CSS Map alternative compilation approach

examples/parcel/src/app.jsx

@@ -9,6 +9,7 @@ import '@compiled/react';
 
 import { primary } from './constants';
 import Annotated from './ui/annotated';
+import CSSMap from './ui/css-map';
 import {
   CustomFileExtensionStyled,
   customFileExtensionCss,
@@ -29,5 +30,6 @@ export const App = () => (
     <React.Suspense fallback={<div>Loading...</div>}>
       <AsyncComponent />
     </React.Suspense>
+    <CSSMap variant="danger">CSS Map</CSSMap>
   </>
 );

examples/parcel/src/ui/css-map.jsx

@@ -0,0 +1,12 @@
+import { css, cssMap } from '@compiled/react';
+
+const styles = cssMap({
+  danger: {
+    color: 'red',
+  },
+  success: {
+    color: 'green',
+  },
+});
+
+export default ({ variant, children }) => <div css={css(styles[variant])}>{children}</div>;

examples/webpack/src/app.jsx

@@ -4,6 +4,7 @@ import { Suspense, lazy } from 'react';
 
 import { primary } from './common/constants';
 import Annotated from './ui/annotated';
+import CSSMap from './ui/css-map';
 import {
   CustomFileExtensionStyled,
   customFileExtensionCss,
@@ -23,5 +24,6 @@ export const App = () => (
     <CustomFileExtensionStyled>Custom File Extension Styled</CustomFileExtensionStyled>
     <div css={customFileExtensionCss}>Custom File Extension CSS</div>
     <Annotated />
+    <CSSMap variant="danger">CSS Map</CSSMap>
   </>
 );

examples/webpack/src/ui/css-map.jsx

@@ -0,0 +1,12 @@
+import { css, cssMap } from '@compiled/react';
+
+const styles = cssMap({
+  danger: {
+    color: 'red',
+  },
+  success: {
+    color: 'green',
+  },
+});
+
+export default ({ variant, children }) => <div css={css(styles[variant])}>{children}</div>;

packages/babel-plugin/src/babel-plugin.ts

@@ -8,6 +8,7 @@ import * as t from '@babel/types';
 import { unique, preserveLeadingComments } from '@compiled/utils';
 
 import { visitClassNamesPath } from './class-names';
+import { visitCssMapPath } from './css-map';
 import { visitCssPropPath } from './css-prop';
 import { visitStyledPath } from './styled';
 import type { State } from './types';
@@ -20,6 +21,7 @@ import {
   isCompiledKeyframesTaggedTemplateExpression,
   isCompiledStyledCallExpression,
   isCompiledStyledTaggedTemplateExpression,
+  isCompiledCSSMapCallExpression,
 } from './utils/is-compiled';
 import { normalizePropsUsage } from './utils/normalize-props-usage';
 
@@ -39,6 +41,7 @@ export default declare<State>((api) => {
     inherits: jsxSyntax,
     pre() {
       this.sheets = {};
+      this.cssMap = {};
       let cache: Cache;
 
       if (this.opts.cache === true) {
@@ -150,7 +153,7 @@ export default declare<State>((api) => {
             return;
           }
 
-          (['styled', 'ClassNames', 'css', 'keyframes'] as const).forEach((apiName) => {
+          (['styled', 'ClassNames', 'css', 'keyframes', 'cssMap'] as const).forEach((apiName) => {
             if (
               state.compiledImports &&
               t.isIdentifier(specifier.node?.imported) &&
@@ -171,6 +174,11 @@ export default declare<State>((api) => {
         path: NodePath<t.TaggedTemplateExpression> | NodePath<t.CallExpression>,
         state: State
       ) {
+        if (isCompiledCSSMapCallExpression(path.node, state)) {
+          visitCssMapPath(path, { context: 'root', state, parentPath: path });
+          return;
+        }
+
         const hasStyles =
           isCompiledCSSTaggedTemplateExpression(path.node, state) ||
           isCompiledStyledTaggedTemplateExpression(path.node, state) ||

