github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/sqle/dfunctions/dolt_merge_base.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 dfunctions
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/dolthub/go-mysql-server/sql"
    21  	"github.com/dolthub/go-mysql-server/sql/expression"
    22  
    23  	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
    24  	"github.com/dolthub/dolt/go/libraries/doltcore/merge"
    25  	"github.com/dolthub/dolt/go/libraries/doltcore/sqle"
    26  )
    27  
    28  const DoltMergeBaseFuncName = "dolt_merge_base"
    29  
    30  type MergeBase struct {
    31  	expression.BinaryExpression
    32  }
    33  
    34  // NewMergeBase returns a MergeBase sql function.
    35  func NewMergeBase(ctx *sql.Context, left, right sql.Expression) sql.Expression {
    36  	return &MergeBase{expression.BinaryExpression{Left: left, Right: right}}
    37  }
    38  
    39  // Eval implements the sql.Expression interface.
    40  func (d MergeBase) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    41  	if _, ok := d.Left.Type().(sql.StringType); !ok {
    42  		return nil, sql.ErrInvalidType.New(d.Left.Type())
    43  	}
    44  	if _, ok := d.Right.Type().(sql.StringType); !ok {
    45  		return nil, sql.ErrInvalidType.New(d.Right.Type())
    46  	}
    47  
    48  	leftSpec, err := d.Left.Eval(ctx, row)
    49  	if err != nil {
    50  		return nil, err
    51  	}
    52  	rightSpec, err := d.Right.Eval(ctx, row)
    53  	if err != nil {
    54  		return nil, err
    55  	}
    56  
    57  	if leftSpec == nil || rightSpec == nil {
    58  		return nil, nil
    59  	}
    60  
    61  	left, right, err := resolveRefSpecs(ctx, leftSpec.(string), rightSpec.(string))
    62  	if err != nil {
    63  		return nil, err
    64  	}
    65  
    66  	mergeBase, err := merge.MergeBase(ctx, left, right)
    67  	if err != nil {
    68  		return nil, err
    69  	}
    70  
    71  	return mergeBase.String(), nil
    72  }
    73  
    74  func resolveRefSpecs(ctx *sql.Context, leftSpec, rightSpec string) (left, right *doltdb.Commit, err error) {
    75  	lcs, err := doltdb.NewCommitSpec(leftSpec)
    76  	if err != nil {
    77  		return nil, nil, err
    78  	}
    79  	rcs, err := doltdb.NewCommitSpec(rightSpec)
    80  	if err != nil {
    81  		return nil, nil, err
    82  	}
    83  
    84  	sess := sqle.DSessFromSess(ctx.Session)
    85  	dbName := ctx.GetCurrentDatabase()
    86  
    87  	dbData, ok := sess.GetDbData(dbName)
    88  	if !ok {
    89  		return nil, nil, sql.ErrDatabaseNotFound.New(dbName)
    90  	}
    91  	doltDB, ok := sess.GetDoltDB(dbName)
    92  	if !ok {
    93  		return nil, nil, sql.ErrDatabaseNotFound.New(dbName)
    94  	}
    95  
    96  	left, err = doltDB.Resolve(ctx, lcs, dbData.Rsr.CWBHeadRef())
    97  	if err != nil {
    98  		return nil, nil, err
    99  	}
   100  	right, err = doltDB.Resolve(ctx, rcs, dbData.Rsr.CWBHeadRef())
   101  	if err != nil {
   102  		return nil, nil, err
   103  	}
   104  
   105  	return
   106  }
   107  
   108  // String implements the sql.Expression interface.
   109  func (d MergeBase) String() string {
   110  	return fmt.Sprintf("DOLT_MERGE_BASE(%s,%s)", d.Left.String(), d.Right.String())
   111  }
   112  
   113  // Type implements the sql.Expression interface.
   114  func (d MergeBase) Type() sql.Type {
   115  	return sql.Text
   116  }
   117  
   118  // WithChildren implements the sql.Expression interface.
   119  func (d MergeBase) WithChildren(ctx *sql.Context, children ...sql.Expression) (sql.Expression, error) {
   120  	if len(children) != 2 {
   121  		return nil, sql.ErrInvalidChildrenNumber.New(d, len(children), 2)
   122  	}
   123  	return NewMergeBase(ctx, children[0], children[1]), nil
   124  }