github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/sqle/dfunctions/hashof.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 dfunctions
    16  
    17  import (
    18  	"context"
    19  	"errors"
    20  	"fmt"
    21  	"strings"
    22  
    23  	"github.com/dolthub/go-mysql-server/sql"
    24  	"github.com/dolthub/go-mysql-server/sql/expression"
    25  
    26  	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
    27  	"github.com/dolthub/dolt/go/libraries/doltcore/ref"
    28  	"github.com/dolthub/dolt/go/libraries/doltcore/sqle"
    29  )
    30  
    31  const HashOfFuncName = "hashof"
    32  
    33  type HashOf struct {
    34  	expression.UnaryExpression
    35  }
    36  
    37  // NewHashOf creates a new HashOf expression.
    38  func NewHashOf(ctx *sql.Context, e sql.Expression) sql.Expression {
    39  	return &HashOf{expression.UnaryExpression{Child: e}}
    40  }
    41  
    42  // Eval implements the Expression interface.
    43  func (t *HashOf) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    44  	val, err := t.Child.Eval(ctx, row)
    45  
    46  	if err != nil {
    47  		return nil, err
    48  	}
    49  
    50  	if val == nil {
    51  		return nil, nil
    52  	}
    53  
    54  	paramStr, ok := val.(string)
    55  
    56  	if !ok {
    57  		return nil, errors.New("branch name is not a string")
    58  	}
    59  
    60  	name, as, err := doltdb.SplitAncestorSpec(paramStr)
    61  	if err != nil {
    62  		return nil, err
    63  	}
    64  
    65  	dbName := ctx.GetCurrentDatabase()
    66  	ddb, ok := sqle.DSessFromSess(ctx.Session).GetDoltDB(dbName)
    67  	if !ok {
    68  		return nil, sql.ErrDatabaseNotFound.New(dbName)
    69  	}
    70  
    71  	var cm *doltdb.Commit
    72  	if strings.ToUpper(name) == "HEAD" {
    73  		sess := sqle.DSessFromSess(ctx.Session)
    74  
    75  		cm, _, err = sess.GetHeadCommit(ctx, dbName)
    76  		if err != nil {
    77  			return nil, err
    78  		}
    79  	} else {
    80  		branchRef, err := getBranchInsensitive(ctx, name, ddb)
    81  		if err != nil {
    82  			return nil, err
    83  		}
    84  
    85  		cm, err = ddb.ResolveCommitRef(ctx, branchRef)
    86  		if err != nil {
    87  			return nil, err
    88  		}
    89  	}
    90  
    91  	cm, err = cm.GetAncestor(ctx, as)
    92  	if err != nil {
    93  		return nil, err
    94  	}
    95  
    96  	h, err := cm.HashOf()
    97  	if err != nil {
    98  		return nil, err
    99  	}
   100  
   101  	return h.String(), nil
   102  }
   103  
   104  func getBranchInsensitive(ctx context.Context, branchName string, ddb *doltdb.DoltDB) (br ref.DoltRef, err error) {
   105  	branchRefs, err := ddb.GetBranches(ctx)
   106  
   107  	if err != nil {
   108  		return br, err
   109  	}
   110  
   111  	for _, branchRef := range branchRefs {
   112  		if strings.ToLower(branchRef.GetPath()) == strings.ToLower(branchName) {
   113  			return branchRef, nil
   114  		}
   115  	}
   116  
   117  	return br, doltdb.ErrBranchNotFound
   118  }
   119  
   120  // String implements the Stringer interface.
   121  func (t *HashOf) String() string {
   122  	return fmt.Sprintf("HASHOF(%s)", t.Child.String())
   123  }
   124  
   125  // IsNullable implements the Expression interface.
   126  func (t *HashOf) IsNullable() bool {
   127  	return t.Child.IsNullable()
   128  }
   129  
   130  // WithChildren implements the Expression interface.
   131  func (t *HashOf) WithChildren(ctx *sql.Context, children ...sql.Expression) (sql.Expression, error) {
   132  	if len(children) != 1 {
   133  		return nil, sql.ErrInvalidChildrenNumber.New(t, len(children), 1)
   134  	}
   135  	return NewHashOf(ctx, children[0]), nil
   136  }
   137  
   138  // Type implements the Expression interface.
   139  func (t *HashOf) Type() sql.Type {
   140  	return sql.Text
   141  }