github.com/MontFerret/ferret@v0.18.0/pkg/stdlib/arrays/unshift.go (about)

     1  package arrays
     2  
     3  import (
     4  	"context"
     5  
     6  	"github.com/MontFerret/ferret/pkg/runtime/core"
     7  	"github.com/MontFerret/ferret/pkg/runtime/values"
     8  	"github.com/MontFerret/ferret/pkg/runtime/values/types"
     9  )
    10  
    11  // UNSHIFT prepends value to a given array.
    12  // @param {Any[]} array - Target array.
    13  // @param {Any} value - Target value to prepend.
    14  // @param {Boolean} [unique=False] - Optional value indicating whether a value must be unique to be prepended. Default is false.
    15  // @return {Any[]} - New array with prepended value.
    16  func Unshift(_ context.Context, args ...core.Value) (core.Value, error) {
    17  	err := core.ValidateArgs(args, 2, 3)
    18  
    19  	if err != nil {
    20  		return values.None, err
    21  	}
    22  
    23  	err = core.ValidateType(args[0], types.Array)
    24  
    25  	if err != nil {
    26  		return values.None, err
    27  	}
    28  
    29  	arr := args[0].(*values.Array)
    30  	value := args[1]
    31  	uniq := values.False
    32  
    33  	if len(args) > 2 {
    34  		err = core.ValidateType(args[2], types.Boolean)
    35  
    36  		if err != nil {
    37  			return values.None, err
    38  		}
    39  
    40  		uniq = args[2].(values.Boolean)
    41  	}
    42  
    43  	result := values.NewArray(int(arr.Length() + 1))
    44  
    45  	if !uniq {
    46  		result.Push(value)
    47  
    48  		arr.ForEach(func(el core.Value, _ int) bool {
    49  			result.Push(el)
    50  
    51  			return true
    52  		})
    53  	} else {
    54  		ok := true
    55  
    56  		// let's just hope it's unique
    57  		// if not, we will terminate the loop and return a copy of an array
    58  		result.Push(value)
    59  
    60  		arr.ForEach(func(el core.Value, idx int) bool {
    61  			if el.Compare(value) != 0 {
    62  				result.Push(el)
    63  
    64  				return true
    65  			}
    66  
    67  			// not unique
    68  			ok = false
    69  			return false
    70  		})
    71  
    72  		if !ok {
    73  			// value is not unique, just return a new copy with same elements
    74  			return arr.Copy(), nil
    75  		}
    76  	}
    77  
    78  	return result, nil
    79  }