Remove toObject option (use css-tree AST directly)

Work directly with css-tree's List objects instead of converting to plain arrays via toPlainObject(). This does not give significant performance improvements, but simplifies the code a bit.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: domenic

lib/CSSStyleDeclaration.js

@@ -127,14 +127,7 @@ class CSSStyleDeclaration {
     }
     try {
       this._updating = true;
-      const valueObj = parseCSS(
-        text,
-        {
-          context: "declarationList",
-          parseValue: false
-        },
-        true
-      );
+      const valueObj = parseCSS(text, { context: "declarationList", parseValue: false });
       if (valueObj?.children) {
         const properties = new Map();
         let shouldSkipNext = false;

lib/parsers.js

@@ -142,17 +142,9 @@ const hasCalcFunc = (val) => {
  *
  * @param {string} val - The CSS string to parse.
  * @param {object} opt - The options for parsing.
- * @param {boolean} [toObject=false] - Whether to return a plain object.
- * @returns {object} The AST or a plain object.
+ * @returns {object} The AST.
  */
-const parseCSS = (val, opt, toObject = false) => {
-  val = prepareValue(val);
-  const ast = cssTree.parse(val, opt);
-  if (toObject) {
-    return cssTree.toPlainObject(ast);
-  }
-  return ast;
-};
+const parseCSS = (val, opt) => cssTree.parse(prepareValue(val), opt);
 
 /**
  * Checks if the value is a valid property value.
@@ -212,13 +204,12 @@ const resolveCalc = (val, opt = { format: "specifiedValue" }) => {
   if (typeof cachedValue === "string") {
     return cachedValue;
   }
-  const obj = parseCSS(val, { context: "value" }, true);
-  if (!obj?.children) {
+  const ast = parseCSS(val, { context: "value" });
+  if (!ast?.children) {
     return;
   }
-  const { children: items } = obj;
   const values = [];
-  for (const item of items) {
+  for (const item of ast.children) {
     const { type: itemType, name: itemName, value: itemValue } = item;
     if (itemType === AST_TYPES.FUNCTION) {
       const value = cssTree
@@ -301,8 +292,8 @@ const parsePropertyValue = (prop, val, opt = {}) => {
       if (error || !matched) {
         parsedValue = false;
       } else {
-        const obj = cssTree.toPlainObject(ast);
-        const items = obj.children;
+        const items = ast.children;
+        const itemCount = items.size;
         const values = [];
         for (const item of items) {
           const { children, name, type, value, unit } = item;
@@ -320,12 +311,12 @@ const parsePropertyValue = (prop, val, opt = {}) => {
                 .generate(item)
                 .replace(/\)(?!\)|\s|,)/g, ") ")
                 .trim();
-              const raw = items.length === 1 ? val : css;
+              const raw = itemCount === 1 ? val : css;
               // Remove "${name}(" from the start and ")" from the end
               const itemValue = raw.slice(name.length + 1, -1).trim();
               if (name === "calc") {
-                if (children.length === 1) {
-                  const [child] = children;
+                if (children.size === 1) {
+                  const child = children.first;
                   if (child.type === AST_TYPES.NUMBER) {
                     values.push({
                       type: AST_TYPES.CALC,

lib/properties/clip.js

@@ -24,7 +24,7 @@ module.exports.parse = (v, opt = {}) => {
         });
         const parsedValues = [];
         for (const item of values) {
-          const parsedValue = parsers.parseCSS(item, { context: "value" }, true);
+          const parsedValue = parsers.parseCSS(item, { context: "value" });
           const val = parsers.resolveNumericValue(parsedValue.children, {
             type: "length"
           });

test/parsers.test.js

@@ -1209,7 +1209,7 @@ describe("parseCSS", () => {
       context: "declarationList",
       parseValue: false
     };
-    const output = parsers.parseCSS(input, opt, true);
+    const output = parsers.parseCSS(input, opt);
     const [
       {
         important,