feat: add .root() to avoid re-parsing inputs when possible (#717)

packages/processor/README.md

@@ -56,6 +56,11 @@ Returns a promise. Add `file` to the `Processor` instance with `css` contents.
 
 Returns a promise. Add `file` to the `Processor` instance, reads contents from disk using `fs`.
 
+### `.root(file, Root)`
+
+Returns a promise. Add `file` to the `Processor` instance, re-uses a Postcss `Root` object, avoiding
+unnecessarily parsing an AST again.
+
 ### `.output({ args })`
 
 Returns a promise. Finalize processing of all added CSS and create combined CSS output file.

packages/processor/processor.js

@@ -41,7 +41,7 @@ class Processor {
  {
  cwd : process.cwd(),
  map : false,
- 
+
  dupewarn : true,
  exportValues : true,
  loadFile : defaultLoadFile,
@@ -123,7 +123,7 @@ class Processor {
  this._log("file()", id);
 
  const text = await this._loadFile(id);
- 
+
  return this._add(id, text);
  }
 
@@ -136,6 +136,15 @@ class Processor {
  return this._add(id, text);
  }
 
+ // Add an existing postcss Root object by name
+ root(file, root) {
+ const id = this._normalize(file);
+
+ this._log("root()", id);
+
+ return this._add(id, root);
+ }
+
  // Remove a file from the dependency graph
  remove(input) {
  // Only want files actually in the array
@@ -351,7 +360,7 @@ class Processor {
 
  // Take a file id and some text, walk it for dependencies, then
  // process and return details
- async _add(id, text) {
+ async _add(id, src) {
  const check = id.toLowerCase();
 
  // Warn about potential dupes if an ID goes past we've seen before
@@ -368,7 +377,7 @@ class Processor {
 
  this._log("_add()", id);
 
- await this._walk(id, text);
+ await this._walk(id, src);
 
  const deps = [ ...this._graph.dependenciesOf(id), id ];
 
@@ -424,7 +433,7 @@ class Processor {
 
  // Process files and walk their composition/value dependency tree to find
  // new files we need to process
- async _walk(name, text) {
+ async _walk(name, src) {
  // No need to re-process files unless they've been marked invalid
  if(this._files[name] && this._files[name].valid) {
  // Do want to wait until they're done being processed though
@@ -440,12 +449,12 @@ class Processor {
  let walked;
 
  const file = this._files[name] = {
- text,
+ text : typeof src === "string" ? src : src.source.input.css,
  exports : false,
  values : false,
  valid : true,
  before : this._before.process(
- text,
+ src,
  params(this, {
  from : name,
  })
@@ -471,7 +480,7 @@ class Processor {
  await Promise.all(
  this._graph.dependenciesOf(name).map((dependency) => {
  const { valid, walked : complete } = this._files[dependency] || false;
- 
+
  // If the file hasn't been invalidated wait for it to be done processing
  if(valid) {
  return complete;

packages/processor/test/__snapshots__/api.test.js.snap

@@ -1,17 +1,5 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`/processor.js API .resolve() should fall back to a default resolver 1`] = `
-Array [
- "packages/processor/test/specimens/local.css",
-]
-`;
-
-exports[`/processor.js API .resolve() should run resolvers until a match is found 1`] = `
-Array [
- "packages/processor/test/specimens/local.css",
-]
-`;
-
 exports[`/processor.js API .compositions should return compositions for loaded files 1`] = `Promise {}`;
 
 exports[`/processor.js API .dependencies() should return the dependencies of the specified file 1`] = `
@@ -310,6 +298,38 @@ Array [
 ]
 `;
 
+exports[`/processor.js API .resolve() should fall back to a default resolver 1`] = `
+Array [
+ "packages/processor/test/specimens/local.css",
+]
+`;
+
+exports[`/processor.js API .resolve() should run resolvers until a match is found 1`] = `
+Array [
+ "packages/processor/test/specimens/local.css",
+]
+`;
+
+exports[`/processor.js API .root() should process a postcss Root 1`] = `
+Object {
+ "wooga": Array [
+ "wooga",
+ ],
+}
+`;
+
+exports[`/processor.js API .root() should process a postcss Root 2`] = `
+Object {
+ "wooga": Array [
+ "wooga",
+ ],
+}
+`;
+
+exports[`/processor.js API .root() should process a postcss Root 3`] = `".wooga { }"`;
+
+exports[`/processor.js API .root() should process a postcss Root 4`] = `".wooga { }"`;
+
 exports[`/processor.js API .string() should process a string 1`] = `
 Object {
  "wooga": Array [

packages/processor/test/api.test.js

@@ -1,5 +1,6 @@
 "use strict";
 
+const postcss = require("postcss");
 const namer = require("@modular-css/test-utils/namer.js");
 const relative = require("@modular-css/test-utils/relative.js");
 
@@ -19,6 +20,21 @@ describe("/processor.js", () => {
  expect(typeof Processor).toBe("function");
  });
 
+ describe(".root()", () => {
+ it("should process a postcss Root", async () => {
+ const file = "./simple.css";
+ const root = postcss.parse(".wooga { }", { from : file });
+ const result = await processor.root(
+ file, root
+ );
+
+ expect(result.exports).toMatchSnapshot();
+ expect(result.details.exports).toMatchSnapshot();
+ expect(result.details.text).toMatchSnapshot();
+ expect(result.details.processed.root.toResult().css).toMatchSnapshot();
+ });
+ });
+
  describe(".string()", () => {
  it("should process a string", async () => {
  const result = await processor.string(