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feat: merging functionality from minipass-json-stream
#246
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,223 @@ | ||
const Parser = require('jsonparse') | ||
const { Minipass } = require('minipass') | ||
|
||
class JSONStreamError extends Error { | ||
constructor (err, caller) { | ||
super(err.message) | ||
Error.captureStackTrace(this, caller || this.constructor) | ||
} | ||
|
||
get name () { | ||
return 'JSONStreamError' | ||
} | ||
} | ||
|
||
const check = (x, y) => | ||
typeof x === 'string' ? String(y) === x | ||
: x && typeof x.test === 'function' ? x.test(y) | ||
: typeof x === 'boolean' || typeof x === 'object' ? x | ||
: typeof x === 'function' ? x(y) | ||
: false | ||
|
||
class JSONStream extends Minipass { | ||
#count = 0 | ||
#ending = false | ||
#footer = null | ||
#header = null | ||
#map = null | ||
#onTokenOriginal | ||
#parser | ||
#path = null | ||
#root = null | ||
|
||
constructor (opts) { | ||
super({ | ||
...opts, | ||
objectMode: true, | ||
}) | ||
|
||
const parser = this.#parser = new Parser() | ||
parser.onValue = value => this.#onValue(value) | ||
this.#onTokenOriginal = parser.onToken | ||
parser.onToken = (token, value) => this.#onToken(token, value) | ||
parser.onError = er => this.#onError(er) | ||
|
||
this.#path = typeof opts.path === 'string' | ||
? opts.path.split('.').map(e => | ||
e === '$*' ? { emitKey: true } | ||
: e === '*' ? true | ||
: e === '' ? { recurse: true } | ||
: e) | ||
: Array.isArray(opts.path) && opts.path.length ? opts.path | ||
: null | ||
|
||
if (typeof opts.map === 'function') { | ||
this.#map = opts.map | ||
} | ||
} | ||
|
||
#setHeaderFooter (key, value) { | ||
// header has not been emitted yet | ||
if (this.#header !== false) { | ||
this.#header = this.#header || {} | ||
this.#header[key] = value | ||
} | ||
|
||
// footer has not been emitted yet but header has | ||
if (this.#footer !== false && this.#header === false) { | ||
this.#footer = this.#footer || {} | ||
this.#footer[key] = value | ||
} | ||
} | ||
|
||
#onError (er) { | ||
// error will always happen during a write() call. | ||
const caller = this.#ending ? this.end : this.write | ||
this.#ending = false | ||
return this.emit('error', new JSONStreamError(er, caller)) | ||
} | ||
|
||
#onToken (token, value) { | ||
const parser = this.#parser | ||
this.#onTokenOriginal.call(this.#parser, token, value) | ||
if (parser.stack.length === 0) { | ||
if (this.#root) { | ||
const root = this.#root | ||
if (!this.#path) { | ||
super.write(root) | ||
} | ||
this.#root = null | ||
this.#count = 0 | ||
} | ||
} | ||
} | ||
|
||
#onValue (value) { | ||
const parser = this.#parser | ||
// the LAST onValue encountered is the root object. | ||
// just overwrite it each time. | ||
this.#root = value | ||
|
||
if (!this.#path) { | ||
return | ||
} | ||
|
||
let i = 0 // iterates on path | ||
let j = 0 // iterates on stack | ||
let emitKey = false | ||
while (i < this.#path.length) { | ||
const key = this.#path[i] | ||
j++ | ||
|
||
if (key && !key.recurse) { | ||
const c = (j === parser.stack.length) ? parser : parser.stack[j] | ||
if (!c) { | ||
return | ||
} | ||
if (!check(key, c.key)) { | ||
this.#setHeaderFooter(c.key, value) | ||
return | ||
} | ||
emitKey = !!key.emitKey | ||
i++ | ||
} else { | ||
i++ | ||
if (i >= this.#path.length) { | ||
return | ||
} | ||
const nextKey = this.#path[i] | ||
