From 1f93d6b6dc0a9927dd578c6fc66708b8b88cac44 Mon Sep 17 00:00:00 2001
From: Anton Medvedev <anton@medv.io>
Date: Sat, 8 Apr 2023 03:17:17 +0200
Subject: [PATCH] Add npm

---
 .github/workflows/test.yml | 12 ++++-
 npm/index.js               | 92 ++++++++++++++++++++++++++++++++++++++
 npm/test.js                | 68 ++++++++++++++++++++++++++++
 3 files changed, 170 insertions(+), 2 deletions(-)
 create mode 100644 npm/index.js
 create mode 100644 npm/test.js

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4fb6c48..28b4e85 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,5 +17,13 @@ jobs:
       with:
         go-version: 1.18
 
-    - name: Build
-      run: go build -v ./...
+    - name: Test
+      run: go test ./...
+
+  node:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Test
+      run: cd npm && node test.js
diff --git a/npm/index.js b/npm/index.js
new file mode 100644
index 0000000..5af795f
--- /dev/null
+++ b/npm/index.js
@@ -0,0 +1,92 @@
+void async function main() {
+  const process = await import('node:process')
+  let input = ''
+  process.stdin.setEncoding('utf8')
+  for await (const chunk of process.stdin)
+    input += chunk
+  const args = process.argv.slice(2)
+
+  let json
+  try {
+    json = JSON.parse(input)
+  } catch (err) {
+    try {
+      json = eval(input)
+    } catch (_) {
+      process.stderr.write(`Invalid JSON: ${err.message}\n`)
+      process.exit(1)
+    }
+  }
+
+  let i, code, output = json
+  for ([i, code] of args.entries()) try {
+    output = transform(output, code)
+  } catch (err) {
+    printErr(err)
+    process.exit(1)
+  }
+
+  if (typeof output === 'undefined')
+    process.stderr.write('undefined\n')
+  else if (typeof output === 'string')
+    console.log(output)
+  else
+    console.log(JSON.stringify(output, null, 2))
+
+  function printErr(err) {
+    let pre = args.slice(0, i).join(' ')
+    let post = args.slice(i + 1).join(' ')
+    if (pre.length > 20) pre = '...' + pre.substring(pre.length - 20)
+    if (post.length > 20) post = post.substring(0, 20) + '...'
+    process.stderr.write(
+      `\n  ${pre} ${code} ${post}\n` +
+      `  ${' '.repeat(pre.length + 1)}${'^'.repeat(code.length)}\n` +
+      `\n${err.stack || err}\n`
+    )
+  }
+}()
+
+function transform(json, code) {
+  if ('.' === code)
+    return json
+
+  if ('?' === code)
+    return Object.keys(json)
+
+  if (/^(\.\w*)+\[]/.test(code))
+    code = fold(code.split('[]'))
+
+  if (/^\.\[/.test(code))
+    return eval(`(function () {
+      return this${code.substring(1)}
+    })`).call(json)
+
+  if (/^\./.test(code))
+    return eval(`(function () {
+      return this${code}
+    })`).call(json)
+
+  if (/^map\(.+?\)$/.test(code))
+    return eval(`(function () {
+      return this.map(x => apply(x, ${code.substring(4, code.length - 1)}))
+    })`).call(json)
+
+  const fn = eval(`(function () {
+    return ${code}
+  })`).call(json)
+
+  return apply(json, fn)
+}
+
+function apply(json, fn) {
+  if (typeof fn === 'function') return fn(json)
+  return fn
+}
+
+function fold(s) {
+  if (s.length === 1)
+    return 'x => x' + s[0]
+  let obj = s.shift()
+  obj = obj === '.' ? 'x' : 'x' + obj
+  return `x => Object.values(${obj}).flatMap(${fold(s)})`
+}
diff --git a/npm/test.js b/npm/test.js
new file mode 100644
index 0000000..1181ef1
--- /dev/null
+++ b/npm/test.js
@@ -0,0 +1,68 @@
+async function test(name, fn) {
+  try {
+    await fn(await import('node:assert/strict'))
+    console.log(`✓ ${name}`)
+  } catch (err) {
+    console.error(`✗ ${name}`)
+    throw err
+  }
+}
+
+async function run(json, code = '') {
+  const {spawnSync} = await import('node:child_process')
+  return spawnSync(`echo '${JSON.stringify(json)}' | node index.js ${code}`, {
+    stdio: 'pipe',
+    encoding: 'utf8',
+    shell: true
+  })
+}
+
+void async function main() {
+  await test('passes json as is', async t => {
+    const {stdout} = await run([{'greeting': 'hello world'}])
+    t.deepEqual(JSON.parse(stdout), [{'greeting': 'hello world'}])
+  })
+
+  await test('works with anon func', async t => {
+    const {stdout} = await run({'key': 'value'}, '\'function (x) { return x.key }\'')
+    t.equal(stdout, 'value\n')
+  })
+
+  await test('works with arrow func', async t => {
+    const {stdout} = await run({'key': 'value'}, '\'x => x.key\'')
+    t.equal(stdout, 'value\n')
+  })
+
+  await test('works with arrow func with param brackets', async t => {
+    const {stdout} = await run({'key': 'value'}, '\'(x) => x.key\'')
+    t.equal(stdout, 'value\n')
+  })
+
+  await test('this is json', async t => {
+    const {stdout} = await run([1, 2, 3, 4, 5], '\'this.map(x => x * this.length)\'')
+    t.deepEqual(JSON.parse(stdout), [5, 10, 15, 20, 25])
+  })
+
+  await test('args chain works', async t => {
+    const {stdout} = await run({'items': ['foo', 'bar']}, '\'this.items\' \'.\' \'x => x[1]\'')
+    t.equal(stdout, 'bar\n')
+  })
+
+  await test('flat map works', async t => {
+    const {stdout} = await run({master: {foo: [{bar: [{val: 1}]}]}}, '.master.foo[].bar[].val')
+    t.deepEqual(JSON.parse(stdout), [1])
+  })
+
+  await test('flat map works on the first level', async t => {
+    const {stdout} = await run([{val: 1}, {val: 2}], '.[].val')
+    t.deepEqual(JSON.parse(stdout), [1, 2])
+  })
+
+  await test('invalid code argument', async t => {
+    const json = {foo: 'bar'}
+    const code = '".foo.toUpperCase("'
+    const {stderr, status} = await run(json, code)
+    t.strictEqual(status, 1)
+    t.ok(stderr.includes(`SyntaxError: Unexpected token '}'`))
+  })
+}()