manual.go

Documentation: cuelang.org/go/pkg/text/tabwriter

     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 tabwriter
    16  
    17  import (
    18  	"fmt"
    19  	"strings"
    20  	"text/tabwriter"
    21  
    22  	"cuelang.org/go/cue"
    23  )
    24  
    25  // Write formats text in columns. See golang.org/pkg/text/tabwriter for more
    26  // info.
    27  func Write(data cue.Value) (string, error) {
    28  	var b strings.Builder
    29  	tw := tabwriter.NewWriter(&b, 0, 4, 1, ' ', 0)
    30  
    31  	write := func(v cue.Value) error {
    32  		b, err := v.Bytes()
    33  		if err != nil {
    34  			return err
    35  		}
    36  		_, err = tw.Write(b)
    37  		if err != nil {
    38  			return err
    39  		}
    40  		return nil
    41  	}
    42  
    43  	switch data.Kind() {
    44  	case cue.BytesKind, cue.StringKind:
    45  		if err := write(data); err != nil {
    46  			return "", err
    47  		}
    48  	case cue.ListKind:
    49  		for i, _ := data.List(); i.Next(); {
    50  			if err := write(i.Value()); err != nil {
    51  				return "", err
    52  			}
    53  			_, _ = tw.Write([]byte{'\n'})
    54  		}
    55  	default:
    56  		return "", fmt.Errorf("tabwriter.Write: unsupported type %v", data.Kind())
    57  	}
    58  
    59  	err := tw.Flush()
    60  	return b.String(), err
    61  }
    62
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