github.com/dolthub/dolt/go@v0.40.5-0.20240520175717-68db7794bea6/store/val/triple.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 val
    16  
    17  import "github.com/dolthub/dolt/go/store/pool"
    18  
    19  const (
    20  	tripleOffSz = int(uint16Size + uint16Size)
    21  )
    22  
    23  func NewTriple[V ~[]byte](pool pool.BuffPool, one, two, three V) (tri Triple[V]) {
    24  	o1 := len(one)
    25  	o2 := len(two) + o1
    26  	end := len(three) + o2
    27  	tri = pool.Get(uint64(end + tripleOffSz))
    28  
    29  	// populate fields
    30  	copy(tri, one)
    31  	copy(tri[o1:], two)
    32  	copy(tri[o2:], three)
    33  
    34  	// populate offsets
    35  	WriteUint16(tri[end:end+2], uint16(o1))
    36  	WriteUint16(tri[end+2:], uint16(o2))
    37  	return
    38  }
    39  
    40  type Triple[V ~[]byte] []byte
    41  
    42  func (t Triple[V]) First() V {
    43  	l := len(t)
    44  	o1 := ReadUint16(t[l-4 : l-2])
    45  	return V(t[:o1])
    46  }
    47  
    48  func (t Triple[V]) Second() V {
    49  	l := len(t)
    50  	o1 := ReadUint16(t[l-4 : l-2])
    51  	o2 := ReadUint16(t[l-2 : l])
    52  	return V(t[o1:o2])
    53  }
    54  
    55  func (t Triple[V]) Third() V {
    56  	l := len(t)
    57  	o2 := ReadUint16(t[l-2 : l])
    58  	return V(t[o2 : l-4])
    59  }