12 files changed, 191 insertions, 0 deletions
diff --git a/@linaria/packages/core/CHANGELOG.md b/@linaria/packages/core/CHANGELOG.md
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+++ b/@linaria/packages/core/CHANGELOG.md
@@ -0,0 +1,27 @@
+# Change Log
+
+All notable changes to this project will be documented in this file.
+See [Conventional Commits](https://conventionalcommits.org) for commit guidelines.
+
+# [3.0.0-beta.4](https://github.com/callstack/linaria/compare/v3.0.0-beta.3...v3.0.0-beta.4) (2021-05-07)
+
+**Note:** Version bump only for package @linaria/core
+
+
+
+
+
+# [3.0.0-beta.3](https://github.com/callstack/linaria/compare/v3.0.0-beta.2...v3.0.0-beta.3) (2021-04-20)
+
+**Note:** Version bump only for package @linaria/core
+
+
+
+
+
+# [3.0.0-beta.2](https://github.com/callstack/linaria/compare/v3.0.0-beta.1...v3.0.0-beta.2) (2021-04-11)
+
+
+### Bug Fixes
+
+* **core:** remove unnecessary spread operators from css and cx ([#746](https://github.com/callstack/linaria/issues/746)) ([#749](https://github.com/callstack/linaria/issues/749)) ([de23a09](https://github.com/callstack/linaria/commit/de23a0926c2583db01e7df5ea9a134f5910f96a1))
diff --git a/@linaria/packages/core/README.md b/@linaria/packages/core/README.md
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+++ b/@linaria/packages/core/README.md
@@ -0,0 +1,35 @@
+<p align="center">
+  <img alt="Linaria" src="https://raw.githubusercontent.com/callstack/linaria/HEAD/website/assets/linaria-logo@2x.png" width="496">
+</p>
+
+<p align="center">
+Zero-runtime CSS in JS library.
+</p>
+
+---
+
+### 📖 Please refer to the [GitHub](https://github.com/callstack/linaria#readme) for full documentation.
+
+## Features
+
+- Write CSS in JS, but with **zero runtime**, CSS is extracted to CSS files during build
+- Familiar **CSS syntax** with Sass like nesting
+- Use **dynamic prop based styles** with the React bindings, uses CSS variables behind the scenes
+- Easily find where the style was defined with **CSS sourcemaps**
+- **Lint your CSS** in JS with [stylelint](https://github.com/stylelint/stylelint)
+- Use **JavaScript for logic**, no CSS preprocessor needed
+- Optionally use any **CSS preprocessor** such as Sass or PostCSS
+
+**[Why use Linaria](../../docs/BENEFITS.md)**
+
+## Installation
+
+```sh
+npm install @linaria/core @linaria/react @linaria/babel-preset @linaria/shaker
+```
+
+or
+
+```sh
+yarn add @linaria/core @linaria/react @linaria/babel-preset @linaria/shaker
+```
diff --git a/@linaria/packages/core/__tests__/cx.test.ts b/@linaria/packages/core/__tests__/cx.test.ts
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index 0000000..97fabff
--- /dev/null
+++ b/@linaria/packages/core/__tests__/cx.test.ts
@@ -0,0 +1,7 @@
+import { cx } from '../src';
+
+it('should filter falsy values', () => {
+  expect(cx('1', 'test', false, '2', 0, '', null, undefined, '3')).toBe(
+    '1 test 2 3'
+  );
+});
diff --git a/@linaria/packages/core/__tests__/detect-core-js.test.js b/@linaria/packages/core/__tests__/detect-core-js.test.js
new file mode 100644
index 0000000..22bfbe4
--- /dev/null
+++ b/@linaria/packages/core/__tests__/detect-core-js.test.js
@@ -0,0 +1,35 @@
+import cp from 'child_process';
+
+const waitForProcess = async (process) => {
+  return new Promise((resolve) => {
+    let output = '';
+    process.stdout.on('data', (chunk) => {
+      output += chunk.toString();
+    });
+    process.on('close', () => {
+      resolve(output);
+    });
+  });
+};
+
+it('Ensures that package do not include core-js dependency after build', async () => {
+  // eslint-disable-next-line import/no-extraneous-dependencies
+  const packageJSON = require('@linaria/babel-preset/package.json');
+  const buildScript = packageJSON.scripts['build:lib'];
+
+  const proc = cp.exec(buildScript, {
+    stdio: 'ignore',
+    env: {
+      ...process.env,
+      DEBUG_CORE_JS: 'true',
+    },
+  });
+  const result = await waitForProcess(proc);
+  // run `DEBUG_CORE_JS=true yarn build:lib` to debug issues with introduced core-js dependency
+  expect(result).not.toContain(
+    'The corejs3 polyfill added the following polyfills'
+  );
+  expect(result).toContain(
+    'Based on your code and targets, the corejs3 polyfill did not add any polyfill'
+  );
+}, 15000);
