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// Copyright 2020 The Xorm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package schemas
import (
"strings"
)
// Quoter represents a quoter to the SQL table name and column name
type Quoter struct {
Prefix byte
Suffix byte
IsReserved func(string) bool
}
var (
// AlwaysFalseReverse always think it's not a reverse word
AlwaysNoReserve = func(string) bool { return false }
// AlwaysReverse always reverse the word
AlwaysReserve = func(string) bool { return true }
// CommanQuoteMark represnets the common quote mark
CommanQuoteMark byte = '`'
// CommonQuoter represetns a common quoter
CommonQuoter = Quoter{CommanQuoteMark, CommanQuoteMark, AlwaysReserve}
)
func (q Quoter) IsEmpty() bool {
return q.Prefix == 0 && q.Suffix == 0
}
func (q Quoter) Quote(s string) string {
var buf strings.Builder
q.QuoteTo(&buf, s)
return buf.String()
}
// Trim removes quotes from s
func (q Quoter) Trim(s string) string {
if len(s) < 2 {
return s
}
var buf strings.Builder
for i := 0; i < len(s); i++ {
switch {
case i == 0 && s[i] == q.Prefix:
case i == len(s)-1 && s[i] == q.Suffix:
case s[i] == q.Suffix && s[i+1] == '.':
case s[i] == q.Prefix && s[i-1] == '.':
default:
buf.WriteByte(s[i])
}
}
return buf.String()
}
func (q Quoter) Join(a []string, sep string) string {
var b strings.Builder
q.JoinWrite(&b, a, sep)
return b.String()
}
func (q Quoter) JoinWrite(b *strings.Builder, a []string, sep string) error {
if len(a) == 0 {
return nil
}
n := len(sep) * (len(a) - 1)
for i := 0; i < len(a); i++ {
n += len(a[i])
}
b.Grow(n)
for i, s := range a {
if i > 0 {
if _, err := b.WriteString(sep); err != nil {
return err
}
}
q.QuoteTo(b, strings.TrimSpace(s))
}
return nil
}
func findWord(v string, start int) int {
for j := start; j < len(v); j++ {
switch v[j] {
case '.', ' ':
return j
}
}
return len(v)
}
func findStart(value string, start int) int {
if value[start] == '.' {
return start + 1
}
if value[start] != ' ' {
return start
}
var k = -1
for j := start; j < len(value); j++ {
if value[j] != ' ' {
k = j
break
}
}
if k == -1 {
return len(value)
}
if (value[k] == 'A' || value[k] == 'a') && (value[k+1] == 'S' || value[k+1] == 's') {
k = k + 2
}
for j := k; j < len(value); j++ {
if value[j] != ' ' {
return j
}
}
return len(value)
}
func (q Quoter) quoteWordTo(buf *strings.Builder, word string) error {
var realWord = word
if (word[0] == CommanQuoteMark && word[len(word)-1] == CommanQuoteMark) ||
(word[0] == q.Prefix && word[len(word)-1] == q.Suffix) {
realWord = word[1 : len(word)-1]
}
if q.IsEmpty() {
_, err := buf.WriteString(realWord)
return err
}
isReserved := q.IsReserved(realWord)
if isReserved && realWord != "*" {
if err := buf.WriteByte(q.Prefix); err != nil {
return err
}
}
if _, err := buf.WriteString(realWord); err != nil {
return err
}
if isReserved && realWord != "*" {
return buf.WriteByte(q.Suffix)
}
return nil
}
// QuoteTo quotes the table or column names. i.e. if the quotes are [ and ]
// name -> [name]
// `name` -> [name]
// [name] -> [name]
// schema.name -> [schema].[name]
// `schema`.`name` -> [schema].[name]
// `schema`.name -> [schema].[name]
// schema.`name` -> [schema].[name]
// [schema].name -> [schema].[name]
// schema.[name] -> [schema].[name]
// name AS a -> [name] AS a
// schema.name AS a -> [schema].[name] AS a
func (q Quoter) QuoteTo(buf *strings.Builder, value string) error {
var i int
for i < len(value) {
start := findStart(value, i)
if start > i {
if _, err := buf.WriteString(value[i:start]); err != nil {
return err
}
}
if start == len(value) {
return nil
}
var nextEnd = findWord(value, start)
if err := q.quoteWordTo(buf, value[start:nextEnd]); err != nil {
return err
}
i = nextEnd
}
return nil
}
// Strings quotes a slice of string
func (q Quoter) Strings(s []string) []string {
var res = make([]string, 0, len(s))
for _, a := range s {
res = append(res, q.Quote(a))
}
return res
}
// Replace replaces common quote(`) as the quotes on the sql
func (q Quoter) Replace(sql string) string {
if q.IsEmpty() {
return sql
}
var buf strings.Builder
buf.Grow(len(sql))
var beginSingleQuote bool
for i := 0; i < len(sql); i++ {
if !beginSingleQuote && sql[i] == CommanQuoteMark {
var j = i + 1
for ; j < len(sql); j++ {
if sql[j] == CommanQuoteMark {
break
}
}
word := sql[i+1 : j]
isReserved := q.IsReserved(word)
if isReserved {
buf.WriteByte(q.Prefix)
}
buf.WriteString(word)
if isReserved {
buf.WriteByte(q.Suffix)
}
i = j
} else {
if sql[i] == '\'' {
beginSingleQuote = !beginSingleQuote
}
buf.WriteByte(sql[i])
}
}
return buf.String()
}