github.com/matrixorigin/matrixone@v0.7.0/pkg/sql/plan/function/builtin/unary/reverse.go (about)

     1  // Copyright 2022 Matrix Origin
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package unary
    16  
    17  import (
    18  	"github.com/matrixorigin/matrixone/pkg/container/types"
    19  	"github.com/matrixorigin/matrixone/pkg/container/vector"
    20  	"github.com/matrixorigin/matrixone/pkg/vectorize/reverse"
    21  	"github.com/matrixorigin/matrixone/pkg/vm/process"
    22  )
    23  
    24  func Reverse(vectors []*vector.Vector, proc *process.Process) (*vector.Vector, error) {
    25  	inputVector := vectors[0]
    26  	resultType := types.T_varchar.ToType()
    27  	inputValues := vector.MustStrCols(inputVector)
    28  	if inputVector.IsScalar() {
    29  		if inputVector.ConstVectorIsNull() {
    30  			return proc.AllocScalarNullVector(resultType), nil
    31  		}
    32  		resultValues := make([]string, 1)
    33  		reverse.Reverse(inputValues, resultValues)
    34  		return vector.NewConstString(resultType, inputVector.Length(), resultValues[0], proc.Mp()), nil
    35  	} else {
    36  		resultValues := make([]string, len(inputValues))
    37  		reverse.Reverse(inputValues, resultValues)
    38  		return vector.NewWithStrings(resultType, resultValues, inputVector.Nsp, proc.Mp()), nil
    39  	}
    40  }