tidb column_filter 源码
tidb column_filter 代码
文件路径：/util/table-filter/column_filter.go
// Copyright 2022 PingCAP, 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 filter
import "strings"
// ColumnFilter is a structure to check if a column should be included for processing.
type ColumnFilter interface {
// MatchColumn checks if a column can be processed after applying the columnFilter.
MatchColumn(column string) bool
}
// columnFilter is a concrete implementation of ColumnFilter.
type columnFilter []columnRule
// ParseColumnFilter a columnFilter from a list of serialized columnFilter rules.
// Column is not case-sensitive on any platform, nor are column aliases.
// So the parsed columnFilter is case-insensitive.
func ParseColumnFilter(args []string) (ColumnFilter, error) {
p := columnRulesParser{
make([]columnRule, 0, len(args)),
matcherParser{
fileName: "<cmdline>",
lineNum: 1,
},
}
for _, arg := range args {
if err := p.parse(arg, true); err != nil {
return nil, err
}
}
reverse(p.rules)
return columnFilter(p.rules), nil
}
// MatchColumn checks if a column can be processed after applying the columnFilter `f`.
// Column is not case-sensitive on any platform, nor are column aliases.
// So we always match in lowercase.
// See also: https://dev.mysql.com/doc/refman/5.7/en/identifier-case-sensitivity.html
func (f columnFilter) MatchColumn(column string) bool {
lowercaseColumn := strings.ToLower(column)
for _, rule := range f {
if rule.column.matchString(lowercaseColumn) {
return rule.positive
}
}
return false
}
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