82 lines
2.1 KiB
Go
82 lines
2.1 KiB
Go
// Copyright 2023 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expression
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import (
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"regexp"
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"github.com/pingcap/tidb/pkg/util/chunk"
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)
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// memorized regexp means the constant pattern.
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// Sometimes user may input a constant pattern, and it's unnecessary to compile
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// the regexp.Regexp each time.
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type regexpMemorizedSig struct {
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memorizedRegexp *regexp.Regexp
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memorizedErr error
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}
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func (reg *regexpMemorizedSig) isMemorizedRegexpInitialized() bool {
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return !(reg.memorizedRegexp == nil && reg.memorizedErr == nil)
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}
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func (reg *regexpMemorizedSig) memorize(compile func(string) (*regexp.Regexp, error), pattern string) {
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re, err := compile(pattern)
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reg.memorizedRegexp = re
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reg.memorizedErr = err
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}
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func releaseBuffers(bf *baseBuiltinFunc, params []*funcParam) {
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for _, pa := range params {
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if pa.getCol() != nil {
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bf.bufAllocator.put(pa.getCol())
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}
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}
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}
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func getBuffers(params []*funcParam) []*chunk.Column {
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buffers := make([]*chunk.Column, 0, 6)
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for _, pa := range params {
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if pa.getCol() != nil {
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buffers = append(buffers, pa.getCol())
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}
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}
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return buffers
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}
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func isResultNull(columns []*chunk.Column, i int) bool {
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for _, col := range columns {
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if col.IsNull(i) {
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return true
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}
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}
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return false
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}
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func fillNullStringIntoResult(result *chunk.Column, num int) {
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result.ReserveString(num)
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for i := 0; i < num; i++ {
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result.AppendNull()
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}
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}
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// check if this is a valid position argument when position is out of range
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func checkOutRangePos(strLen int, pos int64) bool {
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// false condition:
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// 1. non-empty string
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// 2. empty string and pos != 1
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return strLen != 0 || pos != 1
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}
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