qjson

Fast, lightweight JSON encode/decode and query library. It provides an inspectable/mutable JSONTree structure and a powerful QJSON Path query syntax.

Highlights

• High‑performance parsing: decode raw JSON into traversable JSONTree/Node with object pool reuse to reduce GC pressure.
• QJSON Path queries: access by object keys and array indexes; support the # selector and filters (==, =, !==, !=, >, >=, <, <=), plus escaped dots in keys.
• In‑place mutation: set values via SetString/SetInt/SetBool/SetFloat, remove object keys and array elements.
• Readable output: ANSI colored output via ColorfulMarshal and ColorfulMarshalWithIndent for terminal UX.
• Encoding interoperability: json.Marshal/Unmarshal works directly on JSONTree; convert any Go object via ConvertToJSONTree.
• Equality and hashing: structural equality with Equal() and stable hashes with Hash()/Rehash().
• Diff: Diff() produces a list of differences between two trees, useful for change audits and test comparisons.
• Zero external dependencies: standard library only (Go ≥ 1.13).

Install

go get -u github.com/qjpcpu/qjson@latest

Quick Start

package main

import (
  "encoding/json"
  "fmt"
  qjson "github.com/qjpcpu/qjson"
)

func main() {
  // Parse
  tree, err := qjson.Decode([]byte(`{"name":{"first":"Tom","last":"Anderson"},"age":37}`))
  if err != nil { panic(err) }

  // Query
  fmt.Println(tree.Find("name.last").AsString()) // Anderson
  fmt.Println(tree.Find("age").AsInt())          // 37

  // Mutate
  tree.Find("name.first").SetString("Link")
  tree.Find("age").SetInt(12)

  // Encode (std lib)
  data, _ := json.Marshal(tree)
  fmt.Println(string(data)) // {"name":{"first":"Link","last":"Anderson"},"age":12}

  // Color output
  fmt.Println(string(tree.ColorfulMarshal()))
}

QJSON Path Syntax

• Basics: use . to access object keys or array indexes
  • name.last → "Anderson"
  • children.1 → "Alex"
• Selector #: project or filter arrays
  • friends.#.age → [44,68,47]
• Filters inside #(...)
  • Contains: #(=c); Equals: #(==c); Not contains: #(!=c); Not equals: #(!==c)
  • Comparisons: age>47, age>=47, age<47, age<=47
  • Nested: friends.#(nets.#(=="fb"))
• Escaping: keys containing . must escape the dot, e.g. fav\.movie or raw string literal fav\.movie

Modify & Delete

// Modify
tree.Find(`name.first`).SetString("Link")
tree.Find(`age`).SetInt(12)

// Remove object key
tree.Remove(`name.last`)

// Remove array element; clear array
tree.Remove(`children.0`)
tree.Remove(`children.#`)

Object Conversion & Std Encoding

// Any object → JSONTree
tree, err := qjson.ConvertToJSONTree(&struct{ X string `json:"x"` }{X:"1"})

// JSONTree ↔ std lib
var t qjson.JSONTree
json.Unmarshal([]byte(`{"a":1}`), &t)
data, _ := json.Marshal(&t)

Color Output

// Non‑indented color
fmt.Println(string(tree.ColorfulMarshal()))
// Indented color
fmt.Println(string(tree.ColorfulMarshalWithIndent()))

Equality, Hash & Diff

t1, _ := qjson.Decode([]byte(`{"a":1}`))
t2, _ := qjson.Decode([]byte(`{"a":1}`))
fmt.Println(t1.Equal(t2))      // true
fmt.Println(t1.Root.Hash())    // structural hash

// Diff
items := qjson.Diff(t1, t2)
fmt.Println(items.Exist())     // any differences
fmt.Println(items.String())    // human‑readable diff

Performance & Benchmarks

• Object pools and compact data structures improve parsing and manipulation performance.
• Run benchmarks:

go test -bench=. -benchmem

Testing & Coverage

• Run:

go test ./... -cover

• Coverage: use the printed result (e.g. 87%+) from your environment.
• Optional: enable Codecov by adding CODECOV_TOKEN secret and check the badge on PRs.

Compatibility

• Go 1.13 and above.
• Standard library only, no external dependencies.

Notes

• Path syntax includes escaping and filter expressions; validate complex paths in tests first.
• unsafe conversions between string and []byte are used to reduce copies; ensure it fits your environment.
• ANSI color output may not render in some terminals.

License

MIT — see LICENSE.