github.com/cockroachdb/cockroachdb-parser@v0.23.3-0.20240213214944-911057d40c9a/pkg/util/iterutil/iterutil.go (about)

     1  // Copyright 2020 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package iterutil
    12  
    13  import "github.com/cockroachdb/errors"
    14  
    15  var errStopIteration = errors.New("stop iteration")
    16  
    17  // StopIteration returns a sentinel error that indicates stopping the iteration.
    18  //
    19  // This error should not be propagated further, i.e., if a closure returns
    20  // this error, the loop should break returning nil error. For example:
    21  //
    22  //	f := func(i int) error {
    23  //		if i == 10 {
    24  //			return iterutil.StopIteration()
    25  //		}
    26  //		return nil
    27  //	}
    28  //
    29  //	for i := range slice {
    30  //		if err := f(i); err != nil {
    31  //			return iterutil.Map(err)
    32  //		}
    33  //		// continue when nil error
    34  //	}
    35  func StopIteration() error { return errStopIteration }
    36  
    37  // Map the nil if it is StopIteration, or keep the error otherwise
    38  func Map(err error) error {
    39  	if errors.Is(err, errStopIteration) {
    40  		return nil
    41  	}
    42  	return err
    43  }