stmt: add replace statment

stmt/stmts/replace.go

@@ -0,0 +1,99 @@
+// Copyright 2015 PingCAP, 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stmts
+
+import (
+	"github.com/juju/errors"
+	"github.com/pingcap/tidb/context"
+	"github.com/pingcap/tidb/expression"
+	"github.com/pingcap/tidb/plan"
+	"github.com/pingcap/tidb/rset"
+	"github.com/pingcap/tidb/table"
+	"github.com/pingcap/tidb/util/format"
+)
+
+// ReplaceIntoStmt is a statement works exactly like insert, except that if
+// an old row in the table has the same value as a new row for a PRIMARY KEY or a UNIQUE index,
+// the old row is deleted before the new row is inserted.
+// See: https://dev.mysql.com/doc/refman/5.7/en/replace.html
+type ReplaceIntoStmt struct {
+	ColNames   []string
+	Lists      [][]expression.Expression
+	Sel        plan.Planner
+	TableIdent table.Ident
+	SetList    []*expression.Assignment
+	Priority   int
+
+	Text string
+}
+
+// Explain implements the stmt.Statement Explain interface.
+func (s *ReplaceIntoStmt) Explain(ctx context.Context, w format.Formatter) {
+	w.Format("%s\n", s.Text)
+}
+
+// IsDDL implements the stmt.Statement IsDDL interface.
+func (s *ReplaceIntoStmt) IsDDL() bool {
+	return false
+}
+
+// OriginText implements the stmt.Statement OriginText interface.
+func (s *ReplaceIntoStmt) OriginText() string {
+	return s.Text
+}
+
+// SetText implements the stmt.Statement SetText interface.
+func (s *ReplaceIntoStmt) SetText(text string) {
+	s.Text = text
+}
+
+// Exec implements the stmt.Statement Exec interface.
+func (s *ReplaceIntoStmt) Exec(ctx context.Context) (_ rset.Recordset, err error) {
+	stmt := &InsertIntoStmt{ColNames: s.ColNames, Lists: s.Lists, Priority: s.Priority,
+		Sel: s.Sel, Setlist: s.SetList, TableIdent: s.TableIdent, Text: s.Text}
+	t, err := getTable(ctx, stmt.TableIdent)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	cols, err := stmt.getColumns(t.Cols())
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+
+	// Process `replace ... (select ...)`
+	if stmt.Sel != nil {
+		return stmt.execSelect(t, cols, ctx)
+	}
+	// Process `replace ... set x=y ...`
+	if err = stmt.getSetList(); err != nil {
+		return nil, errors.Trace(err)
+	}
+	m, err := stmt.getDefaultValues(ctx, t.Cols())
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	replaceValueCount := len(stmt.Lists[0])
+
+	for i, list := range stmt.Lists {
+		if err = stmt.checkValueCount(replaceValueCount, len(list), i, cols); err != nil {
+			return nil, errors.Trace(err)
+		}
+		// TODO: remove that has the same value as a new row for a PRIMARY KEY or a UNIQUE index.
+		if _, _, err = stmt.addRecord(ctx, t, cols, list, m); err != nil {
+			return nil, errors.Trace(err)
+		}
+	}
+
+	return nil, nil
+}