1// Copyright 2018 The CUE Authors 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 15package list 16 17import ( 18 "fmt" 19 20 "github.com/cockroachdb/apd/v2" 21 22 "cuelang.org/go/internal" 23) 24 25// Avg returns the average value of a non empty list xs. 26func Avg(xs []*internal.Decimal) (*internal.Decimal, error) { 27 if 0 == len(xs) { 28 return nil, fmt.Errorf("empty list") 29 } 30 31 s := apd.New(0, 0) 32 for _, x := range xs { 33 _, err := internal.BaseContext.Add(s, x, s) 34 if err != nil { 35 return nil, err 36 } 37 } 38 39 var d apd.Decimal 40 l := apd.New(int64(len(xs)), 0) 41 _, err := internal.BaseContext.Quo(&d, s, l) 42 if err != nil { 43 return nil, err 44 } 45 return &d, nil 46} 47 48// Max returns the maximum value of a non empty list xs. 49func Max(xs []*internal.Decimal) (*internal.Decimal, error) { 50 if 0 == len(xs) { 51 return nil, fmt.Errorf("empty list") 52 } 53 54 max := xs[0] 55 for _, x := range xs[1:] { 56 if -1 == max.Cmp(x) { 57 max = x 58 } 59 } 60 return max, nil 61} 62 63// Min returns the minimum value of a non empty list xs. 64func Min(xs []*internal.Decimal) (*internal.Decimal, error) { 65 if 0 == len(xs) { 66 return nil, fmt.Errorf("empty list") 67 } 68 69 min := xs[0] 70 for _, x := range xs[1:] { 71 if +1 == min.Cmp(x) { 72 min = x 73 } 74 } 75 return min, nil 76} 77 78// Product returns the product of a non empty list xs. 79func Product(xs []*internal.Decimal) (*internal.Decimal, error) { 80 d := apd.New(1, 0) 81 for _, x := range xs { 82 _, err := internal.BaseContext.Mul(d, x, d) 83 if err != nil { 84 return nil, err 85 } 86 } 87 return d, nil 88} 89 90// Range generates a list of numbers using a start value, a limit value, and a 91// step value. 92// 93// For instance: 94// 95// Range(0, 5, 2) 96// 97// results in 98// 99// [0, 2, 4] 100// 101func Range(start, limit, step *internal.Decimal) ([]*internal.Decimal, error) { 102 if step.IsZero() { 103 return nil, fmt.Errorf("step must be non zero") 104 } 105 106 if !step.Negative && +1 == start.Cmp(limit) { 107 return nil, fmt.Errorf("end must be greater than start when step is positive") 108 } 109 110 if step.Negative && -1 == start.Cmp(limit) { 111 return nil, fmt.Errorf("end must be less than start when step is negative") 112 } 113 114 var vals []*internal.Decimal 115 num := start 116 for { 117 if !step.Negative && -1 != num.Cmp(limit) { 118 break 119 } 120 121 if step.Negative && +1 != num.Cmp(limit) { 122 break 123 } 124 125 vals = append(vals, num) 126 d := apd.New(0, 0) 127 _, err := internal.BaseContext.Add(d, step, num) 128 if err != nil { 129 return nil, err 130 } 131 num = d 132 } 133 return vals, nil 134} 135 136// Sum returns the sum of a list non empty xs. 137func Sum(xs []*internal.Decimal) (*internal.Decimal, error) { 138 d := apd.New(0, 0) 139 for _, x := range xs { 140 _, err := internal.BaseContext.Add(d, x, d) 141 if err != nil { 142 return nil, err 143 } 144 } 145 return d, nil 146} 147