add support for css @property

examples/next/components/HelloWorld.css.ts

@@ -1,11 +1,34 @@
-import { style } from '@vanilla-extract/css';
+import { style, createVar, keyframes, fallbackVar } from '@vanilla-extract/css';
+
+const color = createVar();
+const angle = createVar({
+  syntax: '<angle>',
+  inherits: false,
+  initialValue: '0deg',
+});
+
+const angleKeyframes = keyframes({
+  '100%': {
+    vars: {
+      [angle]: '360deg',
+    }
+  },
+});
 
 export const root = style({
   background: 'pink',
   color: 'blue',
   padding: '16px',
-  transition: 'opacity .1s ease', // Testing autoprefixer
+  transition: `opacity .1s ease, color .1s ease`, // Testing autoprefixer
+  backgroundImage: `linear-gradient(${angle}, rgba(153, 70, 198, 0.35) 0%, rgba(28, 56, 240, 0.46) 100%)`,
+  animation: `${angleKeyframes} 7s infinite ease-in-out both`,
   ':hover': {
     opacity: 0.8,
+    color: color,
   },
+
+  vars: {
+    [color]: '#fef',
+    [angle]: fallbackVar(angle, '138deg'),
+  }
 });

fixtures/themed/src/styles.css.ts

@@ -64,7 +64,10 @@ globalStyle(`body ${iDunno}:after`, {
   content: "'I am content'",
 });
 
-const blankVar1 = createVar();
+const blankVar1 = createVar({
+  syntax: '<number>',
+  inherits: false,
+});
 const blankVar2 = createVar();
 
 export const opacity = styleVariants(

packages/babel-plugin-debug-ids/src/index.ts

@@ -31,7 +31,11 @@ const debuggableFunctionConfig = {
     maxParams: 2,
   },
   createVar: {
-    maxParams: 1,
+    maxParams: 2,
+    hasDebugId: ({ arguments: args }) => {
+      const previousArg = args[args.length - 1];
+      return t.isStringLiteral(previousArg) || t.isTemplateLiteral(previousArg);
+    },
   },
   recipe: {
     maxParams: 2,

packages/css/src/transformCss.test.ts

@@ -6,6 +6,11 @@ import { style } from './style';
 setFileScope('test');
 
 const testVar = createVar();
+const testPropertyVar = createVar({
+  syntax: '<angle>',
+  inherits: false,
+  initialValue: '0deg',
+}, 'test-property');
 const style1 = style({});
 const style2 = style({});
 
@@ -2022,7 +2027,7 @@ describe('transformCss', () => {
     `);
   });
 
-  it('should handle css vars', () => {
+  it('should handle simple css properties', () => {
     expect(
       transformCss({
         composedClassLists: [],
@@ -2075,6 +2080,60 @@ describe('transformCss', () => {
       }
     `);
   });
+
+  it('should handle complicated css properties', () => {
+    expect(
+      transformCss({
+        composedClassLists: [],
+        localClassNames: ['testClass'],
+        cssObjs: [
+          {
+            type: 'local',
+            selector: 'testClass',
+            rule: {
+              display: 'block',
+              vars: {
+                '--my-var': 'red',
+                [testPropertyVar]: '10deg',
+              },
+              selectors: {
+                '&:nth-child(3)': {
+                  vars: {
+                    '--my-var': 'orange',
+                    [testPropertyVar]: '20deg',
+                  },
+                },
+              },
+              '@media': {
+                'screen and (min-width: 700px)': {
+                  vars: {
+                    '--my-var': 'yellow',
+                    [testPropertyVar]: '50deg',
+                  },
+                },
+              },
+            },
+          },
+        ],
+      }).join('\n'),
+    ).toMatchInlineSnapshot(`
+      .testClass {
+        --my-var: red;
+        --test-property__skkcyc1: 10deg;
+        display: block;
+      }
+      .testClass:nth-child(3) {
+        --my-var: orange;
+        --test-property__skkcyc1: 20deg;
+      }
+      @media screen and (min-width: 700px) {
+        .testClass {
+          --my-var: yellow;
+          --test-property__skkcyc1: 50deg;
+        }
+      }
+    `);
+  });
 
