github.com/dolthub/go-mysql-server@v0.18.0/sql/encodings/utf16_bin.go (about)

     1  // Copyright 2022 Dolthub, Inc.
     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 encodings
    16  
    17  // Utf16_bin_RuneWeight returns the weight of a given rune based on its relational sort order from
    18  // the `utf16_bin` collation.
    19  func Utf16_bin_RuneWeight(r rune) int32 {
    20  	weight, ok := utf16_bin_Weights[r]
    21  	if ok {
    22  		return weight
    23  	} else if r >= 0 && r <= 55295 {
    24  		return r + 0
    25  	} else if r >= 57345 && r <= 1114111 {
    26  		return r - 2048
    27  	} else {
    28  		return 2147483647
    29  	}
    30  }
    31  
    32  // utf16_bin_Weights contain a map from rune to weight for the `utf16_bin` collation. The
    33  // map primarily contains mappings that have a random order. Mappings that fit into a sequential range (and are long
    34  // enough) are defined in the calling function to save space.
    35  var utf16_bin_Weights = map[rune]int32{
    36  	57344: 55296,
    37  }