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