   it('should cast property values to pixels when relevant', () => {
     expect(
@@ -2288,13 +2347,13 @@ describe('transformCss', () => {
         ],
       }).join('\n'),
     ).toMatchInlineSnapshot(`
-      .skkcyc2 .skkcyc1:before, .skkcyc2 .skkcyc1:after {
+      .skkcyc3 .skkcyc2:before, .skkcyc3 .skkcyc2:after {
         background: black;
       }
-      ._1g1ptzo1._1g1ptzo10 .skkcyc1 {
+      ._1g1ptzo1._1g1ptzo10 .skkcyc2 {
         background: blue;
       }
-      ._1g1ptzo10._1g1ptzo1 .skkcyc1 {
+      ._1g1ptzo10._1g1ptzo1 .skkcyc2 {
         background: blue;
       }
     `);

packages/css/src/transformCss.ts

@@ -13,6 +13,7 @@ import type {
   CSSSelectorBlock,
   Composition,
   WithQueries,
+  CSSPropertyBlock,
 } from './types';
 import { markCompositionUsed } from './adapter';
 import { forEach, omit, mapKeys } from './utils';
@@ -119,6 +120,7 @@ class Stylesheet {
   localClassNamesSearch: AhoCorasick;
   composedClassLists: Array<{ identifier: string; regex: RegExp }>;
   layers: Map<string, Array<string>>;
+  propertyRules: Array<CSSPropertyBlock>;
 
   constructor(
     localClassNames: Array<string>,
@@ -128,6 +130,7 @@ class Stylesheet {
     this.conditionalRulesets = [new ConditionalRuleset()];
     this.fontFaceRules = [];
     this.keyframesRules = [];
+    this.propertyRules = [];
     this.localClassNamesMap = new Map(
       localClassNames.map((localClassName) => [localClassName, localClassName]),
     );
@@ -150,10 +153,17 @@ class Stylesheet {
 
       return;
     }
+
+    if (root.type === 'property') {
+      this.propertyRules.push(root)
+
+      return;
+    }
+
     if (root.type === 'keyframes') {
       root.rule = Object.fromEntries(
         Object.entries(root.rule).map(([keyframe, rule]) => {
-          return [keyframe, this.transformProperties(rule)];
+          return [keyframe, this.transformVars(this.transformProperties(rule))];
         }),
       );
       this.keyframesRules.push(root);
@@ -573,6 +583,11 @@ class Stylesheet {
       css.push(renderCss({ '@font-face': fontFaceRule }));
     }
 
+    // Render property rules
+    for (const property of this.propertyRules) {
+      css.push(renderCss({ [`@property ${property.name}`]: property.rule }));
+    }
+
     // Render keyframes
     for (const keyframe of this.keyframesRules) {
       css.push(renderCss({ [`@keyframes ${keyframe.name}`]: keyframe.rule }));

packages/css/src/types.ts

@@ -23,7 +23,7 @@ export type CSSProperties = {
 };
 
 export interface CSSKeyframes {
-  [time: string]: CSSProperties;
+  [time: string]: CSSPropertiesWithVars;
 }
 
 export type CSSPropertiesWithVars = CSSProperties & {
@@ -103,12 +103,19 @@ export type CSSLayerDeclaration = {
   name: string;
 };
 