diff --git a/@linaria/packages/core/babel.config.js b/@linaria/packages/core/babel.config.js
new file mode 100644
index 0000000..c9ad680
--- /dev/null
+++ b/@linaria/packages/core/babel.config.js
@@ -0,0 +1,3 @@
+const config = require('../../babel.config');
+
+module.exports = config;
diff --git a/@linaria/packages/core/package.json b/@linaria/packages/core/package.json
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--- /dev/null
+++ b/@linaria/packages/core/package.json
@@ -0,0 +1,40 @@
+{
+  "name": "@linaria/core",
+  "version": "3.0.0-beta.4",
+  "publishConfig": {
+    "access": "public"
+  },
+  "description": "Blazing fast zero-runtime CSS in JS library",
+  "sideEffects": false,
+  "main": "lib/index.js",
+  "module": "esm/index.js",
+  "types": "types/index.d.ts",
+  "files": [
+    "types/",
+    "lib/",
+    "esm/"
+  ],
+  "license": "MIT",
+  "repository": "git@github.com:callstack/linaria.git",
+  "bugs": {
+    "url": "https://github.com/callstack/linaria/issues"
+  },
+  "homepage": "https://github.com/callstack/linaria#readme",
+  "keywords": [
+    "react",
+    "linaria",
+    "css",
+    "css-in-js",
+    "styled-components"
+  ],
+  "scripts": {
+    "build:lib": "cross-env NODE_ENV=legacy babel src --out-dir lib --extensions '.js,.jsx,.ts,.tsx' --source-maps --delete-dir-on-start",
+    "build:esm": "babel src --out-dir esm --extensions '.js,.jsx,.ts,.tsx' --source-maps --delete-dir-on-start",
+    "build": "yarn build:lib && yarn build:esm",
+    "build:declarations": "tsc --emitDeclarationOnly --outDir types",
+    "prepare": "yarn build && yarn build:declarations",
+    "test": "jest --config ../../jest.config.js --rootDir .",
+    "typecheck": "tsc --noEmit --composite false",
+    "watch": "yarn build --watch"
+  }
+}
diff --git a/@linaria/packages/core/src/CSSProperties.ts b/@linaria/packages/core/src/CSSProperties.ts
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index 0000000..0c8e580
--- /dev/null
+++ b/@linaria/packages/core/src/CSSProperties.ts
@@ -0,0 +1,3 @@
+export type CSSProperties = {
+  [key: string]: string | number | CSSProperties;
+};
diff --git a/@linaria/packages/core/src/StyledMeta.ts b/@linaria/packages/core/src/StyledMeta.ts
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index 0000000..e3aa691
--- /dev/null
+++ b/@linaria/packages/core/src/StyledMeta.ts
@@ -0,0 +1,6 @@
+export type StyledMeta = {
+  __linaria: {
+    className: string;
+    extends: StyledMeta;
+  };
+};
diff --git a/@linaria/packages/core/src/css.ts b/@linaria/packages/core/src/css.ts
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+++ b/@linaria/packages/core/src/css.ts
@@ -0,0 +1,15 @@
+import type { CSSProperties } from './CSSProperties';
+import type { StyledMeta } from './StyledMeta';
+
+type CSS = (
+  strings: TemplateStringsArray,
+  ...exprs: Array<string | number | CSSProperties | StyledMeta>
+) => string;
+
+const css: CSS = () => {
+  throw new Error(
+    'Using the "css" tag in runtime is not supported. Make sure you have set up the Babel plugin correctly.'
+  );
+};
+
+export default css;
diff --git a/@linaria/packages/core/src/cx.ts b/@linaria/packages/core/src/cx.ts
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index 0000000..e34fae2
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+++ b/@linaria/packages/core/src/cx.ts
@@ -0,0 +1,9 @@
+export type ClassName = string | false | void | null | 0;
+
+type CX = (...classNames: ClassName[]) => string;
+
+const cx: CX = function cx() {
+  return Array.prototype.slice.call(arguments).filter(Boolean).join(' ');
+};
+
+export default cx;
diff --git a/@linaria/packages/core/src/index.ts b/@linaria/packages/core/src/index.ts
new file mode 100644
index 0000000..60cdc6d
--- /dev/null
+++ b/@linaria/packages/core/src/index.ts
@@ -0,0 +1,4 @@
+export { default as css } from './css';
+export { default as cx } from './cx';
+export type { CSSProperties } from './CSSProperties';
+export type { StyledMeta } from './StyledMeta';
diff --git a/@linaria/packages/core/tsconfig.json b/@linaria/packages/core/tsconfig.json
new file mode 100644
index 0000000..3a01f90
--- /dev/null
+++ b/@linaria/packages/core/tsconfig.json
@@ -0,0 +1,7 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "paths": {},
+    "rootDir": "src/"
+  }
+}