github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/store/datas/workingset.go (about)

     1  // Copyright 2021 Dolthub, Inc.
     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 datas
    16  
    17  import (
    18  	"context"
    19  
    20  	"github.com/dolthub/dolt/go/store/nomdl"
    21  	"github.com/dolthub/dolt/go/store/types"
    22  )
    23  
    24  const (
    25  	WorkspaceMetaField = "meta"
    26  	WorkingSetRefField = "ref"
    27  	WorkingSetName     = "WorkingSet"
    28  )
    29  
    30  type WorkingSetMeta struct {
    31  	Meta types.Struct
    32  }
    33  
    34  var workingSetTemplate = types.MakeStructTemplate(WorkingSetName, []string{WorkingSetRefField})
    35  
    36  // ref is a Ref<Value>, any Value
    37  var valueWorkingSetType = nomdl.MustParseType(`Struct WorkingSet {
    38          ref:  Ref<Value>,
    39  }`)
    40  
    41  // NewWorkingSet creates a new working set object.
    42  // A working set is a value that has been persisted but is not necessarily referenced by a Commit. As the name implies,
    43  // it's storage for data changes that have not yet been incorporated into the commit graph but need durable storage.
    44  //
    45  // A working set struct has the following type:
    46  //
    47  // ```
    48  // struct WorkingSet {
    49  //   meta: M,
    50  //   ref: R,
    51  // }
    52  // ```
    53  // where M is a struct type and R is a ref type.
    54  func NewWorkingSet(_ context.Context, valueRef types.Ref) (types.Struct, error) {
    55  	return workingSetTemplate.NewStruct(valueRef.Format(), []types.Value{valueRef})
    56  }
    57  
    58  func IsWorkingSet(v types.Value) (bool, error) {
    59  	if s, ok := v.(types.Struct); !ok {
    60  		return false, nil
    61  	} else {
    62  		return types.IsValueSubtypeOf(s.Format(), v, valueWorkingSetType)
    63  	}
    64  }