# 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}}},
}
```

### Explicit match

```
filter.NewQuery("Bool:true").Filter(&data)

data = [{str1 42 true {s1 {1}}} {str2 42 true {s2 {2}}}]
```

### Wildcard match

```
filter.NewQuery("String:s*").Filter(&data)

data = [{str1 42 true {s1 {1}}} {str3 42 false {s3 {3}}}]
```

### Nested struct match

```
filter.NewQuery("Struct.Struct.Int:3").Filter(&data)

data = [{str3 42 false {s3 {3}}}]
```

### Multiple matches

```
filter.NewQuery("Struct.String:*2 Bool:true").Filter(&data)

data = [{2str 42 true {s2 {2}}}]
```

## Benchmarks

```
go test -cpu 1,2,4 --bench .
BenchmarkFilterSimple             	 2000000	       899 ns/op	     432 B/op	      12 allocs/op
BenchmarkFilterSimple-2           	 2000000	       896 ns/op	     432 B/op	      12 allocs/op
BenchmarkFilterSimple-4           	 1000000	      1439 ns/op	     432 B/op	      12 allocs/op
BenchmarkGenericFilterSimple      	  500000	      2438 ns/op	    1200 B/op	      24 allocs/op
BenchmarkGenericFilterSimple-2    	  500000	      2406 ns/op	    1200 B/op	      24 allocs/op
BenchmarkGenericFilterSimple-4    	  500000	      2645 ns/op	    1200 B/op	      24 allocs/op
BenchmarkFilterComplex            	  500000	      2929 ns/op	     672 B/op	      42 allocs/op
BenchmarkFilterComplex-2          	  500000	      2918 ns/op	     672 B/op	      42 allocs/op
BenchmarkFilterComplex-4          	  500000	      5574 ns/op	     672 B/op	      42 allocs/op
BenchmarkGenericFilterComplex     	  200000	      7343 ns/op	    1680 B/op	      84 allocs/op
BenchmarkGenericFilterComplex-2   	  200000	      7400 ns/op	    1680 B/op	      84 allocs/op
BenchmarkGenericFilterComplex-4   	  200000	     11979 ns/op	    1680 B/op	      84 allocs/op
```