if (!nextKey) { | ||
return | ||
} | ||
while (true) { | ||
const c = (j === parser.stack.length) ? parser : parser.stack[j] | ||
if (!c) { | ||
return | ||
} | ||
if (check(nextKey, c.key)) { | ||
i++ | ||
if (!Object.isFrozen(parser.stack[j])) { | ||
parser.stack[j].value = null | ||
} | ||
break | ||
} else { | ||
this.#setHeaderFooter(c.key, value) | ||
} | ||
j++ | ||
} | ||
} | ||
} | ||
|
||
// emit header | ||
if (this.#header) { | ||
const header = this.#header | ||
this.#header = false | ||
this.emit('header', header) | ||
} | ||
if (j !== parser.stack.length) { | ||
return | ||
} | ||
|
||
this.#count++ | ||
const actualPath = parser.stack.slice(1) | ||
.map(e => e.key).concat([parser.key]) | ||
if (value !== null && value !== undefined) { | ||
const data = this.#map ? this.#map(value, actualPath) : value | ||
if (data !== null && data !== undefined) { | ||
const emit = emitKey ? { value: data } : data | ||
if (emitKey) { | ||
emit.key = parser.key | ||
} | ||
super.write(emit) | ||
} | ||
} | ||
|
||
if (parser.value) { | ||
delete parser.value[parser.key] | ||
} | ||
|
||
for (const k of parser.stack) { | ||
k.value = null | ||
} | ||
} | ||
|
||
write (chunk, encoding) { | ||
if (typeof chunk === 'string') { | ||
chunk = Buffer.from(chunk, encoding) | ||
} else if (!Buffer.isBuffer(chunk)) { | ||
return this.emit('error', new TypeError( | ||
'Can only parse JSON from string or buffer input')) | ||
} | ||
this.#parser.write(chunk) | ||
return this.flowing | ||
} | ||
|
||
end (chunk, encoding) { | ||
this.#ending = true | ||
if (chunk) { | ||
this.write(chunk, encoding) | ||
} | ||
|
||
const h = this.#header | ||
this.#header = null | ||
const f = this.#footer | ||
this.#footer = null | ||
if (h) { | ||
this.emit('header', h) | ||
} | ||
if (f) { | ||
this.emit('footer', f) | ||
} | ||
return super.end() | ||
} | ||
|
||
static get JSONStreamError () { | ||
return JSONStreamError | ||
} | ||
|
||
static parse (path, map) { | ||
return new JSONStream({ path, map }) | ||
} | ||
} | ||
|
||
module.exports = JSONStream |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,46 @@ | ||
const t = require('tap') | ||
const { JSONStreamError, parse } = require('../lib/json-stream.js') | ||
|
||
t.test('JSONStream', (t) => { | ||
t.test('JSONStreamError constructor', (t) => { | ||
const error = new JSONStreamError(new Error('error')) | ||
t.equal(error.message, 'error') | ||
t.equal(error.name, 'JSONStreamError') | ||
t.end() | ||
}) | ||
|
||
t.test('JSONStream.write', (t) => { | ||
t.test('JSONStream write error from numerical (not string not buffer)', async (t) => { | ||
const stream = parse('*', {}) | ||
try { | ||
stream.write(5) | ||
} catch (error) { | ||
t.equal(error.message, 'Can only parse JSON from string or buffer input') | ||
t.equal(error.name, 'TypeError') | ||
} | ||
t.end() | ||
}) | ||
|
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t.end() | ||
}) | ||
|
||
t.test('JSONStream.end', (t) => { | ||
t.test( | ||
'JSONStream end invalid chunk throws JSONStreamError from parser', | ||
(t) => { | ||
const stream = parse('*', {}) | ||
try { | ||
stream.end('not a valid chunk') | ||
} catch (error) { | ||
t.equal(error.name, 'JSONStreamError') | ||
t.equal(error.message, 'Unexpected "o" at position 1 in state STOP') | ||
} | ||
t.end() | ||
} | ||
) | ||
|
||
t.end() | ||
}) | ||
|
||
t.end() | ||
}) |
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