github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/sqle/dfunctions/squash.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/merge"
    24  	"github.com/dolthub/dolt/go/libraries/doltcore/sqle"
    25  )
    26  
    27  const SquashFuncName = "squash"
    28  
    29  type SquashFunc struct {
    30  	expression.UnaryExpression
    31  }
    32  
    33  func NewSquashFunc(ctx *sql.Context, child sql.Expression) sql.Expression {
    34  	return &SquashFunc{expression.UnaryExpression{Child: child}}
    35  }
    36  
    37  func (s SquashFunc) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    38  	sess := sqle.DSessFromSess(ctx.Session)
    39  
    40  	branchVal, err := s.Child.Eval(ctx, row)
    41  	if err != nil {
    42  		return nil, err
    43  	}
    44  
    45  	branchName, ok := branchVal.(string)
    46  	if !ok {
    47  		return nil, fmt.Errorf("error: SQUASH() was given a non-string branch name")
    48  	}
    49  
    50  	dbName := sess.GetCurrentDatabase()
    51  	ddb, ok := sess.GetDoltDB(dbName)
    52  	if !ok {
    53  		return nil, sql.ErrDatabaseNotFound.New(dbName)
    54  	}
    55  
    56  	root, ok := sess.GetRoot(dbName)
    57  	if !ok {
    58  		return nil, sql.ErrDatabaseNotFound.New(dbName)
    59  	}
    60  
    61  	head, _, headRoot, err := getHead(ctx, sess, dbName)
    62  	if err != nil {
    63  		return nil, err
    64  	}
    65  
    66  	err = checkForUncommittedChanges(root, headRoot)
    67  	if err != nil {
    68  		return nil, err
    69  	}
    70  
    71  	cm, _, err := getBranchCommit(ctx, branchName, ddb)
    72  	if err != nil {
    73  		return nil, err
    74  	}
    75  
    76  	mergeRoot, _, err := merge.MergeCommits(ctx, head, cm)
    77  	if err != nil {
    78  		return nil, err
    79  	}
    80  
    81  	h, err := ddb.WriteRootValue(ctx, mergeRoot)
    82  	if err != nil {
    83  		return nil, err
    84  	}
    85  
    86  	return h.String(), nil
    87  }
    88  
    89  func (s SquashFunc) Resolved() bool {
    90  	return s.Child.Resolved()
    91  }
    92  
    93  func (s SquashFunc) String() string {
    94  	return fmt.Sprintf("SQUASH(%s)", s.Child.String())
    95  }
    96  
    97  func (s SquashFunc) Type() sql.Type {
    98  	return sql.Text
    99  }
   100  
   101  func (s SquashFunc) IsNullable() bool {
   102  	return false
   103  }
   104  
   105  func (s SquashFunc) Children() []sql.Expression {
   106  	return []sql.Expression{s.Child}
   107  }
   108  
   109  func (s SquashFunc) WithChildren(ctx *sql.Context, children ...sql.Expression) (sql.Expression, error) {
   110  	if len(children) != 1 {
   111  		return nil, sql.ErrInvalidChildrenNumber.New(s, len(children), 1)
   112  	}
   113  
   114  	return NewSquashFunc(ctx, children[0]), nil
   115  }