packages/babel-plugin/src/css-map/__tests__/index.test.ts

@@ -0,0 +1,135 @@
+import type { TransformOptions } from '../../test-utils';
+import { transform as transformCode } from '../../test-utils';
+import { ErrorMessages } from '../index';
+
+describe('css map', () => {
+  const transform = (code: string, opts: TransformOptions = {}) =>
+    transformCode(code, { pretty: false, ...opts });
+
+  const styles = `{
+      danger: {
+          color: 'red',
+          backgroundColor: 'red'
+      },
+      success: {
+        color: 'green',
+        backgroundColor: 'green'
+      }
+    }`;
+
+  it('should transform css map', () => {
+    const actual = transform(`
+      import { cssMap } from '@compiled/react';
+
+      const styles = cssMap(${styles});
+    `);
+
+    expect(actual).toInclude(
+      'const styles={danger:"_syaz5scu _bfhk5scu",success:"_syazbf54 _bfhkbf54"};'
+    );
+  });
+
+  it('should error out if variants are not defined at the top-most scope of the module.', () => {
+    expect(() => {
+      transform(`
+      import { cssMap } from '@compiled/react';
+
+      const styles = {
+        map1: cssMap(${styles}),
+      }
+    `);
+    }).toThrow(ErrorMessages.DEFINE_MAP);
+
+    expect(() => {
+      transform(`
+      import { cssMap } from '@compiled/react';
+
+      const styles = () => cssMap(${styles})
+    `);
+    }).toThrow(ErrorMessages.DEFINE_MAP);
+  });
+
+  it('should error out if cssMap receives more than one argument', () => {
+    expect(() => {
+      transform(`
+        import { cssMap } from '@compiled/react';
+
+        const styles = cssMap(${styles}, ${styles})
+      `);
+    }).toThrow(ErrorMessages.NUMBER_OF_ARGUMENT);
+  });
+
+  it('should error out if cssMap does not receive an object', () => {
+    expect(() => {
+      transform(`
+        import { cssMap } from '@compiled/react';
+
+        const styles = cssMap('color: red')
+      `);
+    }).toThrow(ErrorMessages.ARGUMENT_TYPE);
+  });
+
+  it('should error out if spread element is used', () => {
+    expect(() => {
+      transform(`
+        import { css, cssMap } from '@compiled/react';
+
+        const styles = cssMap({
+          ...base
+        });
+      `);
+    }).toThrow(ErrorMessages.NO_SPREAD_ELEMENT);
+  });
+
+  it('should error out if object method is used', () => {
+    expect(() => {
+      transform(`
+        import { css, cssMap } from '@compiled/react';
+
+        const styles = cssMap({
+          danger() {}
+        });
+      `);
+    }).toThrow(ErrorMessages.NO_OBJECT_METHOD);
+  });
+
+  it('should error out if variant object is dynamic', () => {
+    expect(() => {
+      transform(`
+        import { css, cssMap } from '@compiled/react';
+
+        const styles = cssMap({
+          danger: otherStyles
+        });
+      `);
+    }).toThrow(ErrorMessages.STATIC_VARIANT_OBJECT);
+  });
+
+  it('should error out if styles include runtime variables', () => {
+    expect(() => {
+      transform(`
+        import { css, cssMap } from '@compiled/react';
+
+        const styles = cssMap({
+          danger: {
+            color: canNotBeStaticallyEvulated
+          }
+        });
+      `);
+    }).toThrow(ErrorMessages.STATIC_VARIANT_OBJECT);
+  });
+
+  it('should error out if styles include conditional CSS', () => {
+    expect(() => {
+      transform(`
+        import { css, cssMap } from '@compiled/react';
+
+        const styles = cssMap({
+          danger: {
+            color: canNotBeStaticallyEvulated ? 'red' : 'blue'
+          }
+        });
+      `);
+    }).toThrow(ErrorMessages.STATIC_VARIANT_OBJECT);
+  });
+});

