feat: add has_declarations convenience property

Author: bartveneman

src/arena.ts

@@ -70,6 +70,7 @@ export const FLAG_HAS_ERROR = 1 << 1 // Syntax error
 export const FLAG_LENGTH_OVERFLOW = 1 << 2 // Node > 65k chars
 export const FLAG_HAS_BLOCK = 1 << 3 // Has { } block (for style rules and at-rules)
 export const FLAG_VENDOR_PREFIXED = 1 << 4 // Has vendor prefix (-webkit-, -moz-, -ms-, -o-)
+export const FLAG_HAS_DECLARATIONS = 1 << 5 // Has declarations (for style rules)
 
 export class CSSDataArena {
 	private buffer: ArrayBuffer

src/css-node.test.ts

@@ -336,4 +336,56 @@ describe('CSSNode', () => {
 			expect(keyframes.has_block).toBe(true)
 		})
 	})
+
+	describe('has_declarations', () => {
+		test('should return true for style rules with declarations', () => {
+			const source = 'body { color: red; margin: 0; }'
+			const parser = new Parser(source)
+			const root = parser.parse()
+			const rule = root.first_child!
+
+			expect(rule.type).toBe(NODE_STYLE_RULE)
+			expect(rule.has_declarations).toBe(true)
+		})
+
+		test('should return false for empty style rules', () => {
+			const source = 'body { }'
+			const parser = new Parser(source)
+			const root = parser.parse()
+			const rule = root.first_child!
+
+			expect(rule.type).toBe(NODE_STYLE_RULE)
+			expect(rule.has_declarations).toBe(false)
+		})
+
+		test('should return false for style rules with only nested rules', () => {
+			const source = 'body { .nested { color: red; } }'
+			const parser = new Parser(source)
+			const root = parser.parse()
+			const rule = root.first_child!
+
+			expect(rule.type).toBe(NODE_STYLE_RULE)
+			expect(rule.has_declarations).toBe(false)
+		})
+
+		test('should return true for style rules with both declarations and nested rules', () => {
+			const source = 'body { color: blue; .nested { margin: 0; } }'
+			const parser = new Parser(source)
+			const root = parser.parse()
+			const rule = root.first_child!
+
+			expect(rule.type).toBe(NODE_STYLE_RULE)
+			expect(rule.has_declarations).toBe(true)
+		})
+
+		test('should return false for at-rules', () => {
+			const source = '@media screen { body { color: red; } }'
+			const parser = new Parser(source)
+			const root = parser.parse()
+			const media = root.first_child!
+
+			expect(media.type).toBe(NODE_AT_RULE)
+			expect(media.has_declarations).toBe(false)
+		})
+	})
 })

src/css-node.ts

@@ -39,6 +39,7 @@ import {
 	FLAG_HAS_ERROR,
 	FLAG_HAS_BLOCK,
 	FLAG_VENDOR_PREFIXED,
+	FLAG_HAS_DECLARATIONS,
 } from './arena'
 
 // Node type constants (numeric for performance)
@@ -159,6 +160,11 @@ export class CSSNode {
 		return this.arena.has_flag(this.index, FLAG_HAS_BLOCK)
 	}
 
+	// Check if this style rule has declarations
+	get has_declarations(): boolean {
+		return this.arena.has_flag(this.index, FLAG_HAS_DECLARATIONS)
+	}
+
 	// --- Value Node Access (for declarations) ---
 
 	// Get array of parsed value nodes (for declarations only)

src/parser.ts

@@ -10,6 +10,7 @@ import {
 	FLAG_IMPORTANT,
 	FLAG_HAS_BLOCK,
 	FLAG_VENDOR_PREFIXED,
+	FLAG_HAS_DECLARATIONS,
 } from './arena'
 import { CSSNode } from './css-node'
 import { ValueParser } from './value-parser'
@@ -186,6 +187,7 @@ export class Parser {
 			// Try to parse as declaration first
 			let declaration = this.parse_declaration()
 			if (declaration !== null) {
+				this.arena.set_flag(style_rule, FLAG_HAS_DECLARATIONS)
 				this.arena.append_child(style_rule, declaration)
 				continue
 			}