add on option

Author: zoubin

index.js

@@ -11,6 +11,7 @@ var sequence = promisify(require('async-array-methods').forEach)
 module.exports = postcss.plugin('postcss-simple-import', atImport)
 
 function atImport(opts) {
+  var emitter = createEmitter()
   opts = mix({
     atRule: 'import',
     // cache raw contents
@@ -20,8 +21,14 @@ function atImport(opts) {
     // if "a.css" imports "c.css" and "b.css", and we cache final contents
     // then there is no way to prevent "c.css" from being loaded twice
     cache: {},
+    emitter: emitter,
   }, opts)
 
+  if (opts.on) {
+    Object.keys(opts.on).forEach(function (evt) {
+      emitter.on(evt, opts.on[evt])
+    })
+  }
   if (typeof opts.resolve !== 'function') {
     opts.resolve = promisify(resolver(mix({
       packageEntry: 'style',
@@ -118,6 +125,7 @@ function processRoot(root, from, opts) {
       if (opts.onImport) {
         opts.onImport(from, Object.keys(imports), opts.postcssOpts)
       }
+      opts.emitter.emit('imports', Object.keys(imports), from, opts)
       return {
         root: root,
         from: from,
@@ -149,6 +157,7 @@ function processRule(rule, from, opts) {
       // we don't preseve order for globs
       return [].concat(rows)
         .map(function (row) {
+          opts.emitter.emit('import', row.from, from, opts)
           return processRow(row, opts)
         })
     })
@@ -191,6 +200,12 @@ function insertBefore(rule, child) {
   })
 }
 
+function createEmitter() {
+  var emitter = new (require('events'))
+  emitter.setMaxListeners(0)
+  return emitter
+}
+
 function trim(s) {
   return s && s.replace(/['"]/g, '').trim()
 }

test/emitter.js

@@ -0,0 +1,58 @@
+var test = require('tape')
+var atImport = require('..')
+var postcss = require('postcss')
+var path = require('path')
+var fixtures = require('./util/fixtures')
+
+var contents = {
+  d: '@import "e.css";\nd {}',
+  e: '@import "f.css";\ne {}',
+  f: 'f {}',
+}
+
+var entry = fixtures('emitter.css')
+var expectedImports = {}
+expectedImports[entry] = [
+  'glob_imports/a.css', 'glob_imports/b.css', 'glob_imports/c.css',
+  'd.css',
+].map(fixtures.one)
+expectedImports[fixtures('d.css')] = [fixtures('e.css')]
+expectedImports[fixtures('e.css')] = [fixtures('f.css')]
+
+test('emitter', function(t) {
+  var postcssOpts = { from: entry }
+  return postcss(atImport({
+    glob: true,
+    importer: function (url) {
+      var base = path.basename(url, '.css')
+      if (!contents[base]) {
+        return
+      }
+      return Promise.resolve({
+        from: fixtures(url),
+        source: contents[base],
+      })
+    },
+    on: {
+      import: function (file, from, opts) {
+        t.ok(expectedImports[from].indexOf(file) !== -1, file)
+        t.same(opts.postcssOpts, postcssOpts)
+      },
+      imports: function (imports, from, opts) {
+        t.same(imports, expectedImports[from] || [], from)
+        t.same(opts.postcssOpts, postcssOpts)
+      },
+    },
+  }))
+  .process(
+    '@import "./glob_imports/*.css";\n@import "d.css";',
+    postcssOpts
+  )
+  .then(function (result) {
+    t.equal(result.css, 'a {}\nb {}\nc {}\nf {}\ne {}\nd {}')
+  })
+  .catch(function (err) {
+    t.error(err)
+  })
+})
+