filter/README.md

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# filter - a simple struct field filter for go
## Usage
```
// Example data structure
type Example struct {
String string
Int int
Bool bool
Struct Struct1
}
type Struct1 struct {
String string
Struct Struct2
}
type Struct2 struct {
Int int
}
// Filter implements the filter.Filter interface
type Filter []Example
func (v Filter) Len() int { return len(v) }
func (v Filter) Index(i int) interface{} { return v[i] }
func (v *Filter) Remove(i, j int) { *v = append((*v)[:i], (*v)[j:]...) }
// Example data
var data = Filter{
{"str1", 42, true, Struct1{"s1", Struct2{1}}},
{"2str", 42, true, Struct1{"s2", Struct2{2}}},
{"str3", 42, false, Struct1{"s3", Struct2{3}}},
}
```
### Filter logic
Supported logical matching:
* AND - all of the queries have to match
* OR - only one query has to match
* NOT - none of the queries have to match
### Explicit match
```
filter.NewQuery("Bool:true", filter.OR).Filter(&data)
data = [{str1 42 true {s1 {1}}} {str2 42 true {s2 {2}}}]
```
### Wildcard match
```
filter.NewQuery("String:s*", filter.OR).Filter(&data)
data = [{str1 42 true {s1 {1}}} {str3 42 false {s3 {3}}}]
```
### Nested struct match
```
filter.NewQuery("Struct.Struct.Int:3", filter.OR).Filter(&data)
data = [{str3 42 false {s3 {3}}}]
```
### Multiple matches
```
filter.NewQuery("Struct.String:*2 Bool:true", filter.AND).Filter(&data)
data = [{2str 42 true {s2 {2}}}]
```
## Benchmarks
```
go test -cpu 1,2,4 --bench .
BenchmarkFilterSimple 2000000 877 ns/op 432 B/op 12 allocs/op
BenchmarkFilterSimple-2 2000000 865 ns/op 432 B/op 12 allocs/op
BenchmarkFilterSimple-4 1000000 1713 ns/op 432 B/op 12 allocs/op
BenchmarkFilterComplex 500000 3032 ns/op 672 B/op 48 allocs/op
BenchmarkFilterComplex-2 500000 3100 ns/op 672 B/op 48 allocs/op
BenchmarkFilterComplex-4 500000 6235 ns/op 672 B/op 48 allocs/op
BenchmarkFilterComplexOr 500000 2649 ns/op 816 B/op 39 allocs/op
BenchmarkFilterComplexOr-2 500000 2659 ns/op 816 B/op 39 allocs/op
BenchmarkFilterComplexOr-4 500000 5548 ns/op 816 B/op 39 allocs/op
BenchmarkGenericFilterSimple 500000 2340 ns/op 1200 B/op 24 allocs/op
BenchmarkGenericFilterSimple-2 1000000 2307 ns/op 1200 B/op 24 allocs/op
BenchmarkGenericFilterSimple-4 1000000 3615 ns/op 1200 B/op 24 allocs/op
BenchmarkGenericFilterComplex 200000 7073 ns/op 1680 B/op 96 allocs/op
BenchmarkGenericFilterComplex-2 200000 7598 ns/op 1680 B/op 96 allocs/op
BenchmarkGenericFilterComplex-4 200000 10735 ns/op 1680 B/op 96 allocs/op
BenchmarkGenericFilterComplexOr 200000 5406 ns/op 2456 B/op 61 allocs/op
BenchmarkGenericFilterComplexOr-2 300000 5300 ns/op 2456 B/op 61 allocs/op
BenchmarkGenericFilterComplexOr-4 200000 7707 ns/op 2456 B/op 61 allocs/op
```