sql_ast.go

package main

import (
        "strings"
        "fmt"
        "github.com/pingcap/parser/ast"
        "github.com/pingcap/parser"
        _ "github.com/pingcap/tidb/types/parser_driver" // https://github.com/pingcap/parser/issues/43 
)

type visitor struct{}

var (
        level = 0
        sp    = "++"
)

func (v *visitor) Enter(in ast.Node) (out ast.Node, skipChildren bool) {
        s := strings.Repeat("\t", level)
        fmt.Printf("L-%d %s%T %s\n", level, s, in, in.Text())
        level += 1
        return in, false
}

func (v *visitor) Leave(in ast.Node) (out ast.Node, ok bool) {
        level -= 1
        //s := strings.Repeat("\t", level)
        //fmt.Printf("L%d%s%T\n", level, s, in)
        return in, true
}

func main() {
        sql := "SELECT t1.a, t2.b FROM t1 JOIN t2 ON t1.id = t2.fid WHERE t1.c>100"

        sqlParser := parser.New()
        stmtNodes,_, err := sqlParser.Parse(sql, "", "")
        if err != nil {
                fmt.Printf("parse error:\n%v\n%s", err, sql)
                return
        }
        for _, stmtNode := range stmtNodes {
                v := visitor{}
                stmtNode.Accept(&v)
        }
}