flatjson

Fast and dirty parsing of JSON! Decode only the parts you care about!

Why

This parser is very fast (or I mean it's not slow?) and allows you to only parse the things you care about. It also allows you to "visit" all the keys of a JSON entity recursively, in a single pass.

data := []byte(`{
    "hello":["world"],
    "bonjour": {"le": "monde"}
}`)

flatjson.ScanObject(data, 0, &flatjson.Callbacks{
    MaxDepth: 99,
    OnNumber: func(prefixes flatjson.Prefixes, val flatjson.Number) {
        // handle
    },
    OnString: func(prefixes flatjson.Prefixes, val flatjson.String) {
        // handle
    },
    OnBoolean: func(prefixes flatjson.Prefixes, val flatjson.Bool) {
        // handle
    },
    OnNull: func(prefixes flatjson.Prefixes, val flatjson.Null) {
        // handle
    },
})

Speed

In a dumb benchmark:

BenchmarkFlatJSON-12        	 1660015	       722.9 ns/op	 930.93 MB/s	      32 B/op	       2 allocs/op
BenchmarkEncodingJSON-12    	  594927	      2394 ns/op	 311.13 MB/s	     168 B/op	       3 allocs/op

About that name

This library used to support only what I called a "flat" subset of JSON. But now it supports all JSON, but you can still decide how "flat" you want to go. The flatter, the faster :).

Flat JSON is a subset of JSON where the only supported types are objects containing strings, numbers, booleans or null values. There can't be nested objects or arrays. The root element must be an object.