github.com/dolthub/go-mysql-server@v0.18.0/sql/expression/tuple.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 expression
    16  
    17  import (
    18  	"fmt"
    19  	"strings"
    20  
    21  	"github.com/dolthub/go-mysql-server/sql"
    22  	types2 "github.com/dolthub/go-mysql-server/sql/types"
    23  )
    24  
    25  // Tuple is a fixed-size collection of expressions.
    26  // A tuple of size 1 is treated as the expression itself.
    27  type Tuple []sql.Expression
    28  
    29  // NewTuple creates a new Tuple expression.
    30  func NewTuple(exprs ...sql.Expression) Tuple {
    31  	return Tuple(exprs)
    32  }
    33  
    34  // Eval implements the Expression interface.
    35  func (t Tuple) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    36  	if len(t) == 1 {
    37  		return t[0].Eval(ctx, row)
    38  	}
    39  
    40  	var result = make([]interface{}, len(t))
    41  	for i, e := range t {
    42  		v, err := e.Eval(ctx, row)
    43  		if err != nil {
    44  			return nil, err
    45  		}
    46  
    47  		result[i] = v
    48  	}
    49  
    50  	return result, nil
    51  }
    52  
    53  // IsNullable implements the Expression interface.
    54  func (t Tuple) IsNullable() bool {
    55  	if len(t) == 1 {
    56  		return t[0].IsNullable()
    57  	}
    58  
    59  	return false
    60  }
    61  
    62  func (t Tuple) String() string {
    63  	var exprs = make([]string, len(t))
    64  	for i, e := range t {
    65  		exprs[i] = e.String()
    66  	}
    67  	return fmt.Sprintf("(%s)", strings.Join(exprs, ", "))
    68  }
    69  
    70  func (t Tuple) DebugString() string {
    71  	var exprs = make([]string, len(t))
    72  	for i, e := range t {
    73  		exprs[i] = sql.DebugString(e)
    74  	}
    75  	return fmt.Sprintf("TUPLE(%s)", strings.Join(exprs, ", "))
    76  }
    77  
    78  // Resolved implements the Expression interface.
    79  func (t Tuple) Resolved() bool {
    80  	for _, e := range t {
    81  		if !e.Resolved() {
    82  			return false
    83  		}
    84  	}
    85  
    86  	return true
    87  }
    88  
    89  // Type implements the Expression interface.
    90  func (t Tuple) Type() sql.Type {
    91  	if len(t) == 1 {
    92  		return t[0].Type()
    93  	}
    94  
    95  	types := make([]sql.Type, len(t))
    96  	for i, e := range t {
    97  		types[i] = e.Type()
    98  	}
    99  
   100  	return types2.CreateTuple(types...)
   101  }
   102  
   103  // WithChildren implements the Expression interface.
   104  func (t Tuple) WithChildren(children ...sql.Expression) (sql.Expression, error) {
   105  	if len(children) != len(t) {
   106  		return nil, sql.ErrInvalidChildrenNumber.New(t, len(children), len(t))
   107  	}
   108  	return NewTuple(children...), nil
   109  }
   110  
   111  // Children implements the Expression interface.
   112  func (t Tuple) Children() []sql.Expression {
   113  	return t
   114  }