github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/merge/conflict_splitter.go (about)

     1  // Copyright 2020 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 merge
    16  
    17  import (
    18  	"context"
    19  
    20  	"github.com/dolthub/dolt/go/libraries/doltcore/row"
    21  	"github.com/dolthub/dolt/go/libraries/doltcore/rowconv"
    22  	"github.com/dolthub/dolt/go/libraries/doltcore/schema"
    23  	"github.com/dolthub/dolt/go/libraries/doltcore/table/pipeline"
    24  	"github.com/dolthub/dolt/go/libraries/doltcore/table/untyped"
    25  	"github.com/dolthub/dolt/go/store/types"
    26  )
    27  
    28  // MergeVersion defines which version a value of a row corresponds to
    29  type MergeVersion int
    30  
    31  const (
    32  	// BaseVersion represents the state of a row at the most recent ancestor
    33  	BaseVersion MergeVersion = iota
    34  	// OurVersion represents the state of a row on our branch that is being merged into
    35  	OurVersion
    36  	// TheirVersion represents the state of a row on their branch which we are merging
    37  	TheirVersion
    38  	// Blank is used for displaying a row without a version label
    39  	Blank
    40  )
    41  
    42  var typeToMergeVersion = map[string]MergeVersion{
    43  	oursStr:   OurVersion,
    44  	theirsStr: TheirVersion,
    45  	baseStr:   BaseVersion,
    46  }
    47  
    48  // ConflictsSplitter splits a conflict into base, ours, and their version of a row
    49  type ConflictSplitter struct {
    50  	joiner     *rowconv.Joiner
    51  	sch        schema.Schema
    52  	converters map[string]*rowconv.RowConverter
    53  }
    54  
    55  // NewConflictSplitter creates a new ConflictSplitter
    56  func NewConflictSplitter(ctx context.Context, vrw types.ValueReadWriter, joiner *rowconv.Joiner) (ConflictSplitter, error) {
    57  	baseSch := joiner.SchemaForName(baseStr)
    58  	ourSch := joiner.SchemaForName(baseStr)
    59  	theirSch := joiner.SchemaForName(theirsStr)
    60  
    61  	sch, err := untyped.UntypedSchemaUnion(baseSch, ourSch, theirSch)
    62  
    63  	if err != nil {
    64  		return ConflictSplitter{}, err
    65  	}
    66  
    67  	converters := make(map[string]*rowconv.RowConverter)
    68  	converters[oursStr], err = tagMappingConverter(ctx, vrw, ourSch, sch)
    69  
    70  	if err != nil {
    71  		return ConflictSplitter{}, err
    72  	}
    73  
    74  	converters[theirsStr], err = tagMappingConverter(ctx, vrw, theirSch, sch)
    75  
    76  	if err != nil {
    77  		return ConflictSplitter{}, err
    78  	}
    79  
    80  	converters[baseStr], err = tagMappingConverter(ctx, vrw, baseSch, sch)
    81  
    82  	if err != nil {
    83  		return ConflictSplitter{}, err
    84  	}
    85  
    86  	return ConflictSplitter{joiner: joiner, sch: sch, converters: converters}, nil
    87  }
    88  
    89  // GetSchema returns the common schema which all rows will share
    90  func (ds ConflictSplitter) GetSchema() schema.Schema {
    91  	return ds.sch
    92  }
    93  
    94  // SplitConflicts takes a conflict row and splits it into ours, theirs, and base versions and provides pipeline properties
    95  // which can be used to distinguished which is which and what type of conflict occurred.
    96  func (ds ConflictSplitter) SplitConflicts(inRow row.Row, _ pipeline.ReadableMap) (rowData []*pipeline.TransformedRowResult, badRowDetails string) {
    97  	rows, err := ds.joiner.Split(inRow)
    98  	if err != nil {
    99  		return nil, err.Error()
   100  	}
   101  
   102  	var baseRow row.Row
   103  	has := make(map[string]bool)
   104  	baseRow, has[baseStr] = rows[baseStr]
   105  	_, has[oursStr] = rows[oursStr]
   106  	_, has[theirsStr] = rows[theirsStr]
   107  
   108  	if has[baseStr] {
   109  		baseRow, err = ds.converters[baseStr].Convert(baseRow)
   110  
   111  		if err != nil {
   112  			return nil, err.Error()
   113  		}
   114  	}
   115  
   116  	rowData = make([]*pipeline.TransformedRowResult, 0, 3)
   117  	for _, rowType := range []string{baseStr, oursStr, theirsStr} {
   118  		row, ok := rows[rowType]
   119  		props := map[string]interface{}{mergeVersionProp: typeToMergeVersion[rowType]}
   120  
   121  		if ok {
   122  			converted, err := ds.converters[rowType].Convert(row)
   123  
   124  			if err != nil {
   125  				return nil, err.Error()
   126  			}
   127  
   128  			if !has[baseStr] {
   129  				props[mergeRowOperation] = types.DiffChangeAdded
   130  			} else {
   131  				props[mergeRowOperation] = types.DiffChangeModified
   132  			}
   133  
   134  			rowData = append(rowData, &pipeline.TransformedRowResult{RowData: converted, PropertyUpdates: props})
   135  		} else if rowType != baseStr {
   136  			props[mergeRowOperation] = types.DiffChangeRemoved
   137  			rowData = append(rowData, &pipeline.TransformedRowResult{RowData: baseRow, PropertyUpdates: props})
   138  		}
   139  	}
   140  
   141  	return rowData, ""
   142  }