+export type CSSPropertyBlock = {
+  type: 'property';
+  name: string;
+  rule: AtRule.Property
+};
+
 export type CSS =
   | CSSStyleBlock
   | CSSFontFaceBlock
   | CSSKeyframesBlock
   | CSSSelectorBlock
-  | CSSLayerDeclaration;
+  | CSSLayerDeclaration
+  | CSSPropertyBlock;
 
 export type FileScope = {
   packageName?: string;
@@ -155,3 +162,22 @@ export type ThemeVars<ThemeContract extends NullableTokens> = MapLeafNodes<
 export type ClassNames = string | Array<ClassNames>;
 
 export type ComplexStyleRule = StyleRule | Array<StyleRule | ClassNames>;
+
+export type PropertySyntax = 
+    | '<length>'
+    | '<number>' 
+    | '<percentage>' 
+    | '<length-percentage>' 
+    | '<color>' 
+    | '<image>' 
+    | '<url>' 
+    | '<integer>' 
+    | '<angle>' 
+    | '<time>' 
+    | '<resolution>' 
+    | '<transform-function>' 
+    | '<custom-ident>' 
+    | '<transform-list>' 
+    | '*'
+    // needs this to make TS suggestions work
+    | (string & Record<never, never>);

packages/css/src/vars.ts

@@ -1,3 +1,5 @@
+import type { AtRule } from 'csstype';
+
 import {
   get,
   walkObject,
@@ -9,20 +11,58 @@ import cssesc from 'cssesc';
 
 import { Tokens, NullableTokens, ThemeVars } from './types';
 import { validateContract } from './validateContract';
+import { getFileScope } from './fileScope';
 import { generateIdentifier } from './identifier';
-
-export function createVar(debugId?: string): CSSVarFunction {
+import { PropertySyntax } from './types';
+import { appendCss } from './adapter';
+
+type VarDeclaration = {
+  syntax: PropertySyntax | Array<PropertySyntax>;
+  inherits: boolean;
+  initialValue?: string
+};
+
+const buildPropertyRule = ({ syntax, inherits, initialValue }: VarDeclaration): AtRule.Property => ({
+  syntax: `"${Array.isArray(syntax) ? syntax.join(' | ') : syntax}"`,
+  inherits: inherits ? 'true' : 'false',
+  ...(initialValue != null && { initialValue }),
+})
+
+export function createVar(declaration: VarDeclaration, debugId?: string): CSSVarFunction
+export function createVar(debugId?: string): CSSVarFunction
+export function createVar(debugIdOrDeclaration?: string | VarDeclaration, debugId?: string): CSSVarFunction {  
   const cssVarName = cssesc(
     generateIdentifier({
-      debugId,
+      debugId: typeof debugIdOrDeclaration === 'string' ? debugIdOrDeclaration : debugId,
       debugFileName: false,
     }),
     { isIdentifier: true },
   );
 
+  if (debugIdOrDeclaration && typeof debugIdOrDeclaration === 'object') {
+    appendCss({ type: 'property', name: `--${cssVarName}`, rule: buildPropertyRule(debugIdOrDeclaration) }, getFileScope());
+  }
+
   return `var(--${cssVarName})` as const;
 }
 
+export function createGlobalVar(name: string): CSSVarFunction
+export function createGlobalVar(name: string, declaration: VarDeclaration): CSSVarFunction
+export function createGlobalVar(name: string, declaration?: VarDeclaration): string {
+  if (declaration && typeof declaration === 'object') {
+    appendCss({ type: 'property', name: `--${name}`, rule: buildPropertyRule(declaration) }, getFileScope());
+  }
+
+
+  return `var(--${name})`;
+}
+
+export function assertVarName(value: unknown): asserts value is `var(--${string})` {
+  if (typeof value !== 'string' || !/^var\(--.*\)$/.test(value)) {
+    throw new Error(`Invalid variable name: ${value}`);
+  }
+}
+
 export function fallbackVar(
   ...values: [string, ...Array<string>]
 ): CSSVarFunction {
@@ -32,9 +72,7 @@ export function fallbackVar(
     if (finalValue === '') {
       finalValue = String(value);
     } else {
-      if (typeof value !== 'string' || !/^var\(--.*\)$/.test(value)) {
-        throw new Error(`Invalid variable name: ${value}`);
-      }
+      assertVarName(value)
 
       finalValue = value.replace(/\)$/, `, ${finalValue})`);
     }