forked from pingcap/tidb
/
where.go
73 lines (64 loc) · 2 KB
/
where.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
// Copyright 2015 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 plans
import (
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/expression/expressions"
"github.com/pingcap/tidb/field"
"github.com/pingcap/tidb/plan"
"github.com/pingcap/tidb/util/format"
"github.com/pingcap/tidb/util/types"
)
var (
_ plan.Plan = (*FilterDefaultPlan)(nil)
)
// FilterDefaultPlan handles WHERE statement, filters rows by specific
// expressions.
type FilterDefaultPlan struct {
plan.Plan
Expr expression.Expression
}
// Explain implements plan.Plan Explain interface.
func (r *FilterDefaultPlan) Explain(w format.Formatter) {
r.Plan.Explain(w)
w.Format("┌FilterDefaultPlan Filter on %v\n", r.Expr)
w.Format("└Output field names %v\n", field.RFQNames(r.GetFields()))
}
// Do implements plan.Plan Do interface.
func (r *FilterDefaultPlan) Do(ctx context.Context, f plan.RowIterFunc) (err error) {
m := map[interface{}]interface{}{}
fields := r.GetFields()
return r.Plan.Do(ctx, func(rid interface{}, data []interface{}) (bool, error) {
m[expressions.ExprEvalIdentFunc] = func(name string) (interface{}, error) {
return getIdentValue(name, fields, data, field.DefaultFieldFlag)
}
val, err := r.Expr.Eval(ctx, m)
if err != nil {
return false, err
}
if val == nil {
return true, nil
}
// Evaluate the expression, if the result is true, go on, otherwise
// skip this row.
x, err := types.ToBool(val)
if err != nil {
return false, err
}
if x == 0 {
return true, nil
}
return f(rid, data)
})
}