github.com/dolthub/dolt/go@v0.40.5-0.20240520175717-68db7794bea6/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  	"github.com/dolthub/go-mysql-server/sql/types"
    23  
    24  	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
    25  	"github.com/dolthub/dolt/go/libraries/doltcore/merge"
    26  	"github.com/dolthub/dolt/go/libraries/doltcore/sqle/dsess"
    27  )
    28  
    29  const DoltMergeBaseFuncName = "dolt_merge_base"
    30  
    31  type MergeBase struct {
    32  	expression.BinaryExpressionStub
    33  }
    34  
    35  // NewMergeBase returns a MergeBase sql function.
    36  func NewMergeBase(left, right sql.Expression) sql.Expression {
    37  	return &MergeBase{expression.BinaryExpressionStub{LeftChild: left, RightChild: right}}
    38  }
    39  
    40  // Eval implements the sql.Expression interface.
    41  func (d MergeBase) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    42  	if _, ok := d.Left().Type().(sql.StringType); !ok {
    43  		return nil, sql.ErrInvalidType.New(d.Left().Type())
    44  	}
    45  	if _, ok := d.Right().Type().(sql.StringType); !ok {
    46  		return nil, sql.ErrInvalidType.New(d.Right().Type())
    47  	}
    48  
    49  	leftSpec, err := d.Left().Eval(ctx, row)
    50  	if err != nil {
    51  		return nil, err
    52  	}
    53  	rightSpec, err := d.Right().Eval(ctx, row)
    54  	if err != nil {
    55  		return nil, err
    56  	}
    57  
    58  	if leftSpec == nil || rightSpec == nil {
    59  		return nil, nil
    60  	}
    61  
    62  	left, right, err := resolveRefSpecs(ctx, leftSpec.(string), rightSpec.(string))
    63  	if err != nil {
    64  		return nil, err
    65  	}
    66  
    67  	mergeBase, err := merge.MergeBase(ctx, left, right)
    68  	if err != nil {
    69  		return nil, err
    70  	}
    71  
    72  	return mergeBase.String(), nil
    73  }
    74  
    75  func resolveRefSpecs(ctx *sql.Context, leftSpec, rightSpec string) (left, right *doltdb.Commit, err error) {
    76  	lcs, err := doltdb.NewCommitSpec(leftSpec)
    77  	if err != nil {
    78  		return nil, nil, err
    79  	}
    80  	rcs, err := doltdb.NewCommitSpec(rightSpec)
    81  	if err != nil {
    82  		return nil, nil, err
    83  	}
    84  
    85  	sess := dsess.DSessFromSess(ctx.Session)
    86  	dbName := ctx.GetCurrentDatabase()
    87  
    88  	dbData, ok := sess.GetDbData(ctx, dbName)
    89  	if !ok {
    90  		return nil, nil, sql.ErrDatabaseNotFound.New(dbName)
    91  	}
    92  	doltDB, ok := sess.GetDoltDB(ctx, dbName)
    93  	if !ok {
    94  		return nil, nil, sql.ErrDatabaseNotFound.New(dbName)
    95  	}
    96  
    97  	headRef, err := dbData.Rsr.CWBHeadRef()
    98  	if err != nil {
    99  		return nil, nil, err
   100  	}
   101  
   102  	optCmt, err := doltDB.Resolve(ctx, lcs, headRef)
   103  	if err != nil {
   104  		return nil, nil, err
   105  	}
   106  	left, ok = optCmt.ToCommit()
   107  	if !ok {
   108  		return nil, nil, doltdb.ErrGhostCommitEncountered
   109  	}
   110  
   111  	optCmt, err = doltDB.Resolve(ctx, rcs, headRef)
   112  	if err != nil {
   113  		return nil, nil, err
   114  	}
   115  	right, ok = optCmt.ToCommit()
   116  	if !ok {
   117  		return nil, nil, doltdb.ErrGhostCommitEncountered
   118  	}
   119  
   120  	return
   121  }
   122  
   123  // String implements the sql.Expression interface.
   124  func (d MergeBase) String() string {
   125  	return fmt.Sprintf("DOLT_MERGE_BASE(%s,%s)", d.Left().String(), d.Right().String())
   126  }
   127  
   128  // Type implements the sql.Expression interface.
   129  func (d MergeBase) Type() sql.Type {
   130  	return types.Text
   131  }
   132  
   133  // WithChildren implements the sql.Expression interface.
   134  func (d MergeBase) WithChildren(children ...sql.Expression) (sql.Expression, error) {
   135  	if len(children) != 2 {
   136  		return nil, sql.ErrInvalidChildrenNumber.New(d, len(children), 2)
   137  	}
   138  	return NewMergeBase(children[0], children[1]), nil
   139  }