github.com/dolthub/dolt/go@v0.40.5-0.20240520175717-68db7794bea6/store/val/extended_comparator.go (about) 1 // Copyright 2024 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 // ExtendedTupleComparator is a comparator that properly handles extended types. 18 type ExtendedTupleComparator struct { 19 innerCmp TupleComparator 20 handlers []TupleTypeHandler 21 } 22 23 // TODO: compare performance of rolling this logic into the DefaultTupleComparator (nil check or generic handlers that call compare) 24 var _ TupleComparator = ExtendedTupleComparator{} 25 26 // Compare implements the TupleComparator interface. 27 func (c ExtendedTupleComparator) Compare(left, right Tuple, desc TupleDesc) (cmp int) { 28 fast := desc.GetFixedAccess() 29 for i := range fast { 30 start, stop := fast[i][0], fast[i][1] 31 cmp = c.CompareValues(i, left[start:stop], right[start:stop], desc.Types[i]) 32 if cmp != 0 { 33 return cmp 34 } 35 } 36 37 off := len(fast) 38 for i, typ := range desc.Types[off:] { 39 j := i + off 40 cmp = c.CompareValues(j, left.GetField(j), right.GetField(j), typ) 41 if cmp != 0 { 42 return cmp 43 } 44 } 45 return 46 } 47 48 // CompareValues implements the TupleComparator interface. 49 func (c ExtendedTupleComparator) CompareValues(index int, left, right []byte, typ Type) int { 50 switch typ.Enc { 51 case ExtendedEnc, ExtendedAddrEnc: 52 cmp, err := c.handlers[index].SerializedCompare(left, right) 53 if err != nil { 54 panic(err) 55 } 56 return cmp 57 default: 58 return compare(typ, left, right) 59 } 60 } 61 62 // Prefix implements the TupleComparator interface. 63 func (c ExtendedTupleComparator) Prefix(n int) TupleComparator { 64 return ExtendedTupleComparator{c.innerCmp.Prefix(n), c.handlers[:n]} 65 } 66 67 // Suffix implements the TupleComparator interface. 68 func (c ExtendedTupleComparator) Suffix(n int) TupleComparator { 69 return ExtendedTupleComparator{c.innerCmp.Suffix(n), c.handlers[n:]} 70 } 71 72 // Validated implements the TupleComparator interface. 73 func (c ExtendedTupleComparator) Validated(types []Type) TupleComparator { 74 innerCmp := c.innerCmp.Validated(types) 75 if len(c.handlers) == 0 { 76 c.handlers = make([]TupleTypeHandler, len(types)) 77 } else if len(c.handlers) != len(types) { 78 panic("invalid handler count compared to types") 79 } 80 hasHandler := false 81 for i, handler := range c.handlers { 82 switch types[i].Enc { 83 case ExtendedEnc, ExtendedAddrEnc: 84 if handler == nil { 85 panic("extended encoding requires a handler") 86 } else { 87 hasHandler = true 88 } 89 } 90 } 91 if !hasHandler { 92 return innerCmp 93 } 94 return ExtendedTupleComparator{innerCmp, c.handlers} 95 }