@@ -0,0 +1,47 @@
+parse
+SHOW COMPLETIONS AT OFFSET 1 FOR 'creat'
+----
+SHOW COMPLETIONS AT OFFSET 1 FOR 'creat'
+SHOW COMPLETIONS AT OFFSET 1 FOR ('creat') -- fully parenthesized
+SHOW COMPLETIONS AT OFFSET 1 FOR '_' -- literals removed
+SHOW COMPLETIONS AT OFFSET 1 FOR 'creat' -- identifiers removed
+
+parse
+SHOW COMPLETIONS AT OFFSET 1 FOR 'creat'
+----
+SHOW COMPLETIONS AT OFFSET 1 FOR 'creat'
+SHOW COMPLETIONS AT OFFSET 1 FOR ('creat') -- fully parenthesized
+SHOW COMPLETIONS AT OFFSET 1 FOR '_' -- literals removed
+SHOW COMPLETIONS AT OFFSET 1 FOR 'creat' -- identifiers removed
+
+parse
+SHOW COMPLETIONS AT OFFSET 1 FOR 'CREAT'
+----
+SHOW COMPLETIONS AT OFFSET 1 FOR 'CREAT'
+SHOW COMPLETIONS AT OFFSET 1 FOR ('CREAT') -- fully parenthesized
+SHOW COMPLETIONS AT OFFSET 1 FOR '_' -- literals removed
+SHOW COMPLETIONS AT OFFSET 1 FOR 'CREAT' -- identifiers removed
+
+parse
+SHOW COMPLETIONS AT OFFSET 7 FOR 'SELECT 1'
+----
+SHOW COMPLETIONS AT OFFSET 7 FOR 'SELECT 1'
+SHOW COMPLETIONS AT OFFSET 7 FOR ('SELECT 1') -- fully parenthesized
+SHOW COMPLETIONS AT OFFSET 7 FOR '_' -- literals removed
+SHOW COMPLETIONS AT OFFSET 7 FOR 'SELECT 1' -- identifiers removed
+
+parse
+show completions at offset 10 for 'select * fro'
+----
+SHOW COMPLETIONS AT OFFSET 10 FOR 'select * fro' -- normalized!
+SHOW COMPLETIONS AT OFFSET 10 FOR ('select * fro') -- fully parenthesized
+SHOW COMPLETIONS AT OFFSET 10 FOR '_' -- literals removed
+SHOW COMPLETIONS AT OFFSET 10 FOR 'select * fro' -- identifiers removed
+
+parse
+SHOW COMPLETIONS AT OFFSET 4 FOR e'\'se\'';
+----
+SHOW COMPLETIONS AT OFFSET 4 FOR e'\'se\'' -- normalized!
+SHOW COMPLETIONS AT OFFSET 4 FOR (e'\'se\'') -- fully parenthesized
+SHOW COMPLETIONS AT OFFSET 4 FOR '_' -- literals removed
+SHOW COMPLETIONS AT OFFSET 4 FOR e'\'se\'' -- identifiers removed