math.go

Documentation: cuelang.org/go/pkg/list

     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  
    15  package list
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/cockroachdb/apd/v3"
    21  
    22  	"cuelang.org/go/internal"
    23  )
    24  
    25  // Avg returns the average value of a non empty list xs.
    26  func 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.
    49  func 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.
    64  func 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.
    79  func 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  func Range(start, limit, step *internal.Decimal) ([]*internal.Decimal, error) {
   101  	if step.IsZero() {
   102  		return nil, fmt.Errorf("step must be non zero")
   103  	}
   104  
   105  	if !step.Negative && +1 == start.Cmp(limit) {
   106  		return nil, fmt.Errorf("end must be greater than start when step is positive")
   107  	}
   108  
   109  	if step.Negative && -1 == start.Cmp(limit) {
   110  		return nil, fmt.Errorf("end must be less than start when step is negative")
   111  	}
   112  
   113  	var vals []*internal.Decimal
   114  	num := start
   115  	for {
   116  		if !step.Negative && -1 != num.Cmp(limit) {
   117  			break
   118  		}
   119  
   120  		if step.Negative && +1 != num.Cmp(limit) {
   121  			break
   122  		}
   123  
   124  		vals = append(vals, num)
   125  		d := apd.New(0, 0)
   126  		_, err := internal.BaseContext.Add(d, step, num)
   127  		if err != nil {
   128  			return nil, err
   129  		}
   130  		num = d
   131  	}
   132  	return vals, nil
   133  }
   134  
   135  // Sum returns the sum of a list non empty xs.
   136  func Sum(xs []*internal.Decimal) (*internal.Decimal, error) {
   137  	d := apd.New(0, 0)
   138  	for _, x := range xs {
   139  		_, err := internal.BaseContext.Add(d, x, d)
   140  		if err != nil {
   141  			return nil, err
   142  		}
   143  	}
   144  	return d, nil
   145  }
   146
View as plain text