Lossless JSON-to-AST Parser and AST-to-JSON Generator
JSON-ASTy is a JavaScript library providing a lossless JavaScript Object Notation (JSON) to Abstract Syntax Tree (AST) parser and a corresponding AST to JSON generator. It is intended for cases where one has to read JSON into an AST, manipulate the AST and generate JSON from the AST again while fully preserving the formatting of the original JSON. The AST is based on ASTy-ASTq, and hence can powerfully queried with ASTq, and manipulated with ASTy.
$ npm install json-astyconst JsonAsty = require("json-asty")
/* the JSON input */
let json = `{
"foo": {
"bar": true,
"baz": 42.0,
"quux": [ "test1\\"test2", "test3", 7, true ]
}
}`
console.log(`JSON (old):\n${json}`)
/* parse JSON into AST */
let ast = JsonAsty.parse(json)
console.log(`AST Dump (all):\n${JsonAsty.dump(ast, { colors: true })}`)
/* the AST query */
let query = `
.// member [
..// member [
/ string [ pos() == 1 && @value == "foo" ]
]
&&
/ string [ pos() == 1 && @value == "baz" ]
]
/ * [ pos() == 2 ]
`
console.log(`AST Query:\n${query}`)
/* query AST node */
let nodes = ast.query(query)
let node = nodes[0]
console.log(`AST Dump (sub, old):\n${node.dump()}`)
/* manipulate AST node */
let nodeNew = node.create("string").set({ value: "TEST" })
node.parent().del(node).add(nodeNew)
console.log(`AST Dump (sub, new):\n${node.dump()}`)
/* unparse AST into JSON */
let jsonNew = JsonAsty.unparse(ast)
console.log(`JSON (new):\n${jsonNew}`)Output:
JSON (old):
{
"foo": {
"bar": true,
"baz": 42.0,
"quux": [ "test1\"test2", "test3", 7, true ]
}
}
AST Dump (all):
object (prolog: "{\n ", epilog: "}") [1,1]
└── member [2,5]
├── string (body: "\"foo\"", value: "foo", epilog: ": ") [2,5]
└── object (prolog: "{\n ", epilog: "}\n") [2,12]
├── member (epilog: ",\n ") [3,9]
│ ├── string (body: "\"bar\"", value: "bar", epilog: ": ") [3,9]
│ └── boolean (body: "true", value: true) [3,16]
├── member (epilog: ",\n ") [4,9]
│ ├── string (body: "\"baz\"", value: "baz", epilog: ": ") [4,9]
│ └── number (body: "42.0", value: 42) [4,16]
└── member [5,9]
├── string (body: "\"quux\"", value: "quux", epilog: ": ") [5,9]
└── array (prolog: "[ ", epilog: " ]\n ") [5,17]
├── string (body: "\"test1\\\"test2\"", value: "test1\"test2", epilog: ", ") [5,19]
├── string (body: "\"test3\"", value: "test3", epilog: ", ") [5,35]
├── number (body: "7", value: 7, epilog: ", ") [5,44]
└── boolean (body: "true", value: true) [5,47]
AST Query:
.// member [
..// member [
/ string [ pos() == 1 && @value == "foo" ]
]
&&
/ string [ pos() == 1 && @value == "baz" ]
]
/ * [ pos() == 2 ]
AST Dump (sub, old):
number (body: "42.0", value: 42) [4,16]
AST Dump (sub, new):
number (body: "42.0", value: 42) [4,16]
JSON (new):
{
"foo": {
"bar": true,
"baz": "TEST",
"quux": [ "test1\"test2", "test3", 7, true ]
}
}
Copyright © 2018-2024 Dr. Ralf S. Engelschall (http://engelschall.com/)
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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