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Copyright 2017 Google 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,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
package sqlparser
	// DirectiveMultiShardAutocommit is the query comment directive to allow
	// single round trip autocommit with a multi-shard statement.
	DirectiveMultiShardAutocommit = "MULTI_SHARD_AUTOCOMMIT"
	// DirectiveSkipQueryPlanCache skips query plan cache when set.
	DirectiveSkipQueryPlanCache = "SKIP_QUERY_PLAN_CACHE"
	// DirectiveQueryTimeout sets a query timeout in vtgate. Only supported for SELECTS.
	DirectiveQueryTimeout = "QUERY_TIMEOUT_MS"
func isNonSpace(r rune) bool {
	return !unicode.IsSpace(r)
// leadingCommentEnd returns the first index after all leading comments, or
// 0 if there are no leading comments.
func leadingCommentEnd(text string) (end int) {
	hasComment := false
	for pos < len(text) {
		// Eat up any whitespace. Trailing whitespace will be considered part of
		// the leading comments.
		nextVisibleOffset := strings.IndexFunc(text[pos:], isNonSpace)
		if nextVisibleOffset < 0 {
		pos += nextVisibleOffset
		remainingText := text[pos:]
		// Found visible characters. Look for '/*' at the beginning
		// and '*/' somewhere after that.
		if len(remainingText) < 4 || remainingText[:2] != "/*" {
		commentLength := 4 + strings.Index(remainingText[2:], "*/")
		if commentLength < 4 {
			// Missing end comment :/
		hasComment = true
		pos += commentLength
	if hasComment {
		return pos
// trailingCommentStart returns the first index of trailing comments.
// If there are no trailing comments, returns the length of the input string.
func trailingCommentStart(text string) (start int) {
	hasComment := false
	reducedLen := len(text)
	for reducedLen > 0 {
		// Eat up any whitespace. Leading whitespace will be considered part of
		// the trailing comments.
		nextReducedLen := strings.LastIndexFunc(text[:reducedLen], isNonSpace) + 1
		if nextReducedLen == 0 {
		reducedLen = nextReducedLen
		if reducedLen < 4 || text[reducedLen-2:reducedLen] != "*/" {
		// Find the beginning of the comment
		startCommentPos := strings.LastIndex(text[:reducedLen-2], "/*")
		if startCommentPos < 0 {
			// Badly formatted sql :/
		hasComment = true
		reducedLen = startCommentPos
	if hasComment {
		return reducedLen
	return len(text)
// MarginComments holds the leading and trailing comments that surround a query.
type MarginComments struct {
	Leading  string
	Trailing string
// SplitMarginComments pulls out any leading or trailing comments from a raw sql query.
// This function also trims leading (if there's a comment) and trailing whitespace.
func SplitMarginComments(sql string) (query string, comments MarginComments) {
	trailingStart := trailingCommentStart(sql)
	leadingEnd := leadingCommentEnd(sql[:trailingStart])
	comments = MarginComments{
		Leading:  strings.TrimLeftFunc(sql[:leadingEnd], unicode.IsSpace),
		Trailing: strings.TrimRightFunc(sql[trailingStart:], unicode.IsSpace),
	return strings.TrimFunc(sql[leadingEnd:trailingStart], unicode.IsSpace), comments
// StripLeadingComments trims the SQL string and removes any leading comments
func StripLeadingComments(sql string) string {
	sql = strings.TrimFunc(sql, unicode.IsSpace)
	for hasCommentPrefix(sql) {
		switch sql[0] {
		case '/':
			// Multi line comment
			index := strings.Index(sql, "*/")
			if index <= 1 {
				return sql
			// don't strip /*! ... */ or /*!50700 ... */
			if len(sql) > 2 && sql[2] == '!' {
				return sql
			sql = sql[index+2:]
		case '-':
			// Single line comment
			index := strings.Index(sql, "\n")
			if index == -1 {
				return sql
			sql = sql[index+1:]
		sql = strings.TrimFunc(sql, unicode.IsSpace)
	return sql
func hasCommentPrefix(sql string) bool {
	return len(sql) > 1 && ((sql[0] == '/' && sql[1] == '*') || (sql[0] == '-' && sql[1] == '-'))
// ExtractMysqlComment extracts the version and SQL from a comment-only query
// such as /*!50708 sql here */
func ExtractMysqlComment(sql string) (version string, innerSQL string) {
	sql = sql[3 : len(sql)-2]
	digitCount := 0
	endOfVersionIndex := strings.IndexFunc(sql, func(c rune) bool {
		digitCount++
		return !unicode.IsDigit(c) || digitCount == 6
	version = sql[0:endOfVersionIndex]
	innerSQL = strings.TrimFunc(sql[endOfVersionIndex:], unicode.IsSpace)
	return version, innerSQL
const commentDirectivePreamble = "/*vt+"
// CommentDirectives is the parsed representation for execution directives
// conveyed in query comments
type CommentDirectives map[string]interface{}
// ExtractCommentDirectives parses the comment list for any execution directives
// of the form:
//     /*vt+ OPTION_ONE=1 OPTION_TWO OPTION_THREE=abcd */
// It returns the map of the directive values or nil if there aren't any.
func ExtractCommentDirectives(comments Comments) CommentDirectives {
	if comments == nil {
		return nil
	var vals map[string]interface{}
	for _, comment := range comments {
		commentStr := string(comment)
		if commentStr[0:5] != commentDirectivePreamble {
			continue
		if vals == nil {
			vals = make(map[string]interface{})
		// Split on whitespace and ignore the first and last directive
		// since they contain the comment start/end
		directives := strings.Fields(commentStr)
		for i := 1; i < len(directives)-1; i++ {
			directive := directives[i]
			sep := strings.IndexByte(directive, '=')
			// No value is equivalent to a true boolean
			if sep == -1 {
				vals[directive] = true
				continue
			strVal := directive[sep+1:]
			directive = directive[:sep]
			intVal, err := strconv.Atoi(strVal)
			if err == nil {
				vals[directive] = intVal
				continue
			boolVal, err := strconv.ParseBool(strVal)
			if err == nil {
				vals[directive] = boolVal
				continue
			vals[directive] = strVal
	return vals
// IsSet checks the directive map for the named directive and returns
// true if the directive is set and has a true/false or 0/1 value
func (d CommentDirectives) IsSet(key string) bool {
	if d == nil {
		return false
	val, ok := d[key]
		return false
	boolVal, ok := val.(bool)
		return boolVal
	intVal, ok := val.(int)
		return intVal == 1
	return false
// SkipQueryPlanCacheDirective returns true if skip query plan cache directive is set to true in query.
func SkipQueryPlanCacheDirective(stmt Statement) bool {
	switch stmt := stmt.(type) {
	case *Select:
		directives := ExtractCommentDirectives(stmt.Comments)
		if directives.IsSet(DirectiveSkipQueryPlanCache) {
			return true
	case *Insert:
		directives := ExtractCommentDirectives(stmt.Comments)
		if directives.IsSet(DirectiveSkipQueryPlanCache) {
			return true
	case *Update:
		directives := ExtractCommentDirectives(stmt.Comments)
		if directives.IsSet(DirectiveSkipQueryPlanCache) {
			return true
	case *Delete:
		directives := ExtractCommentDirectives(stmt.Comments)
		if directives.IsSet(DirectiveSkipQueryPlanCache) {
			return true
		return false
	return false
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