JSON BinPack Example

README.md

Gists don't let me upload binary files directly. To get the output.bin binary file, run:

echo "0x03 0x01 0x01 0x66 0x6f 0x6f 0xfa 0x01" | xxd -r > output.bin

analysis.txt

0x03 => Size of the array (3)
0x01 => Boolean "true"
0x01 => Size of the string minus minimum plus 1 (3 = 3 - 3 + 1)
0x66 0x6f 0x6f => String "foo"
0xfa 0x01 => Base-128 variable-length unsigned integer 1000, as (1000 / 4) - ceil(-2 / 4)

Reduction from 17 bytes in minified form to 8 bytes (~53%)

document.json

[ true, "foo", 1000 ]

encoding.json

{
  "$schema": "https://www.jsonbinpack.org/schemas/encoding/v1.json",
  "name": "BOUNDED_8BITS_TYPED_ARRAY",
  "options": {
    "minimum": 0,
    "maximum": 10,
    "encoding": {
      "name": "FLOOR_MULTIPLE_ENUM_VARINT",
      "options": {
        "minimum": -2,
        "multiplier": 4
      }
    },
    "prefixEncodings": [
      {
        "name": "BYTE_CHOICE_INDEX",
        "options": {
          "choices": [ false, true ]
        }
      },
      {
        "name": "FLOOR_VARINT_PREFIX_UTF8_STRING_SHARED",
        "options": {
          "minimum": 3
        }
      }
    ]
  }
}

output.hex

0x03 0x01 0x01 0x66 0x6f 0x6f 0xfa 0x01

schema.json

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "array",
  "maxItems": 10,
  "items": {
    "type": "integer",
    "minimum": -2,
    "multipleOf": 4
  },
  "prefixItems": [
    { "type": "boolean" },
    { 
      "type": "string",
      "minLength": 3 
    }
  ]
}

tracing.json

[
  { "type": "start", "path": "/", "offset": 0 },
  { "type": "start", "path": "/options/prefixEncodings/0", "offset": 1 },
  { "type": "end", "path": "/options/prefixEncodings/0", "offset": 1 },
  { "type": "start", "path": "/options/prefixEncodings/1", "offset": 2 },
  { "type": "end", "path": "/options/prefixEncodings/1", "offset": 5 },
  { "type": "start", "path": "/options/encoding", "offset": 6 },
  { "type": "end", "path": "/options/encoding", "offset": 7 },
  { "type": "end", "path": "/", "offset": 7 }
]