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uniform.go
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uniform.go
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/*
* Copyright (c) 2018 XLAB d.o.o
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package sample
import (
"crypto/rand"
"math/big"
)
// UniformRange samples random values from the interval [min, max).
type UniformRange struct {
min *big.Int
max *big.Int
}
// NewUniformRange returns an instance of the UniformRange sampler.
// It accepts lower and upper bounds on the sampled values.
func NewUniformRange(min, max *big.Int) *UniformRange {
return &UniformRange{
min: min,
max: max,
}
}
// Sample samples random values from the interval [min, max).
func (u *UniformRange) Sample() (*big.Int, error) {
maxMinusMin := new(big.Int).Sub(u.max, u.min)
res, err := rand.Int(rand.Reader, maxMinusMin)
if err != nil {
return nil, err
}
res.Add(res, u.min)
return res, err
}
// Uniform samples random values from the interval [0, max).
type Uniform struct {
UniformRange
}
// NewUniform returns an instance of the Uniform sampler.
// It accepts an upper bound on the sampled values.
func NewUniform(max *big.Int) *UniformRange {
return NewUniformRange(big.NewInt(0), max)
}
// Sample samples random values from the interval [0, max).
func (u *Uniform) Sample() (*big.Int, error) {
return rand.Int(rand.Reader, u.max)
}
// Bit samples a single random bit (value 0 or 1).
type Bit struct {
Uniform
}
// NewBit returns an instance of Bit sampler.
func NewBit() *UniformRange {
return NewUniform(big.NewInt(2))
}