chore: import upstream snapshot with attribution

server/ast/set_var.go

@@ -0,0 +1,89 @@
+// Copyright 2023 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ast
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/cockroachdb/errors"
+	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
+
+	"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
+	"github.com/dolthub/doltgresql/server/config"
+)
+
+// nodeSetVar handles *tree.SetVar nodes.
+func nodeSetVar(ctx *Context, node *tree.SetVar) (vitess.Statement, error) {
+	if node == nil {
+		return nil, nil
+	}
+	// USE statement alias
+	if node.Name == "database" {
+		// strip off all quotes from the database name
+		dbName := strings.TrimPrefix(strings.TrimSuffix(node.Values[0].String(), "'"), "'")
+		dbName = strings.TrimPrefix(strings.TrimSuffix(dbName, "\""), "\"")
+		dbName = strings.TrimPrefix(strings.TrimSuffix(dbName, "`"), "`")
+		return &vitess.Use{DBName: vitess.NewTableIdent(dbName)}, nil
+	}
+	if node.Namespace == "" && !config.IsValidPostgresConfigParameter(node.Name) && !config.IsValidDoltConfigParameter(node.Name) {
+		return nil, errors.Errorf(`ERROR: unrecognized configuration parameter "%s"`, node.Name)
+	}
+	if node.IsLocal {
+		// TODO: takes effect for only the current transaction rather than the current session.
+		return nil, errors.Errorf("SET LOCAL is not yet supported")
+	}
+	var expr vitess.Expr
+	var err error
+	if len(node.Values) == 0 {
+		// sanity check
+		return nil, errors.Errorf(`ERROR: syntax error at or near ";"'`)
+	} else if len(node.Values) > 1 {
+		vals := make([]string, len(node.Values))
+		for i, val := range node.Values {
+			vals[i] = val.String()
+		}
+		expr = &vitess.ColName{
+			Name: vitess.NewColIdent(strings.Join(vals, ", ")),
+		}
+	} else {
+		expr, err = nodeExpr(ctx, node.Values[0])
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if node.Namespace == "" {
+		return &vitess.Set{
+			Exprs: vitess.SetVarExprs{&vitess.SetVarExpr{
+				Scope: vitess.SetScope_Session,
+				Name: &vitess.ColName{
+					Name: vitess.NewColIdent(node.Name),
+				},
+				Expr: expr,
+			}},
+		}, nil
+	} else {
+		return &vitess.Set{
+			Exprs: vitess.SetVarExprs{&vitess.SetVarExpr{
+				Scope: vitess.SetScope_User,
+				Name: &vitess.ColName{
+					Name: vitess.NewColIdent(fmt.Sprintf("%s.%s", node.Namespace, node.Name)),
+				},
+				Expr: expr,
+			}},
+		}, nil
+	}
+}