wehub-resource-sync
93 lines
2.7 KiB
Go
93 lines
2.7 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 lnress 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 functions
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import (
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"math"
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"strings"
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"github.com/cockroachdb/apd/v3"
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"github.com/cockroachdb/errors"
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"github.com/dolthub/go-mysql-server/sql"
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"github.com/dolthub/doltgresql/server/functions/framework"
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pgtypes "github.com/dolthub/doltgresql/server/types"
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)
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// initLn registers the functions to the catalog.
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func initLn() {
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framework.RegisterFunction(ln_float64)
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framework.RegisterFunction(ln_numeric)
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}
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// ln_float64 represents the PostgreSQL function of the same name, taking the same parameters.
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var ln_float64 = framework.Function1{
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Name: "ln",
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Return: pgtypes.Float64,
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Parameters: [1]*pgtypes.DoltgresType{pgtypes.Float64},
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Strict: true,
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Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val1 any) (any, error) {
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if val1.(float64) == 0 {
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return nil, errors.Errorf("cannot take logarithm of zero")
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} else if val1.(float64) < 0 {
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return nil, errors.Errorf("cannot take logarithm of a negative number")
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}
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return math.Log(val1.(float64)), nil
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},
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}
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// ln_numeric represents the PostgreSQL function of the same name, taking the same parameters.
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var ln_numeric = framework.Function1{
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Name: "ln",
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Return: pgtypes.Numeric,
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Parameters: [1]*pgtypes.DoltgresType{pgtypes.Numeric},
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Strict: true,
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Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val1 any) (any, error) {
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dec := val1.(*apd.Decimal)
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if dec.Sign() == 0 {
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return nil, errors.Errorf("cannot take logarithm of zero")
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} else if dec.Sign() < 0 {
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return nil, errors.Errorf("cannot take logarithm of a negative number")
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} else if dec.Form == apd.NaN || dec.Form == apd.Infinite {
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return dec, nil
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}
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// calculate precision and scale
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exp := dec.Exponent
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p := dec.NumDigits()
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if exp < -16 {
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p += int64(-exp)
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} else {
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p += 16
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}
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res := new(apd.Decimal)
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_, err := sql.DecimalCtx.WithPrecision(uint32(p)).Ln(res, dec)
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if err != nil {
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return nil, err
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}
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// calculate exponent
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if exp > -16 {
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// use ln result
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parts := strings.Split(res.Text('f'), ".")
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whole := int32(len(parts[0]) / 2)
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exp = whole - 16
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}
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return sql.DecimalRound(res, -exp)
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},
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}
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