tidb base 源码
tidb base 代码
文件路径：/parser/ast/base.go
// 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 ast
import (
"sync"
"github.com/pingcap/tidb/parser/charset"
"github.com/pingcap/tidb/parser/types"
)
// node is the struct implements Node interface except for Accept method.
// Node implementations should embed it in.
type node struct {
utf8Text string
enc charset.Encoding
once *sync.Once
text string
offset int
}
// SetOriginTextPosition implements Node interface.
func (n *node) SetOriginTextPosition(offset int) {
n.offset = offset
}
// OriginTextPosition implements Node interface.
func (n *node) OriginTextPosition() int {
return n.offset
}
// SetText implements Node interface.
func (n *node) SetText(enc charset.Encoding, text string) {
n.enc = enc
n.text = text
n.once = &sync.Once{}
}
// Text implements Node interface.
func (n *node) Text() string {
if n.once == nil {
return n.text
}
n.once.Do(func() {
if n.enc == nil {
n.utf8Text = n.text
return
}
utf8Lit, _ := n.enc.Transform(nil, charset.HackSlice(n.text), charset.OpDecodeReplace)
n.utf8Text = charset.HackString(utf8Lit)
})
return n.utf8Text
}
// OriginalText implements Node interface.
func (n *node) OriginalText() string {
return n.text
}
// stmtNode implements StmtNode interface.
// Statement implementations should embed it in.
type stmtNode struct {
node
}
// statement implements StmtNode interface.
func (sn *stmtNode) statement() {}
// ddlNode implements DDLNode interface.
// DDL implementations should embed it in.
type ddlNode struct {
stmtNode
}
// ddlStatement implements DDLNode interface.
func (dn *ddlNode) ddlStatement() {}
// dmlNode is the struct implements DMLNode interface.
// DML implementations should embed it in.
type dmlNode struct {
stmtNode
}
// dmlStatement implements DMLNode interface.
func (dn *dmlNode) dmlStatement() {}
// exprNode is the struct implements Expression interface.
// Expression implementations should embed it in.
type exprNode struct {
node
Type types.FieldType
flag uint64
}
// TexprNode is exported for parser driver.
type TexprNode = exprNode
// SetType implements ExprNode interface.
func (en *exprNode) SetType(tp *types.FieldType) {
en.Type = *tp
}
// GetType implements ExprNode interface.
func (en *exprNode) GetType() *types.FieldType {
return &en.Type
}
// SetFlag implements ExprNode interface.
func (en *exprNode) SetFlag(flag uint64) {
en.flag = flag
}
// GetFlag implements ExprNode interface.
func (en *exprNode) GetFlag() uint64 {
return en.flag
}
type funcNode struct {
exprNode
}
// functionExpression implements FunctionNode interface.
func (fn *funcNode) functionExpression() {}
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