github.com/matrixorigin/matrixone@v0.7.0/pkg/vectorize/left/left.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 left
    16  
    17  func LeftAllConst(src []string, length []int64, rs []string) []string {
    18  	rs[0] = evalLeft(src[0], length[0])
    19  	return rs
    20  }
    21  
    22  func Left(src []string, length []int64, rs []string) []string {
    23  	for i := range src {
    24  		rs[i] = evalLeft(src[i], length[i])
    25  	}
    26  	return rs
    27  }
    28  
    29  func LeftRightConst(src []string, length []int64, rs []string) []string {
    30  	for i := range src {
    31  		rs[i] = evalLeft(src[i], length[0])
    32  	}
    33  	return rs
    34  }
    35  
    36  func LeftLeftConst(src []string, length []int64, rs []string) []string {
    37  	for i := range length {
    38  		rs[i] = evalLeft(src[0], length[i])
    39  	}
    40  	return rs
    41  }
    42  
    43  func evalLeft(str string, length int64) string {
    44  	runeStr := []rune(str)
    45  	leftLength := int(length)
    46  	if strLength := len(runeStr); leftLength > strLength {
    47  		leftLength = strLength
    48  	} else if leftLength < 0 {
    49  		leftLength = 0
    50  	}
    51  	return string(runeStr[:leftLength])
    52  }