95 lines
3.2 KiB
Go
95 lines
3.2 KiB
Go
// Copyright 2024 Dolthub, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package types
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import (
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"encoding/binary"
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"math"
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"github.com/dolthub/go-mysql-server/sql"
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"github.com/dolthub/doltgresql/core/id"
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)
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// Float64 is a float64.
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var Float64 = &DoltgresType{
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ID: toInternal("float8"),
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TypLength: int16(8),
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PassedByVal: true,
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TypType: TypeType_Base,
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TypCategory: TypeCategory_NumericTypes,
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IsPreferred: true,
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IsDefined: true,
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Delimiter: ",",
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RelID: id.Null,
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SubscriptFunc: toFuncID("-"),
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Elem: internalNullType,
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Array: internalNullType,
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InputFunc: toFuncID("float8in", toInternal("cstring")),
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OutputFunc: toFuncID("float8out", toInternal("float8")),
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ReceiveFunc: toFuncID("float8recv", toInternal("internal")),
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SendFunc: toFuncID("float8send", toInternal("float8")),
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ModInFunc: toFuncID("-"),
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ModOutFunc: toFuncID("-"),
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AnalyzeFunc: toFuncID("-"),
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Align: TypeAlignment_Double,
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Storage: TypeStorage_Plain,
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NotNull: false,
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BaseTypeType: internalNullType,
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TypMod: -1,
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NDims: 0,
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TypCollation: id.NullCollation,
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DefaulBin: "",
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Default: "",
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Acl: nil,
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Checks: nil,
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attTypMod: -1,
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CompareFunc: toFuncID("btfloat8cmp", toInternal("float8"), toInternal("float8")),
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InternalName: "double precision",
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SerializationFunc: serializeTypeFloat64,
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DeserializationFunc: deserializeTypeFloat64,
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}
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// serializeTypeFloat64 handles serialization from the standard representation to our serialized representation that is
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// written in Dolt.
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func serializeTypeFloat64(ctx *sql.Context, t *DoltgresType, val any) ([]byte, error) {
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f64 := val.(float64)
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retVal := make([]byte, 8)
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// Make the serialized form trivially comparable using bytes.Compare: https://stackoverflow.com/a/54557561
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unsignedBits := math.Float64bits(f64)
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if f64 >= 0 {
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unsignedBits ^= 1 << 63
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} else {
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unsignedBits = ^unsignedBits
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}
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binary.BigEndian.PutUint64(retVal, unsignedBits)
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return retVal, nil
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}
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// deserializeTypeFloat64 handles deserialization from the Dolt serialized format to our standard representation used by
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// expressions and nodes.
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func deserializeTypeFloat64(ctx *sql.Context, t *DoltgresType, data []byte) (any, error) {
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if len(data) == 0 {
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return nil, nil
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}
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unsignedBits := binary.BigEndian.Uint64(data)
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if unsignedBits&(1<<63) != 0 {
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unsignedBits ^= 1 << 63
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} else {
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unsignedBits = ^unsignedBits
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}
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return math.Float64frombits(unsignedBits), nil
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}
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