github.com/aacfactory/fns@v1.2.86-0.20240310083819-80d667fc0a17/context/operators/filter.go (about)

     1  /*
     2   * Copyright 2023 Wang Min Xiang
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   * 	http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   *
    16   */
    17  
    18  package operators
    19  
    20  import "github.com/aacfactory/fns/context"
    21  
    22  type FilterFn[T any] func(ctx context.Context, element T) (ok bool, err error)
    23  
    24  func Filter[T any](ctx context.Context, elements []T, fn FilterFn[T]) (targets []T, err error) {
    25  	if elements == nil || len(elements) == 0 {
    26  		return
    27  	}
    28  	for _, e := range elements {
    29  		found, findErr := fn(ctx, e)
    30  		if findErr != nil {
    31  			err = findErr
    32  			return
    33  		}
    34  		if found {
    35  			if targets == nil {
    36  				targets = make([]T, 0, 1)
    37  			}
    38  			targets = append(targets, e)
    39  		}
    40  	}
    41  	return
    42  }