forked from pingcap/tidb
-
Notifications
You must be signed in to change notification settings - Fork 0
/
scalar_function.go
202 lines (178 loc) · 5.84 KB
/
scalar_function.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
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
// Copyright 2016 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package expression
import (
"bytes"
"fmt"
"github.com/juju/errors"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/util/codec"
"github.com/pingcap/tidb/util/types"
)
// ScalarFunction is the function that returns a value.
type ScalarFunction struct {
FuncName model.CIStr
// RetType is the type that ScalarFunction returns.
// TODO: Implement type inference here, now we use ast's return type temporarily.
RetType *types.FieldType
Function builtinFunc
}
// GetArgs gets arguments of function.
func (sf *ScalarFunction) GetArgs() []Expression {
return sf.Function.getArgs()
}
// GetCtx gets the context of function.
func (sf *ScalarFunction) GetCtx() context.Context {
return sf.Function.getCtx()
}
// String implements fmt.Stringer interface.
func (sf *ScalarFunction) String() string {
result := sf.FuncName.L + "("
for i, arg := range sf.GetArgs() {
result += arg.String()
if i+1 != len(sf.GetArgs()) {
result += ", "
}
}
result += ")"
return result
}
// MarshalJSON implements json.Marshaler interface.
func (sf *ScalarFunction) MarshalJSON() ([]byte, error) {
buffer := bytes.NewBufferString(fmt.Sprintf("\"%s\"", sf))
return buffer.Bytes(), nil
}
// NewFunction creates a new scalar function or constant.
func NewFunction(ctx context.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error) {
fc, ok := funcs[funcName]
if !ok {
return nil, errFunctionNotExists.GenByArgs(funcName)
}
funcArgs := make([]Expression, len(args))
copy(funcArgs, args)
f, err := fc.getFunction(funcArgs, ctx)
if err != nil {
return nil, errors.Trace(err)
}
if retType == nil {
return nil, errors.Errorf("RetType cannot be nil for ScalarFunction.")
}
return &ScalarFunction{
FuncName: model.NewCIStr(funcName),
RetType: retType,
Function: f,
}, nil
}
// ScalarFuncs2Exprs converts []*ScalarFunction to []Expression.
func ScalarFuncs2Exprs(funcs []*ScalarFunction) []Expression {
result := make([]Expression, 0, len(funcs))
for _, col := range funcs {
result = append(result, col)
}
return result
}
// Clone implements Expression interface.
func (sf *ScalarFunction) Clone() Expression {
newArgs := make([]Expression, 0, len(sf.GetArgs()))
for _, arg := range sf.GetArgs() {
newArgs = append(newArgs, arg.Clone())
}
switch v := sf.Function.(type) {
case *builtinCastSig:
return NewCastFunc(v.tp, newArgs[0], sf.GetCtx())
case *builtinValuesSig:
return NewValuesFunc(v.offset, sf.GetType(), sf.GetCtx())
}
newFunc, _ := NewFunction(sf.GetCtx(), sf.FuncName.L, sf.RetType, newArgs...)
return newFunc
}
// GetType implements Expression interface.
func (sf *ScalarFunction) GetType() *types.FieldType {
return sf.RetType
}
// Equal implements Expression interface.
func (sf *ScalarFunction) Equal(e Expression, ctx context.Context) bool {
fun, ok := e.(*ScalarFunction)
if !ok {
return false
}
if sf.FuncName.L != fun.FuncName.L {
return false
}
return sf.Function.equal(fun.Function)
}
// IsCorrelated implements Expression interface.
func (sf *ScalarFunction) IsCorrelated() bool {
for _, arg := range sf.GetArgs() {
if arg.IsCorrelated() {
return true
}
}
return false
}
// Decorrelate implements Expression interface.
func (sf *ScalarFunction) Decorrelate(schema *Schema) Expression {
for i, arg := range sf.GetArgs() {
sf.GetArgs()[i] = arg.Decorrelate(schema)
}
return sf
}
// Eval implements Expression interface.
func (sf *ScalarFunction) Eval(row []types.Datum) (types.Datum, error) {
return sf.Function.eval(row)
}
// EvalInt implements Expression interface.
func (sf *ScalarFunction) EvalInt(row []types.Datum, sc *variable.StatementContext) (int64, bool, error) {
return sf.Function.evalInt(row)
}
// EvalReal implements Expression interface.
func (sf *ScalarFunction) EvalReal(row []types.Datum, sc *variable.StatementContext) (float64, bool, error) {
return sf.Function.evalReal(row)
}
// EvalDecimal implements Expression interface.
func (sf *ScalarFunction) EvalDecimal(row []types.Datum, sc *variable.StatementContext) (*types.MyDecimal, bool, error) {
return sf.Function.evalDecimal(row)
}
// EvalString implements Expression interface.
func (sf *ScalarFunction) EvalString(row []types.Datum, sc *variable.StatementContext) (string, bool, error) {
return sf.Function.evalString(row)
}
// EvalTime implements Expression interface.
func (sf *ScalarFunction) EvalTime(row []types.Datum, sc *variable.StatementContext) (types.Time, bool, error) {
return sf.Function.evalTime(row)
}
// EvalDuration implements Expression interface.
func (sf *ScalarFunction) EvalDuration(row []types.Datum, sc *variable.StatementContext) (types.Duration, bool, error) {
return sf.Function.evalDuration(row)
}
// HashCode implements Expression interface.
func (sf *ScalarFunction) HashCode() []byte {
var bytes []byte
v := make([]types.Datum, 0, len(sf.GetArgs())+1)
bytes, _ = codec.EncodeValue(bytes, types.NewStringDatum(sf.FuncName.L))
v = append(v, types.NewBytesDatum(bytes))
for _, arg := range sf.GetArgs() {
v = append(v, types.NewBytesDatum(arg.HashCode()))
}
bytes = bytes[:0]
bytes, _ = codec.EncodeValue(bytes, v...)
return bytes
}
// ResolveIndices implements Expression interface.
func (sf *ScalarFunction) ResolveIndices(schema *Schema) {
for _, arg := range sf.GetArgs() {
arg.ResolveIndices(schema)
}
}