github.com/dolthub/go-mysql-server@v0.18.0/sql/plan/tablealias.go (about)

     1  // Copyright 2020-2021 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 plan
    16  
    17  import (
    18  	"github.com/dolthub/go-mysql-server/sql"
    19  )
    20  
    21  // TableAlias is a node that acts as a table with a given name.
    22  type TableAlias struct {
    23  	*UnaryNode
    24  	name    string
    25  	comment string
    26  	id      sql.TableId
    27  	cols    sql.ColSet
    28  }
    29  
    30  var _ sql.RenameableNode = (*TableAlias)(nil)
    31  var _ sql.CommentedNode = (*TableAlias)(nil)
    32  var _ sql.CollationCoercible = (*TableAlias)(nil)
    33  
    34  // NewTableAlias returns a new Table alias node.
    35  func NewTableAlias(name string, node sql.Node) *TableAlias {
    36  	ret := &TableAlias{UnaryNode: &UnaryNode{Child: node}, name: name}
    37  	if tin, ok := node.(TableIdNode); ok {
    38  		ret.id = tin.Id()
    39  		ret.cols = tin.Columns()
    40  	}
    41  	return ret
    42  }
    43  
    44  // WithId implements sql.TableIdNode
    45  func (t *TableAlias) WithId(id sql.TableId) TableIdNode {
    46  	ret := *t
    47  	ret.id = id
    48  	return &ret
    49  }
    50  
    51  // Id implements sql.TableIdNode
    52  func (t *TableAlias) Id() sql.TableId {
    53  	return t.id
    54  }
    55  
    56  // WithColumns implements sql.TableIdNode
    57  func (t *TableAlias) WithColumns(set sql.ColSet) TableIdNode {
    58  	ret := *t
    59  	ret.cols = set
    60  	return &ret
    61  }
    62  
    63  // Columns implements sql.TableIdNode
    64  func (t *TableAlias) Columns() sql.ColSet {
    65  	return t.cols
    66  }
    67  
    68  // Name implements the Nameable interface.
    69  func (t *TableAlias) Name() string {
    70  	return t.name
    71  }
    72  
    73  func (t *TableAlias) IsReadOnly() bool {
    74  	return t.Child.IsReadOnly()
    75  }
    76  
    77  func (t *TableAlias) WithComment(s string) sql.Node {
    78  	ret := *t
    79  	ret.comment = s
    80  	return &ret
    81  }
    82  
    83  func (t *TableAlias) Comment() string {
    84  	return t.comment
    85  }
    86  
    87  // Schema implements the Node interface. TableAlias alters the schema of its child element to rename the source of
    88  // columns to the alias.
    89  func (t *TableAlias) Schema() sql.Schema {
    90  	childSchema := t.Child.Schema()
    91  	copy := make(sql.Schema, len(childSchema))
    92  	for i, col := range childSchema {
    93  		colCopy := *col
    94  		colCopy.Source = t.name
    95  		copy[i] = &colCopy
    96  	}
    97  	return copy
    98  }
    99  
   100  // WithChildren implements the Node interface.
   101  func (t *TableAlias) WithChildren(children ...sql.Node) (sql.Node, error) {
   102  	if len(children) != 1 {
   103  		return nil, sql.ErrInvalidChildrenNumber.New(t, len(children), 1)
   104  	}
   105  
   106  	ret := NewTableAlias(t.name, children[0])
   107  	ret.comment = t.comment
   108  	ret.cols = t.cols
   109  	ret.id = t.id
   110  	return ret, nil
   111  }
   112  
   113  // CheckPrivileges implements the interface sql.Node.
   114  func (t *TableAlias) CheckPrivileges(ctx *sql.Context, opChecker sql.PrivilegedOperationChecker) bool {
   115  	if t.UnaryNode != nil {
   116  		return t.UnaryNode.Child.CheckPrivileges(ctx, opChecker)
   117  	}
   118  	return true
   119  }
   120  
   121  // CollationCoercibility implements the interface sql.CollationCoercible.
   122  func (t *TableAlias) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
   123  	if t.UnaryNode != nil {
   124  		return sql.GetCoercibility(ctx, t.UnaryNode.Child)
   125  	}
   126  	return sql.Collation_binary, 7
   127  }
   128  
   129  func (t TableAlias) String() string {
   130  	pr := sql.NewTreePrinter()
   131  	_ = pr.WriteNode("TableAlias(%s)", t.name)
   132  	_ = pr.WriteChildren(t.Child.String())
   133  	return pr.String()
   134  }
   135  
   136  func (t TableAlias) DebugString() string {
   137  	pr := sql.NewTreePrinter()
   138  	_ = pr.WriteNode("TableAlias(%s)", t.name)
   139  	_ = pr.WriteChildren(sql.DebugString(t.Child))
   140  	return pr.String()
   141  }
   142  
   143  func (t TableAlias) WithName(name string) sql.Node {
   144  	t.name = name
   145  	return &t
   146  }