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

     1  // Copyright 2019 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  // This file incorporates work covered by the following copyright and
    16  // permission notice:
    17  //
    18  // Copyright 2016 Attic Labs, Inc. All rights reserved.
    19  // Licensed under the Apache License, version 2.0:
    20  // http://www.apache.org/licenses/LICENSE-2.0
    21  
    22  package merge
    23  
    24  import (
    25  	"context"
    26  
    27  	"github.com/dolthub/dolt/go/store/d"
    28  	"github.com/dolthub/dolt/go/store/types"
    29  )
    30  
    31  // candidate represents a collection that is a candidate to be merged. This
    32  // interface exists to wrap Maps, Sets and Structs with a common API so that
    33  // threeWayOrderedSequenceMerge() can remain agnostic to which kind of
    34  // collections it's actually working with.
    35  type candidate interface {
    36  	diff(ctx context.Context, parent candidate, change chan<- types.ValueChanged) error
    37  	get(ctx context.Context, k types.Value) (types.Value, bool, error)
    38  	pathConcat(ctx context.Context, change types.ValueChanged, path types.Path) (out types.Path, err error)
    39  	getValue() types.Value
    40  }
    41  
    42  type mapCandidate struct {
    43  	m types.Map
    44  }
    45  
    46  func (mc mapCandidate) diff(ctx context.Context, p candidate, change chan<- types.ValueChanged) error {
    47  	return mc.m.Diff(ctx, p.(mapCandidate).m, change)
    48  }
    49  
    50  func (mc mapCandidate) get(ctx context.Context, k types.Value) (types.Value, bool, error) {
    51  	return mc.m.MaybeGet(ctx, k)
    52  }
    53  
    54  func (mc mapCandidate) pathConcat(ctx context.Context, change types.ValueChanged, path types.Path) (out types.Path, err error) {
    55  	out = append(out, path...)
    56  	if kind := change.Key.Kind(); kind == types.BoolKind || kind == types.StringKind || kind == types.FloatKind {
    57  		out = append(out, types.NewIndexPath(change.Key))
    58  	} else {
    59  		h, err := change.Key.Hash(mc.m.Format())
    60  
    61  		if err != nil {
    62  			return nil, err
    63  		}
    64  
    65  		out = append(out, types.NewHashIndexPath(h))
    66  	}
    67  	return out, nil
    68  }
    69  
    70  func (mc mapCandidate) getValue() types.Value {
    71  	return mc.m
    72  }
    73  
    74  type setCandidate struct {
    75  	s types.Set
    76  }
    77  
    78  func (sc setCandidate) diff(ctx context.Context, p candidate, change chan<- types.ValueChanged) error {
    79  	return sc.s.Diff(ctx, p.(setCandidate).s, change)
    80  }
    81  
    82  func (sc setCandidate) get(ctx context.Context, k types.Value) (types.Value, bool, error) {
    83  	return k, true, nil
    84  }
    85  
    86  func (sc setCandidate) pathConcat(ctx context.Context, change types.ValueChanged, path types.Path) (out types.Path, err error) {
    87  	out = append(out, path...)
    88  	if kind := change.Key.Kind(); kind == types.BoolKind || kind == types.StringKind || kind == types.FloatKind {
    89  		out = append(out, types.NewIndexPath(change.Key))
    90  	} else {
    91  		h, err := change.Key.Hash(sc.s.Format())
    92  
    93  		if err != nil {
    94  			return nil, err
    95  		}
    96  
    97  		out = append(out, types.NewHashIndexPath(h))
    98  	}
    99  	return out, nil
   100  }
   101  
   102  func (sc setCandidate) getValue() types.Value {
   103  	return sc.s
   104  }
   105  
   106  type structCandidate struct {
   107  	s types.Struct
   108  }
   109  
   110  func (sc structCandidate) diff(ctx context.Context, p candidate, change chan<- types.ValueChanged) error {
   111  	return sc.s.Diff(ctx, p.(structCandidate).s, change)
   112  }
   113  
   114  func (sc structCandidate) get(ctx context.Context, key types.Value) (types.Value, bool, error) {
   115  	if field, ok := key.(types.String); ok {
   116  		return sc.s.MaybeGet(string(field))
   117  	}
   118  
   119  	return nil, false, nil
   120  }
   121  
   122  func (sc structCandidate) pathConcat(ctx context.Context, change types.ValueChanged, path types.Path) (out types.Path, err error) {
   123  	out = append(out, path...)
   124  	str, ok := change.Key.(types.String)
   125  	if !ok {
   126  		t, err := types.TypeOf(change.Key)
   127  
   128  		var typeStr string
   129  		if err == nil {
   130  			typeStr, _ = t.Describe(ctx)
   131  		}
   132  
   133  		d.Panic("Field names must be strings, not %s", typeStr)
   134  	}
   135  	return append(out, types.NewFieldPath(string(str))), nil
   136  }
   137  
   138  func (sc structCandidate) getValue() types.Value {
   139  	return sc.s
   140  }