230 lines
7.0 KiB
Go
230 lines
7.0 KiB
Go
package cli
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import (
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"context"
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"database/sql"
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"fmt"
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"strings"
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)
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// 预检必须先于任何恢复语句；不会擅自关闭实例调度器或修改已有事件状态。
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// 管理员仍须维持维护窗口，禁止外部会话在预检后开启调度或修改事件。
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func preflightMySQLEventRestore(ctx context.Context, conn *sql.Conn, statements []string) error {
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active := false
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for _, statement := range statements {
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// 两种字符串转义模式中任一种无法证明安全，就要求停止调度。
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for _, noBackslash := range []bool{false, true} {
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tokens := mysqlEventTokens(statement, noBackslash)
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if len(tokens) > 0 && tokens[0] == "SET" {
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for _, token := range tokens[1:] {
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if token == "EVENT_SCHEDULER" {
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return fmt.Errorf("MySQL 恢复文件不能修改事件调度器，请由管理员在维护窗口单独管理")
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}
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}
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}
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active = active || mysqlStatementMayEnableEvent(tokens)
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}
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}
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tx, err := conn.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
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if err != nil {
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return err
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}
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defer tx.Rollback()
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var version, scheduler string
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if err := tx.QueryRowContext(ctx, "SELECT VERSION(), @@GLOBAL.event_scheduler").Scan(&version, &scheduler); err != nil {
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return fmt.Errorf("读取 MySQL 事件调度状态失败：%w", err)
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}
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grants, err := readMySQLEffectiveGrants(ctx, tx, version)
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if err != nil {
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return err
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}
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process := false
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for _, grant := range grants {
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match := mysqlPrivilegeGrant.FindStringSubmatch(grant)
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if len(match) != 0 && match[1] == "GRANT" && match[3] == "*" && match[4] == "*" && mysqlHasPrivilege(match[2], "PROCESS") {
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process = true
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}
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}
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if !process {
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return fmt.Errorf("MySQL 恢复需要 PROCESS 权限以确认事件工作线程已退出，不能把不可见线程当成没有运行")
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}
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var workers int
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// 事件工作线程以定义者身份运行，不能按 event_scheduler 用户名筛选。
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// Connect 也可能包含正在建立的普通连接；维护窗口内保守拒绝，不冒险误判为空。
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if err := tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM information_schema.PROCESSLIST WHERE COMMAND = 'Connect'").Scan(&workers); err != nil {
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return fmt.Errorf("读取 MySQL 事件工作线程失败：%w", err)
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}
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if workers != 0 {
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return fmt.Errorf("MySQL 仍有事件工作线程运行，请等待其退出后再恢复；不会自动终止事件")
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}
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if strings.EqualFold(scheduler, "ON") {
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if err := requireMySQLEventVisibility(ctx, tx); err != nil {
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return err
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}
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var enabled int
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if err := tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM information_schema.EVENTS WHERE EVENT_SCHEMA = DATABASE() AND STATUS = 'ENABLED'").Scan(&enabled); err != nil {
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return err
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}
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if active || enabled != 0 {
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return fmt.Errorf("MySQL 事件调度器仍为 ON，备份或目标库含启用事件；请管理员在维护窗口停止调度并等待事件工作线程退出后重试")
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}
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}
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return nil
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}
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func mysqlStatementMayEnableEvent(tokens []string) bool {
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_, active := mysqlEventStatement(tokens)
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return active
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}
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func mysqlEventStatement(tokens []string) (bool, bool) {
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if len(tokens) < 2 || (tokens[0] != "CREATE" && tokens[0] != "ALTER") {
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return false, false
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}
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i := 1
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// 只识别语句开头的对象类型，不把例程正文、注释或标识符中的 EVENT 当成事件。
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if tokens[i] == "DEFINER" {
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i += 3 // 跳过 DEFINER、等号及账户名称。
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if i < len(tokens) && tokens[i] == "@" {
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i += 2
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} else if i+1 < len(tokens) && tokens[i] == "(" && tokens[i+1] == ")" {
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i += 2
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}
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}
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if i >= len(tokens) || tokens[i] != "EVENT" {
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return false, false
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}
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i++
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if i+2 < len(tokens) && tokens[i] == "IF" && tokens[i+1] == "NOT" && tokens[i+2] == "EXISTS" {
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i += 3
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}
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// EVENT、ENABLE、DISABLE 等可能作为未引用的名称，不能把名称当成状态。
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i = mysqlSkipEventName(tokens, i)
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disabled, depth := false, 0
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for ; i < len(tokens); i++ {
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token := tokens[i]
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switch token {
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case "(":
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depth++
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case ")":
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depth--
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default:
