flatten output by default (#82)

Most tools that consume the output from this module convert the output to a flat object, so we might as well do it here.

Some thoughts:

* Files in the test directory unflatten the results so I don't have to re-write the whole test suite for now (see #81)
* There is (IMHO) better error handling for invalid css now

closes #50

Author: bartveneman

package-lock.json

@@ -51,6 +51,7 @@
     "css-shorthand-expand": "^1.2.0",
     "css-unit-sort": "^1.1.1",
     "css-value-browser-h4cks-analyzer": "^1.0.1",
+    "flat": "^4.1.0",
     "is-vendor-prefixed": "^1.0.0",
     "path": "^0.12.7",
     "postcss": "^7.0.2",

package.json

@@ -1,27 +1,37 @@
+const flat = require('flat')
 const parser = require('../parser')
 
-module.exports = input => {
+function flattenObject(obj) {
+  return flat(obj, {safe: true})
+}
+
+module.exports = rawCss => {
   return new Promise(async (resolve, reject) => {
-    try {
-      const css = await parser(input)
+    const css = await parser(rawCss).catch(error => reject(error))
 
-      const atrules = require('./atrules')(css.atRules)
-      const rules = require('./rules')(css.rules)
-      const selectors = require('./selectors')(css.selectors)
-      const declarations = require('./declarations')(css.declarations)
-      const properties = require('./properties')(css.declarations)
-      const values = require('./values')(css.declarations)
-      const stylesheets = require('./stylesheets')(
-        input,
-        atrules,
-        rules,
-        selectors,
-        declarations,
-        properties,
-        values
-      )
+    // CSS undefined means that PostCSS encountered an error
+    if (typeof css === 'undefined') {
+      return reject(new Error('Invalid CSS found, cannot analyze invalid CSS'))
+    }
 
-      resolve({
+    const atrules = require('./atrules')(css.atRules)
+    const rules = require('./rules')(css.rules)
+    const selectors = require('./selectors')(css.selectors)
+    const declarations = require('./declarations')(css.declarations)
+    const properties = require('./properties')(css.declarations)
+    const values = require('./values')(css.declarations)
+    const stylesheets = require('./stylesheets')({
+      rawCss,
+      atrules,
+      rules,
+      selectors,
+      declarations,
+      properties,
+      values
+    })
+
+    return resolve(
+      flattenObject({
         stylesheets,
         atrules,
         rules,
@@ -30,8 +40,6 @@ module.exports = input => {
         properties,
         values
       })
-    } catch (error) {
-      reject(error)
-    }
+    )
   })
 }

src/analyzer/index.js

@@ -1,13 +1,13 @@
-module.exports = (
-  raw,
+module.exports = ({
+  rawCss,
   atrules,
   rules,
   selectors,
   declarations,
   properties,
   values
-) => {
-  const size = Buffer.byteLength(raw, 'utf8')
+}) => {
+  const size = Buffer.byteLength(rawCss, 'utf8')
   const simplicity = require('./simplicity.js')(rules, selectors)
   const cohesion = require('./cohesion.js')(rules, declarations)
   const browserhacks = require('./browserhacks.js')(