Add visitor support

config/jest.config.js

@@ -1,6 +1,6 @@
 let moduleNameMapper
 const transform = {
-  '[/\\\\]tests[/\\\\].*\\.(js|ts)$': [
+  '[/\\\\]tests[/\\\\].*\\.(m?js|ts)$': [
     'babel-jest',
     { configFile: './config/babel.config.js' }
   ]

config/rollup.node-config.mjs

@@ -14,7 +14,7 @@ export default {
     esModule: false,
     preserveModules: true
   },
-  external: ['node:util'],
+  external: ['node:path', 'node:util'],
   plugins: [
     typescript(),
     {

src/cli.ts

@@ -1,5 +1,6 @@
 #!/usr/bin/env node
 
+import { resolve } from 'node:path'
 import { parseArgs } from 'node:util'
 
 import { type Token, prettyToken } from './parse/cst.js'
@@ -9,6 +10,7 @@ import { Composer } from './compose/composer.js'
 import { LineCounter } from './parse/line-counter.js'
 import { type Document } from './doc/Document.js'
 import { prettifyError } from './errors.js'
+import { visit, type visitor } from './visit.js'
 
 const help = `\
 yaml: A command-line YAML processor and inspector
@@ -29,6 +31,7 @@ Additional options for bare "yaml" command:
   --doc, -d     Output pretty-printed JS Document objects.
   --single, -1  Require the input to consist of a single YAML document.
   --strict, -s  Stop on errors.
+  --visit, -v   Apply a visitor to each document (requires a path to import)
   --yaml 1.1    Set the YAML version. (default: 1.2)`
 
 class UserError extends Error {
@@ -43,14 +46,15 @@ class UserError extends Error {
 
 /* istanbul ignore if */
 if (require.main === module)
+  // eslint-disable-next-line @typescript-eslint/no-floating-promises
   main(process.stdin, error => {
     if (error instanceof UserError) {
       console.error(`${help}\n\n${error.message}`)
       process.exitCode = error.code
     } else if (error) throw error
   })
 
-export function main(
+export async function main(
   stdin: NodeJS.ReadableStream,
   done: (error?: Error) => void,
   argv?: string[]
@@ -66,6 +70,7 @@ export function main(
         json: { type: 'boolean', short: 'j' },
         single: { type: 'boolean', short: '1' },
         strict: { type: 'boolean', short: 's' },
+        visit: { type: 'string', short: 'v' },
         yaml: { type: 'string', default: '1.2' }
       }
     })
@@ -129,6 +134,9 @@ export function main(
       const parser = new Parser(lineCounter.addNewLine)
       // @ts-expect-error Version is validated at runtime
       const composer = new Composer({ version: opt.yaml })
+      const visitor: visitor | null = opt.visit
+        ? (await import(resolve(opt.visit))).default
+        : null
       let source = ''
       let hasDoc = false
       let reqDocEnd = false
@@ -151,6 +159,7 @@ export function main(
           prettifyError(source, lineCounter)(warning)
           console.error(warning)
         }
+        if (visitor) visit(doc, visitor)
         if (mode === 'valid') doc.toJS()
         else if (opt.json) data.push(doc)
         else if (opt.doc) {

tests/artifacts/cli-singlequote.mjs

@@ -0,0 +1,6 @@
+/** @type {import('../../src/index').visitor} */
+export default {
+  Scalar(_, node) {
+    node.type = 'QUOTE_SINGLE'
+  }
+}

tests/artifacts/cli-unstyle.cjs

@@ -0,0 +1,10 @@
+/** @type {import('../../src/index').visitor} */
+module.exports = {
+  Collection(_, node) {
+    delete node.flow
+  },
+  Scalar(_, node) {
+    delete node.format
+    delete node.type
+  }
+}

tests/cli.ts

@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-floating-promises */
+
 import { Readable } from 'node:stream'
 import { main } from 'yaml/cli'
 
@@ -128,6 +130,20 @@ const skip = Number(major) < 20
         [{ name: 'YAMLParseError' }]
       )
     })
+    describe('--visit', () => {
+      ok(
+        'unstyle',
+        '{"hello":"world"}',
+        ['--visit', './tests/artifacts/cli-unstyle.cjs'],
+        ['hello: world']
+      )
+      ok(
+        'singlequote',
+        '{"hello":"world"}',
+        ['--visit', './tests/artifacts/cli-singlequote.mjs'],
+        ["{ 'hello': 'world' }"]
+      )
+    })
   })
 
   describe('CST parser', () => {

tests/tsconfig.json

@@ -11,5 +11,5 @@
     "rootDir": "..",
     "types": ["jest", "node"]
   },
-  "include": ["**/*.ts"]
+  "include": ["**/*.ts", "artifacts/cli-*"]
 }

tsconfig.json

@@ -1,6 +1,7 @@
 {
   "compilerOptions": {
     "declaration": true,
+    "module": "ESNext",
     "moduleResolution": "node",
     "noUnusedLocals": true,
     "noUnusedParameters": true,