introduce support for jsonlines input files

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 bin
+.playground

babel.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        targets: {
+          node: 'current'
+        }
+      }
+    ]
+  ]
+}

package.json

@@ -11,7 +11,7 @@
     "lint": "standard --verbose --fix",
     "posttest": "ls -1 *.md | xargs -t -n 1 markdown-link-check",
     "prepublishOnly": "npm run build",
-    "pretest": "npm run lint && npm run build",
+    "pretest": "rm -f ./bin/jfq.js && npm run lint && npm run build",
     "test": "jest"
   },
   "repository": {
@@ -54,6 +54,7 @@
     "js-yaml": "^4.0.0",
     "json-colorizer": "^2.2.2",
     "jsonata": "^1.8.4",
+    "line-reader": "^0.4.0",
     "parse-json": "^5.2.0",
     "read-input": "^0.3.1"
   },

rollup.config.js

@@ -20,6 +20,7 @@ export default {
     'json-colorizer',
     'js-yaml',
     'parse-json',
-    'read-input'
+    'read-input',
+    'line-reader'
   ]
 }

src/__tests__/getopts.js

@@ -4,12 +4,21 @@ import getopts from '../getopts.js'
 const fakeArgv = (...opts) => ([process.execPath, '/tmp/fakePath.js', ...opts])
 
 describe('getting command line options', () => {
+  describe('when --yaml is used together with --jsonlines-input', () => {
+    it('should throw', () => {
+      expect(() => {
+        getopts(fakeArgv('--yaml', '--jsonlines-input', '--jsonlines-output'))
+      }).toThrow(Error)
+    })
+  })
+
   describe('when there are no options', () => {
     it('returns default values', async () => {
       const res = await getopts(fakeArgv())
       expect(res.query).toBe('$')
       expect(res.files).toEqual([])
       expect(res.ndjson).toBe(false)
+      expect(res.jsonlinesInput).toBe(false)
     })
   })
 

src/getopts.js

@@ -10,19 +10,49 @@ export default async argv => {
     .option('-a, --accept-yaml', 'YAML input')
     .option('-p, --plain-text', 'Do not decorate output')
     .option('-q, --query-file <path>', 'JSONata query file')
+    .option('-l, --jsonlines-input', 'JSON Lines Input')
+    .option('-k, --jsonlines-output', 'JSON Lines Output')
     .parse(argv)
     .opts()
 
-  const ndjson = !!options.ndjson
+  const ndjsonOpt = !!options.ndjson
+  const jsonlinesOutputOpt = !!options.jsonlinesOutput
+
+  if (ndjsonOpt && jsonlinesOutputOpt) {
+    throw new Error('can only set --ndjson or --jsonlines-output')
+  }
+
   const json = !!options.json
   const yamlOut = !!options.yaml
   const yamlIn = !!options.acceptYaml
   const plainText = !!options.plainText
   const queryFile = options.queryFile
+  // two aliases
+  const jsonlinesInput = !!options.jsonlinesInput
+  const jsonlinesOutput = ndjsonOpt || jsonlinesOutputOpt
+  const ndjson = jsonlinesOutput
   const files = program.args.slice(0)
 
+  if (yamlIn && jsonlinesInput) {
+    throw new Error('--accept-yaml and --jsonlines can not be set together')
+  }
+
+  if (jsonlinesInput && !jsonlinesOutput) {
+    throw new Error('--jsonlines-input requires --jsonlines-output/ndjson as output')
+  }
+
   const query = await getQuery(queryFile, files)
-  return { query, files, ndjson, json, yamlOut, yamlIn, plainText }
+  return {
+    query,
+    files,
+    ndjson,
+    json,
+    yamlOut,
+    yamlIn,
+    plainText,
+    jsonlinesInput,
+    jsonlinesOutput
+  }
 }
 
 const exists = async (path) => {

src/jfq.js

@@ -2,12 +2,13 @@ import colorize from 'json-colorizer'
 import jsonata from 'jsonata'
 import parseJson from 'parse-json'
 import readInput from 'read-input'
+import * as lineReader from 'line-reader'
 import getopts from './getopts'
 import YAML from 'js-yaml'
 
-const main = async () => {
-  const { files, ndjson, json, yamlIn, yamlOut, query, plainText } = await getopts(process.argv)
-  const evaluator = parseQuery(query)
+const fullFileMode = async (opts, evaluator) => {
+  const { files, ndjson, json, yamlIn, yamlOut, plainText } = opts
+
   const data = await readInput(files)
 
   data.files.forEach(file => {
@@ -22,6 +23,32 @@ const main = async () => {
   })
 }
 
+const streamingMode = async (opts, evaluator) => {
+  const { files, ndjson, json, plainText } = opts
+  if (files && files.length > 1) {
+    console.error('streamingMode / jsonlines only works with one file/stream')
+    process.exit(1)
+  }
+  const input = (files && files[0]) || process.stdin
+  lineReader.eachLine(input, (line, last, continueCb) => {
+    const lineInput = parseJson(line)
+    const result = evaluator.evaluate(lineInput)
+    const output = formatJson(result, ndjson, json, plainText)
+    console.log(output)
+    continueCb()
+  })
+}
+
+const main = async () => {
+  const opts = await getopts(process.argv)
+  const evaluator = parseQuery(opts.query)
+  if (!opts.jsonlinesInput) {
+    await fullFileMode(opts, evaluator)
+  } else {
+    await streamingMode(opts, evaluator)
+  }
+}
+
 const parseQuery = query => {
   try {
     return jsonata(query)