├── Readme.md
└── main.go


/Readme.md:
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 1 | 
 2 | ## filter(1)
 3 | 
 4 |   Filter JSON streams using javascript.
 5 | 
 6 |   ```bash
 7 |   $ echo '{"event":true}{"event":1}{}' | filter "if (j.event) return j"
 8 |   {"event":true}
 9 |   {"event":1}
10 |   ```
11 | 
12 | ## Installation
13 |   
14 |   ```bash
15 |   $ go get github.com/segmentio/filter
16 |   ```
17 | 
18 | ## Usage
19 | 
20 |   ```bash
21 |   Usage: 
22 |     filter <js>
23 | 
24 |     filter -h | --help
25 |     filter -v | --version
26 | 
27 |   Options:
28 |     -h, --help      show help information
29 |     -v, --version   show version information
30 |   ```
31 | 
32 | ## License
33 | 
34 |   MIT


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/main.go:
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 1 | package main
 2 | 
 3 | import "github.com/robertkrimen/otto"
 4 | import "github.com/tj/docopt"
 5 | import "encoding/json"
 6 | import "io"
 7 | import "os"
 8 | 
 9 | // Version.
10 | var Version = "0.0.1"
11 | 
12 | // Usage.
13 | var Usage = `
14 |   Usage: 
15 |     filter <js>
16 | 
17 |     filter -h | --help
18 |     filter -v | --version
19 | 
20 |   Options:
21 |     -h, --help      show help information
22 |     -v, --version   show version information
23 | 
24 | `
25 | 
26 | func main() {
27 | 	args, err := docopt.Parse(Usage, nil, true, Version, false)
28 | 	check(err)
29 | 
30 | 	js := args["<js>"].(string)
31 | 	fn := "(function(){ " + js + " })()"
32 | 	vm := otto.New()
33 | 
34 | 	dec := json.NewDecoder(os.Stdin)
35 | 	enc := json.NewEncoder(os.Stdout)
36 | 
37 | 	for {
38 | 		var v interface{}
39 | 		err := dec.Decode(&v)
40 | 
41 | 		if err == io.EOF {
42 | 			return
43 | 		}
44 | 
45 | 		check(err)
46 | 
47 | 		vm.Set("j", v)
48 | 		val, err := vm.Run(fn)
49 | 		check(err)
50 | 
51 | 		if val.IsDefined() {
52 | 			v, err := val.Export()
53 | 			check(err)
54 | 			enc.Encode(v)
55 | 		}
56 | 	}
57 | }
58 | 
59 | func check(err error) {
60 | 	if err != nil {
61 | 		println("filter: " + err.Error())
62 | 		os.Exit(1)
63 | 	}
64 | }
65 | 


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