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if depth != 0 {
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continue
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}
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switch token {
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case "RENAME":
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if i+1 < len(tokens) && tokens[i+1] == "TO" {
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i = mysqlSkipEventName(tokens, i+2) - 1
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}
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case "DO":
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return true, !disabled
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case "DISABLE":
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disabled = true
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case "ENABLE":
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disabled = false
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}
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}
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}
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return true, !disabled
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}
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func checkMySQLEventRestoreWarnings(ctx context.Context, conn *sql.Conn, statement string) error {
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event, active := mysqlEventStatement(mysqlEventTokens(statement, false))
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otherEvent, otherActive := mysqlEventStatement(mysqlEventTokens(statement, true))
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if !event && !otherEvent {
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return nil
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}
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rows, err := conn.QueryContext(ctx, "SHOW WARNINGS")
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if err != nil {
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return fmt.Errorf("读取 MySQL 事件恢复警告失败：%w", err)
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}
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defer rows.Close()
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for rows.Next() {
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var level, message string
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var code int
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if err := rows.Scan(&level, &code, &message); err != nil {
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return err
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}
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// 到期自动删除、拒绝修改或改变启停状态，不能算作成功恢复。
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if code == 1588 || code == 1589 || code == 1605 || (code == 1544 && (active || otherActive)) {
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return fmt.Errorf("MySQL 事件恢复未保留原定义或状态（警告 %d）：%s", code, message)
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}
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}
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return rows.Err()
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}
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func mysqlSkipEventName(tokens []string, start int) int {
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if start >= len(tokens) {
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return start
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}
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start++
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if start+1 < len(tokens) && tokens[start] == "." {
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start += 2
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}
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return start
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}
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// 只用于调度预检，不执行或改写 SQL。版本化可执行注释按可能执行处理。
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func mysqlEventTokens(statement string, noBackslash bool) []string {
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var tokens []string
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for i := 0; i < len(statement); {
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c := statement[i]
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if c <= ' ' {
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i++
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continue
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}
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if c == '#' || (c == '-' && i+2 < len(statement) && statement[i+1] == '-' && statement[i+2] <= ' ') {
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for i < len(statement) && statement[i] != '\n' {
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i++
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}
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continue
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}
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if c == '/' && i+1 < len(statement) && statement[i+1] == '*' {
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end := strings.Index(statement[i+2:], "*/")
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if end < 0 {
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return append(tokens, "?")
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}
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end += i + 2
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if i+2 < end && statement[i+2] == '!' {
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start := i + 3
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for start < end && statement[start] >= '0' && statement[start] <= '9' {
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start++
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}
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tokens = append(tokens, mysqlEventTokens(statement[start:end], noBackslash)...)
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}
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i = end + 2
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continue
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}
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if c == '\'' || c == '"' || c == '`' {
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i++
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for i < len(statement) {
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if statement[i] == '\\' && c != '`' && !noBackslash {
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i += 2
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continue
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}
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if statement[i] == c {
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i++
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if i < len(statement) && statement[i] == c {
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i++
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continue
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}
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break
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}
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i++
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}
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tokens = append(tokens, "?")
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continue
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}
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start := i
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for i < len(statement) && ((statement[i] >= 'a' && statement[i] <= 'z') || (statement[i] >= 'A' && statement[i] <= 'Z') || (statement[i] >= '0' && statement[i] <= '9') || statement[i] == '_' || statement[i] >= 128) {
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i++
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}
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if i == start {
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i++
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}
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tokens = append(tokens, strings.ToUpper(statement[start:i]))
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}
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return tokens
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}
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