/
field.go
150 lines (124 loc) · 3.53 KB
/
field.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
// Copyright 2024 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package function
import (
"fmt"
"strings"
"github.com/dolthub/go-mysql-server/sql"
"github.com/dolthub/go-mysql-server/sql/types"
)
// Field joins several strings together.
type Field struct {
args []sql.Expression
}
var _ sql.FunctionExpression = (*Field)(nil)
var _ sql.CollationCoercible = (*Field)(nil)
// NewField creates a new Field UDF.
func NewField(args ...sql.Expression) (sql.Expression, error) {
if len(args) < 2 {
return nil, sql.ErrInvalidArgumentNumber.New("FIELD", "2 or more", len(args))
}
return &Field{args}, nil
}
// FunctionName implements sql.FunctionExpression
func (f *Field) FunctionName() string {
return "field"
}
// Description implements sql.FunctionExpression
func (f *Field) Description() string {
return "returns the string at index number."
}
// Type implements the Expression interface.
func (f *Field) Type() sql.Type {
return types.Int64
}
// CollationCoercibility implements the interface sql.CollationCoercible.
func (f *Field) CollationCoercibility(ctx *sql.Context) (sql.CollationID, byte) {
if len(f.args) == 0 {
return sql.Collation_binary, 6
}
collation, coercibility := sql.GetCoercibility(ctx, f.args[0])
for i := 1; i < len(f.args); i++ {
nextCollation, nextCoercibility := sql.GetCoercibility(ctx, f.args[i])
collation, coercibility = sql.ResolveCoercibility(collation, coercibility, nextCollation, nextCoercibility)
}
return collation, coercibility
}
// IsNullable implements the Expression interface.
func (f *Field) IsNullable() bool {
return false
}
// String implements the Stringer interface.
func (f *Field) String() string {
var args = make([]string, len(f.args))
for i, arg := range f.args {
args[i] = arg.String()
}
return fmt.Sprintf("%s(%s)", f.FunctionName(), strings.Join(args, ","))
}
// WithChildren implements the Expression interface.
func (*Field) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewField(children...)
}
// Resolved implements the Expression interface.
func (f *Field) Resolved() bool {
for _, arg := range f.args {
if !arg.Resolved() {
return false
}
}
return true
}
// Children implements the Expression interface.
func (f *Field) Children() []sql.Expression {
return f.args
}
// Eval implements the Expression interface.
func (f *Field) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
if f.args[0] == nil {
return int64(0), nil
}
key, err := f.args[0].Eval(ctx, row)
if err != nil {
return nil, err
}
if key == nil {
return int64(0), nil
}
key, _, err = types.Text.Convert(key)
if err != nil {
return nil, err
}
var val interface{}
for i := 1; i < len(f.args); i++ {
if f.args[i] == nil {
continue
}
val, err = f.args[i].Eval(ctx, row)
if err != nil {
return nil, err
}
if val == nil {
continue
}
val, _, err = types.Text.Convert(val)
if err != nil {
return nil, err
}
if strings.EqualFold(key.(string), val.(string)) {
return int64(i), nil
}
}
return int64(0), nil
}