gh-ost/go/sql/parser.go

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/*
Copyright 2016 GitHub Inc.
See https://github.com/github/gh-ost/blob/master/LICENSE
*/
package sql
import (
"regexp"
"strconv"
"strings"
)
var (
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sanitizeQuotesRegexp = regexp.MustCompile("('[^']*')")
renameColumnRegexp = regexp.MustCompile(`(?i)\bchange\s+(column\s+|)([\S]+)\s+([\S]+)\s+`)
)
type Parser struct {
columnRenameMap map[string]string
}
func NewParser() *Parser {
return &Parser{
columnRenameMap: make(map[string]string),
}
}
func (this *Parser) tokenizeAlterStatement(alterStatement string) (tokens []string, err error) {
terminatingQuote := rune(0)
f := func(c rune) bool {
switch {
case c == terminatingQuote:
terminatingQuote = rune(0)
return false
case terminatingQuote != rune(0):
return false
case c == '\'':
terminatingQuote = c
return false
case c == '(':
terminatingQuote = ')'
return false
default:
return c == ','
}
}
tokens = strings.FieldsFunc(alterStatement, f)
for i := range tokens {
tokens[i] = strings.TrimSpace(tokens[i])
}
return tokens, nil
}
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func (this *Parser) sanitizeQuotesFromAlterStatement(alterStatement string) (strippedStatement string) {
strippedStatement = alterStatement
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strippedStatement = sanitizeQuotesRegexp.ReplaceAllString(strippedStatement, "''")
return strippedStatement
}
func (this *Parser) ParseAlterStatement(alterStatement string) (err error) {
alterTokens, _ := this.tokenizeAlterStatement(alterStatement)
for _, alterToken := range alterTokens {
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alterToken = this.sanitizeQuotesFromAlterStatement(alterToken)
allStringSubmatch := renameColumnRegexp.FindAllStringSubmatch(alterToken, -1)
for _, submatch := range allStringSubmatch {
if unquoted, err := strconv.Unquote(submatch[2]); err == nil {
submatch[2] = unquoted
}
if unquoted, err := strconv.Unquote(submatch[3]); err == nil {
submatch[3] = unquoted
}
this.columnRenameMap[submatch[2]] = submatch[3]
}
}
return nil
}
func (this *Parser) GetNonTrivialRenames() map[string]string {
result := make(map[string]string)
for column, renamed := range this.columnRenameMap {
if column != renamed {
result[column] = renamed
}
}
return result
}
func (this *Parser) HasNonTrivialRenames() bool {
return len(this.GetNonTrivialRenames()) > 0
}