79 lines
2.1 KiB
Go
79 lines
2.1 KiB
Go
// Mgmt
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// Copyright (C) 2013-2019+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package coremath
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import (
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"fmt"
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"math"
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"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
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"github.com/purpleidea/mgmt/lang/types"
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)
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func init() {
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simplepoly.ModuleRegister(ModuleName, "mod", []*types.FuncValue{
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{
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T: types.NewType("func(int, int) int"),
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V: Mod,
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},
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{
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T: types.NewType("func(float, float) float"),
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V: Mod,
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},
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})
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}
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// Mod returns mod(x, y), the remainder of x/y. The two values must be either
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// both of KindInt or both of KindFloat, and it will return the same kind. If
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// you pass in a divisor of zero, this will error, eg: mod(x, 0) = NaN.
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// TODO: consider returning zero instead of erroring?
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func Mod(input []types.Value) (types.Value, error) {
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var x, y float64
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var float bool
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k := input[0].Type().Kind
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switch k {
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case types.KindFloat:
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float = true
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x = input[0].Float()
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y = input[1].Float()
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case types.KindInt:
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x = float64(input[0].Int())
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y = float64(input[1].Int())
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default:
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return nil, fmt.Errorf("unexpected kind: %s", k)
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}
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z := math.Mod(x, y)
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if math.IsNaN(z) {
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return nil, fmt.Errorf("result is not a number")
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}
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if math.IsInf(z, 1) {
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return nil, fmt.Errorf("unexpected positive infinity")
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}
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if math.IsInf(z, -1) {
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return nil, fmt.Errorf("unexpected negative infinity")
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}
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if float {
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return &types.FloatValue{
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V: z,
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}, nil
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}
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return &types.IntValue{
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V: int64(z), // XXX: does this truncate?
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}, nil
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}
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