44 lines
1.4 KiB
Go
44 lines
1.4 KiB
Go
// Copyright 2017 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 parser
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"github.com/juju/errors"
|
|
"github.com/pingcap/tidb/ast"
|
|
"github.com/pingcap/tidb/parser"
|
|
)
|
|
|
|
// getDefaultCharsetAndCollate is copyed from ddl/ddl_api.go.
|
|
func getDefaultCharsetAndCollate() (string, string) {
|
|
return "utf8", "utf8_bin"
|
|
}
|
|
|
|
// ParseExpression parses an ExprNode from a string.
|
|
// Where should we use this?
|
|
// When TiDB bootstraps, it'll load infoschema from TiKV.
|
|
// Because some ColumnInfos have attribute `GeneratedExprString`,
|
|
// we need to parse that string into ast.ExprNode.
|
|
func ParseExpression(expr string) (node ast.ExprNode, err error) {
|
|
expr = fmt.Sprintf("select %s", expr)
|
|
charset, collation := getDefaultCharsetAndCollate()
|
|
stmts, err := parser.New().Parse(expr, charset, collation)
|
|
if err == nil {
|
|
sel := stmts[0].(*ast.SelectStmt)
|
|
node = sel.Fields.Fields[0].Expr
|
|
}
|
|
return node, errors.Trace(err)
|
|
}
|