111 lines
2.3 KiB
Go
111 lines
2.3 KiB
Go
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// Copyright 2020 The Xorm Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package schemas
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import (
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"strings"
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)
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// Quoter represents two quote characters
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type Quoter [2]string
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// CommonQuoter represetns a common quoter
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var CommonQuoter = Quoter{"`", "`"}
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func (q Quoter) IsEmpty() bool {
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return q[0] == "" && q[1] == ""
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}
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func (q Quoter) Quote(s string) string {
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var buf strings.Builder
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q.QuoteTo(&buf, s)
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return buf.String()
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}
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func (q Quoter) ReverseQuote(s string) string {
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reverseQuoter := Quoter{q[1], q[0]}
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return reverseQuoter.Quote(s)
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}
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// Trim removes quotes from s
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func (q Quoter) Trim(s string) string {
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if len(s) < 2 {
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return s
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}
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if s[0:1] == q[0] {
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s = s[1:]
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}
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if len(s) > 0 && s[len(s)-1:] == q[0] {
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return s[:len(s)-1]
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}
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return s
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}
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func (q Quoter) Join(s []string, splitter string) string {
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return q.Quote(strings.Join(s, q.ReverseQuote(splitter)))
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}
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func (q Quoter) QuoteTo(buf *strings.Builder, value string) {
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if q.IsEmpty() {
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buf.WriteString(value)
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return
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}
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prefix, suffix := q[0][0], q[1][0]
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lastCh := 0 // 0 prefix, 1 char, 2 suffix
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i := 0
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for i < len(value) {
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// start of a token; might be already quoted
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if value[i] == '.' {
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_ = buf.WriteByte('.')
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lastCh = 1
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i++
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} else if value[i] == prefix || value[i] == '`' {
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// Has quotes; skip/normalize `name` to prefix+name+sufix
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var ch byte
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if value[i] == prefix {
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ch = suffix
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} else {
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ch = '`'
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}
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_ = buf.WriteByte(prefix)
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i++
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lastCh = 0
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for ; i < len(value) && value[i] != ch && value[i] != ' '; i++ {
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_ = buf.WriteByte(value[i])
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lastCh = 1
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}
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_ = buf.WriteByte(suffix)
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lastCh = 2
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i++
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} else if value[i] == ' ' {
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if lastCh != 2 {
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_ = buf.WriteByte(suffix)
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lastCh = 2
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}
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// a AS b or a b
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for ; i < len(value); i++ {
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if value[i] != ' ' && value[i-1] == ' ' && (len(value) > i+1 && !strings.EqualFold(value[i:i+2], "AS")) {
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break
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}
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_ = buf.WriteByte(value[i])
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lastCh = 1
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}
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} else {
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// Requires quotes
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_ = buf.WriteByte(prefix)
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for ; i < len(value) && value[i] != '.' && value[i] != ' '; i++ {
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_ = buf.WriteByte(value[i])
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lastCh = 1
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}
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_ = buf.WriteByte(suffix)
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lastCh = 2
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}
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}
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}
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