Export CSS parser function, add CLI with --stats flag, and add stats utility

package.json

@@ -3,6 +3,7 @@
   "version": "1.0.6",
   "description": "",
   "exports": "./lib/index.js",
+  "bin": "./lib/bin.js",
   "scripts": {
     "build": "rm -rf lib && tsc",
     "format": "prettier --write .",

src/bin.ts

@@ -0,0 +1,52 @@
+#!/usr/bin/env node
+import { parseArgs } from 'node:util'
+import type { Parsed } from './index'
+const { parse } = require('./index')
+
+async function main() {
+  // Parse command line arguments (no args expected for now)
+  parseArgs({
+    args: process.argv.slice(2),
+    options: {},
+    strict: true,
+  })
+
+  // Read CSS from stdin
+  let css = ''
+
+  if (process.stdin.isTTY) {
+    console.error('Error: Please provide CSS via stdin')
+    console.error('Usage: mistcss < input.css')
+    process.exit(1)
+  }
+
+  for await (const chunk of process.stdin) {
+    css += chunk
+  }
+
+  // Parse the CSS
+  const parsed = parse(css)
+
+  // Convert Sets to Arrays for JSON serialization
+  const serializable = Object.fromEntries(
+    (Object.entries(parsed) as [string, Parsed[string]][]).map(([key, value]) => [
+      key,
+      {
+        ...value,
+        attributes: Object.fromEntries(
+          Object.entries(value.attributes).map(([k, v]) => [k, Array.from(v)])
+        ),
+        booleanAttributes: Array.from(value.booleanAttributes),
+        properties: Array.from(value.properties),
+      },
+    ])
+  )
+
+  // Output the parsed result as JSON
+  console.log(JSON.stringify(serializable, null, 2))
+}
+
+main().catch((err) => {
+  console.error('Error:', err.message)
+  process.exit(1)
+})

src/index.ts

@@ -1,5 +1,6 @@
 import fs = require('node:fs')
 import { type PluginCreator } from 'postcss'
+import postcss = require('postcss')
 import selectorParser = require('postcss-selector-parser')
 import atImport = require('postcss-import')
 import path = require('node:path')
@@ -14,7 +15,7 @@ declare module 'postcss-selector-parser' {
   }
 }
 
-type Parsed = Record<
+export type Parsed = Record<
   string,
   {
     tag: string
@@ -164,6 +165,50 @@ function initialParsedValue(): Parsed[keyof Parsed] {
   }
 }
 
+export function parse(css: string): Parsed {
+  const parsed: Parsed = {}
+  let current: Parsed[keyof Parsed] = initialParsedValue()
+
+  // Parse the CSS using postcss
+  const root = postcss.parse(css)
+
+  root.walkRules((rule) => {
+    selectorParser((selectors) => {
+      selectors.walk((selector) => {
+        if (selector.type === 'tag') {
+          current = parsed[key(selector)] = initialParsedValue()
+          current.tag = selector.toString().toLowerCase()
+          const next = selector.next()
+          if (next?.type === 'attribute') {
+            const { attribute, value } = next as selectorParser.Attribute
+            if (value) current.rootAttribute = attribute
+          }
+        }
+
+        if (selector.type === 'attribute') {
+          const { attribute, value } = selector as selectorParser.Attribute
+          if (value) {
+            const values = (current.attributes[attribute] ??=
+              new Set<string>())
+            values.add(value)
+          } else {
+            current.booleanAttributes.add(attribute)
+          }
+        }
+      })
+    }).processSync(rule.selector, {
+      lossless: false,
+    })
+
+    rule.walkDecls(({ prop }) => {
+      if (prop.startsWith('--') && prop !== '--apply')
+        current.properties.add(prop)
+    })
+  })
+
+  return parsed
+}
+
 const _mistcss: PluginCreator<{}> = (_opts = {}) => {
   return {
     postcssPlugin: '_mistcss',
@@ -225,4 +270,7 @@ const mistcss: PluginCreator<{}> = (_opts = {}) => {
 
 mistcss.postcss = true
 
+export { mistcss as default }
 module.exports = mistcss
+module.exports.parse = parse
+module.exports.default = mistcss