revid.go

Documentation: github.com/go-kivik/kivik/v4/x/fsdb/cdb

     1  // Licensed under the Apache License, Version 2.0 (the "License"); you may not
     2  // use this file except in compliance with the License. You may obtain a copy of
     3  // the License at
     4  //
     5  //  http://www.apache.org/licenses/LICENSE-2.0
     6  //
     7  // Unless required by applicable law or agreed to in writing, software
     8  // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
     9  // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    10  // License for the specific language governing permissions and limitations under
    11  // the License.
    12  
    13  package cdb
    14  
    15  import (
    16  	"bytes"
    17  	"encoding/json"
    18  	"fmt"
    19  	"strconv"
    20  	"strings"
    21  )
    22  
    23  // RevID is a CouchDB document revision identifier.
    24  type RevID struct {
    25  	Seq      int64
    26  	Sum      string
    27  	original string
    28  }
    29  
    30  // Changed returns true if the rev has changed since being read.
    31  func (r *RevID) Changed() bool {
    32  	return r.String() != r.original
    33  }
    34  
    35  // UnmarshalText satisfies the json.Unmarshaler interface.
    36  func (r *RevID) UnmarshalText(p []byte) error {
    37  	r.original = string(p)
    38  	if bytes.Contains(p, []byte("-")) {
    39  		const maxParts = 2
    40  		parts := bytes.SplitN(p, []byte("-"), maxParts)
    41  		seq, err := strconv.ParseInt(string(parts[0]), 10, 64)
    42  		if err != nil {
    43  			return err
    44  		}
    45  		r.Seq = seq
    46  		if len(parts) > 1 {
    47  			r.Sum = string(parts[1])
    48  		}
    49  		return nil
    50  	}
    51  	r.Sum = ""
    52  	seq, err := strconv.ParseInt(string(p), 10, 64)
    53  	if err != nil {
    54  		return err
    55  	}
    56  	r.Seq = seq
    57  	return nil
    58  }
    59  
    60  // UnmarshalJSON satisfies the json.Unmarshaler interface.
    61  func (r *RevID) UnmarshalJSON(p []byte) error {
    62  	if p[0] == '"' {
    63  		var str string
    64  		if e := json.Unmarshal(p, &str); e != nil {
    65  			return e
    66  		}
    67  		r.original = str
    68  		const maxParts = 2
    69  		parts := strings.SplitN(str, "-", maxParts)
    70  		seq, err := strconv.ParseInt(parts[0], 10, 64)
    71  		if err != nil {
    72  			return err
    73  		}
    74  		r.Seq = seq
    75  		if len(parts) > 1 {
    76  			r.Sum = parts[1]
    77  		}
    78  		return nil
    79  	}
    80  	r.original = string(p)
    81  	r.Sum = ""
    82  	return json.Unmarshal(p, &r.Seq)
    83  }
    84  
    85  // MarshalText satisfies the encoding.TextMarshaler interface.
    86  func (r RevID) MarshalText() ([]byte, error) {
    87  	return []byte(r.String()), nil
    88  }
    89  
    90  func (r RevID) String() string {
    91  	if r.Seq == 0 {
    92  		return ""
    93  	}
    94  	return fmt.Sprintf("%d-%s", r.Seq, r.Sum)
    95  }
    96  
    97  // IsZero returns true if r is uninitialized.
    98  func (r *RevID) IsZero() bool {
    99  	return r.Seq == 0
   100  }
   101  
   102  // Equal returns true if rev and revid are equal.
   103  func (r RevID) Equal(revid RevID) bool {
   104  	return r.Seq == revid.Seq && r.Sum == revid.Sum
   105  }
   106
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