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builtin_regexp_util.go
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/
builtin_regexp_util.go
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// Copyright 2023 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 expression
import (
"regexp"
"github.com/pingcap/tidb/pkg/util/chunk"
)
// memorized regexp means the constant pattern.
// Sometimes user may input a constant pattern, and it's unnecessary to compile
// the regexp.Regexp each time.
type regexpMemorizedSig struct {
memorizedRegexp *regexp.Regexp
memorizedErr error
}
func (reg *regexpMemorizedSig) isMemorizedRegexpInitialized() bool {
return !(reg.memorizedRegexp == nil && reg.memorizedErr == nil)
}
func (reg *regexpMemorizedSig) memorize(compile func(string) (*regexp.Regexp, error), pattern string) {
re, err := compile(pattern)
reg.memorizedRegexp = re
reg.memorizedErr = err
}
func releaseBuffers(bf *baseBuiltinFunc, params []*funcParam) {
for _, pa := range params {
if pa.getCol() != nil {
bf.bufAllocator.put(pa.getCol())
}
}
}
func getBuffers(params []*funcParam) []*chunk.Column {
buffers := make([]*chunk.Column, 0, 6)
for _, pa := range params {
if pa.getCol() != nil {
buffers = append(buffers, pa.getCol())
}
}
return buffers
}
func isResultNull(columns []*chunk.Column, i int) bool {
for _, col := range columns {
if col.IsNull(i) {
return true
}
}
return false
}
func fillNullStringIntoResult(result *chunk.Column, num int) {
result.ReserveString(num)
for i := 0; i < num; i++ {
result.AppendNull()
}
}
// check if this is a valid position argument when position is out of range
func checkOutRangePos(strLen int, pos int64) bool {
// false condition:
// 1. non-empty string
// 2. empty string and pos != 1
return strLen != 0 || pos != 1
}