packages/babel-plugin/src/css-map/index.ts

@@ -0,0 +1,153 @@
+import type { NodePath } from '@babel/core';
+import * as t from '@babel/types';
+
+import type { Metadata } from '../types';
+import { buildCodeFrameError } from '../utils/ast';
+import { buildCss } from '../utils/css-builders';
+import { transformCssItems } from '../utils/transform-css-items';
+
+// The messages are exported for testing.
+export enum ErrorMessages {
+  NO_TAGGED_TEMPLATE = 'cssMap function cannot be used as a tagged template expression.',
+  NUMBER_OF_ARGUMENT = 'cssMap function can only receive one argument.',
+  ARGUMENT_TYPE = 'cssMap function can only receive an object.',
+  DEFINE_MAP = 'CSS Map must be declared at the top-most scope of the module.',
+  NO_SPREAD_ELEMENT = 'Spread element is not supported in CSS Map.',
+  NO_OBJECT_METHOD = 'Object method is not supported in CSS Map.',
+  STATIC_VARIANT_OBJECT = 'The variant object must be statically defined.',
+}
+
+const createErrorMessage = (message: string): string => {
+  return `
+${message} 
+To correctly implement a CSS Map, follow the syntax below:
+
+\`\`\`
+import { css, cssMap } from '@compiled/react';
+const borderStyleMap = cssMap({
+    none: { borderStyle: 'none' },
+    solid: { borderStyle: 'solid' },
+});
+const Component = ({ borderStyle }) => <div css={css(borderStyleMap[borderStyle])} />
+\`\`\`
+    `;
+};
+
+/**
+ * Takes `cssMap` function expression and then transforms it to a record of class names and sheets.
+ *
+ * For example:
+ * ```
+ * const styles = cssMap({
+ *    none: { color: 'red' },
+ *    solid: { color: 'green' },
+ * });
+ * ```
+ * gets transformed to
+ * ```
+ * const styles = {
+ *    danger: "_syaz5scu",
+ *    success: "_syazbf54",
+ * };
+ * ```
+ *
+ * @param path {NodePath} The path to be evaluated.
+ * @param meta {Metadata} Useful metadata that can be used during the transformation
+ */
+export const visitCssMapPath = (
+  path: NodePath<t.CallExpression> | NodePath<t.TaggedTemplateExpression>,
+  meta: Metadata
+): void => {
+  // We don't support tagged template expressions.
+  if (t.isTaggedTemplateExpression(path.node)) {
+    throw buildCodeFrameError(
+      createErrorMessage(ErrorMessages.DEFINE_MAP),
+      path.node,
+      meta.parentPath
+    );
+  }
+
+  // We need to ensure CSS Map is declared at the top-most scope of the module.
+  if (!t.isVariableDeclarator(path.parent) || !t.isIdentifier(path.parent.id)) {
+    throw buildCodeFrameError(
+      createErrorMessage(ErrorMessages.DEFINE_MAP),
+      path.node,
+      meta.parentPath
+    );
+  }
+
+  // We need to ensure cssMap receives only one argument.
+  if (path.node.arguments.length !== 1) {
+    throw buildCodeFrameError(
+      createErrorMessage(ErrorMessages.NUMBER_OF_ARGUMENT),
+      path.node,
+      meta.parentPath
+    );
+  }
+
+  // We need to ensure the argument is an objectExpression.
+  if (!t.isObjectExpression(path.node.arguments[0])) {
+    throw buildCodeFrameError(
+      createErrorMessage(ErrorMessages.ARGUMENT_TYPE),
+      path.node,
+      meta.parentPath
+    );
+  }
+
+  const totalSheets: string[] = [];
+  path.replaceWith(
+    t.objectExpression(
+      path.node.arguments[0].properties.map((property) => {
+        if (t.isSpreadElement(property)) {
+          throw buildCodeFrameError(
+            createErrorMessage(ErrorMessages.NO_SPREAD_ELEMENT),
+            property.argument,
+            meta.parentPath
+          );
+        }
+
+        if (t.isObjectMethod(property)) {
+          throw buildCodeFrameError(
+            createErrorMessage(ErrorMessages.NO_OBJECT_METHOD),
+            property.key,
+            meta.parentPath
+          );
+        }
+
+        if (!t.isObjectExpression(property.value)) {
+          throw buildCodeFrameError(
+            createErrorMessage(ErrorMessages.STATIC_VARIANT_OBJECT),
+            property.value,
+            meta.parentPath
+          );
+        }
+
+        const { css, variables } = buildCss(property.value, meta);
+
+        if (variables.length) {
+          throw buildCodeFrameError(
+            createErrorMessage(ErrorMessages.STATIC_VARIANT_OBJECT),
+            property.value,
+            meta.parentPath
+          );
+        }
+
+        const { sheets, classNames } = transformCssItems(css, meta);
+        totalSheets.push(...sheets);
+
+        if (classNames.length !== 1) {
+          throw buildCodeFrameError(
+            createErrorMessage(ErrorMessages.STATIC_VARIANT_OBJECT),
+            property,
+            meta.parentPath
+          );
+        }
+
+        return t.objectProperty(property.key, classNames[0]);
+      })
+    )
+  );
+
+  // We store sheets in the meta state so that we can use it later to generate Compiled component.
+  meta.state.cssMap[path.parent.id.name] = totalSheets;
+};