github.com/nevalang/neva@v0.23.1-0.20240507185603-7696a9bb8dda/internal/runtime/funcs/int_sub.go (about)

     1  package funcs
     2  
     3  import (
     4  	"context"
     5  
     6  	"github.com/nevalang/neva/internal/runtime"
     7  )
     8  
     9  type intSub struct{}
    10  
    11  func (intSub) Create(io runtime.FuncIO, _ runtime.Msg) (func(ctx context.Context), error) {
    12  	seqIn, err := io.In.Port("seq")
    13  	if err != nil {
    14  		return nil, err
    15  	}
    16  
    17  	resOut, err := io.Out.Port("res")
    18  	if err != nil {
    19  		return nil, err
    20  	}
    21  
    22  	return func(ctx context.Context) {
    23  		var (
    24  			acc     int64 = 0
    25  			started bool  = false
    26  		)
    27  
    28  		for {
    29  			var item map[string]runtime.Msg
    30  			select {
    31  			case <-ctx.Done():
    32  				return
    33  			case msg := <-seqIn:
    34  				item = msg.Map()
    35  			}
    36  
    37  			if !started {
    38  				acc = item["data"].Int()
    39  				started = true
    40  			} else {
    41  				acc -= item["data"].Int()
    42  			}
    43  
    44  			if item["last"].Bool() {
    45  				select {
    46  				case <-ctx.Done():
    47  					return
    48  				case resOut <- runtime.NewIntMsg(acc):
    49  					acc = 0
    50  					started = false
    51  					continue
    52  				}
    53  			}
    54  		}
    55  	}, nil
    56  }