add script/analyze-variables.js

script/analyze-variables.js

@@ -0,0 +1,121 @@
+#!/usr/bin/env node
+const globby = require('globby')
+const postcss = require('postcss')
+const atImport = require('postcss-import')
+const syntax = require('postcss-scss')
+const valueParser = require('postcss-value-parser')
+const {readFile} = require('fs-extra')
+
+if (module.parent) {
+  module.exports = analyzeVariables
+} else {
+  const args = process.argv.slice(2)
+  const file = args.length ? args.shift() : 'src/support/index.scss'
+  analyzeVariables(file).then(data => console.log(JSON.stringify(data, null, 2)))
+}
+
+function analyzeVariables(file) {
+  const variables = {}
+
+  const processor = postcss([
+    atImport({path: 'src'}),
+    variablePlugin(variables),
+    require('postcss-node-sass')({includePaths: ['src/support/variables']})
+  ])
+
+  return readFile(file, 'utf8')
+    .then(css => processor.process(css, {from: file, map: false, syntax}))
+    .then(({root, css}) => {
+      root.walkRules(':root', container => {
+        container.walkDecls(decl => {
+          const {prop, value} = decl
+          const actualProp = `$${prop.replace(/^--/, '')}`
+          const entry = variables[actualProp]
+          if (last(entry.values) !== value) {
+            entry.values.push(value)
+          }
+          variables[actualProp] = Object.assign(
+            {
+              computed: value
+            },
+            entry,
+            {refs: []}
+          )
+        })
+      })
+
+      for (const [prop, entry] of Object.entries(variables)) {
+        for (const value of entry.values) {
+          if (variables[value]) {
+            variables[value].refs.push(prop)
+          }
+        }
+      }
+
+      // sort it alphabetically by key
+      return sortObject(variables, ([ak, av], [bk, bv]) => av.refs.length || ak.localeCompare(bk))
+    })
+}
+
+function variablePlugin(variables) {
+  return postcss.plugin('analyze-variables', (options = {}) => {
+    const {cwd = process.cwd()} = options
+    return (root, result) => {
+      const decls = new Map()
+
+      root.walkDecls(/^\$/, decl => {
+        const {prop, value} = decl
+        if (decl.parent === root && !decl.value.startsWith('(')) {
+          decl.value = decl.value.replace(/ *\!default$/, '')
+          decls.set(prop, decl)
+        }
+      })
+
+      for (const [prop, decl] of decls.entries()) {
+        const {nodes} = valueParser(decl.value)
+        const values = [valueParser.stringify(nodes)]
+        while (nodes.some(node => decls.has(node.value))) {
+          for (const node of nodes) {
+            let {value} = node
+            if (decls.has(value)) {
+              node.value = decls.get(node.value).value
+            }
+          }
+          values.push(valueParser.stringify(nodes))
+        }
+
+        const {source} = decl
+        variables[prop] = {
+          values,
+          source: {
+            path: source.input.file.replace(`${cwd}/`, ''),
+            line: source.start.line
+          }
+        }
+      }
+
+      const container = postcss.rule({selector: ':root'})
+      for (const [prop, decl] of decls.entries()) {
+        container.append(
+          postcss.decl({
+            prop: `--${prop.substr(1)}`,
+            value: `#{${decl.value}}`
+          })
+        )
+      }
+      root.append(container)
+    }
+  })
+}
+
+function sortObject(obj, cmp) {
+  const out = {}
+  for (const [key, value] of Object.entries(obj).sort(cmp)) {
+    out[key] = value
+  }
+  return out
+}
+
+function last(list) {
+  return list[list.length - 1]
+}